[libvirt] libvirt, XEN, bridged network and arp

[Daniel P. Berrange]

On Fri, Aug 01, 2008 at 12:21:53PM +0200, Christoph H?ger wrote:
> Hi,
> 
> Ive got a severe networking problem over here: When I boot up my machine
> (debian lenny) using virsh 0.4.4 on an debian etch, a new virtual eth
> device (something like vif97.0) is assigned to that machine and that
> device is attached to my bridge virbr1. That is fine. Not so fine is the
> fact, that no arp packages come over to my bridge for about 5 seconds or
> so.
> During that time I can see a lot of arp-who-has on vifXX.0 but nothing
> on virbr1 so there are no answers and the result is my guest machine not
> mounting nfs directories on boot.
> After some time (e.g. after login) networking works fine - but thats
> definitely too late - I need those directories mounted on boot.

There is a bug in the libvirt default networking - even though the
network is configured with a forward delay of 0, we're not setting
the forward delay. So the kernel default applies which is 15 seconds.
If you explicitly edit the default network config in /etc/libvirt/
to set fd=1 attribute on the <bridge> tag, it'll work-around the
problem. I'm in process of fixing it to honour a fd=0 which is what
we intended to have & broke a few releases back without realizing.

Daniel
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