Efficient fault-tolerant routing in multihop optical WDM networks

This paper addresses the problem of efficient routing in unreliable multiho p optical networks supported by Wavelength Division Multiplexing (WDM). We first define a new cost model for routing in (optical) WDM networks that is more general than the existing models. Our model takes into consideration not only the cost of wavelength access and conversion but also the delay fo r queuing signals arriving at different input channels that share the same output channel at the same node. We then propose a set of efficient algorit hms in a reliable WDM network on the new cost model for each of the three m ost important communication patterns-multiple point-to-point routing, multi cast, and multiple multicast. Finally, we show how to obtain a set of effic ient algorithms in an unreliable WDM network with up to f faulty optical ch annels and wavelength conversion gates. Our strategy is to first enhance th e physical paths constructed by the algorithms for reliable networks to ens ure success of fault-tolerant routing, and then to route among the enhanced paths to establish a set of fault-free physical routes to complete the cor responding routing request for each of the communication patterns.