The Research And Design Of The P2P VoD System Based On Gossip Protocol

The traditional C/S streaming server structure doesn't satisfy a large number of users online at the same time, along with the requirement of streaming content increase from day to day, it is vulnerable to suffer from the bottleneck of system, and the system's scalability is limited. The IP multicast technique has its intrinsic limitation and is difficult of deploying widely. The CDN distributing network is expensive, and it is only divert the bottleneck, having little application. However, in P2P network, the peer is not only a customer but also a server, and it makes the best of idle resources in the network, separates the service to reduce the load of server, and enhances system's scalability. It brings the hope to resolve distributing problem of large-scale streaming data.At present, the research of P2P streaming mostly fastens on live system, but little on VoD system. This paper analyzes the special characteristics in P2P streaming technique, and makes a summary of the key techniques, such as the mechanism of peer selection, the strategy of transmitting data and the incentive mechanism, and so on. Then, this paper analyzes and compares the typical P2P streaming models, gives a result that the P2P streaming model based on Gossip protocol has better reliability and effect than that in tree structure model.Based on above, this paper designs a prototype P2P VoD system based on Gossip protocol, defines the Gossip interactive messages, gives a design of buffer and scheduler mechanism in detail, adopts the buffer management strategy of combining a fix buffer and a dynamic buffer to reduce the initial delay, employs the scheduling strategy based on data driving and improves overall performance to ensure acquiring streaming media data in time. This paper also describes the peer management mechanism in detail, puts concept of "Generation" peer to support forward and backward seek better. At last, to build the P2P simulation environment, this paper compares several P2P simulators, and selects NS2 as the base simulation platform. The paper configures a simulation parameters, designs scripts and scenarios to this system, executes and gives a performace test. The results of tests indicate that the system is feasible and the overall performance is good in reliability, scalability and effectivity.