[bittorrent] Evaluation of the BitTorrent choking algorithm

Arnaud Legout Arnaud.Legout at sophia.inria.fr
Tue Nov 21 16:57:20 EST 2006


I am pleased to announce the availability of the technical report:
Clustering and Sharing Incentives in BitTorrent Systems

Any comments are welcomed.


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.

Arnaud Legout, Ph.D.

INRIA Sophia Antipolis - Planète  Phone :
2004 route des lucioles - BP 93   Fax   :
06902 Sophia Antipolis CEDEX      E-mail: arnaud.legout at sophia.inria.fr
FRANCE                            Web   : http://www-sop.inria.fr/planete/Arnaud.Legout/index.html

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