LAUSR

This work addresses the problem of dedicated protection of multicast sessions in mixed-graph optical networks, where only a fraction of the nodes have optical splitting capabilities. A novel multicast routing algorithm for sparse splitting optical networks (the Modified Steiner Tree Heuristic [MSTH]) is initially presented and is subsequently utilized (together with two existing heuristics [MUS and MSH]) by an effective scheme for the calculation of a pair of disjoint trees. The key idea of this New Arc-Disjoint Trees (NADT) protection technique is to gradually construct the primary tree, verifying that after the addition of each one of the destinations of the multicast session, a secondary (arc-disjoint) tree can still be obtained. Performance results demonstrate that the proposed NADT protection technique clearly outperforms the conventional Arc-Disjoint Trees (ADT) approach in terms of blocking ratio, while incurring only a negligible increase of the average cost of the derived pair of ADT. Furthermore, it is shown that the newly proposed algorithm, MSTH-NADT, is the one having the best performance in terms of cost and blocking, with MSH-NADT having similar, albeit slightly worse, performance. However, as MSH-NADT requires much less CPU time compared to MSTH-NADT, MSH-NADT can be considered the best compromise technique. © 2017 Wiley Periodicals, Inc. NETWORKS, 2017