A Pre-fetching Strategy Based On Two-level Relation In P2P VOD

In recent years, with the rapid development of P2P technology, a lot of applications based on P2P network have been used. As an important application of P2P network, P2P streaming media has attracted widespread attention since it appeared. As traditional streaming media application based on C/S mode needs a central service to take charge of node manager and forward information, it suffers many problems in C/S mode such as heavy loading of server and limited scalability. However, considering that P2P network can weaken the role of the central server and fit streaming service very well, the P2P streaming is proposed.P2P streaming media services are divided into live video technology and video on demand technology. At first, P2P streaming media technology was mainly applied to the live video system. But with people’s further demand on watching their favorite programs, P2P technology for video on demand appeared. P2P VOD system overcomes problems exposed in C/S mode such as heavy loading of server and limited scalability. However, considering the data distribution and randomness of P2P VOD users’ VCR (video cassette recorder) operations, P2P VOD system is hard to locate data with low latency when VCR operations occur, which reduces the users’ viewing experience. Therefore, improving the interaction of P2P VOD system has been widely concerned. In this paper, we propose a pre-fetching strategy with two-level relation, and based on which we design a P2P VOD system called R2VOD. The modules in R2VOD are related to our pre-fetching strategy. In our strategy, we first find the relation which may exist between different peers based on a large number of peers’playing records. Then a peer pre-fetches the data based on the strength of the relation. After that, our pre-fetch scheme will use the relation between different peers to optimize the peer’s neighbor list based on the playing records so that it will be faster to locate and pre-fetch data next time. Moreover, the latency of VCR will be reduced as well.Experimental results show that:The pre-fetching scheme proposed in our paper can significantly reduce the latency when VCR occurs. Meanwhile, without increasing the pressure of tracker, the stability and the fluency of R2VOD can be effectively improved as well.