James Delahunty
19 May 2005 17:30
A "trackerless" version of BitTorrent has been included in the latest release of the software. The BitTorrent site says that it is part of their "ongoing efforts to make publishing files on the Web painless and disruptively cheap". Here's some information directly from the BitTorrent website.
Suppose you bought a television station, you could broadcast your programming to everyone in a 50 mile radius. Now suppose the population of your town tripled. How much more does it cost you to broadcast to 3 times as many people? Nothing. The same is not true of the Web. If you own a website and you publish your latest video on it, as popularity increases, so does your bandwidth bill! Sometimes by a lot! However, thanks to BitTorrent the website owner gets almost near-broadcast economics on the web by harnessing the unused upstream bandwidth of his/her users.
In prior versions of BitTorrent, publishing was a 3 step process. You would:
1. Create a ".torrent" file -- a summary of your file which you can put on your blog or website
2. Create a "tracker" for that file on your webserver so that your downloaders can find each other
3. Create a "seed" copy of your download so that your first downloader has a place to download from
Many of you have blogs and websites, but don’t have the resources to set up a tracker. In the new version, we've created an optional 'trackerless' method of publication. Anyone with a website and an Internet connection can host a BitTorrent download!
While it is called trackerless, in practice it makes every client a lightweight tracker. A clever protocol, based on a Kademlia distributed hash table or "DHT", allows clients to efficiently store and retrieve contact information for peers in a torrent.
When generating a torrent, you can choose to utilize the trackerless system or a traditional dedicated tracker. A dedicated tracker allows you to collect statistics about downloads and gives you a measure of control over the reliability of downloads. The trackerless system makes no guarantees to reliability but requires no resources of the publisher. The trackerless system is not consulted when downloading a traditionally tracked torrent.