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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/18098

Title: 點對點網路使用以牙還牙(Tit-for-Tat)策略之效能界限研究
On the study of performance bounds of p2p networks using Tit-for-Tat strategy
Authors: 何恭廣
Contributors: NTOU:Department of Computer Science and Engineering
國立臺灣海洋大學:資訊工程學系
Keywords: 點對點網路;同儕網路;以牙還牙;容忍型以牙還牙
Peer-to-peer;Tit-for-Tat;tolerable Tit-for-Tat
Date: 2009
Issue Date: 2011-07-04
Abstract: 現今的網路,點對點網路的應用頗受眾人所關注,其中最熱門的應用即是檔案分享的技術。在點對點網路系統中,系統的效能取決於peers的行為。但是自私的peers使用了網路資源卻不願意貢獻資源給系統,影響其他peers的下載與系統效能。也因此有人引入了以牙還牙的策略來對抗自私的行為。在以牙還牙的策略中,為了不吃虧,各個peer的下載量等於它的上傳量。雖然以牙還牙的策略能夠有效的抑制自私行為,然而也因為限制條件過於嚴格反而減少peers之間的檔案傳遞的意願、降低系統效能、甚至可能會癱瘓整個系統。 本篇論文嘗試探討的是容忍型的以牙還牙策略。在此策略之下,下載量與上傳量的差異只有在容忍值之內既可。我們著重在點對點網路的效能界限分析,從參與下載的peers數、pieces數與檔案下載完成所需要時間以及Seed的負載來討論,推導分析出理論效能界限。比較推導結果與其他策略,證明在此策略機制能有效的下載檔案,減輕Seed負載並提升整體系統效益。
In current networks, the peer-to-peer network applications have received much attention. The most popular application is content distribution techniques. In peer-to-peer network, the system performance is depending on the behaviors of each peer. The selfish peers use resources but are willing to contribute, therefore impact the other peer’s download and hurt the whole network system. The peer-to-peer network attempts to reduce the number of selfish peers by employing the Tit-for-Tat strategy. To counterstrike the selfish peer, the upload amount is controlled so that it never exceeds the amount of download. It has been proved that this strategy can reduced the selfish behavior, but the constraint may be too strict to reduce the willingness of content delivering between peers, decrease the system performance, even the entire network might be crashed. This paper studies a tolerable Tit-for-Tat strategy such that the difference between upload and download is only required to be less than a tolerance. We focus on the analysis of the download time and Seed workload, based on the number of participating peers and the number of pieces. We then derive some theoretical bounds on these performances. Compare the derivation of the results and the other strategies, proving that our strategy can efficiently download the file, reduce the Seed workload, and improve the whole system efficiency.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M95570054
http://ntour.ntou.edu.tw/ir/handle/987654321/18098
Appears in Collections:[資訊工程學系] 博碩士論文

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