Internet traffic continues to increase rapidly, which makes wavelength division multiplexing (WDM) a vital enabling technology. Although unicast applications still predominate, multicast applications are becoming popular. To effectively support multicast applications, it is necessary to have multicast capability built into WDM networks. In addition, unicast applications could also benefit from the multicast capability of WDM networks.; In this work, we address several critical problems in multicast enabled WDM networks. Our research objective is to utilize multicasting to enhance the quality of service for unicast requests and to effectively support multicast requests. We first investigate the data loss issue due to burst contention in optical burst switched (OBS) networks. We propose a proactive data recovery scheme called burst cloning. The idea is to replicate a burst and send multiple copies of the burst through the network simultaneously. If all copies are not lost, the destination will receive the data for the burst. In this problem, only unicast requests are considered.; Next, we consider the support of multicast in OBS networks. We propose a small group multicast scheme OXcast and a deflection routing scheme for OXcast to reduce data loss due to burst contention. We then develop an analytical model to evaluate the performance of the proposed schemes. The difficulty in modeling results from the outgoing link dependence due to multicast traffic. The model is verified to be accurate by simulation.; We then extend our discussion from multicast to manycast, a generalization of multicast, in OBS networks. We propose two new schemes, static over-provisioning and dynamic membership, to alleviate the data loss problem due to burst contention. The proposed schemes take into consideration the specific properties of manycasting. The effectiveness of the proposed schemes is verified through simulation.; At last, we turn our attention to a multicast problem in wavelength routedWDM networks: online multicast traffic grooming. We develop a multicast dynamic light-tree grooming algorithm (MDTGA) that can support multi-hop traffic grooming. We implement MDTGA on a new auxiliary graph model. Through simulations, we find that MDTGA has much better performance than the lightpath-based algorithm.
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