[ovs-dev] another provider network idea (was: [RFC] ovn: physical network integraiton (WIP))

[Ben Pfaff]

Please don't drop the list.

On Tue, Jul 14, 2015 at 11:24:36AM -0400, Aaron Conole wrote:
> On Tue, Jul 14, 2015 at 07:59:48AM -0700, Ben Pfaff wrote:
> > I think that the various issues with trying to treat a provider network
> > as a logical network are going to difficult to resolve.  I think that
> > they reflect a conceptual difference between OVN logical networks and
> > provider networks.  OVN knows the hosts on a logical network and where
> > they reside, but it doesn't know that for a provider network, and can't
> > do anything related to specific hosts except in the pathological case
> > where they reside on the same hypervisor.  Broadcast may be a problem,
> > but so is a simple output to any port: it's impossible unless the source
> > and destination ports are on the same hypervisor.  So my thought is that
> > modeling a provider network as an OVN logical network is unlikely to be
> > fruitful (unless we change the OVN logical network model significantly).
> > 
> > Here's an a strawman alternative.  Instead of representing a provider
> > network as a single logical network, represent it as a collection of
> > logical networks, one for each connected port.  Each of these logical
> > networks has only two ports, the VM's port plus a physical port on the
> > hypervisor where the VM resides (or more likely a patch port to the
> > bridge that contains the physical port; the other end of the patch port
> > can be an access port if it's a VLAN provider network).  It seems to me
> > that this models the situation more naturally.
> > 
> > Thoughts?
> 
> If I'm reading this correctly, it sounds as though OVS treats physical ports 
> as a single L2 segment; contrasted with a real switch where each port would be
> it's own L2 segment (and as a consequence, it's own logical L2 network). Is my
> analogy correct?

I don't understand the question.