| The full name of P4P is "Proactive network Provider Participation for P2P". P2P emphasis on "peer", and the exchange between nodes is completely random. Preferring the sources of information with shorter physical distance, local file segment exchange will greatly reduce communication costs, which is simple design principle of P4P. P4P can select node effectively. It strengthens communication between the Internet service providers and applications, reduces traffic load on backbone links and operational costs, and effectively improves the performance of P2P applications. Chord is a structured P2P protocol which implements distributed lookup based on consistent hash algorithm. It is the most classic protocol in the third generation of P2P,and it is scalable. Chord maps a given key onto a node. Depending on the application using Chord, that node might be responsible for storing a value associated with the key. Chord uses consistent hashing to assign keys to nodes. Consistent hashing tends to balance load, since each node receives roughly the same number of keys, and involves relatively little movement of keys when nodes join and leave the system. Three features that distinguish Chord from many other P2P lookup protocols are its simplicity, provable correctness, and provable performance.In order to improve P4P, this paper presents Chord protocol applied in P4P network. We design a hierarchical network model with regional super-node. Using super-node we avoid increasing the routing table and maintaining node information. We design appTracker-less top-level control interface and appTracker-based top-level control interface, use top-level interface for optimization operation, simply discuss caching and heterogeneity, and then analyze the performance of P4P-Chord network model.P4P based on Chord improve the efficiency of the network's locating through hierarchical localization. It resolves all lookups via O(logN)messages to other nodes. And it maintains its routing information as nodes join and leave the system; with high probability each such event results in no more than O(log2N) messages. P4P-Chord with fault tolerance is scalable. Then using interfaces of iTracker we conduct optimization operations to get p-distance. Ultimately we thus get PID, select peer reasonably, and coordinate network topology. The efficiency of network routing is greatly improved.In this paper, we use simulator p2psim to experiment and analyze results. The p2psim is proposed to be the best P2P simulator. It is a free, multi-threaded, and discrete event simulator for evaluation, research, analysis of P2P protocol. Simulation compares the locating efficiency of P4P-Chord with Chord under P2P system. The results show that in the same mean lookup time, the bandwidth of P4P-Chord network is less than the conventional Chord network; the mean lookup time of P4P-Chord network is less than the traditional Chord network under the same bandwidth. The performance of P4P-Chord is better than Chord under P2P systems, and the efficiency of P4P-Chord is greater than Chord under P2P systems. Simulation achieve our desired results. |
