A zoom-in approach to design SDH mesh restorable networks

Mesh restorable networks based on SONET (Synchronous Optical Network, stand ard optical transmission technology widely accepted and implemented in Nort h America) or SDH (Synchronous Digital Hierarchy, the European standard cur rently adopted by the major European telecom operators) are an economically attractive solution in areas where high demand and high connectivity are i nvolved (Wu, 1995). In these networks, the reconfiguration capability of th e digital cross connect systems (DCS) allows to reroute the demand affected by network failures. The degree of sharing of spare capacity in networks b ased on this architecture is high. This paper presents a heuristic algorithm for solving the near-optimal desi gn of SDH mesh-type link restorable networks, i.e. determining the network topology and assigning the capacity to transport the demand in normal situa tions and to allow full link restorability in case of single link failures. The algorithm is based on a Zoom-In technique, a novel approach which form s a compromise between sequential and integrated techniques. The different building blocks of the algorithm are tested extensively and compared with o ther results mentioned in literature. Comparison of the simulation results for the overall design problem with other solution techniques indicates tha t the Zoom-In method is a quite promising approach, able to combine the acc uracy of integrated approaches with the calculation speed of sequential app roaches.