Xen bridge missing after SLES upgrade

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Environment

SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 11 sp1
SUSE Linux Enterprise Server 11 sp2
Xen

Situation

After completing an upgrade, a rare issue with a misconfigured Xen bridge can occur. The result is the lack of networking, or the inability for Xen to start.

Resolution

To solve this issue, you can utilize one of the following solutions:

Automated Correction

Start Yast
Choose the virtulization section
Utilize the Install Hypervisor utility

Manual Correction

Confirm the Xen bridge doesn't exist and that none of the bridge interface names conflict with standard network card names (such as eth0)

brctl show

Remove any incorrect / unused bridges

brctl delbr BRIDGENAME

Create a new Xen bridge (xenbr0 is the default bridge name)

brctl addbr xenbr0

Notice: At this point we will lose network connectivity.
Replace eth0 below with the interface that the Xen domU virtual machines should be communicating from.
Add the public interface to the xenbr0 bridge.

brctl addif xenbr0 eth0

At this point, you will need to migrate any network settings from eth0 to the new xenbr0. For example, if eth0 obtained its IP address over DHCP, you will need to configure xenbr0 for DHCP. eth0 shouldn't have an IP address going forward. You can use Yast here to configure the network interfaces.

Cause

The cause is not completely understood at this time, however it seems related to end-user customizations to Xen.

Disclaimer

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