Versatility of a colorless and directionless WSS based ROADM architecture

In core/metro optical networks there are multi-degree nodes providing N path interconnections and alternate paths for protection. This paper presents the optimum implementation of a colorless and directionless add/drop switching feature in a mesh network, using the WSS based ROADM. The idea of scaling, viewed as an increase in route degree and number of wavelengths handled in each direction is then addressed. Subsequently, we suggest the best ways in which specific advantages like dynamically optimizing light paths by optical bridge-and-roll, avoiding O-E-O operations and blocking specific wavelengths can be leveraged. Finally, practical implementation issues like power loss, OSNR and cost considerations are discussed.