Protection in multi-granular waveband networks [optical WDM systems]

As the number wavelengths in WDM systems continue to increase, the switching fabric of optical cross connects (OXCs.) becomes increasingly complex. This complexity can be reduced by introducing multi-granular OXCs (MG-OXC) into the network. An MG-OXCs is capable of switching an entire group of wavelengths through a single switch port, thereby reducing the number of switching ports and reducing the complexity of the switch fabric. In this paper, we consider the problem of establishing active and backup paths for connections in networks with MG-OXCs. The problem of establishing protected connections for a given traffic demand in MG networks differs from the protection problem in standard wavelength-routed networks in that the primary objective in MG networks is to minimize the number of switch ports in the network. The mode of protection (dedicated or shared) affects the ability to aggregate and route traffic together. We propose a graph-based heuristic that attempts to solve the problem of routing and waveband assignment in an integrated manner. The heuristic reduces the total number of ports in the MG network. We also study the effect of shared protection on the port count.