In Wavelength division multiplexing (WDM) networks using wavelength routing are considered to be potential candidates for the next generation backbone network. As the demand of multicast streaming over the WDM network is increased, the light-tree which is a point-to-multipornt extension of a light-path is introduced to support all-optical multicasting. In this paper, we study the problem of constructing light-tree under sparse splitting optical network to meet the quality of service requirement of interactive real-time application. In particular, we assume that interactive real-time application at the WDM network depends on 1) bounded delay along the paths from the source to each destination, 2) bounded variation among the delays along these paths, and 3) the optical signal quality. To support all-optical multicasting, nodes in the WDM network need to have the light splitting capability. Since the splitting operation induces the loss of optical signal power, we have to consider the power of optical signal to ensure a certain level of quality. In order to ensure an adequate signal quality and to scale to large destination sets, light-tree should be as balanced as possible. However, the problem of determining such a constrained tree is NP-complete. Therefore, we propose heuristic algorithm that demonstrates good behavior of average case in terms of the maximum inter-destination delay variation while trying to ensure signal quality. The experiment results show that the proposed algorithm can construct light-tree which meets the above requirements.
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