Micro Transport Protocol

Micro Transport Protocol or µTP is a protocol used by the µTorrent implementation of the bittorrent protocol to communicate across the internet.

It was devised to automatically slow down^[1] the rate at which packets of data are transmitted between users of peer-to-peer file sharing torrents when the file-sharing traffic interferes with other applications. For example, it should in principle automatically allow the sharing of an ADSL line between a BitTorrent application and a web browser.

As it is difficult for some people to type the Greek letter mu, µTP is often written uTP.

Development

µTP was first publicly introduced in the alpha builds of µTorrent 1.9, though partial support for the protocol was already implemented in the µTorrent 1.8.x Beta branches.^[2][3]

Because it is still being implemented, µTP protocol features are typically hidden or made obscure in the client user interfaces of the BitTorrent clients that support it. There is no open source µTP protocol codebase at this time, making this feature's support with other BitTorrent clients much less uniform. It may take until late 2010 or early 2011 until this feature is readily accessible with a user friendly interface.

Operation

Based upon the User Datagram Protocol (UDP), µTP aims to decrease latency caused by applications using the protocol while maximizing bandwidth when latency is not excessive^[4]. Information from the transport can be used to control the transfer rate of TCP connections to prevent disruption of the used Internet connection.^[5]

See also

• µTorrent
• BitTorrent
• BitTorrent Enhancement Proposal 29 - µTorrent transport protocol
• TCP congestion avoidance algorithm
• TCP-LP

References

1. http://forum.bittorrent.org/viewtopic.php?pid=762#p762
2. µTorrent's switch to UDP and why the sky isn't falling
3. uTorrent shifts towards UDP to make it work better
4. "Post by developer "Greg Hazel" in thread "µTorrent 1.9 alpha"". 2008-11-26. Retrieved 2009-03-08.
5. Technical information about UDP