[ovs-discuss] Openswitch VM to VM traffic switching

Praveen Reguraman preguraman at gmail.com
Thu May 13 21:52:23 UTC 2010

Hi Todd,
            I mentioned that librvirt also uses a tap interface and hence,
needs some check related to tun module. I didnt mean that it can support
custom script. Sorry for not being clear on that one.
Thanks for offering to try this out. I shall also keep trying in the
meanwhile and shall keep you posted if I see any positive developments.

On Thu, May 13, 2010 at 1:25 PM, Todd Deshane <deshantm at gmail.com> wrote:

> Hi Praveen,
> Some comments inline.
> On Thu, May 13, 2010 at 4:09 PM, Praveen Reguraman <preguraman at gmail.com>
> wrote:
> > I tried your script and still ran into
> > the same issue. But I think libvirt also uses a similar way of trying to
> > bring the interface up and I had a problem in the creation of the VM
> since
> > it was failing on TAP/TUN interface.
> Last I checked libvirt didn't have support for passing a custom
> qemu-ifup script.
> >Turns out that it started working fine
> > when I installed it in bridge compatible mode and used the brctl
> commands.
> > May be the br_compat.ko brought in the TUN/TAP drivers for the kernel,
> which
> > was probably not there. I had tried 'modprobe tun' and had a fatal error
> > saying 'tun not found'. However, I learned that with Ubuntu Lucid Lynx,
> > module is built into the kernel. Somehow, the whole thing was confusing
> to
> > me when it worked.
> > Should it be that Openvswitch is always in br_compat mode?
> The bridge compatibility mode is only for backwards compatibility.
> > Or Could I use
> > some kind of fake bridge and work this around?
> It is possible to ovs switches (bridges) to work with KVM, but maybe
> it is still non-obvious.
> I'll make an attempt today or tomorrow and try to post a quick howto.
> Todd
> --
> Todd Deshane
> http://todddeshane.net
> http://runningxen.com
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