Research And Improvr In Chord Algorithm Based On P2P Network

One of fundamental problems confronted by peer-to-peer (P2P) applications is how to efficiently locate the node that stores a particular data item. Different strategies are adopted by different P2P search algorithms, in which the efficiency is different.One of distributed search algorithms, named Chord was analyzed. As the second generation of P2P algorithm, distributed hash table is adopted by Chord as the search strategy. Chord is scalable, with communication cost and the state maintained by each node scaling logarithmically with the number of Chord nodes. Many advantages are hold by Chord algorithm, such as balance load, reliability, expansibility and so on, but the search efficiency of Chord is low.The improved Chord algorithm which addressed the disadvantage of Chord was presented. The finger table of Chord was improved; the formula which calculated the finger table was extended into two, so that the calculating procedure could be conducted in both of clockwise and anti-clockwise directions. At the beginning of the search procedure, the range of the search could be restricted in a half Chord-Circle by this improved Chord. In such a way, the target node could be approached more easily and the search efficiency is clearly superior to original Chord algorithm.It is very common to insert or delete a node in a P2P network, and therefore the adaptability of P2P network must be considered. Through lots of work in this aspect, an assumption of creating a table having r successors for each node was presented and this will solve the problem better.Finally, the simulated testing had showed that the efficiency of the improved Chord is clearly superior to the original Chord in two aspects of average search path length and average search time.