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测量分析P2P文件共享系统是解决P2P优化、网络管理等问题的基础。当前P2P网络设计日趋复杂,并且部分运行机制直接导致测量数据不完整或测量周期过长,比如BitTorrent文件共享系统。针对这一问题,本文抽象出BitTorrent系统的3个测量层次,包括索引测量、节点测量和内容测量,并重点解决了3个层次中的测量难题,设计实现了一个面向BitTorrent的测量系统。在此基础上,本文对BitTorrent系统进行了持续测量,并重点分析了BitTorrent系统的节点行为:节点演化规律和节点到达模型。测量结果表明,节点演化规律和节点到达均呈现强烈的周期性。为此,本文改进了节点到达模型,新模型与实际测量数据拟合效果较好,进一步修正了节点到达模型。 相似文献
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BitTorrent网络流量占据了互联网总流量的很大比例,吸引了大量专家学者的专注,然而现有实测工具无法实时记录BT网络中节点间的流量交互情况,有关真实BT网络中节点间流量的研究很少。建立了一个BT网络节点间流量的数据采集系统,将其部署在全球性实验平台Planetlab之后得到了真实数据,并验证了数据的正确性。通过对实测数据的分析和研究发现:(1)Tracker服务器在为各下载节点随机返回邻居节点列表时会受到各节点入网时间的影响;(2)50%以上的下载节点从种子处下载的数据为零,大部分下载节点的数据下载对种子的依赖性不大,从而深刻地体现出P2P应用模式的优越性。 相似文献
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一种面向BitTorrent的文件快速安全分发方案* 总被引:1,自引:0,他引:1
提出了一种能够很好利用BitTorrent快速传输特性的同时,也能增加文件下载安全控制的方案。BitTorrent是一种流行的快速传输分发文件的方式,但它存在一定的安全问题,如通过BitTorrent分发文件时,很容易被非法用户窃取获得明文文件。在面向BitTorrent协议基础上,结合使用对称加密技术和身份认证机制对其进行了改进:文件在提供下载前进行对称加密,然后通过BitTorrent进行传输分发;用户成功下载文件后需要进行身份认证,合法用户可以安全获得文件加密密钥,解密得到明文文件。实验结果表明该方 相似文献
4.
童毅 《青岛建筑工程学院学报》2010,(4):98-103
针对P2P(Peer to Peer,对等联网)技术在宁夏石嘴山联通互联网网络的运行中存在一定的负面影响,笔者对P2P应用中最广泛采用的BitTorrent(比特流)进行研究,设计出一种BT流量控制系统,使得P2P流量本地化,并且降低出入口流量,从而达到既节省电信运营企业流量结算成本,又能维持用户体验的目的. 相似文献
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Stochastic analysis of file-swarming systems 总被引:1,自引:0,他引:1
File swarming (or file sharing) is one of the most important applications in P2P networks. In this paper, we propose a stochastic framework to analyze a file-swarming system under realistic setting: constraints in upload/download capacity, collaboration among peers and incentive for chunk exchange. We first extend the results in the coupon system [L. Massoulie, M. Vojnovic, Coupon replication systems, in: Proc. ACM SIGMETRICS, Banff, Alberta, Canada, 2005] by providing a tighter performance bound. Then we generalize the coupon system by considering peers with limited upload and download capacity. We illustrate the last-piece problem and show the effectiveness of using forward error-correction (FEC) code and/or multiple requests to improve the performance. Lastly, we propose a framework to analyze an incentive-based file-swarming system. The stochastic framework we propose can serve as a basis for other researchers to analyze and design more advanced features of file-swarming systems. 相似文献
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Analyzing the performance and fairness of BitTorrent-like networks using a general fluid model 总被引:2,自引:0,他引:2
In this paper, a general fluid model is developed to study the performance and fairness of BitTorrent-like networks. The fluid model incorporates two important features previously isolated from system performance models, user settings with multiple groups and inter-group data exchange induced by the choking algorithm. Our numerical results point out some key parameters of performance, such as the staying time of seeders. Generally, selfish behavior does not receive equal performance degradation, and in some scenarios users have strong incentives of free-riding. We also find content delivery can be greatly deterred when malicious free-riders are overwhelming. 相似文献
9.
In this paper we report new results of our continuous effort on analyzing the impact of incentive mechanisms on user behavior
in BitTorrent. In this second measurement and analysis study we find that free riders’ population has significantly increased
comparing to our previous measurement study. We relate this increase to the advance in end-users’ connection speeds and to
users’ increased knowledge in BitTorrent. We also categorize free riders based on the behavior they exhibit in multiple-torrent
system into three types: cheaters, strategic and lucky peers. Furthermore, refuting the findings of other studies, we show
that peers who exploit the system in BitTorrent are both high bandwidth capacity peers and low bandwidth capacity peers. Moreover,
we argue that the Tit-for-Tat mechanism does not discriminate peers based on their bandwidth capacities and that it reacts
successfully against inter-class bandwidth capacity strategic peers. Finally, we propose a memory-backoff approach to the
optimistic unchoke policy that reduces the volume of free riding in BitTorrent.
Manaf Zghaibeh is a PhD candidate at Stevens Institute of Technology, focusing on P2P economics. He holds a Master’s Degree in Telecommunications Management from Stevens and a Bachelor’s Degree in Electrical Engineering from Damascus University. He has been a teaching assistant at NYU since 2002. Fotios Harmantzis is an Assistant Professor at the School of Technology Management at Stevens Institute of Technology. He holds a B.Sc. and M.Sc. in Computer Science from the University of Crete, a MSE in Systems Engineering from the University of Pennsylvania, a Finance MBA from Toronto/NYU, and a PhD in Electrical and Computer Engineering from the University of Toronto. Dr. Harmantzis’ research and teaching interests include mathematics of finance and risk, valuations of investments under uncertainty and economics of IT and telecom. His research work has been presented in several scientific conferences and journals. He has professional experience in the US, Canada and Europe, in the financial services, asset management and consulting business. 相似文献
Fotios C. Harmantzis (Corresponding author)Email: |
Manaf Zghaibeh is a PhD candidate at Stevens Institute of Technology, focusing on P2P economics. He holds a Master’s Degree in Telecommunications Management from Stevens and a Bachelor’s Degree in Electrical Engineering from Damascus University. He has been a teaching assistant at NYU since 2002. Fotios Harmantzis is an Assistant Professor at the School of Technology Management at Stevens Institute of Technology. He holds a B.Sc. and M.Sc. in Computer Science from the University of Crete, a MSE in Systems Engineering from the University of Pennsylvania, a Finance MBA from Toronto/NYU, and a PhD in Electrical and Computer Engineering from the University of Toronto. Dr. Harmantzis’ research and teaching interests include mathematics of finance and risk, valuations of investments under uncertainty and economics of IT and telecom. His research work has been presented in several scientific conferences and journals. He has professional experience in the US, Canada and Europe, in the financial services, asset management and consulting business. 相似文献
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对BitTorrent(BT)类型的P2P系统进行了建模与性能分析。详细地分析了系统中的peer行为。考虑到文件片段对系统的影响,建立了peer模型和seed模型以及文件片段模型、感兴趣与阻塞模型、peer选择模型等。对peer在BT子系统中对邻居peer的感兴趣概率、被邻居peer阻塞的概率以及选择上传peer的概率进行了分析。应用这个模型对peer的上传行为发生的概率与BT子系统peer总数的关系进行了分析, 结果表明, 上传行为发生的概率随着BT子系统peer总数的增加而减少。 相似文献