Abstract: The mismatching issue of topology structure between P2P network overlay and backbone physics network，produces much redundancy communication spending，and affects the efficiency of P2P network searching and transmission seriously.Based on analyzing present serveral solving methods about this issue，under the frame of intelligent node flexibility ovleray network transmitting model that is secure，controled and managed，this paper presents the technology of detecting physics network topology on applicaition layer，and makes the P2P overlay structure more resemble with the backbone physics network.This technology causes lots of message transmitting among LAN or partial network，alleviates greatly the pressure of backbone transmission network，and improves the efficiency of P2P system.The mainly content of this paper is to introduce constructing and maintaining of overlay topology，and the arithmetic of resource searching.

Key words: P2P, application layer, topology detecting, Overlay

摘要： P2P网络Overlay和底层物理网络拓扑结构不匹配问题，造成大量无谓的通信开销，对网络的搜索和传输效率影响很大。在分析该问题现有几种解决方法的基础上，在安全、可控、可管理的智能节点弹性重叠网络传输模型框架下，提出基于应用层的物理网络拓扑探测技术，促使P2P应用层Overlay和底层物理网络拓扑趋于“吻合”，使得主要消息量在本地或局部范围内流动，大大减轻了底层承载网络传输压力，提高了P2P系统效率。重点分析拓扑构造、维护及资源搜索算法。

关键词: P2P, 应用层, 拓扑探测, Overlay