Avoidance of multicast incapable branching nodes for multicast routing in WDM networks

Abstract

In this paper, we study the multicast routing problem in all-optical WDM network under the spare light splitting constraint. To implement a multicast session, several light-trees may have to be used due to limited fanouts of network nodes. Although many multicast routing algorithms have been proposed in order to reduce the total number of wavelength channels used (total cost) for a multicast 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 always taken into consideration. As we know, the shortest path tree results in the optimal delay, but it can not be employed directly for multicast routing in sparse splitting WDM networks. Hence, we propose a novel wavelength routing algorithm, which tries to avoid the multicast incapable branching nodes (MIB, branching nodes without splitting capability) in the shortest path based multicast tree to diminish the link stress and maintains good parts of the shortest path tree to reduce the end-to-end delay. The given algorithm consists of tree steps: (1)DijkstraPro algorithm with priority assignment and node adoption is intro- duced to produce a shortest path tree with up to 38% fewer MIB nodes in NSF topology and 46% fewer MIB nodes in USA Longhual Topology. (2)critical articulation and deepest branch heuristics are used to process the MIB nodes, (3)distance based reconnection algorithm is proposed to create the multicast light-trees. Extensive simulations demontrate its efficiency in terms of link stress and end-to-end delay.

Cost Bounds and Approximation Ratios of Multicast Light-Trees in WDM Networks

“…Hence, here we do not mean to verify the accuracy of the proposed bounds and approximation ratios. Instead, the numerical results are used to show the quality of the resultant light-trees when applying the Member-Only and the Reroute-to-Source algorithms in some popular candidate WDM backbone networks like 14 nodes NSF network [10] and 28 nodes USA Longhaul network [10].…”

Cost Bounds of Multicast Light-Trees in WDM Networks

“…Although many light-tree computation heuristics have been proposed in recent works [3,9,10,11], no literature has addressed the cost bound of multicast lighttrees in sparse splitting WDM networks, let alone the approximation of the light-trees built by heuristics towards the optimal solution. Since the wavelength channel cost is a very important metric for the selection of the multicast lighttrees, it is very interesting and imperative to know at least the cost bound of the light-trees, which could be referenced when designing a WDM network.…”

Multicast Routing in Optical Access Networks

“…Three typical post processing methods namely Re-route-to-Source, Re-route-toAny (Zhang, Wei, & Qiao, 2000) and Avoidanceof-MIB-Nodes (Zhou, Molnár & Cousin, 2008a) will be discussed in the following with some illustrative examples.…”

“…(b) The multicast tree built by Re-route-to-Any. (Zhou et al, 2008a) (Zhou et al, 2008a) capability constraint on the optical nodes. It begins to build the multicast tree from the source and includes the destination nodes one by one.…”