Publication

Abstract : This article presents a systemic method to generate and map an optimal virtual topology onto a certain physical wide area optical fiber network so as to maximize the scaleup which provides an estimate of the network throughput. The problem is to find the best possible virtual topology over a given wavelength-routed all-optical physical topology for wide area coverage. The physical topology consists of wavelength-routing nodes interconnected by fiber links in the network. The virtual topology consists of a set of lightpaths. For a given physical topology and traffic matrix, our objective is to maximize the throughput as well as to minimize the delay. We have also studied the scalability of various parameters, such as queuing delay, propagation delay and average-hop-distance, with increase in throughput. We present a heuristic algorithm for embedding a virtual topology to the given physical fiber network when the number of wavelength channels supported on each fiber is limited. A number of feasible virtual topologies are generated randomly using Prufer number method, and the optimum one is selected. The problem being computationally intractable, we use genetic algorithm (GA)for optimization. As GAs are expected to converge to globally optimal solutions, the proposed approach yields better solutions than previous ones. As a result of immense practical importance of the issues addressed in this work, the algorithms are expected to be significant for practitioners.