Comment 0 for bug 1916761

With Openstack Ussuri using dvr-snat I do the following:

  * create port P1 with address A1 and create vm on node C1 with this port
  * associate floating ip with P1 and ping it
  * observe REACHABLE arp entry for A1 in qrouter arp cache
  * so far so good
  * restart the neutron-l3-agent
  * observe REACHABLE arp entry for A1 is now PERMANENT
  * delete vm and port
  * create port P2 with address A1 and create vm on node C1 with this port
  * vm is unreachable since arp cache contains PERMANENT entry for old port P1 mac/ip combo

If I don't restart the l3-agent, once I have deleted the port it's arp entry does REACHABLE -> STALE and will either be replaced or timeout as expected but once it is set to PERMANENT it will never disappear which means any future use of that ip address (by a port with a different mac) will not work until that entry is manually deleted.