Minimizing the Number of ADMsWith and Without Traffic Grooming: Complexity and Approximability

A relatively new optimization criterion in studies of optical networks is that of minimizing the total number of ADMs. In these networks each given lightpath uses one ADM device at each of its two endpoints, and it is assigned a color, so that at most g lightpaths of the same color can share an edge. Lightpaths of the same color that share an endpoint can use a common ADM at that endpoint. We discuss some recent theoretical results concerning the complexity and approximability of this optimization problem, for the basic case where traffic grooming is not allowed (g = 1), and for the general case of traffic grooming (g > 1)