Bittorrent is an auction: analyzing and improving bittorrent's incentives
Bittorrent is an auction: analyzing and improving bittorrent's incentives
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DOI：
10.1145/1402958.1402987
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发表时间：
2008-08
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影响因子：
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通讯作者：
Dave Levin;Katrina LaCurts;N. Spring;Bobby Bhattacharjee
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文献类型：
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作者：
Dave Levin;Katrina LaCurts;N. Spring;Bobby Bhattacharjee
激励机制在BitTorrent中扮演着至关重要的角色，激励用户上传文件给其他人，以实现所有同伴的快速下载。尽管长期以来人们都认为BitTorrent对策略操纵是强有力的，但最近的研究经验表明，BitTorrent并没有为用户提供遵循协议的激励。我们提出了一个基于拍卖的模型来研究和改进BitTorrent的激励机制。我们的模型背后的洞察力是，BitTorrent使用的不是像人们普遍认为的那样以牙还眼，而是一种拍卖方式来决定为谁服务。我们的模型不仅捕捉了已知的、提高绩效的策略，还塑造了我们对新的、有效的策略的思考。例如，我们的分析表明，与直觉相反，BitTorrent对等体有动机聪明地少报他们拥有的文件片段给他们的邻居。我们实现并评估了对BitTorrent的修改，在该修改中，对等方以一定比例的带宽份额相互奖励。在我们的博弈论模型中，我们证明了比例份额客户是不受策略限制的。通过在PlanetLab（一个本地集群）和实时下载上的实验，我们发现，相对于BitTorrent和BitTyrant客户端，按比例分享的解链器可以产生更快的下载速度，而少报的部分可以产生更长的邻居兴趣。
Incentives play a crucial role in BitTorrent, motivating users to upload to others to achieve fast download times for all peers. Though long believed to be robust to strategic manipulation, recent work has empirically shown that BitTorrent does not provide its users incentive to follow the protocol. We propose an auction-based model to study and improve upon BitTorrent's incentives. The insight behind our model is that BitTorrent uses, not tit-for-tat as widely believed, but an auction to decide which peers to serve. Our model not only captures known, performance-improving strategies, it shapes our thinking toward new, effective strategies. For example, our analysis demonstrates, counter-intuitively, that BitTorrent peers have incentive to intelligently under-report what pieces of the file they have to their neighbors. We implement and evaluate a modification to BitTorrent in which peers reward one another with proportional shares of bandwidth. Within our game-theoretic model, we prove that a proportional-share client is strategy-proof. With experiments on PlanetLab, a local cluster, and live downloads, we show that a proportional-share unchoker yields faster downloads against BitTorrent and BitTyrant clients, and that under-reporting pieces yields prolonged neighbor interest.