On the design problem of multitechnology networks

In this article we propose a model for the topological design problem of mu ltitechnology networks that includes the location of switches and their por t configuration, the design of an access network (with single and double ac cess links) and a backbone network. The model specifically takes into accou nt different types of modular switches where each type is characterized by its cost, its capacity in terms of the number of slots, and by its switch f abric capacity. The mutitechnology qualifier stems from the fact that sever al technologies and rates can be used in the access network. The proposed m odel is of the integer-programming variety, and in order to find a good sol ution, we propose a starting heuristic that provides an initial solution an d the tabu-search algorithm to improve the solution. Lower bounds are propo sed and used to assess the performance of the tabu-based approach. Numerica l results for randomly generated problems with up to 500 clients and 50 pot ential switch sites are presented. The tabu-search algorithm produced solut ions that were, on average, within 2.11% of the best lower bound.