Heuristic and optimal techniques for light-trail assignment in optical ring WDM networks

In this paper we address the problem of constrained optimization (ILP formulation) and propose a set of heuristic algorithms for assigning light-trails [1], [2], [3], [4], [7] and [10] to WDM ring networks to facilitate IP centric dynamic communication at the optical layer. A light-trail is a generalization of a lightpath such that multiple nodes can take part in communication along the path without the need for optical switching. A light-trail represents an opportunistic medium in which multiple spatially distributed sub-lambda flows can be groomed despite without the need for optical switching. A light-trail is analogous to an optical bus such that multiple connections between source–destination pairs can be provisioned under the constraint that no two connections have overlapping time-intervals. This enables traffic grooming at the optical layer. In this paper we first describe a constrained optimization procedure for assigning light-trails in WDM ring networks. We then show five heuristic algorithms that solve the light-trail assignment problem in polynomial time. The heuristic algorithms are based on dynamic (unknown traffic) and static (known traffic) approaches. A simulation study compares the performance of ILP and heuristic algorithms.