Minimizing SONET Add‐Drop Multiplexers in optical UPSR networks using the minimum number of wavelengths

Abstract

AbstractIn SONET/WDM optical networks, a high‐speed wavelength channel is usually shared by multiplexed low‐rate network traffic demands. The multiplexing is known as traffic grooming and carried out by SONET Add‐Drop Multiplexers (SADM). The maximum number of low‐rate traffic demands that can be multiplexed into one wavelength is called the grooming factor. Because SADMs are expensive network devices, a key optimization problem in optical network design is to groom a given set of low‐rate traffic demands such that the number of required SADMs is minimized. This optimization problem is challenging and NP‐hard even for Unidirectional Path‐Switched Ring networks with unitary duplex traffic demands. In this article, we propose two linear‐time approximation algorithms for this NP‐hard problem based on a novel graph partitioning approach. Both algorithms achieve better worst case performance than the previous algorithms. We also show that the upper bounds obtained by our algorithms are very close to the lower bounds for some instances. In addition, both of our algorithms use the minimum number of wavelengths, which are precious resources as well in optical networks. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009