[libvirt-users] how to start virbr0-nic when start NAT network virbr0

[Laine Stump]

On 04/14/2013 09:56 PM, yue wrote:
> in my case  each ethernet must in UP status  even it is a NAT network
> where is the point  i can start its virt-ethernet when i start  a
> NAT-network?

I've discussed this with (who I *think* is) the author of this email on
irc, but just in case anyone in the future does a search for
"virbr0-nic", the short answer is this: ignore the virbr*-nic
interfaces, pretend they don't exist; they are an implementation detail
whose purpose is only to provide the libvirt network's bridge device
with a stable MAC address. They never pass any traffic and they don't
have any useful information that isn't available elsewhere.

If you're really interested in the "why" of this, look at the first bug
report for a description of the problem caused by *not* setting a stable
MAC address on the bridge, and the 2nd for all the followup (including
pointers to the upstream patches that added the -nic tap devices):

https://bugzilla.redhat.com/show_bug.cgi?id=560994
https://bugzilla.redhat.com/show_bug.cgi?id=609463