[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: cloud-init (Ubuntu Eoan)
   Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  Won't Fix
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  Confirmed
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Released
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions


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Mailing list: 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dan Watkins]

I'm trying to understand if there is any work still required on this bug
for cloud-init.  I've tested two network configurations (in lxd
containers).  The first:

  version: 2
  ethernets:
eth0:
  dhcp4: true
  dhcp6: true
  ipv6-mtu: 1337

As this is just a passthrough to netplan, this works as expected:
/proc/sys/net/ipv6/conf/eth0/mtu is 1337, /sys/class/net/eth0/mtu is
1500.

The second:

  version: 1
  config:
  - type: physical
name: eth0
mtu: 1337
subnets:
- type: dhcp
- type: dhcp6

Given that we don't have a separate setting for the IPv6-specific MTU,
this seems to work as I expect: both /proc/sys/net/ipv6/conf/eth0/mtu
and /sys/class/net/eth0/mtu are set to 1337.  I'm not sure, however,
that this is a sufficient test, or if my expectations are correct.

Thoughts, anyone?

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  Won't Fix
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Released
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

** Merge proposal linked:
   https://code.launchpad.net/~paride/curtin/+git/curtin/+merge/387218

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  Won't Fix
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Released
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions

-- 
Mailing list: https://launchpad.net/~touch-packages
Post to : touch-packages@lists.launchpad.net

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Steve Langasek]

** Changed in: cloud-init (Ubuntu Disco)
   Status: New => Won't Fix

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  Won't Fix
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Released
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions

-- 
Mailing list: https://launchpad.net/~touch-packages
Post to : touch-packages@lists.launchpad.net
Unsubscribe : 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

This bug was fixed in the package systemd - 237-3ubuntu10.39

---
systemd (237-3ubuntu10.39) bionic; urgency=medium

  [ Dariusz Gadomski ]
  * 
d/p/lp1762391/0001-Call-getgroups-to-know-size-of-supplementary-groups-.patch,
d/p/lp1762391/0002-user-util-tweak-to-in_gid.patch,

d/p/lp1762391/0003-user-util-Add-helper-functions-for-gid-lists-operati.patch,
d/p/lp1762391/0004-execute-Restore-call-to-pam_setcred.patch,

d/p/lp1762391/0005-execute-Detect-groups-added-by-PAM-and-merge-them-wi.patch,
d/p/lp1762391/0006-test-Add-tests-for-gid-list-ops.patch,

d/p/lp1762391/0007-execute-add-const-to-array-parameters-where-possible.patch,
d/p/lp1762391/0008-execute-allow-pam_setcred-to-fail-ignore-errors.patch:
- Restore call to pam_setcred (LP: #1762391)

  [ Ioanna Alifieraki ]
  * d/p/lp1860548/0001-Revert-Replace-use-of-snprintf-with-xsprintf.patch,
d/p/lp1860548/0002-job-truncate-unit-description.patch:
- use snprintf instead of xsprintf (LP: #1860548)

  [ Dan Streetman ]
  * d/p/lp1833193-network-update-address-when-static-address-was-alrea.patch:
- Update lft when static addr was cfg by dhcp (LP: #1833193)
  * 
d/p/lp1849261/0001-core-when-we-can-t-enqueue-OnFailure-job-show-full-e.patch,

d/p/lp1849261/0002-core-don-t-trigger-OnFailure-deps-when-a-unit-is-goi.patch:
- Only trigger OnFailure= if Restart= is not in effect (LP: #1849261)
  * d/p/lp1671951-network-set-ipv6-mtu-after-link-up-or-device-mtu-cha.patch:
- set ipv6 mtu at correct time (LP: #1671951)
  * d/p/lp1845909/0001-networkd-honour-LinkLocalAddressing.patch,
d/p/lp1845909/0002-networkd-fix-link_up-12505.patch,
d/p/lp1845909/0003-network-do-not-send-ipv6-token-to-kernel.patch,

d/p/lp1845909/0004-network-rename-linux_configure_after_setting_mtu-to-linux.patch,
d/p/lp1845909/0005-network-add-link-setting_genmode-flag.patch,

d/p/lp1845909/0006-network-if-ipv6ll-is-disabled-enumerate-tentative-ipv6-ad.patch,

d/p/lp1845909/0007-network-drop-foreign-config-after-addr_gen_mode-has-been-.patch,

d/p/lp1845909/0008-network-drop-IPv6LL-address-when-LinkLocalAddressing.patch:
- if LinkLocalAddressing=no prevent creation of ipv6ll (LP: #1845909)
  * d/p/lp1859862-network-Do-not-disable-IPv6-by-writing-to-sysctl.patch:
- enable ipv6 when needed (LP: #1859862)
  * d/p/lp1836695-networkd-Add-back-static-routes-after-DHCPv4-lease-e.patch:
- (re)add static routes after getting dhcp4 addr (LP: #1836695)
  * d/t/storage:
- fix buggy test (LP: #1831459)
- without scsi_debug, skip test (LP: #1847816)

 -- Dan Streetman   Thu, 06 Feb 2020 10:00:49
-0500

** Changed in: systemd (Ubuntu Bionic)
   Status: Fix Committed => Fix Released

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Released
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

This bug was fixed in the package systemd - 242-7ubuntu3.7

---
systemd (242-7ubuntu3.7) eoan; urgency=medium

  [ Dariusz Gadomski ]
  * 
d/p/lp1762391/0001-Call-getgroups-to-know-size-of-supplementary-groups-.patch,
d/p/lp1762391/0002-user-util-tweak-to-in_gid.patch,

d/p/lp1762391/0003-user-util-Add-helper-functions-for-gid-lists-operati.patch,
d/p/lp1762391/0004-execute-Restore-call-to-pam_setcred.patch,

d/p/lp1762391/0005-execute-Detect-groups-added-by-PAM-and-merge-them-wi.patch,
d/p/lp1762391/0006-test-Add-tests-for-gid-list-ops.patch,

d/p/lp1762391/0007-execute-add-const-to-array-parameters-where-possible.patch,
d/p/lp1762391/0008-execute-allow-pam_setcred-to-fail-ignore-errors.patch:
- Restore call to pam_setcred (LP: #1762391)

  * d/p/lp1846232/0001-network-honor-MTUBytes-setting.patch,

d/p/lp1846232/0002-network-bump-MTU-bytes-only-when-MTUByte-is-not-set.patch:
- do not always bump MTU with additional 4bytes (LP: #1846232)
  * d/p/lp1671951-network-set-ipv6-mtu-after-link-up-or-device-mtu-cha.patch:
- set ipv6 mtu at correct time (LP: #1671951)
  * 
d/p/lp1845909/0001-network-rename-linux_configure_after_setting_mtu-to-linux.patch,
d/p/lp1845909/0002-network-add-link-setting_genmode-flag.patch,

d/p/lp1845909/0003-network-if-ipv6ll-is-disabled-enumerate-tentative-ipv6-ad.patch,

d/p/lp1845909/0004-network-drop-foreign-config-after-addr_gen_mode-has-been-.patch,

d/p/lp1845909/0005-network-drop-IPv6LL-address-when-LinkLocalAddressing.patch:
- drop foreign config and raise interface after setting genmode
  (LP: #1845909)
  * d/t/storage: without scsi_debug, skip test (LP: #1847816)

 -- Dan Streetman   Thu, 06 Feb 2020 09:45:57
-0500

** Changed in: systemd (Ubuntu Eoan)
   Status: Fix Committed => Fix Released

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Released
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dan Streetman]

** Tags removed: verification-needed verification-needed-bionic 
verification-needed-eoan
** Tags added: verification-done verification-done-bionic verification-done-eoan

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Committed
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions

-- 
Mailing list: 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

Verified Eoan systemd 242-7ubuntu3.7 correctly sets IPv6 MTU
Verified Bionic systemd 237-3ubuntu10.39 correctly sets IPv6 MTU

** Attachment added: "curtin vmtest logs for ipv6 mtu verification"
   
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+attachment/5326389/+files/bug-1671951-curtin-vmtest-verification-v2.tar.gz

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Committed
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Steve Langasek]

Hello Ryan, or anyone else affected,

Accepted systemd into eoan-proposed. The package will build now and be
available at https://launchpad.net/ubuntu/+source/systemd/242-7ubuntu3.7
in a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-eoan to verification-done-eoan. If it does not fix
the bug for you, please add a comment stating that, and change the tag
to verification-failed-eoan. In either case, without details of your
testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: systemd (Ubuntu Eoan)
   Status: In Progress => Fix Committed

** Changed in: systemd (Ubuntu Bionic)
   Status: Fix Released => Fix Committed

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Committed
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

This SRU needs to be reuploaded, due to security update that trumped
this in progress SRU.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  In Progress
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions

-- 
Mailing list: https://launchpad.net/~touch-packages
Post to : touch-packages@lists.launchpad.net
Unsubscribe : 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

This SRU needs to be reuploaded, due to security update that trumped
this in progress SRU.

** Changed in: systemd (Ubuntu Eoan)
   Status: Fix Committed => In Progress

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  In Progress
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions

-- 
Mailing list: 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

This bug was fixed in the package systemd - 237-3ubuntu10.38

---
systemd (237-3ubuntu10.38) bionic-security; urgency=medium

  * SECURITY UPDATE: local privilege escalation via DynamicUser
- debian/patches/CVE-2019-384x-1.patch: introduce
  seccomp_restrict_suid_sgid() for blocking chmod() for suid/sgid files
  in src/shared/seccomp-util.c, src/shared/seccomp-util.h.
- debian/patches/CVE-2019-384x-2.patch: add test case for
  restrict_suid_sgid() in src/test/test-seccomp.c.
- debian/patches/CVE-2019-384x-3.patch: expose SUID/SGID restriction as
  new unit setting RestrictSUIDSGID= in src/core/dbus-execute.c,
  src/core/execute.c, src/core/execute.h,
  src/core/load-fragment-gperf.gperf.m4, src/shared/bus-unit-util.c.
- debian/patches/CVE-2019-384x-4.patch: document the new
  RestrictSUIDSGID= setting in man/systemd.exec.xml.
- debian/patches/CVE-2019-384x-5.patch: turn on RestrictSUIDSGID= in
  most of our long-running daemons in units/systemd-*.service.in.
- debian/patches/CVE-2019-384x-6.patch: imply NNP and SUID/SGID
  restriction for DynamicUser=yes service in man/systemd.exec.xml,
  src/core/unit.c.
- debian/patches/CVE-2019-384x-7.patch: fix compilation on arm64 in
  src/test/test-seccomp.c.
- CVE-2019-3843
- CVE-2019-3844
  * SECURITY UPDATE: memory leak in button_open
- debian/patches/CVE-2019-20386.patch: fix event in
  src/login/logind-button.c.
- CVE-2019-20386
  * SECURITY UPDATE: heap use-after-free with async polkit queries
- debian/patches/CVE-2020-1712-1.patch: on async pk requests,
  re-validate action/details in src/shared/bus-util.c.
- debian/patches/CVE-2020-1712-2.patch: introduce API for re-enqueuing
  incoming messages in src/libsystemd/libsystemd.sym,
  src/libsystemd/sd-bus/sd-bus.c, src/systemd/sd-bus.h.
- debian/patches/CVE-2020-1712-3.patch: when authorizing via PK
  re-resolve callback/userdata instead of caching it in
  src/shared/bus-util.c.
- debian/patches/CVE-2020-1712-4.patch: fix typo in function name in
  src/libsystemd/libsystemd.sym, src/libsystemd/sd-bus/sd-bus.c,
  src/systemd/sd-bus.h, src/shared/bus-util.c.
- debian/libsystemd0.symbols: added new symbols.
- CVE-2020-1712
  * This package does _not_ contain the changes from 237-3ubuntu10.34 in
bionic-proposed.

 -- Marc Deslauriers   Tue, 04 Feb 2020
20:07:56 -0500

** Changed in: systemd (Ubuntu Bionic)
   Status: Fix Committed => Fix Released

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2019-20386

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2019-3843

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2019-3844

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-1712

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Committed
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

Curtin vmtest verification for bionic using systemd from -proposed has
run successfully.


(neipa) ipv6_mtu % egrep "237-3ubuntu10.34" 
output/BionicTestNetworkMtu/logs/install-serial.log
[  126.923480] cloud-init[1176]: Get:10 http://archive.ubuntu.com/ubuntu 
bionic-proposed/main amd64 libsystemd0 amd64 237-3ubuntu10.34 [206 kB]
[  126.999639] cloud-init[1176]: Get:11 http://archive.ubuntu.com/ubuntu 
bionic-proposed/main amd64 libnss-systemd amd64 237-3ubuntu10.34 [104 kB]
[  127.012854] cloud-init[1176]: Get:12 http://archive.ubuntu.com/ubuntu 
bionic-proposed/main amd64 libpam-systemd amd64 237-3ubuntu10.34 [107 kB]
[  127.018126] cloud-init[1176]: Get:13 http://archive.ubuntu.com/ubuntu 
bionic-proposed/main amd64 systemd amd64 237-3ubuntu10.34 [2910 kB]
[  127.112992] cloud-init[1176]: Get:14 http://archive.ubuntu.com/ubuntu 
bionic-proposed/main amd64 udev amd64 237-3ubuntu10.34 [1101 kB]
[  127.230646] cloud-init[1176]: Get:15 http://archive.ubuntu.com/ubuntu 
bionic-proposed/main amd64 libudev1 amd64 237-3ubuntu10.34 [55.4 kB]
[  127.237607] cloud-init[1176]: Get:16 http://archive.ubuntu.com/ubuntu 
bionic-proposed/main amd64 systemd-sysv amd64 237-3ubuntu10.34 [13.2 kB]
[  130.615970] cloud-init[1176]: Preparing to unpack 
.../libsystemd0_237-3ubuntu10.34_amd64.deb ...
[  130.619809] cloud-init[1176]: Unpacking libsystemd0:amd64 (237-3ubuntu10.34) 
over (237-3ubuntu10.33) ...
[  130.671345] cloud-init[1176]: Setting up libsystemd0:amd64 
(237-3ubuntu10.34) ...
[  130.734901] cloud-init[1176]: Preparing to unpack 
.../libnss-systemd_237-3ubuntu10.34_amd64.deb ...
[  130.738718] cloud-init[1176]: Unpacking libnss-systemd:amd64 
(237-3ubuntu10.34) over (237-3ubuntu10.33) ...
[  130.775590] cloud-init[1176]: Preparing to unpack 
.../libpam-systemd_237-3ubuntu10.34_amd64.deb ...
[  130.780829] cloud-init[1176]: Unpacking libpam-systemd:amd64 
(237-3ubuntu10.34) over (237-3ubuntu10.33) ...
[  130.817036] cloud-init[1176]: Preparing to unpack 
.../systemd_237-3ubuntu10.34_amd64.deb ...
[  130.938621] cloud-init[1176]: Unpacking systemd (237-3ubuntu10.34) over 
(237-3ubuntu10.33) ...
[  131.534337] cloud-init[1176]: Preparing to unpack 
.../udev_237-3ubuntu10.34_amd64.deb ...
[  131.631496] cloud-init[1176]: Unpacking udev (237-3ubuntu10.34) over 
(237-3ubuntu10.33) ...
[  131.877032] cloud-init[1176]: Preparing to unpack 
.../libudev1_237-3ubuntu10.34_amd64.deb ...
[  131.880841] cloud-init[1176]: Unpacking libudev1:amd64 (237-3ubuntu10.34) 
over (237-3ubuntu10.33) ...
[  131.921311] cloud-init[1176]: Setting up libudev1:amd64 (237-3ubuntu10.34) 
...
[  131.923955] cloud-init[1176]: Setting up systemd (237-3ubuntu10.34) ...
[  132.376367] cloud-init[1176]: Preparing to unpack 
.../systemd-sysv_237-3ubuntu10.34_amd64.deb ...
[  132.379899] cloud-init[1176]: Unpacking systemd-sysv (237-3ubuntu10.34) over 
(237-3ubuntu10.33) ...
[  135.341098] cloud-init[1176]: Setting up libnss-systemd:amd64 
(237-3ubuntu10.34) ...
[  135.355290] cloud-init[1176]: Setting up systemd-sysv (237-3ubuntu10.34) ...
[  135.897825] cloud-init[1176]: Setting up udev (237-3ubuntu10.34) ...
[  136.901473] cloud-init[1176]: Setting up libpam-systemd:amd64 
(237-3ubuntu10.34) ...
[  141.343998] cloud-init[1176]: Processing triggers for systemd 
(237-3ubuntu10.34) ...
[  181.788269] cloud-init[1176]: systemd is already the newest version 
(237-3ubuntu10.34).
(neipa) ipv6_mtu % cat 
output/BionicTestNetworkMtu/collect/etc_netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource.  Changes
# to it will not persist across an instance reboot.  To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
interface0:
addresses:
- 192.168.1.2/24
- 2001:4800:78ff:1b:be76:4eff:fe06:1000/64
ipv6-mtu: 1501
match:
macaddress: '52:54:00:12:34:00'
mtu: 1601
set-name: interface0
interface1:
addresses:
- 192.168.2.2/24
- 2001:4800:78ff:1b:be76:4eff:fe06:2000/64
ipv6-mtu: 1501
match:
macaddress: '52:54:00:12:34:02'
mtu: 1501
set-name: interface1
interface2:
dhcp4: true
match:
macaddress: '52:54:00:12:34:04'
set-name: interface2
interface4:
addresses:
- 2001:4800:78ff:1b:be76:4eff:fe06:5000/64
- 192.168.5.2/24
ipv6-mtu: 8900
match:
macaddress: '52:54:00:12:34:08'
mtu: 9000
set-name: interface4
interface5:
addresses:
- 2001:4800:78ff:1b:be76:4eff:fe06:6000/64
- 192.168.6.2/24
ipv6-mtu: 1480
match:

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

Curtin vmtest verification for eoan using systemd from -proposed has run
successfully.

(neipa) ipv6_mtu % egrep "242-7ubuntu3.3" 
output/EoanTestNetworkMtu/logs/install-serial.log
[  136.520219] cloud-init[765]: Get:12 http://archive.ubuntu.com/ubuntu 
eoan-proposed/main amd64 libnss-systemd amd64 242-7ubuntu3.3 [126 kB]
[  136.527400] cloud-init[765]: Get:13 http://archive.ubuntu.com/ubuntu 
eoan-proposed/main amd64 udev amd64 242-7ubuntu3.3 [1202 kB]
[  136.693312] cloud-init[765]: Get:14 http://archive.ubuntu.com/ubuntu 
eoan-proposed/main amd64 libudev1 amd64 242-7ubuntu3.3 [76.9 kB]
[  136.701002] cloud-init[765]: Get:15 http://archive.ubuntu.com/ubuntu 
eoan-proposed/main amd64 systemd-sysv amd64 242-7ubuntu3.3 [9360 B]
[  136.722467] cloud-init[765]: Get:17 http://archive.ubuntu.com/ubuntu 
eoan-proposed/main amd64 libpam-systemd amd64 242-7ubuntu3.3 [130 kB]
[  136.743657] cloud-init[765]: Get:19 http://archive.ubuntu.com/ubuntu 
eoan-proposed/main amd64 systemd amd64 242-7ubuntu3.3 [3440 kB]
[  137.138458] cloud-init[765]: Get:20 http://archive.ubuntu.com/ubuntu 
eoan-proposed/main amd64 libsystemd0 amd64 242-7ubuntu3.3 [262 kB]
[  142.884502] cloud-init[765]: Preparing to unpack 
.../libnss-systemd_242-7ubuntu3.3_amd64.deb ...
[  142.887869] cloud-init[765]: Unpacking libnss-systemd:amd64 (242-7ubuntu3.3) 
over (242-7ubuntu3.2) ...
[  142.924747] cloud-init[765]: Preparing to unpack 
.../udev_242-7ubuntu3.3_amd64.deb ...
[  142.962745] cloud-init[765]: Unpacking udev (242-7ubuntu3.3) over 
(242-7ubuntu3.2) ...
[  143.165029] cloud-init[765]: Preparing to unpack 
.../libudev1_242-7ubuntu3.3_amd64.deb ...
[  143.168604] cloud-init[765]: Unpacking libudev1:amd64 (242-7ubuntu3.3) over 
(242-7ubuntu3.2) ...
[  143.206268] cloud-init[765]: Setting up libudev1:amd64 (242-7ubuntu3.3) ...
[  143.272647] cloud-init[765]: Preparing to unpack 
.../systemd-sysv_242-7ubuntu3.3_amd64.deb ...
[  143.275554] cloud-init[765]: Unpacking systemd-sysv (242-7ubuntu3.3) over 
(242-7ubuntu3.2) ...
[  143.594537] cloud-init[765]: Preparing to unpack 
.../libpam-systemd_242-7ubuntu3.3_amd64.deb ...
[  143.599803] cloud-init[765]: Unpacking libpam-systemd:amd64 (242-7ubuntu3.3) 
over (242-7ubuntu3.2) ...
[  143.680250] cloud-init[765]: Preparing to unpack 
.../systemd_242-7ubuntu3.3_amd64.deb ...
[  143.785319] cloud-init[765]: Unpacking systemd (242-7ubuntu3.3) over 
(242-7ubuntu3.2) ...
[  144.362457] cloud-init[765]: Preparing to unpack 
.../libsystemd0_242-7ubuntu3.3_amd64.deb ...
[  144.366022] cloud-init[765]: Unpacking libsystemd0:amd64 (242-7ubuntu3.3) 
over (242-7ubuntu3.2) ...
[  144.423950] cloud-init[765]: Setting up libsystemd0:amd64 (242-7ubuntu3.3) 
...
[  149.340746] cloud-init[765]: Setting up udev (242-7ubuntu3.3) ...
[  152.700118] cloud-init[765]: Setting up systemd (242-7ubuntu3.3) ...
[  154.478301] cloud-init[765]: Setting up systemd-sysv (242-7ubuntu3.3) ...
[  154.481899] cloud-init[765]: Setting up libnss-systemd:amd64 
(242-7ubuntu3.3) ...
[  154.485400] cloud-init[765]: Setting up libpam-systemd:amd64 
(242-7ubuntu3.3) ...
[  198.012728] cloud-init[765]: systemd is already the newest version 
(242-7ubuntu3.3).
(neipa) ipv6_mtu % cat 
output/EoanTestNetworkMtu/collect/etc_netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource.  Changes
# to it will not persist across an instance reboot.  To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
interface0:
addresses:
- 192.168.1.2/24
- 2001:4800:78ff:1b:be76:4eff:fe06:1000/64
ipv6-mtu: 1501
match:
macaddress: '52:54:00:12:34:00'
mtu: 1601
set-name: interface0
interface1:
addresses:
- 192.168.2.2/24
- 2001:4800:78ff:1b:be76:4eff:fe06:2000/64
ipv6-mtu: 1501
match:
macaddress: '52:54:00:12:34:02'
mtu: 1501
set-name: interface1
interface2:
dhcp4: true
match:
macaddress: '52:54:00:12:34:04'
set-name: interface2
interface4:
addresses:
- 2001:4800:78ff:1b:be76:4eff:fe06:5000/64
- 192.168.5.2/24
ipv6-mtu: 8900
match:
macaddress: '52:54:00:12:34:08'
mtu: 9000
set-name: interface4
interface5:
addresses:
- 2001:4800:78ff:1b:be76:4eff:fe06:6000/64
- 192.168.6.2/24
ipv6-mtu: 1480
match:
macaddress: 52:54:00:12:34:0c
mtu: 1480
set-name: interface5
(neipa) ipv6_mtu % grep . output/EoanTestNetworkMtu/collect/interface0_*
output/EoanTestNetworkMtu/collect/interface0_dev_mtu:1601

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

** Attachment added: "curtin vmtest logs for ipv6 mtu verification"
   
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+attachment/5325665/+files/bug-1671951-curtin-vmtest-verification.tar.gz

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Committed
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Steve Langasek]

Hello Ryan, or anyone else affected,

Accepted systemd into bionic-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/systemd/237-3ubuntu10.34 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-bionic to verification-done-bionic. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-bionic. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: systemd (Ubuntu Bionic)
   Status: In Progress => Fix Committed

** Tags removed: verification-done-bionic
** Tags added: verification-needed-bionic

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Committed
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Steve Langasek]

Hello Ryan, or anyone else affected,

Accepted systemd into eoan-proposed. The package will build now and be
available at https://launchpad.net/ubuntu/+source/systemd/242-7ubuntu3.3
in a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-eoan to verification-done-eoan. If it does not fix
the bug for you, please add a comment stating that, and change the tag
to verification-failed-eoan. In either case, without details of your
testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: systemd (Ubuntu Eoan)
   Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-eoan

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  In Progress
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  Fix Committed
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  Fix Released

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

This bug was fixed in the package systemd - 244.1-0ubuntu2

---
systemd (244.1-0ubuntu2) focal; urgency=medium

  [ Dimitri John Ledkov ]
  * shutdown: do not detach autoclear loopback devices
Author: Dimitri John Ledkov
File: debian/patches/shutdown-do-not-detach-autoclear-loopback-devices.patch

https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=3978d34b59e98cdd01836c41a10442967636b8fc

  [ Balint Reczey ]
  * Revert upstream commit breaking IPv4 DHCP in LXC containers in 244.1
(LP: #1857123)
File: 
debian/patches/Revert-network-if-sys-is-rw-then-udev-should-be-around.patch

https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=39c12f8e736afd1b7bdeb13ff6bccaea85020873

systemd (244.1-0ubuntu1) focal; urgency=medium

  * New upstream version 244.1
- network: set ipv6 mtu after link-up or device mtu change (LP: #1671951)
- & other changes
  * Refresh patches.
- Dropped changes:
  * d/p/lp-1853852-*: fix issues with muliplexed shmat calls (LP: #1853852)
Files:
- debian/patches/lp-1853852-seccomp-fix-multiplexed-system-calls.patch
- 
debian/patches/lp-1853852-seccomp-mmap-test-results-depend-on-kernel-libseccom.patch

https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=382271662c60c339b0a404c7a1772fe5670516ef
  * 
d/p/lp1671951-network-set-ipv6-mtu-after-link-up-or-device-mtu-cha.patch:
set ipv6 mtu at correct time
  * pstore: Don't start systemd-pstore.service in containers.
Usually it is not useful and can also fail making
boot-and-services autopkgtest fail. (LP: #1856729)
File: 
debian/patches/pstore-Don-t-start-systemd-pstore.service-in-containers.patch

https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=28b5a03769cbed9d3170ebac38508b867530a2d6
  * Revert: network: do not drop foreign config if interface is in initialized 
state.
This fixes FTBFS with the other network-related reverts.
File: 
debian/patches/Revert-network-do-not-drop-foreign-config-if-interface-is.patch

https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/commit/?id=22a9fa3bb03ba2a629926af39ea7df81fe33c9b8

systemd (244-3ubuntu5) focal; urgency=medium

  [ Dariusz Gadomski ]
  * 
d/p/lp1762391/0001-user-util-Add-helper-functions-for-gid-lists-operati.patch,
d/p/lp1762391/0002-execute-Restore-call-to-pam_setcred.patch,

d/p/lp1762391/0003-execute-Detect-groups-added-by-PAM-and-merge-them-wi.patch,
d/p/lp1762391/0004-test-Add-tests-for-gid-list-ops.patch,

d/p/lp1762391/0005-execute-add-const-to-array-parameters-where-possible.patch,
d/p/lp1762391/0006-execute-allow-pam_setcred-to-fail-ignore-errors.patch:
- Restore call to pam_setcred (LP: #1762391)

  [ Dan Streetman ]
  * d/t/storage: without scsi_debug, skip test (LP: #1847816)

systemd (244-3ubuntu4) focal; urgency=medium

  * d/p/lp1671951-network-set-ipv6-mtu-after-link-up-or-device-mtu-cha.patch:
set ipv6 mtu at correct time (LP: #1671951)
  * d/p/0001-network-rename-linux_configure_after_setting_mtu-to-linux.patch,
d/p/0002-network-add-link-setting_genmode-flag.patch,
d/p/0003-network-if-ipv6ll-is-disabled-enumerate-tentative-ipv6-ad.patch,
d/p/0004-network-drop-foreign-config-after-addr_gen_mode-has-been-.patch:
- drop foreign config and raise interface after setting genmode
  (LP: #1845909)

systemd (244-3ubuntu3) focal; urgency=medium

  * shutdown: cherry-pick PR#14409 to fix detach of loopback devices
for Ubuntu Core 20
File: debian/patches/shutdown-modernizations-pr-14409.patch
https://github.com/systemd/systemd/pull/14409.diff

systemd (244-3ubuntu2) focal; urgency=medium

  * d/p/debian/UBUNTU-Support-system-image-read-only-etc.patch:
- re-add missing bits for timedated.c (LP: #1778936)

 -- Balint Reczey   Wed, 22 Jan 2020 16:27:49 +0100

** Changed in: systemd (Ubuntu Focal)
   Status: In Progress => Fix Released

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  In Progress
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  In Progress
Status in cloud-init source package in 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dan Streetman]

as disco is EOL next week, marking this won't fix for disco.

** Changed in: systemd (Ubuntu Disco)
   Status: In Progress => Won't Fix

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  In Progress
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  In Progress
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Won't Fix
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  In Progress
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  In Progress

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions

-- 
Mailing list: https://launchpad.net/~touch-packages
Post to : 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

** Merge proposal linked:
   
https://code.launchpad.net/~ddstreet/ubuntu/+source/systemd/+git/systemd/+merge/376801

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  In Progress
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  In Progress
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  In Progress
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  In Progress
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  In Progress

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dan Streetman]

** Also affects: cloud-init (Ubuntu Focal)
   Importance: Undecided
   Status: Confirmed

** Also affects: systemd (Ubuntu Focal)
   Importance: Medium
   Status: Fix Released

** Also affects: netplan.io (Ubuntu Focal)
   Importance: Undecided
   Status: Fix Released

** Also affects: cloud-init (Ubuntu Eoan)
   Importance: Undecided
   Status: New

** Also affects: systemd (Ubuntu Eoan)
   Importance: Undecided
   Status: New

** Also affects: netplan.io (Ubuntu Eoan)
   Importance: Undecided
   Status: New

** Bug watch added: github.com/systemd/systemd/issues #13914
   https://github.com/systemd/systemd/issues/13914

** Also affects: systemd via
   https://github.com/systemd/systemd/issues/13914
   Importance: Unknown
   Status: Unknown

** Changed in: systemd (Ubuntu Focal)
   Status: Fix Released => In Progress

** Changed in: systemd (Ubuntu Focal)
 Assignee: (unassigned) => Dan Streetman (ddstreet)

** Changed in: systemd (Ubuntu Eoan)
   Status: New => In Progress

** Changed in: systemd (Ubuntu Eoan)
 Assignee: (unassigned) => Dan Streetman (ddstreet)

** Changed in: systemd (Ubuntu Disco)
   Status: Triaged => In Progress

** Changed in: systemd (Ubuntu Disco)
 Assignee: (unassigned) => Dan Streetman (ddstreet)

** Changed in: systemd (Ubuntu Bionic)
   Status: Triaged => In Progress

** Changed in: systemd (Ubuntu Bionic)
 Assignee: Balint Reczey (rbalint) => Dan Streetman (ddstreet)

** Changed in: netplan.io (Ubuntu Eoan)
   Status: New => Fix Released

** Tags added: bionic ddstreet disco eoan focal systemd

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd:
  Unknown
Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  In Progress
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  In Progress
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  In Progress
Status in cloud-init source package in Eoan:
  New
Status in netplan.io source package in Eoan:
  Fix Released
Status in systemd source package in Eoan:
  In Progress
Status in cloud-init source package in Focal:
  Confirmed
Status in netplan.io source package in Focal:
  Fix Released
Status in systemd source package in Focal:
  In Progress

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dan Streetman]

I opened this upstream
https://github.com/systemd/systemd/pull/13915

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

Testing with @ddstreet's systemd ppa, I can confirm that bionic, disco
and eoan correctly set MTU on first boot, no systemd-restart needed.

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Balint Reczey]

@ddstreet You systemd builds in the PPA fix the issue for me on Bionic
and Disco, IPv6 MTU is applied after reboot with the configuration.

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Balint Reczey]

I have not tested first boot, @raharper could you please test that?

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Balint Reczey]

In my test I modified a multipass launched VM's netplan config to:

multipass@safe-hornet:~$ cat /etc/netplan/50-cloud-init.yaml 
# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
ethernets:
ens3:
dhcp4: true
mtu: 1496
match:
macaddress: 52:54:00:4c:5b:ac
set-name: ens3
dhcp4-overrides:
use-mtu: false
dhcp6-overrides:
use-mtu: false
ipv6-mtu: 1284
version: 2


Also disabled cloud-init overwriting it:

multipass@safe-hornet:~$ cat 
/etc/cloud/cloud.cfg.d/99-disable-network-config.cfg 
network: {config: disabled}

IPv6 MTU is properly set on Eoan after reboot:

multipass@safe-hornet:~$ sysctl net.ipv6.conf.ens3.mtu
net.ipv6.conf.ens3.mtu = 1284

... but not on Disco or Bionic. To be continued...

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dan Streetman]

> cloud-init is not doing anything special here, we render the config
and call netplan generate

Sorry, yes I meant that netplan should be putting the MTUBytes inside
the .network and not using a .link file.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

@Dan,

Ill try the ppa and report back.

cloud-init is not doing anything special here, we render the config and call 
netplan generate.
If we take cloud-init out of the picture, and just have a file in /etc/netplan 
it will still fail due to the udev issue you specify. Shouldn't netplan itself 
handle container-based rendering if [Link] sections when running inside a 
container?

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

-- 
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Post to : touch-packages@lists.launchpad.net
Unsubscribe : https://launchpad.net/~touch-packages
More help   : 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dan Streetman]

@raharper could you give the systemd in this ppa a test:
https://launchpad.net/~ddstreet/+archive/ubuntu/systemd

also, you're setting the MTUBytes via .link file, but that won't work
inside an lxd container as that setting only has any effect during udev
processing of interface 'add' uevent, which doesn't happen inside an lxd
container because 1) the interface already exists when the container
boots up and 2) systemd-udev-trigger.service has no effect (unlike bare
metal systems or vms) because unprivileged containers can't force uevent
generation by writing to sysfs uevent nodes.  Instead try adding a
[Link] section to the .network file with the MTUBytes; that will get
applied every time networkd starts.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

@Balint, after further testing, here's where things are:


-
On LXD Containers
-

On Bionic
  1) First boot: neither interface mtu, nor ipv6 mtu is applied.
  2) Restarting systemd-networkd:  neither interface nor ipv6-mtu is applied
  3) netplan apply: interface mtu is set correctly, ipv6 mtu is not.

On Disco
  1) First boot: neither interface mtu, nor ipv6 mtu is applied.
  2) Restarting systemd-networkd: neither interface nor ipv6-mtu is applied
  3) netplan apply: both interface and ipv6 MTU are set correctly.

On Eoan
  1) First boot: neither interface mtu, nor ipv6 mtu is applied
  2) Restarting systemd-networkd: neither interface nor ipv6-mtu is applied
  3) netplan apply: both interface and ipv6 MTU are set correctly.

--
On VMs
--

On Bionic
  1) First boot: interface MTU is set, ipv6 MTU is not applied.
  2) Restarting systemd-networkd: both interface and ipv6 MTU are set correctly
  3) netplan apply not needed
  4) After reboot, same as (1)

On Disco
  1) First boot: interface MTU is set, ipv6 MTU is not applied.
  2) Restarting systemd-networkd: both interface and ipv6 MTU are set correctly
  3) netplan apply not needed
  4) After reboot, same as (1)
 
On Eoan
  1) First boot: interface MTU is set, ipv6 MTU is not applied.
  2) Restarting systemd-networkd: both interface and ipv6 MTU are set correctly
  3) netplan apply not needed
  4) After reboot, same as (1)

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Balint Reczey]

@raharper, do I understand correctly that this occurs only on first boot and is 
fixed when installing eoan's netplan.io on bionic?
Also a full Disco systemd works or not? (Disco system, Disco netplan.io, Disco 
systemd)

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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Re: [Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

On Fri, Oct 25, 2019 at 1:31 PM Dan Streetman 
wrote:

> I looked at this for a few minutes, and it seems strange that it works
> at all (at boot) since networkd sets the ipv6 mtu before bringing the
> link up, but the kernel resets the ipv6 mtu to the device mtu on link
> up.  I must be missing something.
>

I'm glad you saw that.  I'm seeing this as well on my curtin vmtest
(automated deployment and data collection during first boot).

I have to restart networkd for it to work on the first boot.
Subsequent boots it seems to work fine without a restart of networkd.


> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1671951
>
> Title:
>   networkd should allow configuring IPV6 MTU
>
> To manage notifications about this bug go to:
>
> https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions
>

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dan Streetman]

I looked at this for a few minutes, and it seems strange that it works
at all (at boot) since networkd sets the ipv6 mtu before bringing the
link up, but the kernel resets the ipv6 mtu to the device mtu on link
up.  I must be missing something.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Mathieu Trudel-Lapierre]

Thanks. Let's put both tasks as Triaged again then, since it's obviously
not fixed in disco and bionic.

I don't think this qualifies as a regression though, since the feature
was never available before. It's just not finished since the systemd
side of this isn't complete.

** Changed in: systemd (Ubuntu Bionic)
   Status: Fix Released => Triaged

** Changed in: systemd (Ubuntu Disco)
   Status: New => Triaged

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Triaged
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  Triaged

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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Unsubscribe : 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

I did some more testing today.  I upgraded systemd and netplan.io to
disco level, rebooted and tested the MTU  settings; disco packages fail
as well.  I then upgraded to eoan systemd/netplan.io rebooted and the
MTU settings are correct.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  New

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

In the Eoan version of systemd, I can see in the logs these messages:

Oct 24 18:52:32.753746 ubuntu systemd-networkd[1167]: Setting 
'/proc/sys/net/ipv6/conf/interface1/proxy_ndp' to '0'
Oct 24 18:52:32.753848 ubuntu systemd-networkd[1167]: Setting 
'/proc/sys/net/ipv6/conf/interface1/use_tempaddr' to '0'
Oct 24 18:52:32.753884 ubuntu systemd-networkd[1167]: Setting 
'/proc/sys/net/ipv6/conf/interface1/accept_ra' to '0'
Oct 24 18:52:32.753962 ubuntu systemd-networkd[1167]: Setting 
'/proc/sys/net/ipv6/conf/interface1/mtu' to '5634'

These are not emitted in bionic or disco versions of systemd.

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  New

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

The original netplan yaml I was testing was simpler, but also failed so
I tried to see if additional settings would make a difference, but it
did not.

network:
version: 2
ethernets:
interface0:
dhcp4: true
match:
macaddress: '52:54:00:12:34:00'
set-name: interface0
interface1:
addresses:
- 192.168.1.2/24
- 2001:4800:78ff:1b:be76:4eff:fe06:1000/64
match:
macaddress: '52:54:00:12:34:02'
mtu: 
ipv6-mtu: 5634
set-name: interface1

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  New

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

I cannot verify this is working on bionic with ipv6 static addresses.

root@ubuntu:~# lsb_release -rd
Description:Ubuntu 18.04.3 LTS
Release:18.04
root@ubuntu:~# cat /etc/cloud/build.info 
build_name: server
serial: 20191021
root@ubuntu:~# uname -a
Linux ubuntu 4.15.0-66-generic #75-Ubuntu SMP Tue Oct 1 05:24:09 UTC 2019 
x86_64 x86_64 x86_64 GNU/Linux
root@ubuntu:~# apt-cache policy netplan.io
netplan.io:
  Installed: 0.98-0ubuntu1~18.04.1
  Candidate: 0.98-0ubuntu1~18.04.1
  Version table:
 *** 0.98-0ubuntu1~18.04.1 500
500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
100 /var/lib/dpkg/status
 0.40.1~18.04.4 500
500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 
Packages
 0.36.1 500
500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
root@ubuntu:~# apt-cache policy systemd
systemd:
  Installed: 237-3ubuntu10.31
  Candidate: 237-3ubuntu10.31
  Version table:
 *** 237-3ubuntu10.31 500
500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
100 /var/lib/dpkg/status
 237-3ubuntu10.29 500
500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 
Packages
 237-3ubuntu10 500
500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages


root@ubuntu:~# cat /etc/netplan/50-cloud-init.yaml 
# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
interface0:
dhcp4: true
match:
macaddress: '52:54:00:12:34:00'
set-name: interface0
interface1:
dhcp4: false
dhcp6: false
addresses:
- 192.168.1.2/24
- 2001:4800:78ff:1b:be76:4eff:fe06:1000/64
match:
macaddress: '52:54:00:12:34:02'
mtu: 
ipv6-mtu: 5634
set-name: interface1
accept-ra: false
dhcp6-overrides:
   use-mtu: false
link-local: [ ]

root@ubuntu:~# ip link show interface1
3: interface1:  mtu  qdisc fq_codel state 
UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:12:34:02 brd ff:ff:ff:ff:ff:ff
# sysctl net.ipv6.conf.interface1.mtu 
net.ipv6.conf.interface1.mtu = 

root@ubuntu:~# cat /run/systemd/network/10-netplan-interface1.link 
[Match]
MACAddress=52:54:00:12:34:02

[Link]
Name=interface1
WakeOnLan=off
MTUBytes=
root@ubuntu:~# cat /run/systemd/network/10-netplan-interface1.network 
[Match]
MACAddress=52:54:00:12:34:02
Name=interface1

[Network]
LinkLocalAddressing=no
Address=192.168.1.2/24
Address=2001:4800:78ff:1b:be76:4eff:fe06:1000/64
IPv6AcceptRA=no
IPv6MTUBytes=5634

# journalctl -o short-precise -b 0 | egrep -i "(MTU|interface1)"
Oct 23 21:28:47.968910 ubuntu kernel: virtio_net virtio3 interface1: renamed 
from ens6
Oct 23 21:28:50.636014 ubuntu systemd-networkd[670]: Ignoring 
/run/systemd/network/10-netplan-interface1.network, because it's not a regular 
file with suffix .netdev.
Oct 23 21:28:50.636090 ubuntu systemd-networkd[670]: Ignoring 
/run/systemd/network/10-netplan-interface1.link, because it's not a regular 
file with suffix .netdev.
Oct 23 21:28:50.636706 ubuntu systemd-networkd[670]: Ignoring 
/run/systemd/network/10-netplan-interface1.link, because it's not a regular 
file with suffix .network.
Oct 23 21:28:50.640507 ubuntu systemd-networkd[670]: interface7: Saved original 
MTU: 1500
Oct 23 21:28:50.642454 ubuntu systemd-networkd[670]: interface6: Saved original 
MTU: 1500
Oct 23 21:28:50.643050 ubuntu systemd-networkd[670]: interface5: Saved original 
MTU: 1500
Oct 23 21:28:50.643629 ubuntu systemd-networkd[670]: interface4: Saved original 
MTU: 1500
Oct 23 21:28:50.644214 ubuntu systemd-networkd[670]: interface3: Saved original 
MTU: 1500
Oct 23 21:28:50.644939 ubuntu systemd-networkd[670]: interface2: Saved original 
MTU: 1500
Oct 23 21:28:50.645025 ubuntu systemd-networkd[670]: interface1: New device has 
no master, continuing without
Oct 23 21:28:50.645107 ubuntu systemd-networkd[670]: interface1: Flags change: 
+MULTICAST +BROADCAST
Oct 23 21:28:50.645175 ubuntu systemd-networkd[670]: interface1: Link 3 added
Oct 23 21:28:50.645456 ubuntu systemd-networkd[670]: interface1: udev 
initialized link
Oct 23 21:28:50.647448 ubuntu systemd-networkd[670]: interface1: Saved original 
MTU: 
Oct 23 21:28:50.648100 ubuntu systemd-networkd[670]: interface0: Saved original 
MTU: 1500
Oct 23 21:28:50.648670 ubuntu systemd-networkd[670]: lo: Saved original MTU: 0
Oct 23 21:28:50.655303 ubuntu systemd-networkd[670]: interface1: Interface name 
change detected, interface1 has been renamed to ens6.
Oct 23 21:28:50.655431 ubuntu 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

This bug was fixed in the package systemd - 237-3ubuntu10.31

---
systemd (237-3ubuntu10.31) bionic; urgency=medium

  [ Dimitri John Ledkov ]
  * Add conflicts with upstart and systemd-shim. (LP: #1773859)
  * d/p/debian/UBUNTU-units-disable-journald-watchdog.patch
- units: Disable journald Watchdog (LP: #1773148)
  * d/p/cryptsetup-add-support-for-sector-size-option-8881.patch
- cryptsetup: add support for sector-size= option (LP: #1776626)
  * d/p/systemctl-correctly-proceed-to-immediate-shutdown-if-sche.patch
- systemctl: correctly proceed to immediate shutdown if scheduling fails
  (LP: #1670291)
  * d/p/networkd-add-support-to-configure-IPv6-MTU-8664.patch
- networkd: add support to set IPv6MTUBytes (LP: #1671951)

 -- Balint Reczey   Mon, 30 Sep 2019 17:23:17 +0200

** Changed in: systemd (Ubuntu Bionic)
   Status: Fix Committed => Fix Released

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Released
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  New

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

This bug was fixed in the package netplan.io - 0.98-0ubuntu1~19.04.1

---
netplan.io (0.98-0ubuntu1~19.04.1) disco; urgency=medium

  * Backport netplan.io 0.98 to 19.04. (LP: #1840832)

 -- Mathieu Trudel-Lapierre   Mon, 26 Aug 2019
16:41:36 -0400

** Changed in: netplan.io (Ubuntu Disco)
   Status: Fix Committed => Fix Released

** Changed in: netplan.io (Ubuntu Bionic)
   Status: Fix Committed => Fix Released

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  New

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

-- 
Mailing list: https://launchpad.net/~touch-packages
Post to : touch-packages@lists.launchpad.net
Unsubscribe : 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

This bug was fixed in the package netplan.io - 0.98-0ubuntu1~18.04.1

---
netplan.io (0.98-0ubuntu1~18.04.1) bionic; urgency=medium

  * Backport netplan.io 0.98 to 18.04. (LP: #1840832)
  * Keep patches specific to 18.04 support:
- disable-networkd-tunnels-ipip-gre.patch: disable tests for unsupported
  tunnel types (ipip and gre) in the 18.04 version of systemd-networkd.
  * Drop debian/patches/glib_changes.patch: No longer necessary, changes were
made upstream to better account for the changes in HashTable.
  * debian/netplan.io.install: add /usr/share/dbus-1

netplan.io (0.98-0ubuntu1) eoan; urgency=medium

  * New upstream release: 0.98 (LP: #1840832)
- Added new "feature flags" to identify new features
- Added support for "use-domains" for DHCP overrides
- Added support for setting IPv6 MTU Bytes (LP: #1671951)
- Added a DBus interface to query and run 'netplan apply' via other apps
- Various build system fixes
- Improved validation for bonding modes
- Added support for "hash:" for hashed 802.1x passwords (LP: #1819831)
- Tolerate devices without a /sys path (LP: #1810043)
- Fix incorrect separator for networkd with ARP IP targets (LP: #1829264)
  * debian/control: Add Build-Depends on libsystemd-dev for DBus feature, and
on dbus-x11 for dbus-launch used in tests.

 -- Mathieu Trudel-Lapierre   Mon, 26 Aug 2019
16:36:03 -0400

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  New

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

   

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Brian Murray]

** Also affects: cloud-init (Ubuntu Disco)
   Importance: Undecided
   Status: New

** Also affects: systemd (Ubuntu Disco)
   Importance: Undecided
   Status: New

** Also affects: netplan.io (Ubuntu Disco)
   Importance: Undecided
   Status: New

** Changed in: netplan.io (Ubuntu Disco)
   Status: New => Fix Committed

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in cloud-init source package in Disco:
  New
Status in netplan.io source package in Disco:
  Fix Released
Status in systemd source package in Disco:
  New

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Mathieu Trudel-Lapierre]

Verification-done on disco:

ubuntu@ip-172-30-0-243:~$ lsb_release -cs
disco
ubuntu@ip-172-30-0-243:~$ dpkg -l netplan.io systemd | grep ii
ii  netplan.io 0.98-0ubuntu1~19.04.1 amd64YAML network 
configuration abstraction for various backends
ii  systemd240-6ubuntu5.7amd64system and service manager
ubuntu@ip-172-30-0-243:~$ sudo netplan apply
ubuntu@ip-172-30-0-243:~$ ip link
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN mode 
DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0:  mtu  qdisc fq_codel state UP 
mode DEFAULT group default qlen 1000
link/ether 06:92:5b:c9:b5:3d brd ff:ff:ff:ff:ff:ff
ubuntu@ip-172-30-0-243:~$ networkctl
IDX LINK TYPE   OPERATIONAL SETUP 
  1 lo   loopback   carrier unmanaged 
  2 eth0 ether  routableconfigured

2 links listed.
ubuntu@ip-172-30-0-243:~$ sysctl net.ipv6.conf.eth0.mtu
net.ipv6.conf.eth0.mtu = 5634
ubuntu@ip-172-30-0-243:~$ cat /etc/netplan/50-cloud-init.yaml 
# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
eth0:
dhcp4: true
match:
macaddress: 06:92:5b:c9:b5:3d
set-name: eth0
ipv6-mtu: 5634
mtu: 
dhcp6: true
dhcp4-overrides:
use-mtu: false
dhcp6-overrides:
use-mtu: false


** Tags added: verification-done-disco

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Mathieu Trudel-Lapierre]

Verification-done on bionic:

ubuntu@ip-172-30-0-140:/run/systemd/network$ lsb_release -cs
bionic
ubuntu@ip-172-30-0-140:/run/systemd/network$ dpkg -l netplan.io | grep ii
ii  netplan.io 0.98-0ubuntu1~18.04.1 amd64YAML network 
configuration abstraction for various backends
ubuntu@ip-172-30-0-140:/run/systemd/network$ dpkg -l systemd | grep ii
ii  systemd237-3ubuntu10.31 amd64system and service manager
ubuntu@ip-172-30-0-140:/run/systemd/network$ cat 
/etc/netplan/50-cloud-init.yaml 
# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
eth0:
dhcp4: true
match:
macaddress: 06:e0:25:2e:08:ef
set-name: eth0
ipv6-mtu: 5634
mtu: 
dhcp6: true
dhcp4-overrides:
use-mtu: false
dhcp6-overrides:
use-mtu: false
ubuntu@ip-172-30-0-140:/run/systemd/network$ sudo netplan apply
ubuntu@ip-172-30-0-140:/run/systemd/network$ networkctl
IDX LINK TYPE   OPERATIONAL SETUP 
  1 lo   loopback   carrier unmanaged 
  2 eth0 ether  routableconfigured

2 links listed.
ubuntu@ip-172-30-0-140:/run/systemd/network$ sysctl net.ipv6.conf.eth0.mtu
net.ipv6.conf.eth0.mtu = 5634
ubuntu@ip-172-30-0-140:/run/systemd/network$ ip link
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN mode 
DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0:  mtu  qdisc fq_codel state UP 
mode DEFAULT group default qlen 1000
link/ether 06:e0:25:2e:08:ef brd ff:ff:ff:ff:ff:ff
ubuntu@ip-172-30-0-140:/run/systemd/network$ 


** Tags removed: verification-needed verification-needed-bionic zesty
** Tags added: verification-done-bionic

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Steve Langasek]

Hello Ryan, or anyone else affected,

Accepted systemd into bionic-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/systemd/237-3ubuntu10.30 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-bionic to verification-done-bionic. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-bionic. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: systemd (Ubuntu Bionic)
   Status: In Progress => Fix Committed

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Balint Reczey]

** Changed in: systemd (Ubuntu Bionic)
   Status: Fix Committed => In Progress

** Changed in: systemd (Ubuntu Bionic)
 Assignee: (unassigned) => Balint Reczey (rbalint)

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  In Progress

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Francis Ginther]

** Tags added: id-5d67fe691c14484db556d212

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

See comment #20;  ipv6 mtu is 1280 -> DEVICE_MTU.

I'm testing something in the middle now.

On Eoan with:

network:
version: 2
ethernets:
ens3:
addresses: [10.5.0.16/16]
gateway4: 10.5.0.1
dhcp4: false
match:
macaddress: fa:16:3e:c9:1e:fb
mtu: 8958
ipv6-mtu: 8960
set-name: ens3
nameservers:
addresses: [10.5.0.2]
search: [project.serverstack]


It works.  Now on bionic-proposed, it does not.


Aug 28 16:59:56.659125 b-test-ipv6-mtu systemd-networkd[1149]: 
/run/systemd/network/10-netplan-ens3.network:11: Unknown lvalue 'IPv6MTUBytes' 
in section 'Network'


So, looks like bionic systemd is missing something.

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

err, on Eoan, I used ipv6-mtu 6000.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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Re: [Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

I thought custom ipv6 MTU may not be lower than ipv4 one.

Hence request for 6000 ipv6 is not valid, when link is on 8958.

Can you try 9000?


On Wed, 28 Aug 2019, 15:41 Ryan Harper, <1671...@bugs.launchpad.net> wrote:

> I launched a bionic image on serverstack, updated the netplan.io to
> proposed, modified the network config to set ipv6-mtu to 6000 and
> rebooted.
>
> root@b-test-ipv6-mtu:~# apt-cache policy netplan.io
> netplan.io:
>   Installed: 0.98-0ubuntu1~18.04.1
>   Candidate: 0.98-0ubuntu1~18.04.1
>   Version table:
>  *** 0.98-0ubuntu1~18.04.1 500
> 500 http://nova.clouds.archive.ubuntu.com/ubuntu
> bionic-proposed/main amd64 Packages
> 100 /var/lib/dpkg/status
>  0.97-0ubuntu1~18.04.1 500
> 500 http://nova.clouds.archive.ubuntu.com/ubuntu
> bionic-updates/main amd64 Packages
>  0.40.1~18.04.4 500
> 500 http://security.ubuntu.com/ubuntu bionic-security/main amd64
> Packages
>  0.36.1 500
> 500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic/main
> amd64 Packages
>
> root@b-test-ipv6-mtu:~# cat /etc/netplan/50-cloud-init.yaml
> network:
> version: 2
> ethernets:
> ens3:
> dhcp4: true
> match:
> macaddress: fa:16:3e:4d:3c:6a
> set-name: ens3
> ipv6-mtu: 6000
>
> root@b-test-ipv6-mtu:/run/systemd/network# cat 10-netplan-ens3.link
> [Match]
> MACAddress=fa:16:3e:4d:3c:6a
>
> [Link]
> Name=ens3
> WakeOnLan=off
> root@b-test-ipv6-mtu:/run/systemd/network# cat 10-netplan-ens3.network
> [Match]
> MACAddress=fa:16:3e:4d:3c:6a
> Name=ens3
>
> [Network]
> DHCP=ipv4
> LinkLocalAddressing=ipv6
> IPv6MTUBytes=6000
>
> [DHCP]
> RouteMetric=100
> UseMTU=true
>
>
> ~# cat /sys/class/net/ens3/mtu
> 8958
> ~# sysctl net.ipv6.conf.ens3.mtu
> net.ipv6.conf.ens3.mtu = 8958
>
> --
> You received this bug notification because you are subscribed to systemd
> in Ubuntu.
> Matching subscriptions: systemd
> https://bugs.launchpad.net/bugs/1671951
>
> Title:
>   networkd should allow configuring IPV6 MTU
>
> To manage notifications about this bug go to:
>
> https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions
>

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

I tested with your single-file approach and that also fails.  Note that
bionic now has systemd 237, so maybe something is missing (or regressed)
?

$ apt-cache policy systemd
systemd:
  Installed: 237-3ubuntu10.26
  Candidate: 237-3ubuntu10.26
  Version table:
 *** 237-3ubuntu10.26 500
500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic-proposed/main 
amd64 Packages
100 /var/lib/dpkg/status
 237-3ubuntu10.25 500
500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic-updates/main 
amd64 Packages
 237-3ubuntu10.19 500
500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 
Packages
 237-3ubuntu10 500
500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic/main amd64 
Packages

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

Followup on my comments, are any changes required in networkd to support
this in bionic?

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

I launched a bionic image on serverstack, updated the netplan.io to
proposed, modified the network config to set ipv6-mtu to 6000 and
rebooted.

root@b-test-ipv6-mtu:~# apt-cache policy netplan.io 
netplan.io:
  Installed: 0.98-0ubuntu1~18.04.1
  Candidate: 0.98-0ubuntu1~18.04.1
  Version table:
 *** 0.98-0ubuntu1~18.04.1 500
500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic-proposed/main 
amd64 Packages
100 /var/lib/dpkg/status
 0.97-0ubuntu1~18.04.1 500
500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic-updates/main 
amd64 Packages
 0.40.1~18.04.4 500
500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 
Packages
 0.36.1 500
500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic/main amd64 
Packages

root@b-test-ipv6-mtu:~# cat /etc/netplan/50-cloud-init.yaml 
network:
version: 2
ethernets:
ens3:
dhcp4: true
match:
macaddress: fa:16:3e:4d:3c:6a
set-name: ens3
ipv6-mtu: 6000

root@b-test-ipv6-mtu:/run/systemd/network# cat 10-netplan-ens3.link 
[Match]
MACAddress=fa:16:3e:4d:3c:6a

[Link]
Name=ens3
WakeOnLan=off
root@b-test-ipv6-mtu:/run/systemd/network# cat 10-netplan-ens3.network 
[Match]
MACAddress=fa:16:3e:4d:3c:6a
Name=ens3

[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6
IPv6MTUBytes=6000

[DHCP]
RouteMetric=100
UseMTU=true


~# cat /sys/class/net/ens3/mtu 
8958
~# sysctl net.ipv6.conf.ens3.mtu
net.ipv6.conf.ens3.mtu = 8958

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Brian Murray]

Hello Ryan, or anyone else affected,

Accepted netplan.io into bionic-proposed. The package will build now and
be available at
https://launchpad.net/ubuntu/+source/netplan.io/0.98-0ubuntu1~18.04.1 in
a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-bionic to verification-done-bionic. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-bionic. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: netplan.io (Ubuntu Bionic)
   Status: New => Fix Committed

** Tags removed: verification-done verification-done-bionic
** Tags added: verification-needed verification-needed-bionic

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:
version: 2
ethernets:
  eth0:
dhcp4: true
dhcp6: true
ipv6-mtu: 6000

   * Check that MTU bytes, is at least IPv6MTUBytes on the interface:

  $ sysctl net.ipv6.conf.eth0.mtu
  net.ipv6.conf.eth0.mtu = 6000

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of netplan.io =

  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]

   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Mathieu Trudel-Lapierre]

** Description changed:

+ = netplan.io =
+ 
+ [Impact]
+ 
+  * IPv6 traffic failing to send/receive due to incompatible/low MTU
+ setting. Specifically, IPv6 traffic may have higher MTU requirements
+ than IPv4 traffic and thus may need to be overridden and/or set to a
+ higher value than IPv6 traffic.
+ 
+ [Test Case]
+  * Apply a netplan configuration that specifices ipv6-mtu:
+ 
+ network:
+   version: 2
+   ethernets:
+ eth0:
+   dhcp4: true
+   dhcp6: true
+   ipv6-mtu: 6000
+ 
+  * Check that MTU bytes, is at least IPv6MTUBytes on the interface:
+ 
+ $ sysctl net.ipv6.conf.eth0.mtu
+ net.ipv6.conf.eth0.mtu = 6000
+ 
+ [Regression Potential]
+ 
+  * This is a future compatible backport of an additional keyword not
+ used by default. It may result in MTU change to a higher value, which
+ should not cause loss of connectivity.
+ 
+ [Other Info]
+ 
+  * Original bug report below
+ 
+ = end of netplan.io =
+ 
  = systemd =
  
  [Impact]
  
-  * IPv6 traffic failing to send/receive due to incompatible/low MTU
+  * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.
  
  [Test Case]
  
-  * Use IPv6MTUBytes= setting in a .network unit
-  * Restart systemd-network
-  * Check that there no error messages / warnings about not-recognizing this 
option
-  * Check that MTU bytes, is at least IPv6MTUBytes on the interface
+  * Use IPv6MTUBytes= setting in a .network unit
+  * Restart systemd-network
+  * Check that there no error messages / warnings about not-recognizing this 
option
+  * Check that MTU bytes, is at least IPv6MTUBytes on the interface
  
  [Regression Potential]
  
-  * This is a future compatible backport of an additional keyword not
+  * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.
  
  [Other Info]
-  
-  * Original bug report below
+ 
+  * Original bug report below
  
  = end of systemd =
  
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.
  
  Upstream has discussed this issue here:
  
  https://github.com/systemd/systemd/pull/1533
  
  But it's been closed in favor of only setting via RA.
  
  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.
  
  Some context from those discussions
  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.
  
  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.
  
  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.
  
  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = netplan.io =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]
   * Apply a netplan configuration that specifices ipv6-mtu:

  network:

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Launchpad Bug Tracker]

This bug was fixed in the package netplan.io - 0.98-0ubuntu1

---
netplan.io (0.98-0ubuntu1) eoan; urgency=medium

  * New upstream release: 0.98 (LP: #1840832)
- Added new "feature flags" to identify new features
- Added support for "use-domains" for DHCP overrides
- Added support for setting IPv6 MTU Bytes (LP: #1671951)
- Added a DBus interface to query and run 'netplan apply' via other apps
- Various build system fixes
- Improved validation for bonding modes
- Added support for "hash:" for hashed 802.1x passwords (LP: #1819831)
- Tolerate devices without a /sys path (LP: #1810043)
- Fix incorrect separator for networkd with ARP IP targets (LP: #1829264)
  * debian/control: Add Build-Depends on libsystemd-dev for DBus feature, and
on dbus-x11 for dbus-launch used in tests.

 -- Mathieu Trudel-Lapierre   Wed, 21 Aug 2019
14:49:16 -0400

** Changed in: netplan.io (Ubuntu)
   Status: In Progress => Fix Released

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  Fix Released
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Mathieu Trudel-Lapierre]

** Changed in: netplan.io (Ubuntu)
   Status: New => In Progress

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  In Progress
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Francis Ginther]

** Tags added: id-5cc72cfe22e00d7a830c4ce4

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

This was done inside a VM.
This was all done in a single /etc/systemd/network/10-netplan-ens3.network 
file. Note that [Link] is a valid section in a .network file. Note that i took 
netplan generated .network file as a base, and then modified it with above 
shown options. Disabled netplan. Rebooted.

I'm not quite sure how you can reproduce this inside a lxd container,
since it's not using a physical link, but a .netdev devices. I expect
that specifying similar things in .network should work, but it might
not. That is because a veth pair is precreated outside of the container,
and one may need to adjust the host-side of the veth pair which is a
priviledged operation.

Note that e.g. one can set MTU on virtual devices created using .netdev
units.

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Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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Re: [Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

On Tue, Dec 4, 2018 at 9:31 AM Ryan Harper 
wrote:

>
>
> On Tue, Dec 4, 2018 at 6:31 AM Dimitri John Ledkov 
> wrote:
>
>> Using systemd 237-3ubuntu10.10
>>
>> Using:
>> [Match]
>> Name=ens3
>> [Network]
>> DHCP=ipv4
>> IPv6MTUBytes=1600
>> [Link]
>> MTUBytes=1800
>> [DHCP]
>> UseMTU=no
>> RouteMetric=100
>>
>
> Do you put this in the same .network file or .link file?
>

FWIW, I'm not able to make this work inside a LXD container.  Could you
provide more details on how you validated and in what environment?

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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Re: [Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

On Tue, Dec 4, 2018 at 6:31 AM Dimitri John Ledkov 
wrote:

> Using systemd 237-3ubuntu10.10
>
> Using:
> [Match]
> Name=ens3
> [Network]
> DHCP=ipv4
> IPv6MTUBytes=1600
> [Link]
> MTUBytes=1800
> [DHCP]
> UseMTU=no
> RouteMetric=100
>

Do you put this in the same .network file or .link file?

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

Using systemd 237-3ubuntu10.10

Using:
[Match]
Name=ens3
[Network]
DHCP=ipv4
IPv6MTUBytes=1600
[Link]
MTUBytes=1800
[DHCP]
UseMTU=no
RouteMetric=100

I do get:

$ cat /sys/class/net/ens3/mtu
1800
$ cat /proc/sys/net/ipv6/conf/ens3/mtu
1600

Thus one can set a different from the device, ipv6-specific mtu.

** Tags removed: verification-needed verification-needed-bionic
** Tags added: verification-done verification-done-bionic

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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Re: [Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

On Mon, Nov 26, 2018 at 11:11 PM Jay Vosburgh
<1671...@bugs.launchpad.net> wrote:
>
> Regarding #2 from comment #19:
>
> As the defined range for the ipv6.mtu is from IPV6_MIN_MTU to the
> device's MTU, and the existing API returns an error if the ipv6.mtu is
> out of range, I think it's reasonable for a configuration with the
> ipv6.mtu > device MTU to fail.

I think that's reasonable too.  We'll need to file a separate bug with
MAAS to ensure that
it knows it should set device MTU >= to the ipv6 MTU configured.  This
will ensure
the configuration that gets generated will include both a raised
device MTU and an IPV6 MTU.

>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1671951
>
> Title:
>   networkd should allow configuring IPV6 MTU
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Jay Vosburgh]

Regarding #2 from comment #19:

As the defined range for the ipv6.mtu is from IPV6_MIN_MTU to the
device's MTU, and the existing API returns an error if the ipv6.mtu is
out of range, I think it's reasonable for a configuration with the
ipv6.mtu > device MTU to fail.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

It seems there are some limitations to what systemd will do with
IPv6BytesMTU.

1) if LinkLocalAddressing is not disabled, it will clobber any
IPv6BytesMTU value set.

[Network]
LinkLocalAddressing=ipv6
Address=10.10.10.10/24
IPv6MTUBytes=1470

This results in: /proc/sys/net/ipv6/conf//mtu having a value of
1500

if I disable LinkLocalAddressing like so:

[Network]
LinkLocalAddressing=no
Address=10.10.10.10/24
IPv6MTUBytes=1470

Then I get 1470.

This seems like a bug; do we need an upstream issue to track this?


2) systemd-networkd will not raise the device MTU limit automatically.  The 
default device MTU is 1500.  If you set IPv6BytesMTU to 1520, then 
systemd-networkd emits this message:

Nov 26 19:13:59 rharper-b2 systemd-networkd[593]: eth2: Cannot set IPv6
MTU for interface: Invalid argument

which is the same message you get if you: echo "1520" >
/proc/sys/net/ipv6/conf//mtu:

# echo 1520 > /proc/sys/net/ipv6/conf/eth2/mtu  
bash: echo: write error: Invalid argument


If this is considered "acceptable" behavior for systemd, then it will leave 
netplan with a decision when it is presented with a config which sets an 
ipv6-mtu bytes value that is bigger than the default device value (1500), or 
bigger than an specified device mtu.  Will it report an error with the config?

Should we file an upstream issue to see if networkd is willing to raise
the device limit (or possibly emit a more helpful message to indicate
that networkd cannot set an IPv6 MTU greater than the underlying device
MTU?

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Łukasz Zemczak]

Hello Ryan, or anyone else affected,

Accepted systemd into bionic-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/systemd/237-3ubuntu10.8 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-bionic to verification-done-bionic. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-bionic. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: systemd (Ubuntu Bionic)
   Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-bionic

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  Fix Committed

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those discussions

  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

** Description changed:

+ = systemd =
+ 
+ [Impact]
+ 
+  * IPv6 traffic failing to send/receive due to incompatible/low MTU
+ setting. Specifically, IPv6 traffic may have higher MTU requirements
+ than IPv4 traffic and thus may need to be overridden and/or set to a
+ higher value than IPv6 traffic.
+ 
+ [Test Case]
+ 
+  * Use IPv6MTUBytes= setting in a .network unit
+  * Restart systemd-network
+  * Check that there no error messages / warnings about not-recognizing this 
option
+  * Check that MTU bytes, is at least IPv6MTUBytes on the interface
+ 
+ [Regression Potential]
+ 
+  * This is a future compatible backport of an additional keyword not
+ used by default. It may result in MTU change to a higher value, which
+ should not cause loss of connectivity.
+ 
+ [Other Info]
+  
+  * Original bug report below
+ 
+ = end of systemd =
+ 
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.
  
  Upstream has discussed this issue here:
  
  https://github.com/systemd/systemd/pull/1533
  
  But it's been closed in favor of only setting via RA.
  
  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.
  
- 
  Some context from those discussions
- 
  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.
  
- Yes.  Anything that creates a PMTUD black hole can result in
+ Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.
  
- One example here is egress from an ipsec tunnel wherein the next
+ One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.
  
- In essence, any of these sort of cases that require an explicit
+ In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  In Progress

Bug description:
  = systemd =

  [Impact]

   * IPv6 traffic failing to send/receive due to incompatible/low MTU
  setting. Specifically, IPv6 traffic may have higher MTU requirements
  than IPv4 traffic and thus may need to be overridden and/or set to a
  higher value than IPv6 traffic.

  [Test Case]

   * Use IPv6MTUBytes= setting in a .network unit
   * Restart systemd-network
   * Check that there no error messages / warnings about not-recognizing this 
option
   * Check that MTU bytes, is at least IPv6MTUBytes on the interface

  [Regression Potential]

   * This is a future compatible backport of an additional keyword not
  used by default. It may result in MTU change to a higher value, which
  should not cause loss of connectivity.

  [Other Info]
   
   * Original bug report below

  = end of systemd =

  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  Some context from those 

[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

** Changed in: systemd (Ubuntu Bionic)
   Status: New => In Progress

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  In Progress

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Scott Moser]

** Changed in: cloud-init (Ubuntu)
   Status: New => Confirmed

** Changed in: cloud-init (Ubuntu Bionic)
   Status: New => Confirmed

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  Confirmed
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  Confirmed
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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Re: [Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

This may now be a cloud-init bug if the support is there since this is
a network-config v1 -> cloud-init  renders netplan.
On Fri, Sep 28, 2018 at 9:12 AM Scott Moser  wrote:
>
> Hm...
>
> Our tests show that this is not fixed in cosmic or bionic.
>
> https://jenkins.ubuntu.com/server/job/curtin-vmtest-devel-amd64/533/console
> shows curtin's vmtest failing.  Partial output shows:
>
> ==
> ERROR: test_ipv6_mtu_smaller_than_ipv4_v6_iface_first 
> (vmtests.test_network_mtu.CosmicTestNetworkMtu)
> --
> Traceback (most recent call last):
>   File 
> "/var/lib/jenkins/slaves/torkoal/workspace/curtin-vmtest-devel-amd64/curtin-533/tests/vmtests/__init__.py",
>  line 468, in wrapper
> raise RuntimeError(msg)
> RuntimeError: 
> skip_by_date(CosmicTestNetworkMtu.test_ipv6_mtu_smaller_than_ipv4_v6_iface_first)
>  LP: #1671951 fixby=2018-09-26 removeby=2018-10-17: (PAST_FIXBY) Failed: 1480 
> != 1500
>  >> begin captured stdout << -
> iface=interface4 subnets=[{'address': 
> '2001:4800:78ff:1b:be76:4eff:fe06:5000', 'netmask': 64, 'type': 'static', 
> 'mtu': 1480}, {'address': '192.168.5.2/24', 'type': 'static', 'mtu': 1501}]
> subnet:{'address': '2001:4800:78ff:1b:be76:4eff:fe06:5000', 'netmask': 64, 
> 'type': 'static', 'mtu': 1480}
> mtu_data:{'device': 1500, 'ipv6': 1500}
> subnet_mtu=1480 ipv6_mtu=1500
>
> - >> end captured stdout << --
>
>
> ** Attachment added: "console log of curtin vmtest amd64 533"
>
> https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+attachment/5194078/+files/curtin-vmtest-devel-amd64-533-console.log
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1671951
>
> Title:
>   networkd should allow configuring IPV6 MTU
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  New
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  New
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

Actually there needs to be changes to netplan to emit the correct
IPV6BytesMtu setting to networkd; and then cloud-init can emit the
correct netplan yaml for that.  This feature is on the netplan roadmap
here:

https://trello.com/c/nIjLIRSG/6-support-ipv6-mtu-bytes-configuration



** Also affects: netplan.io (Ubuntu)
   Importance: Undecided
   Status: New

** Also affects: cloud-init (Ubuntu)
   Importance: Undecided
   Status: New

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Title:
  networkd should allow configuring IPV6 MTU

Status in cloud-init package in Ubuntu:
  New
Status in netplan.io package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Fix Released
Status in cloud-init source package in Bionic:
  New
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Scott Moser]

Hm...

Our tests show that this is not fixed in cosmic or bionic.

https://jenkins.ubuntu.com/server/job/curtin-vmtest-devel-amd64/533/console
shows curtin's vmtest failing.  Partial output shows:

==
ERROR: test_ipv6_mtu_smaller_than_ipv4_v6_iface_first 
(vmtests.test_network_mtu.CosmicTestNetworkMtu)
--
Traceback (most recent call last):
  File 
"/var/lib/jenkins/slaves/torkoal/workspace/curtin-vmtest-devel-amd64/curtin-533/tests/vmtests/__init__.py",
 line 468, in wrapper
raise RuntimeError(msg)
RuntimeError: 
skip_by_date(CosmicTestNetworkMtu.test_ipv6_mtu_smaller_than_ipv4_v6_iface_first)
 LP: #1671951 fixby=2018-09-26 removeby=2018-10-17: (PAST_FIXBY) Failed: 1480 
!= 1500
 >> begin captured stdout << -
iface=interface4 subnets=[{'address': '2001:4800:78ff:1b:be76:4eff:fe06:5000', 
'netmask': 64, 'type': 'static', 'mtu': 1480}, {'address': '192.168.5.2/24', 
'type': 'static', 'mtu': 1501}]
subnet:{'address': '2001:4800:78ff:1b:be76:4eff:fe06:5000', 'netmask': 64, 
'type': 'static', 'mtu': 1480}
mtu_data:{'device': 1500, 'ipv6': 1500}
subnet_mtu=1480 ipv6_mtu=1500

- >> end captured stdout << --


** Attachment added: "console log of curtin vmtest amd64 533"
   
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+attachment/5194078/+files/curtin-vmtest-devel-amd64-533-console.log

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Bionic:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
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Re: [Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

On Wed, Aug 29, 2018 at 8:41 AM Dimitri John Ledkov
 wrote:
>
> Do we need this in bionic?

Yes

>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1671951
>
> Title:
>   networkd should allow configuring IPV6 MTU
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Bionic:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

This is now in cosmic.

** Changed in: systemd (Ubuntu)
   Status: Confirmed => Fix Released

** Also affects: systemd (Ubuntu Bionic)
   Importance: Undecided
   Status: New

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Bionic:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

Do we need this in bionic?

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Bionic:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Francis Ginther]

** Tags added: id-5b74352f76a21f210334eafd

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov ]

The v239 merge for cosmic is in progress at the moment. There are a few
regressions that need to be worked around.

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

I've just seen that upstream systemd v239 claims to support IPV6MtuBytes

https://lwn.net/Articles/758128/


* networkd's .network files now support a new IPv6MTUBytes= option for
setting the MTU used by IPv6 explicitly as well as a new MTUBytes=
option in the [Route] section to configure the MTU to use for
specific routes. It also gained support for configuration of the DHCP
"UserClass" option through the new UserClass= setting. It gained
three new options in the new [CAN] section for configuring CAN
networks. The MULTICAST and ALLMULTI interface flags may now be
controlled explicitly with the new Multicast= and AllMulticast=
settings.

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Francis Ginther]

** Tags added: id-5a6a5c89cfbc4063786d54f6

-- 
You received this bug notification because you are a member of Ubuntu
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Scott Moser]

** Changed in: systemd (Ubuntu)
   Status: New => Confirmed

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

** Branch linked: lp:~raharper/curtin/trunk.vmtest-remove-bug-timers

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Nish Aravamudan]

Unsubscribing sponsors based upon IRC discussion with rharper:

10:57 < nacc> rharper: is LP: #1671951 actually ready to sponsor?
10:57 < ubottu> Launchpad bug 1671951 in systemd (Ubuntu) "networkd should 
allow configuring IPV6 MTU" [Medium,New] 
https://launchpad.net/bugs/1671951
11:07 < rharper> nacc: it was, but not sure of the status now;  the debdiff 
 likely needs refreshed against systemd in artful;  I'm not 
 sure of xnox or anyone else attempted to re-work the issue 
 upstream;
11:08 < nacc> rharper: ok, can i unsub sponsors for now?
11:08 < rharper> sure

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Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
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Re: [Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

On Wed, May 17, 2017 at 1:14 PM, Dimitri John Ledkov  wrote:

> I'm very naive, so please bear with me if this is a silly question. As
> far as I can tell the existing MTU setting in networkd will apply to
> both ipv4 and ipv6 simultaniously. Are you arguing that you want
> specific control of MTU and use different values for ipv4 and ipv6?
>

Yes


AFAICT, the MTUBytes field which is a link property, applies to the device
itself.

IPv6 has a separate *protocol* level MTU where it is used to fragment IPv6
packets
so they can be tunneled (among other things) over IPv4.  There's also a
specific
IPv6 MTU setting to prevent IPv6 packets from being to small (I think 1280
is the
minimum MTU allowable for IPv6 packets.

Subsequently, the kernel has *two* MTUs, Device (ethernet, ppp, etc) and
IPv6 protocal

device: /sys/class/net//mtu
ipv6: /proc/sys/net/ipv6/conf//mtu

Would it not be sufficient to set the appropriatly-lowest/highest common
> denominator value for MTU?
>

It is not.  In the case that you want to use 9000 MTU on an ipv6 address,
one
 needs to ensure that the MTU of the underlying device is raised from the
default to 9000
otherwise the V6 MTU means nothing.

In some cases you want to raise the MTU of the underlying device, but *not*
raise the MTU of the IPV6
this is a tunneling case:

eth0 mtu 9000
ipv6 mtu 1480

So, yes, we want independent control over v4 and v6 MTU.

Note, the upstream discussions (IMHO) punt the problem to Router
Advertisements;  however what
does remain is that we currently have this control with ifupdown (with some
help of pre/post scripts).

I had a start at getting this working in networkd, however I wasn't able to
achieve the independent control



>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1671951
>
> Title:
>   networkd should allow configuring IPV6 MTU
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/
> 1671951/+subscriptions
>

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

I'm very naive, so please bear with me if this is a silly question. As
far as I can tell the existing MTU setting in networkd will apply to
both ipv4 and ipv6 simultaniously. Are you arguing that you want
specific control of MTU and use different values for ipv4 and ipv6?
Would it not be sufficient to set the appropriatly-lowest/highest common
denominator value for MTU?

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

This also needs some discussion w.r.t how to handle IPV6-only devices;
namely if you want to set the IPV6 MTU to something higher than the
underlying device's current setting then the device MTU would need to be
raised as well.  That needs to be implemented and added to the patch.

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Dimitri John Ledkov]

Please submit this as a pullrequest upstream.

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Mathew Hodson]

** Changed in: systemd (Ubuntu)
   Importance: Undecided => Medium

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Brian Murray]

** Tags added: zesty

-- 
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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ubuntu Foundations Team Bug Bot]

The attachment "ipv6_mtu.debdiff" seems to be a debdiff.  The ubuntu-
sponsors team has been subscribed to the bug report so that they can
review and hopefully sponsor the debdiff.  If the attachment isn't a
patch, please remove the "patch" flag from the attachment, remove the
"patch" tag, and if you are member of the ~ubuntu-sponsors, unsubscribe
the team.

[This is an automated message performed by a Launchpad user owned by
~brian-murray, for any issue please contact him.]

** Tags added: patch

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

I've a build of this fix here:

https://launchpad.net/~raharper/+archive/ubuntu/cloud-init-dev
(systemd=232-19ubuntu3~fixbuild1)

I've tested this minimally in a Zesty VM and it's successfully applies
an IPV6MTU in addition to the device mtu (if that's also included).

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https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
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[Touch-packages] [Bug 1671951] Re: networkd should allow configuring IPV6 MTU

[Ryan Harper]

** Patch added: "ipv6_mtu.debdiff"
   
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+attachment/4835554/+files/ipv6_mtu.debdiff

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You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1671951

Title:
  networkd should allow configuring IPV6 MTU

Status in systemd package in Ubuntu:
  New

Bug description:
  1) Zesty
  2) systemd-232-19
  3) I need to configure the IPV6 MTU for tunneling by adding an 
IPv6MTUBytes=1480 value in the .network file for an interface with an IPV6 
static address in the [Network] section
  4) networkd does not parse or read the value and does not apply this 
configuration to the interface.

  Upstream has discussed this issue here:

  https://github.com/systemd/systemd/pull/1533

  But it's been closed in favor of only setting via RA.

  However, we know of multiple use-case which are currently supported in
  ifdupdown where we want to retain control over IPV6 MTU values outside
  of PMTU Discovery configurations.

  
  Some context from those discussions

  
  >> Client systems that route their ipv6 packets to a 6in4 router also
  >> have to have their ipv6 mtu lowered.  They could lower their link mtu,
  >> so their ipv6 packets are small enough, but that reduces performance
  >> of their ipv4 network.

  Yes.  Anything that creates a PMTUD black hole can result in
  situations where the higher header overhead of IPv6 will cause IPv4 to
  pass but IPv6 traffic to be dropped.

  One example here is egress from an ipsec tunnel wherein the next
  hop MTU is too low for IPv6 datagrams to pass.  Another is VM ->
  whatever -> host bridge -> tunnel ingress.  If the datagram cannot enter
  the tunnel due to size, it is dropped, and an ICMP response uses the
  tunnel address as a source, which may not be routable back to the
  origin.  This one is an issue with IPv4 as well, and is one case where
  manually setting the IPv6 MTU lower than the (also manually set) device
  MTU is of benefit.

  In essence, any of these sort of cases that require an explicit
  setting of the device MTU will likely require a setting of the IPv6 mtu
  as well to account for its larger header overhead.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1671951/+subscriptions

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