The New BitTorrent Congestion Control Algorithm

November 16, 2011
CSB 477 (Open Meeting Area)
Speaker: Prof. Dario Rossi (TELECOM ParisTech)
Hosted by: Columbia University Joint CS/EE Networking Seminar Series


BitTorrent, one of the most widespread file sharing P2P applications, has recently been updated to eliminate use of TCP by introducing an application-level congestion control protocol. This new protocol aims to efficiently use the available link capacity while avoiding interference with other user traffic (e.g., Web, VoIP, and gaming) sharing the same access link.

In this talk, we first provide a primer on this protocol, which is being standardized by the IETF Low-Extra Delay Background Transport (LEDBAT) Working Group. We then report on our research on the performance of LEDBAT. Our experiments, simulation, and analysis are motivated by two complementary viewpoints.

Our studies of the congestion control algorithm behind LEDBAT unveil (and correct) a latecomer unfairness problem in the original design, and allow us to compare the level of low priority to other lower than best-effort protocols (such as TCP-LP and TCP-NICE). We also adopt a P2P swarm viewpoint to focus on the impact that LEDBAT has on torrent completion time, the primary QoE metrics for P2P users.

Further information is available online.

Speaker Biography

Dario Rossi (M'02) received his MSc and PhD from Politecnico di Torino in 2001 and 2005 respectively. During 2003/2004, he was with the CS Department at University of California, Berkeley. Since October 2006, he has been an Associate Professor at Telecom ParisTech, Paris, where he is responsible for several European research projects, such as FP7 NAPA-WINE, Celtic TIGER, TIGER2 and TRANS, ANR Connect. He has coauthored over 70 papers in leading conferences and journals, holds 4 patents, and has participated in the program committees of more than 20 conferences including IEEE INFOCOM, ICC, IPCCC, and GLOBECOM. His research interests include peer-2-peer networks, Internet traffic measurement, green networking, and traffic engineering.

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