對傳統(tǒng)虛擬專用網的概念進行擴展，提出并建立了分布式虛擬專用網的模型，解決了傳統(tǒng)虛擬專用網系統(tǒng)內部無法防止的搭線竊聽問題。對分布式虛擬專用網的性能改進作了定量分析，分析結果顯示其可以大幅度提高系統(tǒng)的并行性，且單個節(jié)點存儲容量從O(n2)下降到O()，實現增長線性化，并給出一個系統(tǒng)實現，測試結果表明可以顯著改善系統(tǒng)的安全性和提高效率。

關 鍵 詞 虛擬專用網; 分布式虛擬專用網; IP安全性; 安全策略數據庫; 安全關聯數據庫

Raise the concept of distributed VPN and create the system model, which extend the concept of classical VPN. From the as aspects of security, it overcome the classical VPN’s disadvantages of failing to protect the internal communication of LANs. The result of DVPN's performance analyzing indicates that it can enhance the parallelity of the system,reduce the storage requirement from complexity O(2n) to O() and make the database grow linearly. As well,give a system implementation, which proves that it can improve the security and efficiency of the system.