Here's my layout:
laptop+shorewall (MTU:1500) - hotel router (MTU:?) - internet -
Westell modem/router (MTU:1492) - desktop+shorewall (MTU:1500)
Shouldn't PMTUD change the desktop's MTU to 1492?
Your desktop's PMTUD will get an ICMP response from Westell as it tries to
traverse through it
OK, does PMTUD lower the outgoing packet size on my system due to the
hotel router's lower MTU or does the hotel router itself fragment my
1500 byte packets in order to send them out? Just curious.
If you are sending out packets with the DF bit set no fragmentation will
take place -
On Monday 02 Sep 2013 19:34:25 Grant wrote:
Here's my layout:
laptop+shorewall (MTU:1500) - hotel router (MTU:?) - internet -
Westell modem/router (MTU:1492) - desktop+shorewall (MTU:1500)
Shouldn't PMTUD change the desktop's MTU to 1492?
Your desktop's PMTUD will get an ICMP response
How is PMTUD enabled/disabled on Gentoo? I've recently been made
aware of the existence of MTU and I'm wondering if mine is set
properly for a cell phone tethered connection.
Thanks Mick. Can you generally rely on PMTUD to set the MTU optimally
or should this be experimented with when
On Sunday 01 Sep 2013 08:40:20 Grant wrote:
How is PMTUD enabled/disabled on Gentoo? I've recently been made
aware of the existence of MTU and I'm wondering if mine is set
properly for a cell phone tethered connection.
Thanks Mick. Can you generally rely on PMTUD to set the MTU
Thanks Mick. Can you generally rely on PMTUD to set the MTU optimally
or should this be experimented with when changing connections?
Short answer: default Linux machine settings behave properly as network
devices and acknowledge packets larger than their MTU value with the
appropriate
Communications between IPv4 end points use PMTUD by setting a Don't Fragment
(DF) bit in the headers of the outgoing packet. If a router/server along the
path has a smaller MTU, it will drop that packet and respond with an ICMP
'Destination Unreachable -- Fragmentation Needed' packet
On Sunday 01 Sep 2013 11:31:10 Grant wrote:
If you are still troubled by the proxy connection stalling problem, have
you tried transferring large files over the network using scp/sftp to
see if you are also getting similar symptoms? This would isolate it to
the application level (squid)
If you are still troubled by the proxy connection stalling problem, have
you tried transferring large files over the network using scp/sftp to
see if you are also getting similar symptoms? This would isolate it to
the application level (squid) or if the problem remains would point to
On Sunday 01 Sep 2013 12:17:28 Grant wrote:
Communications between IPv4 end points use PMTUD by setting a Don't
Fragment (DF) bit in the headers of the outgoing packet. If a
router/server along the path has a smaller MTU, it will drop that packet
and respond with an ICMP 'Destination
Could ICMP packets not getting through be to blame for my proxy server
problem? My laptop can't seem to ping anyone (blocked at the firewall
in this hotel I suppose) and certainly the proxy server can't ping my
laptop.
Not all ICMP packets are relevant to detecting the MTU of a node. A
On Sunday 01 Sep 2013 14:59:19 Grant wrote:
Could ICMP packets not getting through be to blame for my proxy server
problem? My laptop can't seem to ping anyone (blocked at the firewall
in this hotel I suppose) and certainly the proxy server can't ping my
laptop.
Not all ICMP packets
The hotel's router/modem may be using PPPoE to authenticate with their ISP,
which has a larger header size and requires an MTU of 1492 (1464+28=1492)
So, although your NIC is configured to the full ethernet MTU size, the router
drops the size down to 1492 to be able to squeeze it out through
On Sunday 01 Sep 2013 17:17:37 Grant wrote:
OK, does PMTUD lower the outgoing packet size on my system due to the
hotel router's lower MTU or does the hotel router itself fragment my
1500 byte packets in order to send them out? Just curious.
If you are sending out packets with the DF bit set
OK, does PMTUD lower the outgoing packet size on my system due to the
hotel router's lower MTU or does the hotel router itself fragment my
1500 byte packets in order to send them out? Just curious.
If you are sending out packets with the DF bit set no fragmentation will take
place - the
On Sunday 01 Sep 2013 18:54:45 Grant wrote:
OK, does PMTUD lower the outgoing packet size on my system due to the
hotel router's lower MTU or does the hotel router itself fragment my
1500 byte packets in order to send them out? Just curious.
If you are sending out packets with the DF
How is PMTUD enabled/disabled on Gentoo? I've recently been made
aware of the existence of MTU and I'm wondering if mine is set
properly for a cell phone tethered connection.
- Grant
On Tuesday 27 Aug 2013 09:10:39 Grant wrote:
How is PMTUD enabled/disabled on Gentoo? I've recently been made
aware of the existence of MTU and I'm wondering if mine is set
properly for a cell phone tethered connection.
- Grant
# sysctl -A | grep -i pmtu
net.ipv4.ip_no_pmtu_disc = 0
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