Do incentives build robustness in bit torrent

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]  David Hales,et al.  How to cheat BitTorrent and why nobody does , 2005 .

[2]  John R. Douceur,et al.  The Sybil Attack , 2002, IPTPS.

[3]  Laurent Massoulié,et al.  Coupon replication systems , 2008, TNET.

[4]  Eddie Kohler,et al.  Exploiting BitTorrent For Fun , 2006, IPTPS.

[5]  B. Cohen,et al.  Incentives Build Robustness in Bit-Torrent , 2003 .

[6]  W. Hamilton,et al.  The evolution of cooperation. , 1984, Science.

[7]  Laurent Massoulié,et al.  Faithfulness in internet algorithms , 2004, PINS '04.

[8]  Arun Venkataramani,et al.  iPlane: an information plane for distributed services , 2006, OSDI '06.

[9]  Guillaume Urvoy-Keller,et al.  Rarest first and choke algorithms are enough , 2006, IMC '06.

[10]  Xiaoning Ding,et al.  Measurements, analysis, and modeling of BitTorrent-like systems , 2005, IMC '05.

[11]  R. Srikant,et al.  Modeling and performance analysis of BitTorrent-like peer-to-peer networks , 2004, SIGCOMM '04.

[12]  Stefan Schmid,et al.  Free Riding in BitTorrent is Cheap , 2006, HotNets.

[13]  Robert Tappan Morris,et al.  TCP behavior with many flows , 1997, Proceedings 1997 International Conference on Network Protocols.

[14]  Mustaque Ahamad,et al.  Incentives in BitTorrent induce free riding , 2005, P2PECON '05.

[15]  Eddie Kohler,et al.  MultiQ: automated detection of multiple bottleneck capacities along a path , 2004, IMC '04.

[16]  Bin Fan,et al.  The Delicate Tradeoffs in BitTorrent-like File Sharing Protocol Design , 2006, Proceedings of the 2006 IEEE International Conference on Network Protocols.

[17]  Stefan Saroiu,et al.  A Measurement Study of Peer-to-Peer File Sharing Systems , 2001 .

[18]  Venkata N. Padmanabhan,et al.  Analyzing and Improving a BitTorrent Networks Performance Mechanisms , 2006, Proceedings IEEE INFOCOM 2006. 25TH IEEE International Conference on Computer Communications.