Just had an (in my sense) obscure situation.
I have a Xen Server with bridged networking. Everything works fine since month. A while ago i configuresd a second bridge. only some DomUs get an channel on this bridge - my Dom0 doesn't need to / should'nt use this bridge. So just 5 minutes ago while rebooting the xen host (because of an other problem with the UPS) i decided to removed the fixed ip from the the interface of the Dom0 which belongs to the second bridge. So after reboot i noticed that none of the interfaces on the second bridge is available. I couldn't find a problem. Everything was just like before the reboot, except the interface of the Dom0 had no IP address.
After a while i tried to give the DomO interface of this bridge an IP again and ... BOOM ... everything is up and running again!
WTF? Why is it important to have the interface of a bridge configured in the Dom0? Even when confiugured 'wrong' (complitely different netowkr settings as the network really hanging on the bridge) everythjing works fine ... I don't get it. Could please someone explain?
Tnaks a lot!