Optimizing Reserve Capacities of Partially Equipped SDH Networks

When a failure occurs on some edge of a telecommunication network, the amount of traac going through this edge has to be rerouted on some reserve paths. This leads to the restoration problem which consists in determining minimum cost spare capacities to be used for rerouting purposes. We consider here a special case due to the introduction of digital cross-connects in some of the nodes of the network. Such equipment allows automatic rerouting and then rerouting by nodes with cross-connect is imposed if possible. We propose a model formulation and we show that the problem can be solved with heuristics developed for the basic restoration problem when they are applied to a suitably deened auxiliary graph. These algorithms are then improved and good approximate solutions are obtained for real-size instances.