Structured P2P systems use the distributed hash table(DHT) to map data into the corresponding node.

Starting from the result that the intervals between nodes obey the geometric distribution and based on the probability theory,the rules of intervals distribution on Distributed Hash Table(DHT) and the probabilistic properties of the number of nodes appearing on a section of address space were studied.

Distributed hash table (DHT) is a new Peer-to-Peer (P2P) networking pattern,which has many advantages, such as efficiency, scalability and low cost, and has beenwidely deployed in various large-scaled distributed systems, ranging from file sharing,contents distribution, streaming media to VoIP.

This paper studies some important DHT Topologies from an algebraic standpoint.

Resource locating algorthim in the structured P2P Network adopts algorthim based on DHT which locates resource by key words.

In the structured network, DHT searching technology is a popular resource locating method, that relays the query between peers using DHT.

The structured P2P system adopts routing algorithms which support a distributed hash table(DHT) functionality,locates and searches data objects by precise keywords.

Based on the development motivation and the principles of P2P-based searching,this paper presents a hierarchical and distributed Hash Table system,which is also called PDHS model.

An application using a distributed hash table (DHT) with N nodes must choose a DHT protocol from the spectrum between O(1) lookup protocols and O(logN).