cat /home/ovs/clus.xml

<network>
<name>clus</name>
<forward mode='bridge'/>
<bridge name='br64'/>
<virtualport type='openvswitch'/>
</network>

далее

virsh net-define /home/ovs/clus.xml
virsh net-start clus
virsh net-autostart clus
virsh attach-interface --domain VM1 --type network --source clus --model e1000 --persistent