Columbia University Joint CS/EE Networking Seminar Series

The New BitTorrent Congestion Control Algorithm

Prof. Dario Rossi


Wednesday, November 16th, 1-2PM, CSB 477 (Open Meeting Area)

Abstract: BitTorrent, one of the most widespread file sharing P2P applications, recently got rid of TCP by introducing an application-level congestion control protocol.The aim of this new protocol is to efficiently use the available link capacity, while avoiding to interfere with the rest of user traffic (e.g., Web, VoIP and gaming) sharing the same access bottleneck.

On this talk, we first provide a primer on this protocol, which is under standardisation at the IETF Low-Extra Delay BAckground Transport (LEDBAT) Working Group. We then report on our research activities that, using experiments, simulation and analysis, address the performance of LEDBAT adopting two complementary viewpoints.

On the one hand, we study the congestion control algorithm behind LEDBAT: our results unveil (and correct) a latecomer unfairness problem of the original design, and allow to compare the level of low priority with respect to other lower than best-effort protocols (such as TCP-LP and TCP-NICE). On the other hand, we adopt a P2P swarm viewpoint, and focus on the impact that LEDBAT has on the torrent completion time, the primary QoE metrics for P2P users.

Further information is available online at

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 is 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 he 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.