Dynamic hierarchical multicast routing with delay-bandwidth constraints

In order to solve the scalability problem of QoS routing in large networks, large networks are structured hierarchically by grouping router nodes into different domains. Routing algorithms based on hierarchical networks are investigated and become one of the most effective solutions for the scalability problem. The authors conduct a comprehensive study on dynamic hierarchical multicast routing with delay-bandwidth constraints based on PNNI hierarchical network model in this paper. A novel topology aggregation method, Stair method, has been proposed in the authors' previous work, which is the first step for hierarchical routing and in which two QoS parameters (delay and bandwidth) are considered. On this basis, the authors further study the Multicast Tree State Information (MTSI) that tree nodes need to maintain for multicast routing and the aggregation problem of internal MTSI of a domain. Pseudo Tree Border Node (PTBN) mode for MTSI aggregation is then proposed in this paper. Finally Delay-Bandwidth constrained Hierarchical Multicast Routing (DBHMR) algorithm using aggregated topology information and multicast tree state information is designed, which supports group members to join and leave multicast group dynamically. Simulation results show that the whole routing system achieves large compression of topology information and multicast tree state information not only stored in but also exchanged by nodes and at the same time gains the similar route efficiency compared with the flat network. Scalable multicast routing in large networks is realized eventually in this paper.