Understanding BitTorrent: an experimental perspective

Legout, Arnaud;Urvoy-Keller, Guillaume;Michiardi, Pietro
INRIA Research report (inria-00000156, version 3-9 November 2005)

BitTorrent is a recent, yet successful peer-to-peer protocol focused on efficient content delivery. To gain a better understanding of the key algorithms of the protocol, we have instrumented a client and run experiments on a large number of real torrents. Our experimental evaluation is peer oriented, instead of tracker oriented, which allows us to get detailed information on all exchanged messages and protocol events. In particular, we have explored the properties of the two key algorithms of BitTorrent: the choke and the rarest first algorithms. We have shown that they both perform remarkably well, but that the old version of the choke algorithm, that is still widely deployed, suffers from several problems. We have also explored the dynamics of a peer set that captures most of the torrent variability and provides important insights for the design of realistic models of BitTorrent. Finally, we have evaluated the protocol overhead. We have found in our experiments a small protocol overhead and explain under which conditions it can increase.

Digital Security
Eurecom Ref:
© INRIA. Personal use of this material is permitted. The definitive version of this paper was published in INRIA Research report (inria-00000156, version 3-9 November 2005) and is available at :

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