The Bittorrent P2P File-Sharing System: Measurements and Analysis

Abstract

Of the many P2P file-sharing prototypes in existence, BitTorrent is one of the few that has managed to attract millions of users. BitTorrent relies on other (global) components for file search, employs a moderator system to ensure the integrity of file data, and uses a bartering technique for downloading in order to prevent users from freeriding. In this paper we present a measurement study of BitTorrent in which we focus on four issues, viz. availability, integrity, flashcrowd handling, and download performance. The purpose of this paper is to aid in the understanding of a real P2P system that apparently has the right mechanisms to attract a large user community, to provide measurement data that may be useful in modeling P2P systems, and to identify design issues in such systems.

Correlating Topology and Path Characteristics of Overlay Networks and the Internet

“…From the modeling point of view, our main results are that (i) BitTorrent users are not distributed evenly across the Internet (we find that the majority of BitTorrent users are located in Europe), (ii) the average download bandwidth has reached 500 Kbps (double the value observed in our previous investigation [17]) and should be modeled differently based on the continent location of peers, and (iii) less than 250 Autonomous Systems and less than 500 Internet Organizations are used by the majority of peers. Finally, we correlate the information to provide strong evidence that BitTorrent users are well connected by the Internet in terms of bandwidth and hop count.…”

“…The bursty behavior observed for larger swarm sizes is due to the smaller number of observations of those swarm sizes. The aggregate average bandwidth fluctuated around 500 Kbps, double the bandwidth reported in [17]. We explain this difference by the bias of the previous measurements: except for 10% of the files, the measurements in [17] targeted files with too small swarm sizes.…”

“…We have developed size evaluators for four well-known BitTorrent web sites: Mininova (the replacement of the previously largest web site, SuprNova [17], which is now defunct), Novatina, Pirate Bay, and TorrentPortal. At the time of the measurements, these sites were the top four BitTorrent web sites in the slyck.com's rankings 5 .…”

“…BitTorrent is currently the largest P2P file-sharing network with over one third of the world's P2P traffic [12], thus generating more than 15% of the total Internet traffic 2 . Furthermore, BitTorrent can efficiently handle flashcrowd effects [17] (offering popular data to a large number of users, immediately after the data release), and offers a pollutionfree sharing environment to its users [17].…”

“…For this, we have designed and implemented MULTIPROBE, a large-scale P2P measurement framework. With MULTIPROBE, we build on the experience accumulated in our previous work [17], where we have investigated 1 Slyck.com lists size information for many large P2P networks. the high-level characteristics and the user behavior of BitTorrent, without correlating the underlaying Internet.…”