[ovs-discuss] Multiple OVSs or multiple datapaths with one OVS

[Ben Pfaff]

You can use multiple bridges with 1.10 or later, including master, but
those bridges use a single kernel datapath.

Why do you care whether you use multiple kernel datapaths?

On Fri, Apr 12, 2013 at 02:55:30PM -0700, Aishwarya wrote:
> I am using the master branch which is OVS 1.10 or higher. So does that mean
> I will not be able to test multiple datapaths with a single ovs-vswitchd
> daemon with 1.10 and higher? You answered yes to #2 above? Is this true
> with 1.10 too?
> 
> Thanks.
> 
> 
> On Fri, Apr 12, 2013 at 2:43 PM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > On Fri, Apr 12, 2013 at 02:27:09PM -0700, Aishwarya wrote:
> > > 1) Running 2 OVS user space daemons on the same machine, and creating a
> > > bridge per OVS process.
> > >
> > > 2) Running a single OVS and creating 2 different bridges with the same
> > OVS
> > > process.
> > >
> > > Couple of questions:
> > > 1. Is (1) even supported?
> >
> > It won't work, out of the box, if you use the OVS kernel module.  You
> > might be able to get it to work with some effort, especially if you
> > use the userspace datapath only.
> >
> > > 2. My use case is that I basically want to be able to test with multiple
> > > datapaths on the same machine. With my experimentation, I feel (2) should
> > > satisfy this. Is that true?
> >
> > Yes.
> >
> > > 3. Does a single bridge correspond to a single datapath? If not, what is
> > > the real difference between the concept of a bridge and datapath?
> >
> > A bridge is an Ethernet or OpenFlow concept.  A datapath is an
> > implementation detail.  Before OVS 1.10 there was a one-to-one
> > relationship between bridges and datapaths; in OVS 1.10 and later
> > there is only one datapath even if there are many bridges.
> >