A Scalable Solution to Network Design Problems: Decomposition with Exhaustive Routing Search

Many network design problems encompass two tasks, routing and resource allocation, that are so intricately intertwined as to contribute significantly to the intractability of such problems. In this paper, we make two contributions to addressing general network design problems of this nature. First, we present a new decomposition method that optimally decouples resource allocation from routing, making it possible to tackle each of these aspects separately. Second, we develop a recursive branch-and-bound algorithm to search the routing space exhaustively, yet in a scalable manner. We apply our method to a well-known intractable problem in optical networks, routing and spectrum assignment (RSA). Our results indicate that the recursive algorithm is able to search efficiently the entire routing space of topologies representative of large-scale wide area networks.