The Analysis And Research Of The Chord Protocol In P2P Network

As a network model,P2P (Peer to Peer) is now widely used.Chord is a simple accurate and highly efficient ring model of P2P,and it's inquiry efficiency depends on fingertable which has been maintained by itself. Therefore, the research of Chord fingertable has a very important significance.Query efficiency of Chord depends on the fingertable,thus, in this thesis, we found that exist certain amounts of redundancies in the fingertable of Chord, and fingertable only stores the node information in the first half of the ring through the analysis of fingertable. Therefore, the existence of such redundant nodes information and fingertable which lacks of the storage of after semi-ring information lead to a less efficient query of Chord. In order to improve the query efficiency of Chord, two-way fingertable structure is proposed to optimize the fingertable of Chord. Firstly, the redundancy in the fingertable is removed, then, part of the node information in a reverse ring is used to replace the redundancy, at the same time, the remaining information in the reverse ring is added to the original fingertable, finally bidirectional query is realized.It means bidirectional Chord ring query can be realized without increasing too much information in the fingertable. consequently, the efficiency of query is improved.For the improved Chord, the efficiency of query is theoretically analyzed and calculated in this thesis. The average routing hops of query in the improved Chord is derived from the average routing hops of query in the original Chord, and the redundancy rate is derived from the redundant information in the fingertable. According to redundancy rate and comparing the original fingertable with the improved fingertable, the theoretical formula of the item numbers increased in the fingertable can be obtained. In order to verify the theoretical results, java language is used for simulation. The operating results of the simulator firstly verify the compatibility of its theoretical value. Then, it gives the comparison table of the average query hops between the improved fingertable and the original fingertable. Finally, the improved Chord query is better than before according to actual data from the data of figure.