Micro Transport Protocol
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Micro Transport Protocol (μTP, sometimes uTP) is an open User Datagram Protocol-based (UDP-based) variant of the BitTorrent peer-to-peer file-sharing protocol intended to mitigate poor latency and other congestion control problems found in conventional BitTorrent over Transmission Control Protocol (TCP), while providing reliable, ordered delivery.
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 it interferes with other applications. For example, the protocol should automatically allow the sharing of a DSL line between a BitTorrent application and a web browser.
Development
[edit ]μTP emerged from research at Internet2 on QoS and high-performance bulk transport, was adapted for use as a background transport protocol by Plicto, founded by Stanislav Shalunov and Ben Teitelbaum[2] and later acquired by BitTorrent, Inc. in 2006, and further developed within its new owner.[3] It was first introduced in the μTorrent 1.8.x beta branches, and publicized in the alpha builds of μTorrent 1.9.[4] [5]
The implementation of μTP used in μTorrent was later separated into the "libutp" library and published under the MIT license.[6] [7]
The first free software client to implement μTP was KTorrent 4.0.[8] [9] libtorrent implements μTP since version 0.16.0[10] and it is used in qBittorrent since 2.8.0.[11] Tixati implements μTP since version 1.72.[12] Vuze (formerly Azureus) implements μTP since version 4.6.0.0.[13] Transmission implements μTP since version 2.30.[14]
μTP congestion control
[edit ]The congestion control algorithm used by μTP, known as Low Extra Delay Background Transport (LEDBAT), aims to decrease the latency caused by applications using the protocol while maximizing bandwidth when latency is not excessive.[15] [16] Additionally, information from the μTP congestion controller can be used to choose the transfer rate of TCP connections.[17]
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LEDBAT is described in RFC 6817. As of 2009, the details of the μTP implementation were different from those of the then-current Internet Draft.[18]
μTP also adds support for NAT traversal using UDP hole punching between two port-restricted peers where a third unrestricted peer acts as a STUN server.[19] [20]
See also
[edit ]- TCP congestion control
- Multipurpose Transaction Protocol (MTP)
- QUIC
- Real-Time Media Flow Protocol (RTMFP)
- Stream Control Transmission Protocol (SCTP UDP Encapsulation; RFC 6951)
- UDP-based Data Transfer Protocol (UDT)
References
[edit ]- ^ "Forum.bittorrent.org / A few comments about μTP (BEP-29)". Archived from the original on March 1, 2010. Retrieved November 15, 2009.
- ^ This Is How Your BitTorrent Downloads Move So Fast, Fastcolabs, 2013年07月29日, Retrieved November 6, 2013
- ^ http://www.slideshare.net/eCommConf/eric-klinker-presentation-at-emerging-communication-conference-awards-2010-america/11 uTP timeline, slide 11, "This Green Revolution-improving the yield of your network investment", eComm America Conference, San Francisco, CA, April 2010.
- ^ Beijnum, Iljitsch van (2008年12月02日). "?Torrent's switch to UDP and why the sky isn't falling". Ars Technica. Retrieved 2021年05月11日.
- ^ "uTorrent shifts towards UDP to make it work better". www.thinkbroadband.com. 3 December 2008. Retrieved 2021年05月11日.
- ^ "Libutp, an open source implementation of μTP, has now been released (Page 1) / Announcements / μTorrent Community Forums". Archived from the original on 2011年01月23日. Retrieved 2011年01月15日.
- ^ bittorrent/libutp, BitTorrent Inc., 2021年05月08日, retrieved 2021年05月11日
- ^ "KTorrent First BitTorrent Client To Adopt Open Source uTP * TorrentFreak" . Retrieved 2021年05月11日.
- ^ "KTorrent 4.0 is out". 24 May 2010. Archived from the original on 2015年04月02日.
- ^ "Google Code Archive - Long-term storage for Google Code Project Hosting". code.google.com. Retrieved 2021年05月11日.
- ^ "qBittorrent Official Website". www.qbittorrent.org. Retrieved 2021年05月11日.
- ^ "Tixati.com - News". www.tixati.com. Retrieved 2021年05月11日.
- ^ "Version 4400 4702 Changelog - VuzeWiki". wiki.vuze.com. Retrieved 2021年05月11日.
- ^ "Changes – Transmission". Archived from the original on 2015年05月24日. Retrieved 2012年07月12日.
- ^ "Technical information about UDP". Archived from the original on 2009年05月12日. Retrieved 2008年12月23日.
- ^ "Forum.bittorrent.org / A few comments about μTP (BEP-29)". Archived from the original on March 1, 2010. Retrieved November 15, 2009.
- ^ "Post by developer "Greg Hazel" in thread "μTorrent 1.9 alpha"". 2008年11月26日. Archived from the original on February 8, 2009. Retrieved 2009年03月08日.
- ^ "Forum.bittorrent.org / A few comments about μTP (BEP-29)". Archived from the original on July 25, 2011. Retrieved November 15, 2009.[full citation needed ]
- ^ "ΜTorrent 1.9 alpha 15380 (Page 1) / Announcements / μTorrent Community Forums". Archived from the original on March 25, 2013. Retrieved December 23, 2012.
- ^ "Distributed UDP hole punching for the BitTorrent protocol (Page 1) / Protocol Design Discussion / μTorrent Community Forums". Archived from the original on June 19, 2013. Retrieved December 23, 2012.
External links
[edit ]- BitTorrent Enhancement Proposal 29 - μTorrent transport protocol
- TCP Low Priority
- swift - the multiparty transport protocol
