[libvirt] Problem in attaching a interface to a domain

Hello, I am facing problems in creating a network bridge using libvirt. My requirement is, i need to create a bridge on the host machine. The bridge shd get ip address from dhcp server(instead of static). I am not getting what exactly the xml format that virsh is looking for? I am using the following xml for creating a bridge. <network> <name>local</name> <bridge name="virbr1" /> <source dev="eth1"/> <mac address="00:11:22:33:44:55"/> </network> The bridge is getting created but not with the specified device and mac address. Bridge is not getting ip address at all. Can you please tell me the xml format for my requirement? Thanks.