6. Photonic Network Architectures II: Wavelength Arbitration and Routing

Wavelength-routed networks use individual wavelengths which can be statically or dynamically allocated to source-destination pairs using combinations of modulators, filters, and waveguides. Wavelength-routed networks use wavelength selectivity in order to route data through the network, in contrast to circuit-switched networks which utilize wavelength selectivity for bandwidth aggregation. The wavelength arbitration technique limits the point-to-point bandwidth to a subset of the total number of wavelengths available in the system. This chapter considers architectures where each point-to-point link is composed of a single wavelength channel (unless specified) for simplicity of discussion. This assumption is true of most wavelength-routed networks that have been proposed in literature. These architectures typically exhibit lower latencies than circuit-switched architectures since they do not require the path-setup protocol. Fundamentally, the latency of wavelength-routed networks is only limited by the speed of light and the time required to perform CDR. This chapter describes some of the fundamental building blocks of wavelength-routed architectures and explores some examples of architectures that have been proposed.