Comment 4 for bug 1577721

So on compute node restart, nova does hard reboot of all instances on that node which causes corresponding ovs ports to be deleted and recreated. This is normal behavior.

From neutron code I can see that OVS agent has special handling for the case when ovs port was deleted and instantly recreated: it just ignores 'deleted' event, processes port and puts it to ACTIVE state. I was able to reproduce the scenario but didn't hit the bug.
Environment with repro is needed to further debug the issue. Marking as incomplete for now.