Doug Vitale Tech Blog

Posts Tagged ‘p2p

BitTorrent: How it works and how to use it

BitTorrent is not an application you install; it is a network protocol that facilitates decentralized (or distributed) file sharing over the Internet. In this way it is similar to the functionality provided by traditional peer-to-peer (P2P) applications like Napster in the 1990’s, Kazaa, and Limewire. However, BitTorrent differs fundamentally from these older P2P sharing applications because it introduces components such as BitTorrent websites, torrents, trackers, seeders, and leeches (definitions below).

BitTorrent is also unique in how it efficiently uses bandwidth to achieve high data transfer rates. If the file you want is available from multiple hosts, BitTorrent establishes connections with them and downloads chunks of the file simultaneously. Therefore you trade one large, multimegabyte or multigigabyte download for several individual downloads, each of which is handling a much smaller sized data transfer. Additionally BitTorrent allows you to share these parts of a file even if the file itself isn’t fully downloaded on your end.
Typical BitTorrent network with data flow paths shown

Image source: Threestory Studio

Going further, the BitTorrent protocol is designed to ensure that its users share (upload) as much as they take (download). This feature is known as tit-for-tat and is meant to prevent users from downloading without uploading. In fact, BitTorrent tries to reward its generous users like so: the more files you share with others, the faster your downloads are. Obviously the number of users sharing the file you want will also play a role in determining download speed.

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Written by Doug Vitale

February 1, 2012 at 4:20 PM

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