Primary and secondary route selection in backbone communication networks

This paper addresses the problem of selecting primary and secondary routes for every pair of communicating nodes in a backbone communication network. A primary route and a secondary route constitute a route pair. A route pair is selected from among all possible route pairs in the network. The secondary route is link-disjoint from the primary route. A nonlinear integer mathematical programming model to minimize the mean delay faced by messages is developed. The model captures situations where a single link failure would divert traffic to the appropriate secondary routes. A solution procedure based on a relaxation of the problem is presented. Computational results indicate that the procedure is very effective.