[ovirt-users] IP forwarding... Cannot access guest IP

[Dan Kenigsberg]

On Tue, Apr 29, 2014 at 06:33:14AM -0400, richard.seguin at marisec.ca wrote:
> Hi Dan,
> 
> Yes I am an ovirt user.  Basically, I am running into an issue running xen inside of kvm.  Our scenario is that this is lab environment, and we enjoy the luxury of spinning up kvm instances (as opposed to installing on bare metal each time we need something). Our product uses Xen, and we are pretty much stuck with it for the time being.
> 
> I think what I am running into is a double bridge issue... Xen has a bridge, and so does kvm obviously.  I am able to ping dom0 (which is just the bridge itself) on Xen from the outside world, but I am not able to ping udom... and... udom doesn't have access out either.   When I was using vmware, I enabled promisc mode on the virtual switch, and this solution worked fine... 
> 
> If we ignore the types of technology that I am using,  and just focus on the networking, what would I be looking at as possibilities?  Or... a better question would be, does ovirt have a promiscuous flag somewhere that I can set?

I cannot say that I understand your setup, but if you have nested
virtuallization (such as a Xen udom) you may experience ovirt's
no-mac-spoofing rule: by default we disallow our VMs to emit traffic
that has different mac address from the one assigned by oVirt.

To avoid this, follow http://www.ovirt.org/Vdsm_Hooks#Installing_a_hook
and report if that's the issue.