[libvirt] Xen: How to describe bridged network adapter in libvirt-XML?

Hi, I'm looking for a solution to convert the Xen configuration line vif = ["bridge=eth0"] to the libvirt XML description format which can be used by the createLinux() function (using Python). I tried several things like <interface type="bridge"> <source bridge="eth0" /> <target dev="eth0" /> <mac address="aa:00:00:00:00:12" /> <script path="/etc/xen/scripts/vif-bridge" /> </interface> but they didn't work. Everytime I start up the guest using libvirt, no virtual network device is created (= there's no "vifXX.0" when running "brctl show"). It works perfectly with the Xen configuration line mentioned above. Hope you can help me with that. Best regards, Andreas