Research Of P2P-VOD System Peer Cache Mechanism

The Quality of Service of the Peer-to-Peer Video-on-Demand(P2P-VoD) system is difficult to be ensured because of the distributed peer nodes, the dynamic and heterogeneous characteristics of the P2P networks, and the high-demand real-time requirements. The high performance of caching strategy is one of the important technologies related to the QoS of the P2P-VoD system. And, the cache mechanism containes a cache manage algorithm and a cache replace algorithm. This paper annlyzes and compares the internal and external researches of the cache mechanism, and researches the cache managed algorithm and the cache replaced algorithm in the P2P-VoD system.Firstly, the adaptive cache managed and replaced algorithm of peer nodes in P2P-VoD system are researched. Based on analyzing the existed cache managed and replaced algorithms, we find that the existed algorithms can not meet the real-time demand requirements, and adapt the dynamic and heterogeneous of the systems. So, the adaptive cache managed algorithm WACache and the adaptive cache replaced algorithm WACacheS are introduced.. The weight of the block is determined by its deadline, contribution and popularity.Secondly, This paper designes a P2P-VoD system simulation platform which based on the NS2 simulation platform. When analyzes the existed simulation tools, we find that the existed tools can not meet the versatility requirements of the simulation of caching algorithms in P2P-VoD system. Therefore, a simulation platform of caching algorithms is intuoduced on the basis of the open source platform NS2.Finally,the simulation experiments of the P2P-VoD cache algorithms are developed on the designed simulation platform which is based on NS2. The designed adaptive cache managed algorithm WACache of the peer node is simulated and analysed with the other existed cache managed algorithms of peer node in P2P-VoD systems. And, the designed adaptive cache replaced algorithm is simulated and analysed with the other existed cache replaced algorithms of peer node in P2P-VoD system.The QoS of the P2P-VoD system is improved by the adaptive cache mechanism on the basis of simulation.