Multicast traffic grooming in wavelength-routed WDM mesh networks using dynamically changing light-trees

In this paper, we address the online multicast traffic grooming problem in wavelength-routed wavelength division multiplexing (WDM) mesh networks with sparse grooming capability. We develop a multicast dynamic light-tree grooming algorithm (MDTGA) that can support multihop traffic grooming by taking advantage of light-trees. In this algorithm, a light-tree can be dropped, branched, and extended when a route is to be established for a new request; a light-tree can also be contracted when some branches carry no effective traffic after requests depart from the network. The difficulty of the algorithm lies in the dynamic characteristic of light-trees. We implement MDTGA on a new auxiliary-graph model. For the purpose of comparison, we also implement a lightpath-based grooming algorithm by putting a constraint on the optical-splitting capability of the nodes. Through extensive simulations, we find that MDTGA has much better performance than the lightpath-based algorithm.