Regenerator Cost Optimization in Path Networks With Traffic Grooming∗

In optical networks regenerators have to be placed on lightpaths in order to regenerate the signal. In addition, grooming enables the use of the same regenerator by several lightpaths. In this work we consider the problem of minimizing the number of regenerators used in traffic grooming in optical networks. We focus on networks with path topology and on the case in which a regenerator has to be placed at every internal node of each lightpath. Up to g (the grooming factor) lightpaths can use the same regenerator. In graph theoretic terms the problem is to partition a given set of paths into subsets such that in each subset each edge of the underlying graph is used by at most g paths so that the total cost is minimum. The cost of each subset is the number of intermediate nodes of the subgraph it spans. We give off-line and on-line algorithms and lower bounds for general instances and also some specific families of input instances. Topics: Algorithms and data structures, Current challenges (optic network)