Do BitTorrent-Like VoD Systems Scale under Flash-Crowds?
Do BitTorrent-Like VoD Systems Scale under Flash-Crowds?
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类似 BitTorrent 的 VoD 系统能否在 Flash-Crowds 下扩展？
DOI：
10.1109/p2p.2010.5569998
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
J. Pouwelse
中科院分区：
文献类型：
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作者：
L. D'Acunto;T. Vinkó;J. Pouwelse
BitTorrent用于文件共享的效率激发了许多基于BitTorrent的P2P视频点播协议。已经证明，这些系统在稳定状态下是可扩展的：提供给用户的服务质量不依赖于系统中的用户数量。然而，人们还不太清楚这些系统在快闪人群下是如何扩展的。在这项工作中，我们建立了一个通用的类BitTorrent视频点播系统的模型，我们发现在闪存拥挤的情况下，服务质量(Qos)随着用户数的增加而下降。此外，我们的分析表明，在快闪人群的一开始，可以获得给定服务级别的最大并发用户数与两个基本系统参数内在地相关，即初始服务容量和底层P2P协议的分片交换效率。最后，我们说明了节点转变为种子节点(即已完成下载并留在系统中进行上传的节点)在系统规模上的影响。
The efficiency of BitTorrent for file sharing has inspired a number of BitTorrent-based P2P protocols for Video-on-Demand (VoD). It has been shown that these systems are scalable in steady-state: the service quality provided to the users does not depend on the number of users in the system. However, it is not well understood how these systems scale under flash-crowds. In this work, we model a general BitTorrent-like VoD system and we find that under a flash-crowd the quality-of-service (QoS) degrades with the number of users. Also, our analysis shows that, at the very beginning of a flash-crowd, the maximum number of simultaneous users that can obtain a given service level is intrinsically related to two fundamental system parameters, namely the initial service capacity and the efficiency of piece exchange of the underlying P2P protocol. Finally, we illustrate the impact of peers turning into seeders (i.e peers that have finished downloading and remain in the system to upload) on the system scale.