P2p Based Vod System Design And Realization

In recent years, the statistics report for china Internet developing situation showsthat, China's broadband users is rapidly rising. More than half of them have usedstreaming media services. As the occupation of high‐bandwidth, the system of C/Smode is difficult to provide high‐quality services.In C / S mode, all of the resources and services provided by the server, the networkand storage space of clients are wasted, and the system will stop working if there is aserver failure. The P2P(peer to peer) technologies solved the problems.P2P meansequality, a peer can download from other peers, and upload to other peers too.In P2P networks, there is no central server, peers are all servers, so the capabilities,robustness, scalability of system are more higher than the C/S mode.This article can be divided into two parts. The first part describes the streamingmedia system and the basic concept of P2P technologies, which is necessary forunderstanding of the second part.The second part includes the research and design of P2P VOD system. The p2pmodule is based on Bittorrent protocol, and some changes have been made. Bittorentis a quick and efficient file‐sharing system. According to the characteristics of VODsystem, a new piece‐choice method has been designed, and a coordination mechanismbetween the nodes has been designed to maximize network efficiency. The chokingmechanism has been extended and modified to incent peers.In this P2P VOD system, the server can upload files to clients, in order to share theload of server. And the clients have to calculate which file can be deleted when thestorage space is low. These methods can balance the file Distribution in system andthat will be improve the service.