4.2 VM Network Degradation When Using VxLANs

When you use VxLANs for virtual machine traffic (the default), there may be performance degredation of up to 40% of the virtual machine network traffic between compute nodes. This is due to the libvirt driver not supporting the multiqueue feature, and the default OpenStack MTU setting of 1500 being set too low. This is a known upstream bug in OpenStack. For information on this OpenStack upstream bug, see:

https://bugs.launchpad.net/neutron/+bug/1419069

Bug: 22109298