Research And Implementation Of BT-Based P2P VoD System

The streaming media has become one of the most widely and the most important applications in the current Internet, while customers prefer VoD more because of its interactive function. In the case that the traditional IP Multicast and CDN (Content Distribution Network) technology can not meet the needs of application, P2P technology has become the main method to solve such problems. The introduction of P2P technology into VoD system has become a better solution, however, streaming media is a special application with stringent resources requirements for its long lasting time and playback deadlines, all these make P2P streaming media system face a lot of challenges.In this paper, a BT-based protocol is used in P2P VoD (Video on Demand) system, which is called BTVoD system. We deeply research and analyze the possibility of the idea, propose some performance metrics, explain some feasible key technologies in BTVoD system. Further more, among these key technologies, the data scheduling algorithm is considered penetratingly because it usually impacts many performance metrics strongly. Depending on the analysis of existing data scheduling algorithm shortcoming, we put forward a Scheduling Algorithm Based on Selectivity of Peers, called as SSP algorithm, to resolve the issue that how to realize effectively data share among peers with different characteristics in P2P VoD system, and to improve the overall system quality of service (Qos). The SSP algorithm consists of three parts: First, when the chunks are requested, Process of Request Algorithm comprehensively takes into account the bandwidth capacity and data information of its neighbor peers to make the full use of each neighbor peer resource. Second, when for the neighbor peer services, the Process of Service Algorithm deals with chunks respectively according to their priorities to improve the continuity in playing video of peers. Third, Process of TimeOut Algorithm will urgently deal with those chunks which haven't been downloaded punctually to improve the robustness of system. From the analysis of simulation results in NS2, SSP algorithm is favorable to enhance the peers' continuity of video, to reduce the pressure of server's load, and applies for P2P VoD peers with remarkable differences environment. Finally, based on BitTorrent-like protocol, BTVoD system is implemented. The main part of design and implementation was explained in detail. The results of implementation also show that BTVoD system is suitable in large-scale network applications.