A computer network includes an inside network and an external network. The
inside network may communicate with the external network over a first
path through a first inner load balancer, a first set of firewalls, and a
second outer load balancer. The inside network may also communicate with
the external network over a second path through a second inner load
balancer, a second set of firewalls, and a second outer load balancer. In
normal operating conditions, traffic is flowing on both the first and
second paths. Probes are passed over each path to monitor the operating
status of the path. If a failure occurs in the first inner load balancer,
its operating status is changed to standby and the second inner load
balancer becomes active for the traffic previously handled by the first
inner load balancer. The associated first outer load balancer,
recognizing that a probe has not been received to indicate an operating
state of the first path, changes its state to standby so that the second
outer load balancer becomes active for the traffic previously handled by
the first outer load balancer.