Research On Server Scability Of Bit Torrent_like P2P_VoD System

With the development of the Internet and the widely usage of the broadband access technology, VOD has become one of the most popular streaming applications over the Internet. Providing large-scale VOD services over the Internet has become an urgent problem needed be solved at the present stage, and reducing server load is an effective way. To meet the high flow, high scalability and low delay streaming requirement, steaming media system has gone through several stages according to the different data distribution strategies. (1) The traditional client/server mode. In this mode, as the increasing of size of network, the streaming media server could easily become the bottleneck of system. (2) IP multicast technology. It can't be widely used in the Internet due to the management and congestion control problem of multicast. (3) CDN (Content Delivery Network).Owing to its hard deployment and high cost, it is difficult to be widely applied.In order to solve the problems above, P2P technology has been widely applied to the streaming media system. In the P2P streaming system, the problem of inconsistence of access bandwidth of users is widespread. In addition, the user mode can join and exit the system at any time, which results in very dynamic networks. What's more, high bandwidth, long service time, strict sequences of playing and transmission delay requirements have been bringing great challenge to P2P streaming media on-demang system.This paper focuses on the difficulty of large-scale deployment of internet VOD service, and proposes the corresponding solution based on making future research on P2P streaming media system based on BT.The main purpose to apply P2P technology to streaming media content is to make full use of the upload ability of end-users to improve streaming media applications performance. An effective solution is to improve the data requests hit rates between the peers to reduce server load. First, we expand on the file sharing model, making it suitable for analysis of on-demand system server load. Then, based on this model, analyzing the impact of the effective of data requests caused by fragment available for sharing and peer group size. The results of experiment on MATLAB show that a proper number of data blocks and collaboration size of collaboration nodes can reduce server load.Data scheduling strategy is the core issue of the Streaming media system. A proper data scheduling strategy can take advantage of the peer's neighbors'bandwidth resources and cache data block, reduce the number of system access and improve system scalability. This paper presents a Bandwidth-based Multi-supplier Data Scheduling strategy, which take the heterogeneity of nodes into account fully in the data scheduling process. According to the emergency degree and rarity of the block, cache image and bandwidth of the neighbor nodes, ensuring that the requested data block can arrive at the premise time, take full advantage of the bandwidth resources of neighbors to reduce server load. OMNET++ simulation results show that BBNDS can reduce the server load effectively.