Re: [openstack-dev] [qa] Should it be allowed to attach 2 interfaces from the same subnet to a VM?

2014-12-02 Thread Steve Gordon
- Original Message -
 From: Danny Choi (dannchoi) dannc...@cisco.com
 To: openstack-dev@lists.openstack.org
 
 Hi,
 
 When I attach 2 interfaces from the same subnet to a VM, there is no error
 returned and
 both interfaces come up.
 
 lab@tme211:/opt/stack/logs$ nova interface-attach --net-id
 e38dba4a-74ed-4312-ba21-2a04b5c5a5b5 cirros-1
 
 lab@tme211:/opt/stack/logs$ nova list
 
 +--+--+++-+---+
 
 | ID   | Name | Status | Task State |
 | Power State | Networks  |
 
 +--+--+++-+---+
 
 | 9d88d0b5-2453-4657-8058-987980ec7744 | cirros-1 | ACTIVE | -  |
 | Running | private=10.0.0.10 |
 
 +--+--+++-+---+
 
 lab@tme211:/opt/stack/logs$ nova interface-attach --net-id
 e38dba4a-74ed-4312-ba21-2a04b5c5a5b5 cirros-1
 
 lab@tme211:/opt/stack/logs$ nova list
 
 +--+--+++-+--+
 
 | ID   | Name | Status | Task State |
 | Power State | Networks |
 
 +--+--+++-+--+
 
 | 9d88d0b5-2453-4657-8058-987980ec7744 | cirros-1 | ACTIVE | -  |
 | Running | private=10.0.0.10, 10.0.0.11 |
 
 +--+--+++-+--+
 
 
 $ ifconfig
 
 eth0  Link encap:Ethernet  HWaddr FA:16:3E:92:2D:2B
 
   inet addr:10.0.0.10  Bcast:10.0.0.255  Mask:255.255.255.0
 
   inet6 addr: fe80::f816:3eff:fe92:2d2b/64 Scope:Link
 
   UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
 
   RX packets:514 errors:0 dropped:0 overruns:0 frame:0
 
   TX packets:307 errors:0 dropped:0 overruns:0 carrier:0
 
   collisions:0 txqueuelen:1000
 
   RX bytes:48342 (47.2 KiB)  TX bytes:41750 (40.7 KiB)
 
 
 eth1  Link encap:Ethernet  HWaddr FA:16:3E:EF:55:BC
 
   inet addr:10.0.0.11  Bcast:10.0.0.255  Mask:255.255.255.0
 
   inet6 addr: fe80::f816:3eff:feef:55bc/64 Scope:Link
 
   UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
 
   RX packets:49 errors:0 dropped:0 overruns:0 frame:0
 
   TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
 
   collisions:0 txqueuelen:1000
 
   RX bytes:3556 (3.4 KiB)  TX bytes:1120 (1.0 KiB)
 
 
 
 Should this operation be allowed?

Support for this was explicitly added in Juno:

https://blueprints.launchpad.net/nova/+spec/multiple-if-1-net

Do you have a concrete reason in mind as to why this should *not* be allowed?

Thanks,

Steve

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Re: [openstack-dev] [qa] Should it be allowed to attach 2 interfaces from the same subnet to a VM?

2014-12-02 Thread Danny Choi (dannchoi)
Hi Andrea,

Though both interfaces come up, only one will response to the ping from the 
neutron router.
When I disable it, then the second one will response to ping.
So it looks like only one interface is useful at a time.

My question is is there any useful case for this, I.e. Why would you do this?

Thanks,
Danny


Date: Tue, 2 Dec 2014 10:44:57 +
From: Andrea Frittoli 
andrea.fritt...@gmail.commailto:andrea.fritt...@gmail.com
To: OpenStack Development Mailing List (not for usage questions)
openstack-dev@lists.openstack.orgmailto:openstack-dev@lists.openstack.org
Subject: Re: [openstack-dev] [qa] Should it be allowed to attach 2
interfaces from the same subnet to a VM?
Message-ID:
cab7wygv4+ji-tj5jkvg98kw0hxot8zlnuk+nzvjywfdijio...@mail.gmail.commailto:cab7wygv4+ji-tj5jkvg98kw0hxot8zlnuk+nzvjywfdijio...@mail.gmail.com
Content-Type: text/plain; charset=UTF-8

Hello Danny,

I think so. Any special concern with a VM using more than one port on a subnet?

andrea

On 2 December 2014 at 02:04, Danny Choi (dannchoi) 
dannc...@cisco.commailto:dannc...@cisco.com wrote:
Hi,

When I attach 2 interfaces from the same subnet to a VM, there is no error
returned and
both interfaces come up.

lab@tme211:/opt/stack/logs$ nova interface-attach --net-id
e38dba4a-74ed-4312-ba21-2a04b5c5a5b5 cirros-1

lab@tme211:/opt/stack/logs$ nova list

+--+--+++-+---+

| ID   | Name | Status | Task State |
Power State | Networks  |

+--+--+++-+---+

| 9d88d0b5-2453-4657-8058-987980ec7744 | cirros-1 | ACTIVE | -  |
Running | private=10.0.0.10 |

+--+--+++-+---+

lab@tme211:/opt/stack/logs$ nova interface-attach --net-id
e38dba4a-74ed-4312-ba21-2a04b5c5a5b5 cirros-1

lab@tme211:/opt/stack/logs$ nova list

+--+--+++-+--+

| ID   | Name | Status | Task State |
Power State | Networks |

+--+--+++-+--+

| 9d88d0b5-2453-4657-8058-987980ec7744 | cirros-1 | ACTIVE | -  |
Running | private=10.0.0.10, 10.0.0.11 |

+--+--+++-+--+


$ ifconfig

eth0  Link encap:Ethernet  HWaddr FA:16:3E:92:2D:2B

   inet addr:10.0.0.10  Bcast:10.0.0.255  Mask:255.255.255.0

   inet6 addr: fe80::f816:3eff:fe92:2d2b/64 Scope:Link

   UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

   RX packets:514 errors:0 dropped:0 overruns:0 frame:0

   TX packets:307 errors:0 dropped:0 overruns:0 carrier:0

   collisions:0 txqueuelen:1000

   RX bytes:48342 (47.2 KiB)  TX bytes:41750 (40.7 KiB)


eth1  Link encap:Ethernet  HWaddr FA:16:3E:EF:55:BC

   inet addr:10.0.0.11  Bcast:10.0.0.255  Mask:255.255.255.0

   inet6 addr: fe80::f816:3eff:feef:55bc/64 Scope:Link

   UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

   RX packets:49 errors:0 dropped:0 overruns:0 frame:0

   TX packets:8 errors:0 dropped:0 overruns:0 carrier:0

   collisions:0 txqueuelen:1000

   RX bytes:3556 (3.4 KiB)  TX bytes:1120 (1.0 KiB)



Should this operation be allowed?


Thanks,

Danny


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Re: [openstack-dev] [qa] Should it be allowed to attach 2 interfaces from the same subnet to a VM?

2014-12-02 Thread Steve Gordon
- Original Message -
 From: Danny Choi (dannchoi) dannc...@cisco.com
 To: openstack-dev@lists.openstack.org
 
 Hi Andrea,
 
 Though both interfaces come up, only one will response to the ping from the
 neutron router.
 When I disable it, then the second one will response to ping.
 So it looks like only one interface is useful at a time.
 
 My question is is there any useful case for this, I.e. Why would you do this?
 
 Thanks,
 Danny

The rationale is given in the spec 
(http://specs.openstack.org/openstack/nova-specs/specs/juno/implemented/nfv-multiple-if-1-net.html)
 as:


NFV functions occasionally require multiple interfaces to be attached to a 
single network from the same VM, for reasons described below in the ‘use cases’ 
section. When this is required, the VNF generally cannot be used under 
Openstack.

VNFs are often large, complex pieces of code, and may be supplied by third 
parties. For various reasons, it is not uncommon that it is necessary to feed 
traffic out of an interface and into another interface (when the VNF implements 
multiple functions and the functions cannot be chained internally) or to feed 
traffic from e.g. the internet into multiple interfaces to run them through 
separate processing functions internally.

The limitation can be seen as one of the VNF. Clearly, the VNF could be changed 
to put multiple addresses or functions on a single port (to fix the incoming 
traffic issue) or to connect functions internally (to fix the passthrough 
problem.

The problem with this solution is that the timescale for getting such a fix is 
often prohibitive. VNFs are large, complex pieces of code, and often the 
supplier of the VNF is not the same organisation as that trying to use the VNF 
within Openstack, necessitating a feature change request which may well not be 
possible within reasonable timescales.

We propose changing the code within Nova to remove this limitation.


-Steve

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Re: [openstack-dev] [qa] Should it be allowed to attach 2 interfaces from the same subnet to a VM?

2014-12-02 Thread Clint Byrum
Excerpts from Danny Choi (dannchoi)'s message of 2014-12-02 08:34:07 -0800:
 Hi Andrea,
 
 Though both interfaces come up, only one will response to the ping from the 
 neutron router.
 When I disable it, then the second one will response to ping.
 So it looks like only one interface is useful at a time.
 

I believe both interfaces can be used independently by setting
arp_announce to 1 or 2. As in:

sysctl -w net.ipv4.conf.all.arp_announce=2

Might want to try both settings. The documentation is here:

https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt

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