Reroute Strategies for Fault Tolerant Packet Switching Networks

Packet switching virtual circuit networks can respond to internal trunk failures by rerouting calls in progress around the failure. The reroute may be effected at the network edges (Source Reroute) or at the nodes terminating the failed trunk (Local Reroute). The objective is to reconnect active calls fast enough to prevent premature session disconnects (end-user timeout). A key component of the total reconnect delay is the time to detect the failure. A trunk failure can be detected locally by monitoring error rates at the data link level. Failure detection at the network edges can be done via explicit signaling from the local nodes (after local detection).