支持时延-带宽约束的动态层次组播路由

Dynamic Hierarchical Multicast Routing with Delay-Bandwidth Constraints

层次网络及层次路由成为解决大规模网络QoS路由可扩展性问题的一个主要手段.文中对PNNI层次网络模型下的时延-带宽多QoS约束的动态组播路由问题进行了全面研究:在已提出支持时延-带宽约束的拓扑聚集算法(Stair)的基础上,进一步对组播树节点需维护的组播树状态信息及其聚集问题进行研究,并提出"伪树上边界节点"模式的域内组播树状态信息的聚集方法,最后设计了基于聚集拓扑信息和组播树状态信息的动态层次组播路由算法.仿真结果显示,该路由不仅大量压缩了存储和扩散的拓扑信息和组播树状态信息,同时还保持了与平面网络近似的路由效率,实现了大规模网络情况下组播路由的扩展.

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.