P2P(peer-to-peer)檔案分享系統已經發展多年，在此環境中進行資源的探測存在著查詢訊息過多以及冗長的搜尋時間等問題，導致網路頻寬嚴重的耗費。目前的研究顯示出在P2P檔案分享系統中有許多的free-rider也是造成大量查詢訊息的主因，這些節點利用系統下載檔案而本身分享檔案的數量很少甚至不分享檔案，因此對於這些節點進行查詢不容易得到回應。在這篇論文中，我們提出一個搜尋策略，稱為IES(information exchange search)，在搜尋的過程中考量節點的回應能力，進行資訊交換和查詢的工作，提供節點更有效的查詢目標以及減少將查詢訊息傳遞給可能是free-rider的節點。本論文的模擬考慮節點加入和離開系統的情況，與先前的方法進行比較，我們提出的方法最多能減少約百分之四十的網路流量以及百分之三十的搜尋時間，對於P2P網路之搜尋具有更理想的效能。

P2P (peer-to-peer) file sharing systems have been developed for years. There exist some critical problems, like producing lots of query messages and long search latency. Recent researches show that a large amount of peer in the system is the free-rider, who downloads files but less willing to share; that is, queries are seldom hit by those peers. In this thesis, we propose a search algorithm, called IES (information exchange search), to solve these issues. We consider the potential of a peer in the searching process for information exchanging and query forwarding. In contrast to the former, our simulations take the churn situation into account and show that IES can reduce about 40% network traffic and 30% search latency at most while conducting file probing in the system.

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