Micro Transport Protocol: Difference between revisions

Revision as of 03:12, 22 August 2022

Revision as of 16:25, 30 August 2022

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'''Micro Transport Protocol''' or '''μTP''' (sometimes also '''uTP''') is an [[open standard|open]] [[User Datagram Protocol|UDP]]-based variant of the [[BitTorrent]] [[peer-to-peer file sharing]] [[Protocol (computing)|protocol]] intended to mitigate poor latency and other [[network congestion#Congestion control|congestion control]] problems found in conventional BitTorrent over [[Transmission Control Protocol|TCP]], while providing reliable, ordered delivery.

It was devised to automatically slow down<ref>{{cite web|url=http://forum.bittorrent.org/viewtopic.php?pid%3D762#p762 |title=ArchivedForum.bittorrent.org copy/ A few comments about µTP (BEP-29) |access-date=November 15, 2009 |url-status=dead|archive-url=https://web.archive.org/web/20100301125306/http://forum.bittorrent.org/viewtopic.php?pid=762 |archive-date=March 1, 2010 }}</ref> the rate at which packets of data are transmitted between users of [[peer-to-peer]] file sharing [[BitTorrent|torrent]]s when it interferes with other applications. For example, the protocol should automatically allow the sharing of an [[Digital subscriber line|DSL line]] between a BitTorrent application and a web browser.

==Development==

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==μTP congestion control==

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.<ref>{{Cite web |url=http://searchnetworking.techtarget.com.au/articles/27957-Torrents-of-Disruption-on-the-Way- |title=Technical information about UDP |access-date=2008-12-23 |archive-url=https://web.archive.org/web/20090512123108/http://searchnetworking.techtarget.com.au/articles/27957-Torrents-of-Disruption-on-the-Way- |archive-date=2009-05-12 |url-status=dead }}</ref><ref>{{cite web|url=http://forum.bittorrent.org/viewtopic.php?pid%3D762#p762 |title=ArchivedForum.bittorrent.org copy/ A few comments about µTP (BEP-29) |access-date=November 15, 2009 |url-status=dead|archive-url=https://web.archive.org/web/20100301125306/http://forum.bittorrent.org/viewtopic.php?pid=762 |archive-date=March 1, 2010 }}</ref> Additionally, information from the μTP congestion controller can be used to choose the transfer rate of TCP connections.<ref>{{cite web|url=http://forum.utorrent.com/viewtopic.php?pid=377209#p377209 |date=2008-11-26 |title=Post by developer "Greg Hazel" in thread "μTorrent 1.9 alpha" |access-date=2009-03-08 |url-status=dead|archive-url=https://web.archive.org/web/20090208093326/http://forum.utorrent.com/viewtopic.php?pid=377209 |archive-date=February 8, 2009 }}</ref>

{{Internet|expanded=Protocols}}

LEDBAT is described in {{IETF RFC|6817}}. As of 2009, the details of the μTP implementation were different from those of the then-current Internet Draft.<ref>{{cite web|url=http://forum.bittorrent.org/viewtopic.php?pid%3D753#p753 |title=ArchivedForum.bittorrent.org copy/ A few comments about µTP (BEP-29) |access-date=November 15, 2009 |url-status=dead|archive-url=https://web.archive.org/web/20110725080523/http://forum.bittorrent.org/viewtopic.php?pid=753 |archive-date=July 25, 2011 }}{{Full citation needed|date=December 2014}}</ref>

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.<ref>{{cite web|url=http://forum.utorrent.com/viewtopic.php?id%3D49813 |title=ΜTorrent 1.9 alpha 15380 (Page 1) / Announcements / µTorrent Community Forums |access-date=December 23, 2012 |url-status=dead|archive-url=https://web.archive.org/web/20130325195455/http://forum.utorrent.com/viewtopic.php?id=49813 |archive-date=March 25, 2013 }}</ref><ref>{{cite web|url=http://forum.utorrent.com/viewtopic.php?pid%3D407732#p407732 |title=Distributed UDP hole punching for the BitTorrent protocol (Page 1) / Protocol Design Discussion / µTorrent Community Forums |access-date=December 23, 2012 |url-status=dead|archive-url=https://web.archive.org/web/20130619125216/http://forum.utorrent.com/viewtopic.php?pid=407732 |archive-date=June 19, 2013 }}</ref>