Traffic Grooming in WDM Networks

The recent emergence of wavelength-division multiplexing technology has led to a tremendous increase in the available transmission capacity in wide area networks. Consequently, these networks may no longer be limited by transmission bandwidth, but rather by the processing capability of electronic switches, routers, and multiplexers in the network. This realization has led to a new wave of research aimed at overcoming the electronic bottleneck by providing optical bypass at the WDM layer. Traffic grooming can be used as a bypass mechanism by which low-rate circuits are assigned to wavelengths in order to minimize the amount of electronic multiplexing equipment. Recently, this topic has received a significant amount of attention in both the research and commercial arenas. In this article we give an overview of the traffic grooming problem and survey some representative work in this area. While most recent work has focused on grooming in SONET rings, grooming traffic in general mesh networks is an important emerging problem.