An efficient algorithm for solving traffic grooming problems in optical networks

We consider the virtual topology and traffic routing (VTTR) problem, a subproblem of traffic grooming that arises as a fundamental network design problem in optical networks. The objective of VTTR is to determine the minimum number of light-paths so as to satisfy a set of traffic demands, and does not take into account physical layer constraints; a routing and wavelength assignment (RWA) algorithm must reconcile the virtual topology obtained by VTTR with the physical topology. We propose an efficient algorithms that uses a partial LP relaxation technique with lazy constraints to improve substantially the scalability of VTTR, and, hence, of traffic grooming. Our approach delivers a desirable tradeoff between running time and quality of solution.