BitTorrent tracker | improving torrent reliability

Improving torrent reliability

Trackers are the primary reason for a damaged BitTorrent "swarm". (Other reasons are mostly related to damaged or hacked clients uploading corrupt data.) The reliability of trackers has been improved through two main innovations in the BitTorrent protocol.

Multi-tracker torrents

Multi-tracker torrents contain multiple trackers in a single torrent file. This provides redundancy in the case that one tracker fails, the other trackers can continue to maintain the swarm for the torrent. One disadvantage to this is that it becomes possible to have multiple unconnected swarms for a single torrent where some users can connect to one specific tracker while being unable to connect to another. This can create a disjoint set which can impede the efficiency of a torrent to transfer the files it describes. Additional extensions such as Peer exchange and DHT mitigate this effect by rapidly merging otherwise disjoint graphs of peers.

Trackerless torrents

Vuze (formerly Azureus) was the first BitTorrent client to implement such a system through the distributed hash table (DHT) method. An alternative and incompatible DHT system, known as Mainline DHT, was developed simultaneously and later adopted by the BitTorrent (Mainline), µTorrent, Transmission, rTorrent, KTorrent, BitComet, and Deluge clients.

Current versions of the official BitTorrent client, µTorrent, BitComet, Transmission and BitSpirit all share compatibility with Mainline DHT. Both DHT implementations are based on Kademlia. As of version, Vuze also supports Mainline DHT in addition to its own distributed database through use of an optional application plugin [MainlineDHT Plugin]. This potentially allows the Vuze client to reach a bigger swarm.

Most BitTorrent clients also use Peer exchange (PeX) to gather peers in addition to trackers and DHT. Peer exchange checks with known peers to see if they know of any other peers. With the release of Vuze, all major BitTorrent clients now have compatible peer exchange.

Other Languages
български: Торент тракер
Ελληνικά: Tracker
português: BitTorrent tracker
русский: BitTorrent-трекер
slovenščina: Sledilnik
українська: BitTorrent-трекер