摘要： 为降低多播组的维护开销、改善多播树的负载平衡，提出一种考虑节点优先级的方法，并将该方法应用于Zigzag协议。该协议采用分层分簇的思想，由簇首节点负责管理本簇而由父节点负责分发数据。因为考虑到节点的异构性，该协议使能力强的节点担当首节点与父节点以提高多播组性能。通过实验验证与理论推导得出，与Zigzag 协议相比，改进后的协议在新节点加入多播组时，开销大大减小，节点退出时开销也相应减小，而多播树的负载平衡也有所改善。

关键词: 应用层多播, 优先级, 异构

Abstract: In order to reduce maintenance overhead of multicast group and improve load balancing of multicast tree, the paper introduces a method of taking node priority into consideration and applies the method to Zigzag protocol. The Zigzag protocol adopts the machinery of hierarchy and cluster, and the head peer of a cluster takes charge of administrating the cluster while the father peer takes charge of distributing data. Due to the node isomerism, the protocol chooses high priority node as dead peer and father peer to increase the performance of multicast group. Through theoretic deduction and simulation experiments, the overhead of improved protocol decreases greatly when a new client joins and when a client departs. The protocol also improves load balancing of multicast tree.

Key words: Application Layer Multicast(ALM), priority, isomerism

中图分类号: 

• TP393.02