[Openstack-operators] Neutron and linuxbridge

Édouard Thuleau thuleau at gmail.com
Mon Feb 17 08:20:25 UTC 2014

Hi Joe,

Which version of the Linux kernel do you use? Do you need to set multicast
on your fabric?

We worked in Havana to improve the overlay propagation on the fabric and we
made a mechanism driver for the ML2 plugin called 'l2-pop' (one bug still
persist on H [1]). Did you use it?

In my opinion, the LB agent with VXLAN is very simpler (no flows, kernel
integrated, 1 bridge = 1 network, netfilter aware...) and as effective than
OVS agent. And I think, it's more stable than OVS.
The only one inconvenient, it needs for the moment, a recent Linux kernel
(and iproute2 binaries, obviously). I recommend the release 3.11 (version
distributed with Ubuntu LTS 12.04.4 actually) to have all the powerful of
the VXLAN module (edge replication for multicast, broadacst and unknown
unicast). Some distributions backport that module on older kernel (like
RedHat, it seems to me).

Another improvement, a local ARP responder (to avoid ARP broadcasting
emulation overlay which is costly) is available with VXLAN module and
recent iproute2 version and the l2-pop MD uses it, while the OVS agent
doesn't yet support it [2]. Just a remark, when it's used, unknown unicast
(packets where destination does not match entry in fdb populated by the
l2-pop MD) are drop by default (it's not configurable. A kernel an iproute2
improvement needed).

In my opinion, the default agent that OpenStack CI should use for testing
must be the LB agent. I think it's more stable and easy to debug.

[1] https://review.openstack.org/#/c/71821/
[2] https://review.openstack.org/#/c/49227/


On Sat, Feb 15, 2014 at 12:39 PM, Joe Topjian <joe at topjian.net> wrote:

> Hello,
> I'm curious if anyone uses the linuxbridge driver in production?
> I've just finished setting up a lab environment using ML2, linuxbridge,
> and vxlan and everything works just as it did with OVS.
> I see benefits of a *much* simpler network layout, a non-deprecated vif
> driver, and none of the OVS issues that have been discussed on this list.
> But maybe I'm missing something... what are the reasons of using OVS over
> linuxbridge? All of the official installation guides use it and I've never
> seen anyone mention linuxbridge on this list.
> Joe
> _______________________________________________
> OpenStack-operators mailing list
> OpenStack-operators at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
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