Distributed Circuit Control for the DCS

Processor-controlled time slot interchange equipments now in production for commercial applications could provide the cross-connect switching element of a Distributed Circuit Control (DCC) capability for a digital Defense Communications System (DCS). Real time automated rerouting of circuits around wartime damage could be effected by employing a routing algorithm implemented in software to generate channel cross-connect instructions for the time slot interchange hardware. Three candidate algorithms, designed originally for call or packet routing, were modified for routing and rerouting end-to-end dedicated circuits under the constraints of the National Communications System (NCS) restoration priority system. This paper focuses on the network modeling effort that was undertaken to provide quantitative data to support a comparative evaluation of the candidate algorithms. Predicted performance data are presented for the modified algorithms applied to a set of symmetric networks and operated in both allocation (routing) and trunk-fail (rerouting) modes. Parameters measured included circuit reroute time, quality of the routes, stability of the algorithm, network resources required, and processor sizing.