An Algorithm Based on Directed Graph

Aiming at constructing a delay and delay variation bounded Steiner tree in the real-time streaming media communication, we discuss in this paper a multicast routing algorithm based on searching a directed graph (MRASDH).In the construction of the multicast tree, there always exist some nodes and links in the network topology that do not affect the outcome of the tree constructed. Therefore, based on the principle to shrink the search space by deleting these nonrelative nodes and edges to the utmost, and utilizing the ant algorithm, this algorithm generates for each destination node a directed sub-graph of the network topology, in which each node owns a bounded out-degree, and then merges all these sub-graphs into a new directed graph, which serves as the new search space. After these, the algorithm applies the simulated annealing algorithm on the new space for the optimization, and can finally obtain a multicast tree satisfying the constraints. The performance analysis and simulation results have demonstrated that this algorithm can effectively construct a multicast tree with the delay and delay variation constraints while presenting a lower time complexity than the current ones, which means a much better result would be achieved when the system scale rises greatly.