Optical networks based on wavelength-division multiplexing (WDM) technology offer the promise to satisfy the bandwidth requirements of the Internet infrastructure, and provide a scalable solution to support the bandwidth needs of future applications in the local and wide areas. In a wavelengthrouted network, an optical channel, referred to as a lightpath, is set up between two network nodes for communication. Using WDM technology, an optical fiber link can support multiple non-overlapping wavelength channels, each of which can be operated at the data rate of 10 Gbps or 40 Gbps today. On the other hand, only a fraction of customers are expected to have a need for such a high bandwidth. Due to the large cost of the optical backbone infrastructure and enormous WDM channel capacity, connection requests with diverse low-speed bandwidth requirements need to be efficiently groomed onto highcapacity wavelength channels. This book investigates the optimized design, provisioning, and performance analysis of traffic-groomable WDM networks, and proposes and evaluates new WDM network architectures. Significant amount of research effort has been devoted to traffic grooming in SONET/WDM ring networks since the current telecom networks are mainly deployed in the form of ring topologies or interconnected rings. As the long-haul backbone networks are evolving to irregular mesh topologies, traffic grooming in optical WDM mesh networks becomes an extremely important and practical research topic for both industry and academia. Chapter 1 gives an overview of traffic grooming in optical WDM network. The remaining chapters focus on traffic grooming in WDM mesh networks only.

In a wavelength-routed WDM network, instead of asking for the capacity of a full wavelength channel, a connection may only require a small fraction of

the wavelength capacity. Chapter 2 investigates the problem of grooming static traffic demands, i.e., a set of pre-known low-speed traffic streams, onto highcapacity lightpaths in a WDM-based optical mesh network. A mathematical formulation of this problem is presented and several connection-provisioning heuristics are also investigated. To address the traffic-grooming problem. Chapter 3 presents a generic graph model, which captures the various capabilities and constraints of a network and which can be applied to both static and dynamic traffic-grooming problems. Based on the graph model, a grooming algorithm is proposed and different grooming policies are compared and evaluated. This graph model forms a principle method for solving traffic-grooming problems and is used and extended throughout the book.