[ovs-dev] OVN and OpenStack Provider Networks

Ben Pfaff blp at nicira.com
Tue Jun 23 21:10:19 UTC 2015


On Tue, Jun 23, 2015 at 04:54:20PM -0400, Russell Bryant wrote:
> On 06/23/2015 04:17 PM, Ben Pfaff wrote:
> > On Mon, Jun 22, 2015 at 02:34:07PM -0400, Russell Bryant wrote:
> >> On 06/15/2015 08:00 PM, Ben Pfaff wrote:
> >>> On Wed, Jun 10, 2015 at 03:13:54PM -0400, Russell Bryant wrote:
> >>>> Provider Networks
> >>>> =================
> >>>>
> >>>> OpenStack Neutron currently has a feature referred to as "provider
> >>>> networks".  This is used as a way to define existing physical networks
> >>>> that you would like to integrate into your environment.
> >>>>
> >>>> In the simplest case, it can be used in environments where they have no
> >>>> interest in tenant networks.  Instead, they want all VMs hooked up
> >>>> directly to a pre-defined network in their environment.  This use case
> >>>> is actually popular for private OpenStack deployments.

[...]

> > I had to read this several times, but maybe I understand it now.  Let me
> > recap for verification.
> > 
> > A "tenant network" is what OVN calls a logical network.  OVN can
> > construct it as an L2-over-L3 overlay with STT or Geneve or whatever.
> > Tenant networks can be connected to physical networks via OVN gateways.
> > 
> > A "provider network" is just a physical L2 network (possibly
> > VLAN-tagged).  In such a network, on the sending side, OVN would rely on
> > normal L2 switching for packets to reach their destinations, and on the
> > receiving side, OVN would not have a reliable way to determine the
> > source of a packet (it would have to infer it from the source MAC).  Is
> > that accurate?
> 
> Yes, all of that matches my understanding of things.
> 
> I worry that not being able to explain it well might mean I don't have
> it all right, so I hope some other Neutron devs chime in to confirm, as
> well.

OK, let's go on then.

Some more recap, on the reason why this would need to be in OVN.  If I'm
following, that's because users are likely to want to have VMs that
connect both to provider networks and to tenant networks on the same
hypervisor, and that means that they need Neutron plugins for each of
those, and there's naturally a reluctance to install the bits for two
different plugins on every hypervisor.  Is that correct?  If it is, then
I'll go back and reread the ideas we had elsewhere in this thread; I'm
better equipped to understand them now.

Thanks,

Ben.



More information about the dev mailing list