Virtual topologies for multicasting with multiple originators in WDM networks

In this paper, we consider the problem of multicasting with multiple originators in WDM optical networks. In this problem, we are given a set S of source nodes and a set D of destination nodes in a network. All source nodes are capable of providing data to any destination node. Our objective is to find a virtual topology in the WDM network which satisfies given constraints on available resources and is optimal with respect to minimizing the maximum hop distance. Although the corresponding decision problem is NP-complete in general, we give polynomial time algorithms for the cases of unidirectional paths and rings.