Current Series Release Notes

4.3.0

New Features

• Added support for os-vif to pre-create TAP devices when using OVS/OVN. The VIFPortProfileOpenVSwitch object now supports two new fields:

  • create_tap: When set to True, os-vif will create the TAP device with the correct MAC address and MTU before adding it to OVS.

  • multiqueue: When set to True along with create_tap, the TAP device will be created with multiqueue support enabled for improved performance with multiple vCPUs. The multiqueue setting is determined by Nova from the hw:vif_multiqueue_enabled flavor extra spec or image property.

  When the [ovn]/ovs_create_tap config option is enabled in Neutron’s ML2/OVN mechanism driver, Neutron sets the ovs_create_tap flag in the vif_details during port binding. Nova then reads this value and propagates it to os-vif via the create_tap field, and configures libvirt with managed="no" so it uses the pre-created TAP device. This reduces live migration downtime by ensuring the network is fully wired before the VM starts.

  See bug 2069718.