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Monitoring firewall service

To maintain high availability, WSMs monitor firewall health status and send packets only to healthy firewalls. There are two methods of firewall service monitoring: ICMP and HTTP. Each WSM monitors the health of the firewalls at scheduled intervals.

If a WSM IP interface fails to respond to a user-specified health check interval, it (and, by implication, the associated firewall), is placed in a Server Failed state. At this time, the partner WSM stops routing traffic to that IP interface and, instead, distributes it across the remaining healthy WSM IP interfaces and firewalls.

When a WSM IP interface is in the Server Failed state, its partner WSM continues to forward health checks at user-defined intervals. After a specified number of successful checks, the IP interface (and its associated firewall) is brought back into service. You can configure the WSM to allow, for example, one-second intervals between health checks or pings, two failed health checks to remove the firewall, and four successful health checks to restore the firewall to the real server group. For more information, see Health Checking.

See also:


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