The firewalls use hello message and heartbeats to verify that the peer device 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 device. The heartbeat is an
ICMP ping to the HA peer over the control link, and the peer responds to the ping to
establish that the devices are connected and responsive. For details on the HA timers
that trigger a failover, see HA Timers. (The HA timers for the CN-Series firewall are the same as that of
the PA-5200 Series firewalls).