Efficient reconfiguration of logical topologies: Multiobjective design algorithm and adaptation policy

Communication networks are facing continuous variations of traffic patterns as well as occasional failures of network equipment. Wavelength-routed optical networks (WRONs) offer the possibility of dynamically adapting to traffic conditions by means of reconfiguring the logical topology, that is, the set of lightpaths embedded in it. However, reconfiguration has a cost, the number of packets lost during the reconfiguration process. Hence, it is necessary to use efficient reconfiguration policies and algorithms to design the logical topologies. In this paper, a new algorithm is proposed to design logical topologies that jointly minimizes the number of lightpaths changed (reconfiguration cost) and the network congestion (reconfiguration reward). This method is based on the combination of genetic algorithms with Pareto optimality techniques. Thus, the algorithm provides a set of optimal (or near-optimal) solutions in terms of both parameters, the Pareto optimal set. Moreover, a novel policy to minimize the packet loss ratio considering all the solutions provided by the algorithm is also proposed. A simulation study is presented to show how the combination of the new algorithm and policy can reduce in more than one order of magnitude the packet loss ratio in stationary state and respond to abrupt changes in less time when compared with previous work on logical topology reconfiguration.