Light-Trail Assignment in WDM Optical Networks

Light-trail has emerged as a promising candidate for enabling IP over WDM networks. The problem of static light-trail assignment is to find a set of light-trails to cover the given traffic demands, such that the total number of light-trails required is minimized. Because of the power loss caused by splitting at each hop, the length of a light-trail is limited. Existing light-trail assignment algorithms adopt ILP (Integer Linear Programming) approach. Due to the high complexity of ILP, such algorithms are not scalable. In this paper, we propose an efficient heuristic algorithm LTA (Light-Trail Assignment) to solve this problem. In LTA, each light-trail is judiciously assigned based on the request discreteness, the shortest path length and the traffic volume of each request. A reference node mechanism is also designed to enhance the solution. Numerical results show that LTA always returns sub-optimal solutions.