14. Traffic Grooming

A particular thread of research in optical networking that is concerned with the efficient assignment of traffic demands to available network bandwidth became known as traffic grooming in the mid-1990s. Initially motivated by the distinctly different network characteristics of optical and electronic communication channels, the area focused on how subwavelength traffic components were to be mapped to wavelength communication channels, such that the need to convert traffic back to the electronic domain at intermediate network nodes, for the purpose of differential routing, was minimized. Over time, it broadened to include joint considerations with other network design goals and constraints. It was influenced in turn by existing technology limitations, and in turn served to influence continuing technology trends. Traffic grooming has had a significant effect on both the research and practice of transport networking. It continues to be a meaningful area not just in historical terms, but as a wealth of techniques that can be called upon for considering the traffic engineering problem afresh as each new development at the optical layer, or change in economic realities of networking equipment or traffic requirements, redefines the conditions of that problem.