Optical restoration at the wavelength-multiplex-section level in WDM mesh networks

In the presence of rapidly growing demand, long-haul multiwavelength lightwave networks face the increasingly critical task of not only transporting large traffic volumes, but also of restoring them in the event of failures. This may be naturally done in two distinct ways: by rerouting individual wavelengths (wavelength-paths), or by rerouting full bundles of multiplexed wavelengths (wavelength-multiplex sections). We here evaluate the prospects for restoration at the wavelength-multiplex-scction level in national-scale long-haul wavelength-division-multiplexed mesh networks. The approach is found to offer the potential of substantial economic benefits, given current transponder costs. These benefits will largely vanish, however, if transponder costs decline by an order of magnitude.