Optimal design of logical topologies in wavelength-routed optical networks with multicast traffic

In this paper we discuss the optimal design of logical topologies in wavelength-routed WDM networks supporting unicast and multicast transfer of IP datagrams. We first explain the key aspects of the problem, emphasizing the fact that in IP networks the routing algorithms are an input to the optimization problem, not an optimization target. We then provide a mixed integer linear programming formulation of the optimization problem., which however leads to unacceptably high complexity for networks of non-trivially small size. We then propose both greedy and metaheuristic approaches for the sub-optimal design of logical topologies with acceptable complexity. Finally, we derive lower bounds that allow the assessment of the performance of the proposed algorithms. Some numerical results indicate that the proposed metaheuristics largely outperform the greedy approaches, and are able to obtain very good logical topologies.