Research On A Hierarchical Model Of Peer-to-Peer Network Based On Distributed Hash Table

Peer-to-Peer (P2P) system is a research field with rapid development.For the application areas of P2P systems have gradually expanded from traditional file sharing to distribute computing over Internet, some key features such as deterministic locating and low query overheads are needed for P2P systems. P2P system,based on Distributed Hash Table (DHT), can provide a serial of nice performance such as the consistent distribution of mega data in the Internet, the exact locating of routings with few hops, high fault-tolerance and self-organization etc., so it has become the research hot.DHT technique is tightly related to the whole design of P2P systems, it deeply affects the core problems——resource locating and resource searching in P2P systems. DHT technique triggers a radical revolution for the topology of P2P model and changes the topology from a kind of random, unstructured topology to deterministic, ordered structure topology. DHT technique results in a revolution on routing technique and changes the traditional routing, which based on unidirectional broadcast, into the unicast routing according to exact direction.In current DHT based routing algorithms, routing tasks are distributed across all system peers,and it made it solved that a query request is finished in a certain number of logical hops. However, a logical hop could happen between two widely separated peers with high network link latency and it greatly influences system routing delay performance. A hierarchical peer-to-peer network model aimed at the problem of routing delay performance was proposed, and the model organizes nodes into a multi-layer network by partitioning different region. Different region contains different Chord ring. Routing tasks are first executed in the lowest level region ring before they go up to higher-level rings. After finding a hop node, Routing tasks are executed again in the lowest level region containing the hop node. This procedure repeats until finding the predecessor of the target node. A large portion of routing hops previously executed in the global P2P ring via many different big regions are now replaced by hops in lower level region rings. The result of emulating routing algorithm of the model indicates that the routing delay performance can be highly improved...