The HA peers use hello messages and heartbeats to verify
that the peer is responsive and operational. Hello messages are
sent from one peer to the other at the configured Hello Interval
to verify the state of the other. The heartbeat is an ICMP ping
to the HA peer, and the peer responds to the ping to establish that
the peers are connected and responsive. By default, the interval
is 1,000 milliseconds for the heartbeat and 8,000ms for hello messages.