A Tool to dimension optimal Traffic Aggregation in Transport Networks of Reconfigurable Optical ADD/DROP Multiplexers

Wavelength Division Multiplexing (WDM in the following) is now established as a successful technique to provide high bandwidth for backbones, metropolitan and local area networks. But optical networks must be more easily configured and managed to meet the performance requirements. Indeed, future optical networks will also require that the WDM layer delivers advanced functionalities such as dynamic reconfigurability, automatic wavelength provisioning and a reconfigurable bandwidth between sources and destinations. For this reason Reconfigurable Optical Add and Drop Multiplexer (ROADM) appears as a practical solution for cost-effective advanced optical networks and multiple architectures for ROADM has emerged in the last years (see for instance Tang and Alan Shore (2006) and Shankar et al. (2007) and references therein). Briefly a ROADM can be viewed as a device consisting in three parts: a demultiplexer, a multiplexer and optical Wavelength Selective Switch (WSS in the following) sandwiched in between (see Fig. 1). Here we denote as a channel a wavelength on a particular link. The first f channels entering the ROADM are in transit and they do not functionally enter the optical WSS (they may however physically enter the switch to be optically regenerated but this is out of the scope of our paper). The remaining channels enter the WSS where they are switched.