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BitTorrent系统面临着严重的搭便车问题。研究BitTorrent系统的搭便车问题及其激励机制,对P2P文件共享系统有重要意义。介绍当前BitTorrent系统激励机制的研究现状,分析BitTorrent文件共享系统的搭便车现象及其激励机制,提出了一个种子带宽分配策略。通过模拟实验实现了该策略,并分析了模拟实验的结果。 相似文献
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Enhancing tit-for-tat for incentive in BitTorrent networks 总被引:2,自引:0,他引:2
Weidong Liu Dongsheng Peng Chuang Lin Zhen Chen Jiaxing Song 《Peer-to-Peer Networking and Applications》2010,3(1):27-35
BitTorrent achives great success in its high performance for file distribution. It is commonly believed that this owes to
Tit-for-Tat strategy adopted in choking algorithm for incentive in BitTorrent protocol. But there are still many issues in
incentive mechanism in BitTorrent. In this paper, we study Tit-for-Tat strategy by constructing a game model in P2P environments
and deducing the constraint under which the strict Tit-for-Tat is an equilibrium strategy. We then enhance and adapt the Tit-for-Tat
strategy to the dynamic property in P2P networks, and deduce the constraint under which it is still an equilibrium strategy.
We also study through simulations the performance improvement of the enhanced Tit-for-Tat, and give suggestion on how to choose
proper system parameters under different network conditions. Finally, based on the enhanced Tit-for-Tat strategy, we propose
a method to improve incentive in BitTorrent networks to cope with free-riding and fairness issues. 相似文献
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激励机制是BitTorrent协议的重要组成部分,它鼓励用户上传以获得更快的下栽速度,并提高系统整体性能。原有BitTorrent激励机制存在大量的搭便车节点,极大影响了激励效果,因此提出了一种新的激励策略,并给出了具体的实施算法。对应用这种新激励机制的BitTorrent协议进行了详细的着色Petri网(colored Petri nets,CPN)形式化建模分析,在验证模型正确性的基础上,进行基于模型模拟的性能分析实验,结果表明该激励机制能够严格限制搭便车节点行为,达到更好的激励效果。 相似文献
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张红伟 《数字社区&智能家居》2009,(20)
由于p2p网络节点的匿名性和贡献资源的自愿性,绝大多数节点不愿共享自己的资源,从而导致大量搭便车现象的出现。在使用BitTorrent下载的过程中,为了能得到对方更快的下载速率,各个节点也能够为相应节点提供较快的下载速率,但在下载完成以后,大部分节点就不再为其他节点提供下载服务。在分析BitTorrent协议的基础上,该文提出了一种差异服务的激励机制,该激励机制能够激励节点持续不断地为其他节点提供下载服务,即使是在该节点下载完成以后也是如此。 相似文献
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Oznur Ozkasap Mine Caglar Ali Alagoz 《Journal of Network and Computer Applications》2009,32(3):666-683
We propose and design a peer-to-peer system, SeCond, addressing the distribution of large sized content to a large number of end systems in an efficient manner. In contrast to prior work, it employs a self-organizing epidemic dissemination scheme for state propagation of available blocks and initiation of block transmissions. In order to exploit heterogeneity of peers, enhance the utilization of system resources and for the ease of deployment, scalability, and adaptivity to dynamic peer arrivals/departures, we propose mechanisms for adjusting protocol parameters dynamically according to the bandwidth usages. We describe design and analysis details of our protocol SeCond. Comprehensive performance evaluations and comparison with the BitTorrent system model have been accomplished for a wide range of scenarios. Performance results include scalability analysis for different arrival/departure patterns, flash-crowd scenario, overhead analysis, and fairness ratio. The major metrics we study include the average file download time, load on the primary seed, uplink/downlink utilization, and communication overhead. We show that SeCond is a scalable and adaptive protocol which takes the heterogeneity of the peers into account. The protocol is as fair as BitTorrent although it has no explicit strategy addressing free-riding. We also illustrate the applicability of an analytical fluid model to the behavior of SeCond. 相似文献
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BitTorrent文件共享系统中的搭便车(free-riding)节点会使系统性能大幅下降,目前,BitTorrent主要采用choking策略来抑制搭便车行为,但与choking合作而存在的随机选择节点的unchoking策略仍然给搭便车行为提供了机会.提出了一种基于概率连接交换(probabilistic link exchange,简称PLX)的unchoking策略,在实现unchoking功能的同时,有效地抑制了搭便车行为.由于搭便车节点不提供上传,所以choking以后没有指向搭便车节点的连接,此时, PLX的连接交换机制就能抑制搭便车节点进入文件共享系统.另外,通过对连接交换概率的数学控制,PLX可以区分节点对共享系统的贡献,并根据贡献大小调整其在共享网络中的位置,进一步保证了公平性.最后,对PLX的影响进行了深入的理论分析和模拟实验验证,结果表明:PLX unchoking策略较现有的抵抗搭便车的方法更简单、直接,在效果上有明显提升. 相似文献
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BitTorrent激励机制的目标是保证节点上传和下载之间的公平性,但相比公平性而言,实际应用中的节点更优先考虑的是文件下载时间,据此文中提出了一种缩短文件下载时间优先的自适应BitTorrent激励协议AIPS.文中首先基于Markov模型对BitTorrent现有激励机制的效果给出了定量分析,分析了激励机制下的文件传输结构,并用概率分析方法给出了该传输结构下最小化文件下载时间的条件.应用分析结果文中定义了一个以缩短文件下载时间为效用的博弈,在该博弈达到Nash平衡时各节点采用的策略就是激励协议AIPS.模拟实验表明文中提出的AIPS较现有的BitTorrent激励协议能明显提高文件共享系统性能,提高文件下载效率. 相似文献
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由于p2p网络节点的匿名性和贡献资源的自愿性,绝大多数节点不愿共享自己的资源,从而导致大量搭便车现象的出现。该文在分析搭便车现象的基础上,介绍了两种基本的激励机制模型,讨论了博弈理论在激励机制模型中的应用。 相似文献
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在大数据环境下,对移动众包系统的研究已经成为移动社会网络(MSN)的研究热点。然而由于网络个体的自私性,容易导致移动众包系统的不可信问题,为了激励个体对可信策略的选取,提出一种基于声誉的移动众包系统的激励机制——RMI。首先,结合演化博弈理论和生物学中的Wright-Fisher模型研究移动众包系统的可信演化趋势;在此基础上,分别针对free-riding问题和false-reporting问题建立相应的声誉更新方法,从而形成一套完整的激励机制,激励感知用户和任务请求者对可信策略的选取;最后通过模拟实验对提出的激励机制的有效性和适应性进行了验证。结果显示,与传统的基于社会规范的声誉更新方法相比,RMI有效地提高了移动众包系统的可信性。 相似文献
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Distributed message relaying is an important function of a peer-to-peer system to discover service providers. Existing search protocols in unstructured peer-to-peer systems create huge burden on communications, cause long response time, or result in unreliable performance. Moreover, with self-interested peers, these systems are vulnerable to the free-riding problem. In this paper we present an incentive mechanism that not only mitigates the free-riding problem, but also achieves good system efficiency in message relaying for peer discovery. In this mechanism promised rewards are passed along the message propagation process. A peer is rewarded if a service provider is found via a relaying path that includes this peer. The mechanism allows peers to rationally trade-off communication efficiency and reliability while maintaining information locality. We provide some analytic insights to the symmetric Nash equilibrium strategies of this game, and an approximate approach to calculate this equilibrium. Experiments show that this incentive mechanism brings a system utility generally higher than breadth-first search and random walks, based on both the estimated utility from our approximate equilibrium and the utility generated from learning in the incentive mechanism. 相似文献
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Maria-Victoria Belmonte Manuel Díaz Jose-Luis Pérez-de-la-Cruz Ana Reyna 《Journal of Network and Computer Applications》2013,36(1):484-497
Although the proportion of Peer-to-Peer (P2P) traffic has declined in recent years in favor of video streaming and one-click hosting, P2P traffic is predicted to increase in the years to come. Moreover, P2P principles can be applied to improve both, video streaming and one-click hosting, so, P2P is going to continue to be an active research area. This paper presents COINS, a new coalition-formation and incentive mechanism based on game theory. This mechanism encourages cooperative behavior, since contributing peers receive in return a better quality of service, whilst preventing the free-riding problem. To achieve this, we define a “Responsiveness bonus” that reflects the overall contribution of the peer to the system, and we use the game theory utility concept to calculate it. Empirical results, obtained through simulations, show the ability of the coalitions to effectively stop free-riding and promote contribution, increasing the performance of the P2P network and obtaining an improvement in download time. In addition, we prove that users that pursue self-interested strategies, and that contribute, benefit the system. 相似文献
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Le Chang Yangyang Liu Zhonghua Wei Jianping Pan 《Peer-to-Peer Networking and Applications》2011,4(3):274-288
BitTorrent nowadays is one of the most important peer-to-peer (P2P) file-sharing applications on the Internet, and it has
also inspired many other P2P applications such as live or on-demand video streaming services. On the other hand, Network Address
Translation (NAT) has become pervasive in almost all networking scenarios, from residential Internet access to enterprise
networks. Despite the effort of NAT traversal, it is still very likely that P2P applications cannot receive incoming connection
requests properly if they are behind NAT. To quantify the performance impact of NAT on BitTorrent-like P2P systems, we have
created and validated a detailed but tractable mathematical model. We have also proposed and briefly examined a simple but
effective strategy to mitigate the negative impact on NAT peers. In this paper, we further extend our model to cover the proposed
biased optimistic unchoke strategy, and optimize the system performance in terms of both average peer download time and system
finish time. We also create a new, faster Java-based BitTorrent simulator, which is used to validate the extended model and
show the optimality of the proposed strategy and its boundary conditions. 相似文献
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Private BitTorrent community, known as “BitTorrent Darknet” or “Private Tracker (PT)”, has received much attention in the research literature recently. Different from public BitTorrent community, PT can only be accessed by its registered members, and it can provide ultra-high downloading speed due to its effective Sharing Ratio Enforcement (SRE) incentive mechanism which stimulates members to contribute content as much as possible. Although the downloading performance in PTs with high Seeder-to-Leecher Ratio (SLR) is much better than in public BitTorrent communities, our measurements show that SRE mechanism can induce “Poor Downloading Motivation” problem for members who want to increase their sharing ratios to survive and thrive in PT. This problem may discourage PT members’ enthusiasm from contributing to community. To improve sustainability of PTs, we adopt the Predator–prey model to analyze high SLR phenomenon, study the optimal stable SLR range to PTs. Moreover, we develop a queuing model to simulate the seeding/leeching process in a single torrent in PT, and try to maximize the swarming performance with minimum seeding peers. This solution can help PT achieve the optimal SLR range. 相似文献
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BitTorrent is one of the most popular Peer-to-Peer (P2P) applications for file sharing over the Internet. Video files take up a large proportion of space among the BitTorrent shared files. Recently, BitTorrent has attracted researchers’ interests, as an alternative method of providing video on demand (VoD) service. In this paper, we concentrate on enabling BitTorrent to support VoD service in existing swarms while maintaining the download efficiency of file-sharing users. We first examine the content properties of the BitTorrent system to explore the demands and challenges of VoD service in BitTorrent swarms. The efficiency of BitTorrent for various piece selection policies is then compared through measurement on PlanetLab. We also use an optimization mathematical model to analyze the hybrid BitTorrent system in which downloading peers and streaming peers coexist. Both measurement results and model analysis indicate the problem of system efficiency decline in the BitTorrent-based VoD systems, in comparison with the original BitTorrent file-sharing system. Our proposed approach, unlike existing strategies that are limited to changing the piece selection policy to allow BitTorrent to support streaming services, modifies both piece and peer selection policies to provide a “streaming while downloading” service in the BitTorrent system with downloading peers. For the peer selection policy, a CAP (Closest-Ahead Peers) method is applied to make better use of the peers’ upload bandwidths. For the piece selection policy, a sliding window-based hybrid method that combines the rarest-first policy with the sequential policy is proposed. To demonstrate the performance of our proposed approach, an evaluation is made using various metrics on PlanetLab. The results show that our proposed method has higher throughput and better streaming continuity than the sequential policy and BiToS. 相似文献
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针对P2P网络中节点共享存储资源时存在的“搭便车”问题,在节点存储资源分配时引入控制机制,节点根据请求者的贡献值分配其存储资源,以使贡献值小的节点获取资源少,从而抑制搭便车行为。仿真实验表明,该控制机制的动态规划算法能有效地实现P2P网络中存储资源分配的公平性,达到控制节点搭便车行为的目的。 相似文献