Why I did it
A race condition exists while the TPH is processing a netlink message - if a second netlink message arrives during processing it will be missed since TPH is not listening for other messages.
Another bug was found where TPH was unnecessarily restarting since it was checking admin status instead of operational status of portchannels.
How I did it
Subscribe to APPL_DB for updates on LAG operational state
Track currently sniffed interfaces
How to verify it
Send tunnel packets with destination IP of an unresolved neighbor, verify that ping commands are run
Shut down a portchannel interface, verify that sniffer does not restart
Send tunnel packets, verify ping commands are still run
Bring up portchannel interface, verify that sniffer restarts
Signed-off-by: Lawrence Lee <lawlee@microsoft.com>