Design of stacked self-healing rings using a genetic algorithm

Ring structures in telecommunications are taking on increasing importance because of their ‘self-healing’ properties. We consider a ring design problem in which several stacked self-healing rings follow the same route, and, thus, pass through the same set of nodes. Traffic can be exchanged among these stacked rings at a designated hub node. Each non-hub node may be connected to multiple rings. It is necessary to determine to which rings each node should be connected, and how traffic should be routed on the rings. The objective is to optimize the trade-off between the costs for connecting nodes to rings and the costs for routing demand on multiple rings. We describe a genetic algorithm that finds heuristic solutions for this problem. The initial generation of solutions includes randomly generated solutions, complemented by ‘seed’ solutions obtained by applying a greedy randomized adaptive search procedure to two related problems. Subsequent generations are created by recombining pairs of ‘parent’ solutions. Computational experiments compare the genetic algorithm with a commercial integer-programming package.