8 Chapter - WDM Network Design

Abstract

This chapter discusses the design of wavelength-routing networks. There is a clear benefit to building wavelength-routing networks, as opposed to simple point-to-point wavelength division multiplexing (WDM) links. The main benefit is that traffic that is not to be terminated within a node can be passed through by the node, resulting in significant savings in higher-layer terminating equipment. The design of these networks is more complicated than the design of traditional networks. It includes the design of the higher-layer topology (IP or SONET), which is the light-path topology design problem, and its realization in the optical layer, which is the routing and wavelength assignment problem. This chapter also discusses the wavelength-dimensioning problem. The problem here is to provide sufficient capacity on the links of the wavelength-routing network to handle the expected demand for lightpaths. This problem is solved today by periodically forecasting a traffic matrix and (re)designing the network to support the forecasted matrix. Alternatively, statistical traffic demand models can be employed to estimate the required capacities; two such models are discussed in this chapter.