中文摘要：

在分析现有三个版本组成员管理IGMP的基础上，对多播路由器的组成员管理提出一种新的扩充策略．该策略认为多播路由器查询或主机报告物理子网中没有多播组成员存在，不是立即向上端路由器发送剪枝信息，而是根据该物理子网与多播组的上下文关系延迟发送剪枝信息。这样可以避免当很快可能有主机加入该多播组时再重新发送加入信息．这种机制能够减少由于物理子网成员的减少或增加引起路由器的剪枝而带来的代价，可以减少组成员维护的代价．用Petri网对策略进行了描述与论证，分析表明该策略下多播路由器的状态变换是活的以及循环的，多播路由器可以有效地节省总的代价．

英文摘要：

According to three existing IGMPs, a new management policy ot dynamic multicast group members was given which extended the multicast group management protocol on the multicast router. In this policy, when the router find that the group had no local members or no reports were received from the local physical network, it will delay sending prune branch in[ormation to up-level multicast routers based on the relationship between the local network and the multicast group, rather than immediately sending pruning information to up-level multicast touters and stopping transmitting data grams to its directly attached physical network. This mechanism might decrease the costs of frequently sending prune branch information and broadcast membership information because of multicast group members frequent leaving and joining. The simulation of Petri Net showed the new policy was alive and recurrence. It was from the cost analysis seen that this policy was efficient in managing multicast group members.