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  • Internet


BitTorrent is not just another peer-to-peer solution. This ever more popular protocol is widely used legally as an alternative to centralised downloading.

Against the stormy background of P2P, BitTorrent is probably a case apart. It uses a simple idea: the user no longer downloads a single file from another user's computer, but from a multitude of users simultaneously, while they send other parts of the file that they are downloading to other users.

This is a big difference, particularly with the way the Gnutella and FastTrack networks work. On these networks, the user permanently shares part of their hard drive (generally a directory): when they are online, the other users can access their hard drive and retrieve what they are interested in. There are problems as soon as several people want to retrieve the same file: a queue forms, and each has to await their turn to "enter" the hard drives of users who have the file.

With BitTorrent, the users who download a file are themselves making it available to other users as they download it, and as soon as they stop (by stopping the "torrent"), they are no longer sharing anything. Paradoxically, because the file is made up of a large number of sources (all the users who are themselves downloading at a given moment), the more people want it, the faster it downloads.

BitTorrent for everything and everybody

But although it is widely used today for illegal file exchanges, there is nothing to suggest that BitTorrent will remain confined to illegal P2P.

There are sites containing lists of "legal" torrents (e.g. “Legal Torrents",, with both music files made available by labels owning the operating rights, and the latest books by Lawrence Lessig which he placed under Creative Commons licence from the outset.

The process is also being used increasingly by community sites housing multiple applications (in particular Sourceforge,, as an alternative to downloading from a centralised server.

BitTorrent can thus very easily be used by any content producer. What is more, it is even a serious alternative to the standard ways of making large files available to the public. The main benefit of BitTorrent is that it takes the load off a company's server(s) and frees up its bandwidth: in a similar way to the principle of grid computing, the downloading task is shared among the users who retrieve the file peer to peer, and once the virtuous circle has been entered, there is very little call on the server that delivered the file in the first place.

Moreover, there are several applications available for you to create torrents yourself, and even to play the role of tracer, for a file that you want to make available. The technique is thus cheap and allows small companies to become distributors of large files to an almost unlimited number of people.

Original article by Cyril Fievet -






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