Research On Cooperative Cache In P2P Network

As development of the P2P network, it is widely applied on peer to peer computing, cooperative work, and content sharing, etc. There will be a huge data request and data transmission with the P2P application increasing, and it will result in the network congestion or other network problem to reduce the performance of the P2P network. Cache is an effective mechanism to improve the performance of the computer system. Though Web Cache has been used to improve the performance of the traditional computer network system, it is not enough for the requirement of the sharing data between multi-peers in P2P network. So the Cooperative Cache was born.The Cooperative Cache means that a peer in P2P network not only can get data from local cache, but also can get data from another peer's cache. The Cache Hit and utilization of the cache will be improved by it, and then the performance of the P2P network will be improved as well. So it is very important to improve and prefect the cooperative cache protocol. This thesis analyzes existing cooperative cache protocol, and points out that the cooperative cache should include two parts:the first one is the cache replacement algorithm, which is adapt for the characteristic of the cooperative cache in P2P network; the second one is the cooperative cache protocol which is adapt for the cache replacement algorithm. Based on these standpoints, the Ant Colony Algorithm based Cache Replacement Algorithm and the ReadOnly/ReadWrite Group Based Cooperative Cache Protocol (R/WGCC Protocol for short) are presented.The existing cache replacement algorithm, the characteristic of the cache replacement algorithm on cooperative cache in P2P network are analyzed in the discussion of ant colony algorithm based cache replacement algorithm, and the traditional cache replacement algorithm can't worked well for the application of cooperative cache in P2P network is pointed out. Having analyzed the difference between cache replacement and the 0/1 Knapsack problem, the generalized description, the formal specification and the mathematical model for cache replacement problem are presented in this thesis, so cache replacement problem is a type of 0/1 Knapsack problem. Base on this conclusion, according to the character of the cooperative cache in P2P network to modify the ant colony algorithm which is used for solving 0-1 Knapsack problem, the Ant Colony Algorithm based Cache Replacement Algorithm is presented. A Simulation experiments is carried out to validate its feasibility and capability.In discussion of R/WGCC protocol in this thesis, the advantages and disadvantages of the existing cooperative cache protocols are analyzed, a new grouping algorithm for cache group is presented, and the basic thought of this algorithm is to distinguish the different type of the peer in P2P network then divide these peers into the Read Group or Write Group. Three types of the operation for cooperative cache protocol are presented, these operations use average pheromone concentration which is getting from Ant Colony Algorithm based Cache Replacement Algorithm to estimate the utilization of the cache, and manage the cache resource and cooperative caching between peers in different cache group.Finally, the Ant Colony Algorithm based Cache Replacement Algorithm and the R/WGCC protocol are carried out to validate their feasibility and capability by means of OPNET Modeler and a simulator program written by author.