Traffic grooming in WDM ring networks to minimize the maximum electronic port cost

Abstract— We consider the problem of traffic grooming in WDM ring networks. Traffic grooming is a variant of the wellknown logical topology design problem, and is concerned with the development of techniques for combining low speed traffic components onto high speed channels in order to minimize network cost. Previous studies have focused on aggregate representations of the network cost. In this work, we consider a Min-Max objective, in which it is desirable to minimize the cost at the node where this cost is maximum. Such an objective is of high practical value when dimensioning a network for unknown future traffic demands and/or for dynamic traffic scenarios. We present new theoretical results which demonstrate that traffic grooming with the Min-Max objective is NP-Complete even when wavelength assignment is not an issue. We also present a new polynomial-time traffic grooming algorithm for minimizing the maximum electronic port cost in both uniand bi-directional rings. We evaluate our algorithm through experiments with a wide range of problem instances, by varying the network size, number of wavelengths, traffic load, and traffic pattern. Our results indicate that our algorithm produces solutions which are always close to the optimal and/or the lower bound, and which scale well to large network sizes, large number of wavelengths, and high loads. We also demonstrate that, despite its focus on minimizing the maximum cost, our algorithm also performs well in terms of the aggregate electronic port cost over all ring nodes.