Waveband switching in optical networks

The rapid advances in dense wave length-division multiplexing technology with hundreds of wavelengths per fiber and worldwide fiber deployment have brought about a tremendous increase in the size (i.e., number of ports) of photonic cross-connects, as well as in the cost and difficulty associated with controlling such large cross-connects. Waveband Switching (WBS) has attracted attention for its practical importance in reducing the port count, associated control complexity, and cost of photonic cross-connects. In this article we show that WBS is different from traditional wavelength routing, and thus techniques developed for wavelength-routed networks (including, for example, those for traffic grooming) cannot be directly applied to effectively address WBS-related problems. We describe two multigranular OXC architectures for WBS. By using the multilayer MG-OXC in conjunction with intelligent WBS algorithms for both static and dynamic traffic, we show that one can achieve considerable savings in the port count. We also present various WBS schemes and lightpath grouping strategies, and discuss issues related to waveband conversion and failure recovery in WBS networks.