Fen Zhou, Miklos Molnar, and Bernard Cousin (2010)
Approximation Ratios of Multicast Light-trees in WDM Networks
In: IEEE Global Telecommunications Conference (GLOBECOM 2010), edited by IEEE, Miami, USA, pages 1-6.
All-optical multicast routing (AOMR) is implemented by the
concept of light-tree in WDM networks. The cost-optimal
multicast light-tree is NP-hard to compute, especially when
taking sparse splitting into account. Thus many heuristic
algorithms have been proposed. In this paper, the
approximation ratios of two classical heuristic AOMR
algorithms for sparse splitting WDM network are studied.
Let K be the number of destinations in a multicast session,
it is proved that Reroute-to-Source (R2S) algorithm
achieves a tight approximation ratio equal to K in the
non-equally-weighted WDM network while Member-Only (MO)
algorithm approaches the optimal solution with a ratio
inferior to (K2+3K)/4 for any WDM network. It is also found
that if the WDM network G is unweighted, both the
approximation ratios of R2S and MO are no bigger than the
diameter of the network Diam(G). Simulation results
illustrate that both R2S and MO obtain good performances in
candidate WDM backbone NSF network, which are far from the
worst cases.