Comment 1 for bug 1822884

This scenario doesn't really make sense to me:

1. RDO -> RDO use the old flow (only one entry in the ml2_port_bindings table at all times)

Because if the RDO nodes are running Rocky code, they should hit this in the live migration task in the conductor service:

https://github.com/openstack/nova/blob/stable/rocky/nova/conductor/tasks/live_migrate.py#L282

Which enables the new flow if:

1. The neutron "Port Bindings Extended" API extension is available
2. Both the source and target nova-compute service versions in the "services" table in the cell database are version >= 35, which if you're running Rocky everywhere should be the case, but you said you have some RDO computes that are still Queens.

So I'd double check that first.