P2P流媒体：一种新型的流媒体服务体系

流媒体应用是推动未来宽带应用的主动力，但流媒体对带宽的高占用特性使其在Internet上大规模应用面临诸多困难。虽然IP组播能减轻服务器和网络负载，但众多原因使之在短期内难以广泛实现；CDN(Content Dellvery Network)通过把服务和内容“推”向网络的“边缘”，也能减轻服务器和网络负载。但其昂贵的费用使得一般ICPs无法承担。在Internet环境下最近兴起的P2P(Peer-to-Peer)技术在提高资源利用率、扩展服务能力等方面具有潜在的巨大优势，P2P技术在流媒体中的应用能够充分利用以往被忽视的众多客户机的资源，是一种性价比良好的流媒体服务体系。本文首先指出了P2P流媒体应用中所面临的挑战，并着重从多播树协议、QoS保证、激励机制等方面阐述了P2P流媒体的研究现状，分析讨论了存在的问题，并指出了今后的研究方向。

P2P Media Streaming:a New Type of Media Streaming Service Architecture

Media streaming will become the mainly driving force for future broadband network application. But media streaming imposes a high load on the underlying network and the streaming server, and there still exists many difficulties for deploying it in a large-scale. IP Multicast could be the best way to overcome this drawback since it was designed for group-oriented application. However, its deployment on the Internet is still limited due to several fundamental concerns. CDN (Content Delivery Network) push the content and service to the Internet edge, which could alleviate burden on media servers and network infrastructure.but normal ICPs could not afford the expensive charge. The recently rising Peer-to-Peer technologies has huge potential on efficiently resource usage, system scalability and so on. P2P media streaming can efficiently using large mount of clients' resource which have been ignored before, and it will become a cost-effective media streaming service architecture. In this paper we first point out exist challenges for P2P media streaming , then mainly introduced some recent research result such as protocol of multicast tree, QoS guarantee and incentive mechanism and so on. Some exist problems are discussed. The orientations of the future research are also given.