The role of the wideband digital cross-connect system in survivable ring networks

The wideband digital cross-connect system (W-DCS) plays a crucial role in support of the dual-node interconnected ring, whether the interconnected rings are unidirectional path switched self-healing rings or bidirectional line switched rings. The authors describe the functionality of the W-DCS in both unidirectional and bidirectional interconnected rings, and compare the economics of W-DCS and non-W-DCS approaches. A general model for a survivable network is presented. The model is based on specific metropolitan applications that network providers are currently satisfying. Next, four possible solutions to the survivable network problem are presented. The four solutions illustrate the use of both unidirectional and bidirectional dual-node interconnected rings and illustrate functions that can be performed by the W-DCS to reduce equipment and fiber costs significantly. The economics of the four solutions for different transport ring capacity requirements is examined. In general, the most cost-effective solution is one that utilizes a bidirectional transport ring with a W-DCS to groom and protect several access loops. The two-fiber bidirectional transport ring/W-DCS implementation is the most cost-effective solution if it can provide enough bandwidth to meet the capacity requirements of the transport ring. If additional bandwidth is required, the four-fiber bidirectional ring/W-DCS solution should be implemented