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149
Do Incentives Build Robustness in BitTorrent
- In NSDI’07
, 2007
"... A fundamental problem with many peer-to-peer systems is the tendency for users to “free ride”—to consume resources without contributing to the system. The popular file distribution tool BitTorrent was explicitly designed to address this problem, using a tit-for-tat reciprocity strategy to provide po ..."
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Cited by 132 (11 self)
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A fundamental problem with many peer-to-peer systems is the tendency for users to “free ride”—to consume resources without contributing to the system. The popular file distribution tool BitTorrent was explicitly designed to address this problem, using a tit-for-tat reciprocity strategy to provide positive incentives for nodes to contribute resources to the swarm. While BitTorrent has been extremely successful, we show that its incentive mechanism is not robust to strategic clients. Through performance modeling parameterized by real world traces, we demonstrate that all peers contribute resources that do not directly improve their performance. We use these results to drive the design and implementation of BitTyrant, a strategic BitTorrent client that provides a median 70% performance gain for a 1 Mbit client on live Internet swarms. We further show that when applied universally, strategic clients can hurt average per-swarm performance compared to today’s BitTorrent client implementations. 1
Can Internet Video-on-Demand Be Profitable
- in Proceedings of ACM SIGCOMM
, 2007
"... Video-on-demand in the Internet has become an immensely popular service in recent years. But due to its high bandwidth requirements and popularity, it is also a costly service to provide. We consider the design and potential benefits of peer-assisted video-on-demand, in which participating peers ass ..."
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Cited by 129 (7 self)
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Video-on-demand in the Internet has become an immensely popular service in recent years. But due to its high bandwidth requirements and popularity, it is also a costly service to provide. We consider the design and potential benefits of peer-assisted video-on-demand, in which participating peers assist the server in delivering VoD content. The assistance is done in such a way that it provides the same user quality experience as pure client-server distribution. We focus on the single-video approach, whereby a peer only redistributes a video that it is currently watching. Using a nine-month trace from a client-server VoD deployment for MSN Video, we assess what the 95 percentile server bandwidth costs would have been if a peer-assisted employment had been instead used. We show that peer-assistance can dramatically reduce server bandwidth costs, particularly if peers prefetch content when there is spare upload capacity in the system. We consider the impact of peer-assisted VoD on the cross-traffic among ISPs. Although this traffic is significant, if care is taken to localize the P2P traffic within the ISPs, we can eliminate the ISP cross traffic while still achieving important reductions in server bandwidth. We also develop a simple analytical model which captures many of the critical features of peer-assisted VoD, including its operational modes.
Clustering and sharing incentives in bittorrent systems
- In Proc. of ACM SIGMETRICS ’07
, 2007
"... Peer-to-peer protocols play an increasingly instrumental role in Internet content distribution. Consequently, it is important to gain a full understanding of how these protocols behave in practice and how their parameters impact overall performance. We present the first experimental investigation of ..."
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Cited by 99 (7 self)
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Peer-to-peer protocols play an increasingly instrumental role in Internet content distribution. Consequently, it is important to gain a full understanding of how these protocols behave in practice and how their parameters impact overall performance. We present the first experimental investigation of the peer selection strategy of the popular BitTorrent protocol in an instrumented private torrent. By observing the decisions of more than 40 nodes, we validate three BitTorrent properties that, though widely believed to hold, have not been demonstrated experimentally. These include the clustering of similar-bandwidth peers, the effectiveness of BitTorrent’s sharing incentives, and the peers ’ high average upload utilization. In addition, our results show that BitTorrent’s new choking algorithm in seed state provides uniform service to all peers, and that an underprovisioned initial seed leads to the absence of peer clustering and less effective sharing incentives. Based on our observations, we provide guidelines for seed provisioning by content providers, and discuss a tracker protocol extension that addresses an identified limitation of the protocol. 1
BitTorrent is an Auction: Analyzing and Improving BitTorrent’s Incentives, in:
- Proc. of the ACM SIGCOMM
, 2008
"... ABSTRACT 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 ..."
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Cited by 72 (2 self)
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ABSTRACT 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 underreporting pieces yields prolonged neighbor interest.
Understanding the power of pull-based streaming protocol: Can we do better
- IEEE JSAC
, 2007
"... Abstract — Most of the real deployed peer-to-peer streaming systems adopt pull-based streaming protocol. In this paper, we demonstrate that, besides simplicity and robustness, with proper parameter settings, when the server bandwidth is above several times of the raw streaming rate, which is reasona ..."
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Cited by 67 (1 self)
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Abstract — Most of the real deployed peer-to-peer streaming systems adopt pull-based streaming protocol. In this paper, we demonstrate that, besides simplicity and robustness, with proper parameter settings, when the server bandwidth is above several times of the raw streaming rate, which is reasonable for practical live streaming system, simple pull-based P2P streaming protocol is nearly optimal in terms of peer upload capacity utilization and system throughput even without intelligent scheduling and bandwidth measurement. We also indicate that whether this near optimality can be achieved depends on the parameters in pull-based protocol, server bandwidth and group size. Then we present our mathematical analysis to gain deeper insight in this characteristic of pull-based streaming protocol. On the other hand, the optimality of pull-based protocol comes from a cost-tradeoff between control overhead and delay, that is, the protocol has either large control overhead or large delay. To break the tradeoff, we propose a pull-push hybrid protocol. The basic idea is to consider pull-based protocol as a highly efficient bandwidthaware multicast routing protocol and push down packets along the trees formed by pull-based protocol. Both simulation and real-world experiment show that this protocol is not only even more effective in throughput than pull-based protocol but also has far lower delay and much smaller overhead. And to achieve near optimality in peer capacity utilization without churn, the server bandwidth needed can be further relaxed. Furthermore, the proposed protocol is fully implemented in our deployed GridMedia system and has the record to support over 220,000 users simultaneously online. Index Terms — p2p streaming, pull-based, pull-push hybrid, capacity utilization, throughput, delay I.
Exploiting Similarity for Multi-Source Downloads using File Handprints
- In USENIX NSDI’07
"... Many contemporary approaches for speeding up large file transfers attempt to download chunks of a data ob-ject from multiple sources. Systems such as BitTorrent quickly locate sources that have an exact copy of the de-sired object, but they are unable to use sources that serve similar but non-identi ..."
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Cited by 58 (9 self)
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Many contemporary approaches for speeding up large file transfers attempt to download chunks of a data ob-ject from multiple sources. Systems such as BitTorrent quickly locate sources that have an exact copy of the de-sired object, but they are unable to use sources that serve similar but non-identical objects. Other systems automati-cally exploit cross-file similarity by identifying sources for each chunk of the object. These systems, however, require a number of lookups proportional to the number of chunks in the object and a mapping for each unique chunk in every identical and similar object to its corre-sponding sources. Thus, the lookups and mappings in such a system can be quite large, limiting its scalability. This paper presents a hybrid system that provides the
Antfarm: Efficient Content Distribution with Managed Swarms
"... This paper describes Antfarm, a content distribution system based on managed swarms. A managed swarm couples peer-to-peer data exchange with a coordinator that directs bandwidth allocation at each peer. Antfarm achieves high throughput by viewing content distribution as a global optimization problem ..."
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Cited by 55 (1 self)
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This paper describes Antfarm, a content distribution system based on managed swarms. A managed swarm couples peer-to-peer data exchange with a coordinator that directs bandwidth allocation at each peer. Antfarm achieves high throughput by viewing content distribution as a global optimization problem, where the goal is to minimize download latencies for participants subject to bandwidth constraints and swarm dynamics. The system is based on a wire protocol that enables the Antfarm coordinator to gather information on swarm dynamics, detect misbehaving hosts, and direct the peers ’ allotment of upload bandwidth among multiple swarms. Antfarm’s coordinator grants autonomy and local optimization opportunities to participating nodes while guiding the swarms toward an efficient allocation of resources. Extensive simulations and a PlanetLab deployment show that the system can significantly outperform centralized distribution services as well as swarming systems such as BitTorrent. 1
PULSE: An Adaptive, Incentive-Based, Unstructured P2P Live Streaming System
- J. IEEE Trans. on Multimedia
"... Abstract—Large-scale live media streaming is a challenge for traditional server-based approaches. To appropriately support big audiences, broadcasters must be able to allocate huge bandwidth and computational resources. The costs involved with such an infrastructure exclude all but the established c ..."
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Cited by 46 (1 self)
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Abstract—Large-scale live media streaming is a challenge for traditional server-based approaches. To appropriately support big audiences, broadcasters must be able to allocate huge bandwidth and computational resources. The costs involved with such an infrastructure exclude all but the established content producers from exploiting the Internet as a distribution medium. Publishers of not-yet-popular content, unless they manage to properly pre-dict their maximum audience size, will likely fail to dimension correctly their broadcast infrastructure. Peer-to-peer systems for live streaming allow the users to support content distribution by contributing their unused resources: this increases the scalability of the content distribution while reducing at the same time the economical burden on the streaming provider. This paper presents and evaluates PULSE, an unstructured mesh-based peer-to-peer system designed to support live streaming to large audiences under the arbitrary resource availability as is typically the case for the Internet. PULSE is a highly dynamic system: it constantly op-timizes its mesh of data connections using a feedback-driven peer selection strategy that is based on pairwise incentives. We evaluate the behavior of PULSE under realistic scenarios via simulation and emulation, and present the advantages of our approach, namely a best-effort response to system-wide resource scarcity, high resilience to node churn, and good hop-count properties of the average data distribution paths. Index Terms—Incentives, live streaming, mesh-based, peer-to-peer, unstructured. I.
Analysis of bittorrent-like protocols for on-demand stored media streaming
- In Proc.of the 2008 ACM SIGMETRICS Int. Conf
, 2008
"... This paper develops analytic models that characterize the behavior of on-demand stored media content delivery using BitTorrent-like protocols. The models capture the effects of different piece selection policies, including Rarest-First and two variants of In-Order. Our models provide insight into tr ..."
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Cited by 39 (3 self)
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This paper develops analytic models that characterize the behavior of on-demand stored media content delivery using BitTorrent-like protocols. The models capture the effects of different piece selection policies, including Rarest-First and two variants of In-Order. Our models provide insight into transient and steady-state system behavior, and help explain the sluggishness of the system with strict In-Order streaming. We use the models to compare different retrieval policies across a wide range of system parameters, including peer arrival rate, upload/download bandwidth, and seed residence time. We also provide quantitative results on the startup delays and retrieval times for streaming media delivery. Our results provide insights into the optimal design of peer-to-peer networks for on-demand media streaming.
Content availability and bundling in swarming systems
, 2009
"... All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately. ..."
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Cited by 31 (3 self)
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All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
