Chassis-Application Monitoring
Chassis-application health monitoring is always enabled. The Firepower 4100/9300 chassis supervisor checks the Firewall Threat Defense application periodically (every second). If the Firewall Threat Defense device is up and cannot communicate with the Firepower 4100/9300 chassis supervisor for 3 seconds, the Firewall Threat Defense device generates a syslog message and leaves the cluster.
If the Firepower 4100/9300 chassis supervisor cannot communicate with the application after 45 seconds, it reloads the Firewall Threat Defense device. If the Firewall Threat Defense device cannot communicate with the supervisor, it removes itself from the cluster.