Maximizing Throughput for Traffic Grooming with Limited Grooming Resources

In SONET/WDM networks, low-rate traffic demands are usually multiplexed to share a high-speed wavelength channel. The multiplexing/de-multiplexing is known as traffic grooming and performed by SONET add-drop multiplexers (SADM). The grooming factor, denoted by k, is the maximum number of low-rate traffic demands that can be multiplexed into one wavelength channel. SADMs are expensive and thus a critical optimization problem for traffic grooming is to maximize the number of accommodated traffic demands subject to a given number of SADMs. In this paper, we focus on the unidirectional path-switched ring (UPSR) networks with unitary duplex traffic demands. We assume that each network node is equipped with a limited number L of SADMs, and our objective is to maximize the throughput for a given set of traffic demands. We prove the NP-hardness of this Maximum Throughput traffic grooming problem, and propose a (k+1)-approximation algorithm. Extensive simulations are conducted to validate the performance of the algorithm. We also study the case that the given set of traffic demands is the all-to-all set. We propose an algorithm which accommodates at least (nL|radick|)/2 traffic demands, and prove that an optimal solution can accommodate at most nLradick/radic2 traffic demands for the all-to-all set on a UPSR network of n nodes. The solution of our algorithm is at most a constant factor (about radic2) away from the optimal solution.