Preplanned recovery with redundant multicast trees in optical networks

In this paper, we investigate the problem of Preplanned Recovery with Redundant Multicast Trees (PRRMT) in optical networks. The redundant trees ensure the source node remains connected to all destination nodes for a multicast session request under single edge failures. Our objective is to minimize the total number of links used for both trees. We formulate PRRMT as an integer linear program (ILP), and also develop a heuristic algorithm. The ILP approach and heuristic algorithm are experimentally evaluated on 14-node NSFNET and 21-node Italian network. Experimental results show that: (1) ILP approach leads to optimal solutions but requires prohibitively long time, (2) Our heuristic algorithm yields optimal or near-optimal results in very short time, and (3) The edge-disjoint trees can protect the transmission for an edge failure.