[openstack-dev] [nova][neutron] bridge name generator for vif plugging

Ian Wells ijw.ubuntu at cack.org.uk
Mon Dec 15 10:15:56 UTC 2014

Hey Ryota,

A better way of describing it would be that the bridge name is, at present,
generated in *both* Nova *and* Neutron, and the VIF type semantics define
how it's calculated.  I think you're right that in both cases it would make
more sense for Neutron to tell Nova what the connection endpoint was going
to be rather than have Nova calculate it independently.  I'm not sure that
that necessarily requires two blueprints, and you don't have a spec there
at the moment, which is a problem because the Neutron spec deadline is upon
us, but the idea's a good one.  (You might get away without a Neutron spec,
since the change to Neutron to add the information should be small and
backward compatible, but that's not something I can make judgement on.)

If we changed this, then your options are to make new plugging types where
the name is exchanged rather than calculated or use the old plugging types
and provide (from Neutron) and use if provided (in Nova) the name.  You'd
need to think carefully about upgrade scenarios to make sure that changing
version on either side is going to work.

VIF_TYPE_TAP, while somewhat different in its focus, is also moving in the
same direction of having a more logical interface between Nova and
Neutron.  That plus this points that we should have VIF_TYPE_TAP handing
over the TAP device name to use, and similarly create a VIF_TYPE_BRIDGE
(passing bridge name) and slightly modify VIF_TYPE_VHOSTUSER before it gets
established (to add the socket name).

Did you have any thoughts on how the metadata should be stored on the port?

On 15 December 2014 at 10:01, Ryota Mibu <r-mibu at cq.jp.nec.com> wrote:
> Hi all,
> We are proposing a change to move bridge name generator (creating bridge
> name from net-id or reading integration bridge name from nova.conf) from
> Nova to Neutron. The followings are BPs in Nova and Neutron.
>     https://blueprints.launchpad.net/nova/+spec/neutron-vif-bridge-details
>     https://blueprints.launchpad.net/neutron/+spec/vif-plugging-metadata
> I'd like to get your comments on this change whether this is relevant
> direction. I found related comment in Nova code [3] and guess these
> discussion had in context of vif-plugging and port-binding, but I'm not
> sure there was consensus about bridge name.
> https://github.com/openstack/nova/blob/2014.2/nova/network/neutronv2/api.py#L1298-1299
> Thanks,
> Ryota
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