Some studies on the logical topology design of large multi-hop optical networks

Abstract

Existing approaches for logical topology design and routing for multi-hop optical networks become intractable for large networks. One approach is to treat the logical topology design problem separately from the routing problem which can be solved as a LP problem. The straightforward formulation of the LP problem has been reported but this is also feasible only for relatively smaller networks since the basis size for the simplex method is O(n(superscript 3)) where n is the number of nodes in the network. In this paper, by exploiting the special structure of the routing problem, we present an efficient column generation scheme embedded into the revised simplex method. This approach makes it feasible to handle networks with relatively large number of nodes. To study the approach experimentally we have used a number of traffic based heuristics for generating the logical topologies. These include a variation of the well known HLDA heuristic and two simple traffic based heuristics to generate logical topologies based on regular graphs. Many researchers feel that regular graphs are not well suited for wide area optical networks. The interesting result is that logical topologies based on regular graphs perform quite well compared to others. This suggests that it is useful to consider regular graphs as possible topologies for wide area networks and should be included as potential candidates for large wide area networks.