O problema da reconfiguração nas redes WDM multifibras

Abstract

An optical telecommunication network is configured to transmit a given traffic in order to meet a given objective. However the demand changes with time and infrastructure development. The reconfiguration problem stands in this context. It consists in being able to alter the configuration of the network to adjust it to the new traffic. It is generally necessary to interrupt partially or totally the traffic to reconfigure a network. Considering the amount of data flowing on it, it may not be possible to regularly stop the network, even for a short amount of time. Many parameters have to be taken into account to find out a good solution, and many metrics can be used in order to measure the quality of a solution.In a first part, we focus on the reconfiguration problem as a ono-objectiveoptimization problem. We propose a mathematical model representing the reconfiguration problem. However solving exactly the proposed model may require a high computational time. We also propose a greedy and a simulated annealing heuristics. Depending on the metric optimized, the solutions have different characteristics. The greedy algorithm is fast and provides decent solutions whereas the simulated annealing algorithm provides solutions competing with the optimal ones.In a second part, we focus on the multiobjective aspect of the reconfiguration problem. We consider at the same time different metrics and search for a set of solutions representing different interesting trade-offs instead of a unique solution. We propose an algorithm based on our mathematical formulation. We also adapt an evolutionary algorithm. The proposed methods succeed in finding different interesting trade-offs. Giving a little flexibility with respect to a metric generally allows to significantly improve the solutions with respect to the other metrics.