Xena Series Release Notes

2.6.0

Bug Fixes

• The os-vif OVS plugin now supports using per-port OVS bridges when hybrid plug is not used. This is disabled by default and can be enabled by defining [os_vif_ovs]/per_port_bridge=True in the compute service nova.conf. This capability should only be enabled if you are deploying with ml2/ovn and experience packet loss during live migrations. This is not supported on windows or when using ironic smartnic ports. This option was introduced to address bug: #1933517. When using OVN as a network backend OVN requires the OVS interface to both have an ofport-id and the neutron port uuid defined in the external_ids field. When the port is plugged if [os_vif_ovs]/per_port_bridge is not enabled then the OVS port will not be assigned an openflow port id until the tap device is created on the host. On loaded system with many flows and ports it can take a few second for OVN to detect the creation of the tap device and install the correct flows. During that interval packets can be dropped. When [os_vif_ovs]/per_port_bridge is enabled, os-vif will add the VM tap device to a new bridge that is connected to the integration bridge via a patch port. This enables OVN to install the openflow rules on the integration bridge before the tap is created reducing the possibility for packet loss during a live migration. By default per port bridges are disabled and this feature is considered experimental, however it will likely be enabled by default in the future after we gain experience with how this bridge topology scales in larger deployments.