Optimal regenerator placement for path protection in impairment-aware WDM networks

This paper addresses the regenerator placement problem (RPP) when designing resilient, impairment aware WDM optical networks. For the RPP, we have proposed two solutions; an optimal solution for small networks (less than 10 nodes) and a near-optimal heuristic solution for practical-sized networks. The optimal solution uses an Integer Linear Program which can be implemented by any solver for mathematical programming. The heuristic makes use of an approach, proposed in a recent paper, that requires a formulation involving an exponential number of constraints. It was shown in that paper that this formulation can be solved very efficiently using a branch-and-cut algorithm and that the approach may be used to design resilient networks which guarantees restoration. In this paper we have shown that this branch-and-cut approach may be used as a part of a highly efficient heuristic which gave optimal results in an overwhelming number of cases that we tested.