Hi I am using Libvirt 1.1.2 with Openstack Havana (RC2, nova-network) and openvswitch 1.4.2+git20120612-9.1. Libvirt vif driver ( nova.virt.libvirt.vif.LibvirtGenericVIFDriver) generates config likes this: <interface type='bridge'> <mac address='fa:16:3e:44:30:a4'/> <source bridge='br0'/> <model type='virtio'/> <filterref filter='nova-instance-instance-000003d8-fa163e0b07a7'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> and instance fails to start with: 2013-10-16 11:16:13.004+0000: 11943: info : virNetDevProbeVnetHdr:122 : Enabling IFF_VNET_HDR 2013-10-16 11:16:13.105+0000: 11943: error : virNetDevBridgeAddPort:370 : Unable to add bridge br0 port vnet0: Operation not supported If I add <virtualport type='openvswitch' /> inside <interface type='bridge'>...</interface> it seems to work fine. Is it nova-network or libvirt bug or some misconfiguration? regards -- Maciej Gałkiewicz Shelly Cloud Sp. z o. o., Sysadmin http://shellycloud.com/, macias@shellycloud.com KRS: 0000440358 REGON: 101504426