I have a Centos 5.5 server with Xen 3.2 and libvirt for virt-manager installed. Before installed libvirt I have the bridge configuration just like the documentation on Xen says:

xenbr0, eth0 and peth0 interfaces.

After installed libvirt my configuration got:

eth0, peth0 and virbr0

So the virbr0 was added instead of xenbr0, I read the documentation and this is a NAT adaptor for libvirt. So in order to get a bridge adaptor I got this guide:


But my peth0 is still up so I presume that xen bridge is still up. Can someone explain me how to proper setup a bridge network interface with Xen and libvirt because with the guide I followed I got a new adaptor called br0 which is the bridge but it has the same MAC address of my eth0 NIC.

I will apreciate any help.


You can specify that bridge in the /etc/xen/xend-config.sxp file.

Look at the line starting with (network-script. For full options of the xen-bridges look at /etc/xen/scripts/network-bridge.

In your case "bridge= and netdev=" should be sufficient.

But this should only be used if you have only one bridge. For anything else it is recommended to use OS-level configurations.

For a very complex setup with bonds, vlan-trunks and more than 4 bridges I wrote my own init-script on SLES10 - since the OS-level configuration files were not able to do what I wanted.

On more current OSes this should be (almost) no problem.

  • Do you have any special ip route setup on the dom0 to allow that the virtual machines can see each other on the same network? I am having trouble with this. – mongaru Aug 1 '12 at 15:56
  • @mongaru no - nothing special. Check if you have firewalls enabled either on Dom0 or on the DomUs... – Nils Aug 1 '12 at 20:39

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