Comment 1 for bug 1901707

I started digesting the linked bug and stuff referred from there and I find it surprisingly complex. Could we re-state the piece of the problem you want to separate here, to help somebody take this bug? I don't want to be dense, but I usually find that re-stating a problem in shorter, simpler way helps solving it.

Is this problem present on master?

Is this dependent on nova using the multiple bindings feature? (I guess yes, because the nova side of that was merged in rocky.)

Is this specific to who plugs the port on the destination host: libvirt and/or os-vif? If yes, which one?

Could we have steps to reproduce this? I get this a race, so the reproduction probably won't be 100%. I also get firewall_driver=iptables_hybrid and live_migration_wait_for_vif_plug=true (default value) is needed. Is there anything else needed to reproduce this bug?

For what it's worth these are the current triggers for neutron to send os-server-external-events to nova:
https://opendev.org/openstack/neutron/src/commit/cbaa328f2ba80ba0af33f43887a040cdd08e508b/neutron/notifiers/nova.py#L102-L103

I believe the first (and currently only) notification neutron sends is needed and used, so we should not change whether or when that is sent. Is this understanding correct?

Do you believe there should be a 2nd notification sent from neutron to nova? If yes, at what time (triggered by what) should it be sent?