Broadcasting topology information in the Survivable Signaling Network

The authors describe the broadcast algorithm used in the Survivable Signaling Network (SSN). SSN provides the Nationwide Emergency Telecommunications System (NETS) a highly survivable and robust network for national security emergency preparedness calls being set up over AT&T Switched Network. SSN achieves this high survivability and robustness through the application of broadcast algorithms to disseminate network status and to ultimately determine the routing of signaling traffic. The SSN broadcast algorithm is based on the Arpanet broadcast algorithm. However, the long node and link recovery times inherent in the Arpanet algorithm are intolerable in telephone signaling. The SSN algorithm extends the Arpanet algorithm to provide a rapid recovery from node and link crashes. It accomplishes this in a simple fashion consistent with the Arpanet algorithm