In recent years the intellectual property division of AT&T has patented quite a few unusual inventions. Today we can add another to the list after the telecoms company was granted a patent which aims to keep torrent files available for as long as possible.
In the patent (pdf), which was awarded yesterday, the ISP points out that BitTorrent is a very effective way of sharing files online. However, AT&T also signals some drawbacks, including the fact that some torrent swarms stop working because there are no complete copies of the file available.
“As more and more peers download a complete copy of the file, the performance of the torrent deteriorates to the point that it becomes difficult for the file to be located and downloaded. As a result, current BitTorrent systems are not desirable for downloading older files,” the patent reads.
Since there are often many swarms downloading the same content via different trackers, it could be that the file lives on elsewhere. Similarly, other peers might be willing to start seeding the dead torrent again. AT&T’s patent pairs these sources to increase the availability of files downloaded via BitTorrent.
The patent proposes to add “collaboration information” which may be obtained from each peer when it joins a torrent swarm. If a torrent has no active seeds available, this information can point the downloader to “dormant peers” or external trackers that still have active seeders.
“If the file is not available at an active peer, the tracker node has two options; it may contact some of the listed dormant peers to see if they are willing to make the file available, and/or it may contact a remote tracker node listed for the file,” the patent reads.
“If the file is made available by a dormant peer and/or at a remote torrent, the local peer can then establish a peer-to-peer communication with the dormant peer or a peer on the remote torrent, and download the file therefrom. As a result, the local peer can locate and download files that are not available on its current torrent from both dormant peers and peers in other torrents.”
The idea to point people to other trackers is not new. Most torrents come with multiple trackers nowadays to ensure that a file remains available for as long as possible. AT&T’s proposed invention would automate this feature.
The idea to contact “dormant peers” is more novel. In short, that means that people who previously downloaded a file, but are no longer seeding it, can get a request to make it available again.
Whether the ISPs has any real life applications for their invention is yet unknown. The current patent was granted this week, but the first application dates back to 2005, a time when BitTorrent wasn’t quite as mainstream as it is today.
The patent certainly doesn’t mean that the ISP encourages sharing copyrighted files. Among other anti-piracy innovations, AT&T previously patented systems to track content being shared via BitTorrent and other P2P networks and report those offenders to the authorities.