In this articlewestudy themulticast routing problem in all-opticalWDMnetworksunder the spare light splitting constraint. To implement a multicast session,several light-trees may have to be used due to the limited fanouts of networknodes. Although many multicast routing algorithms have been proposed in orderto reduce the total number of wavelength channels used (total cost) for amulticast session, the maximum number of wavelengths required in one fiber link(link stress) and the end-to-end delay are two parameters which are not alwaystaken into consideration. It is known that the shortest path tree (SPT) resultsin the optimal end-to-end delay, but it can not be employed directly formulticast routing in sparse light splitting WDM networks. Hence, we propose anovel wavelength routing algorithm which tries to avoid the multicast incapablebranching nodes (MIBs, branching nodes without splitting capability) in theshortest-path-based multicast tree to diminish the link stress. Good parts ofthe shortest-path-tree are retained by the algorithm to reduce the end-to-enddelay. The algorithm consists of tree steps: (1) aDijkstraPro algorithmwithpriority assignment and node adoption is introduced to produce a SPT with up to38% fewer MIB nodes in the NSF topology and 46% fewerMIB nodes in the USALonghaul topology, (2) critical articulation and deepest branch heuristics areused to process the MIB nodes, (3) a distance-based light-tree reconnectionalgorithm is proposed to create the multicast light-trees. Extensivesimulations demonstrate the algorithm's efficiency in terms of link stress andend-to-end delay.
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