Abstract: The performance requirements of application layer multicast are not identical in different business areas, and the network environment is more complex as follows: the multicast node is diversified, the communication channel is complex, the node scale is large, the amount of data is magnified and so on. The multicast programs should be optimized by analyzing the existing application layer multicast and combining new applications demands. By analyzing the evaluating indicator of application layer multicast, application layer multicast optimization method would be divided into the coding features optimization, the hierarchical clustering optimization, the node performance optimization, the optimal parent selection optimization and the routing information maintenance optimization. Through comparing the performance indicators of different types of optimization methods, the applicable environments were introduced separately, and further research directions were discussed finally.

Key words: application layer multicast, coding features optimization, hierarchical clustering optimization, node performance optimization, distribution efficiency

摘要： 应用层组播在不同业务领域的性能要求不完全相同，而应用层组播的网络环境也更加复杂，如：组播节点多元化、通信信道复杂化、节点规模庞大化、数据通信量扩大化等，因此需要结合已有应用层组播技术，针对特定业务的优化目标，对组播方案进行优化改进。通过分析应用层组播评价指标，将应用层组播优化方法分为编码特性优化、分层分簇优化、节点性能优化、选择最优父节点优化、路由信息维护优化，比较了不同类型优化方法的性能指标，给出了各自的适用环境，最后讨论了进一步的研究方向。

关键词: 应用层组播, 编码特性优化, 分层分簇优化, 节点性能优化, 分发效率