Minimum-Cost Multicast Routing for Multi-Layered Multimedia Distribution

In this paper, we attempt to solve the problem of min-cost multicast routing for multi-layered multimedia distribution. More specifically, for (i) a given network topology (ii) the destinations of a multicast group and (iii) the bandwidth requirement of each destination, we attempt to find a feasible routing solution to minimize the cost of a multicast tree for multi- layered multimedia distribution. This problem has been proved to be NP-hard. We propose two adjustment procedures, namely: the tie breaking procedure and the drop-and-add procedure to enhance the solution quality of the modified T-M heuristic. We also formally model this problem as an optimization problem and apply the Lagrangean relaxation method and the subgradient method to solve the problem. Computational experiments are performed on regular networks, random networks, and scale-free networks. According to the experiment results, the Lagrangean based heuristic can achieve up to 23.23% improvement compared to the M-T-M heuristic.