P2P视频会议系统中的媒体流组播树的生成与维护

Construction and Maintenance of the Multicast Tree for a P2P Video-conferencing System

P2P的技术把视频会议服务器的功能分散到客户端,从而解决视频会议系统中存在的网络和系统资源瓶颈问题。本文综合利用P2P技术和传统视频会议的优点,提出一种有中心管理服务器的P2P视频会议系统结构,并对节点间的数据交互和控制机制进行了研究。根据当前的Internet跨网段间不支持IP层组播的实际情况,提出在局域网内采用IP组播、在子网间采用单播的应用层组播方式进行媒体流传输。考虑P2P网络中每个节点都有自治的、动态的、自利的等特性,本文提出一种基于投标-招标机制的媒体流组播树的生成与维护算法。

As video severs＇ tasks are distributed to its clients in P2P systems, a P2P based video conferencing system is able to solve the bottleneck problem of network and system resources. Taking advantage of P2P technology and traditional video conferencing systems, a P2P based video conferencing architecture is proposed and a new scheme of peer management and communication is put forward in this paper. Considering the fact that Internet can＇t support IP-layer multicasting between LANs, media-stream transmission adopts IP layer multicasting only within a LAN, and application-layer multicasting between LANs. According to autonomation, dynamic, selfishness of peers in P2P systems, a new algorithm for constructing and maintaining muticasting tree is designed with the principle of invitation and bidding.