QoS-Constrained Multicast Routing

Multicast services have been increasing used by various applications in Internet for their more resources-efficient, lower operating load of servers and lower traffic loads. Recent studies focused on the QoS-driven multicast routing, which is one of the key techniques to supporting multimedia applications. The rational and effective multicast routing algorithms and protocols are very important to network performance. This thesis addresses four aspects of multicast routing in computer networks.1. One network model with asymmetric links was established by research of quality of service(QoS)-guaranteed multicast routing problems. And we designed a function ((t) to reflect the routing algorithms' ability in balancing traffic load in networks. With the aim of balancing network loads, we presented a new multicast routing genetic algorithm based bandwidth and delay constraints (BDMGA). The convergence analysis and simulation results over random networks show that BDMGA achieves its good performance in balancing traffic, which could avoid link blocking and enhance the network behavior efficiently. Moreover, the proposed algorithm can generate multicast tree with lower cost in any networks and can also achieve optimal multicast tree rapidly in small network. 2. Based on the proposed QoS-constrained multicast routing protocols, we presented and verified a new multiple QoS constrained multicast routing protocol (MQMP). A unicast routing protocol was used in MQMP. And MQMP applied two ways, local search and multicast tree search, to find more than one candidate paths for a new member. All candidate paths can meet the applications' QoS requirements. MQMP can improve the success rate for the new member joining and decrease resources expense. A method in MQMP was designed to guarantee that the multicast trees are loop-free. And this method also can optimize the cost of multicast trees. 3. Group multicasting is a kind of communication mechanism whereby each member of a group sends messages to all the other members of the same group. It is more important for group multicast routing algorithms to manage the network resources efficiently and satisfy the QoS requirements of each individual application. We built a new metric Bdf(v), which is a function of available bandwidth and delay of link. We also proposed two routing algorithms for group multicast with end-to-end delay bound -- DCGMA1 and DCGMA2. The simulation results show that the algorithms have advantages in the overall network cost of routing trees, in the traffic load balancing, and in the number of successful found solutions. 4. For every router in computer networks is not identical in ability for multicasting, we considered degree-constrained multicast routing problem. We presented three degree-constrained multicast routing algorithms with QoS bounded -- BCGA based on genetic algorithm, BSPTA based on Dijkstra's algorithm and BMSTA based on TM Steiner tree algorithm. The performances of three algorithms were analyzed through the simulations.