Micro Transport Protocol
Encyclopedia
Micro Transport Protocol or µTP (sometimes also uTP) is an open
UDP
-based variant of the BitTorrent peer-to-peer file sharing
protocol intended to mitigate poor latency and other congestion control issues found in conventional bittorrent over TCP, while providing reliable, ordered delivery.
It was devised to automatically slow down 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 an ADSL line between a BitTorrent application and a web browser.
on QoS
and high-performance bulk transport, was adapted for use as a background transport protocol by Plicto, which was acquired by BitTorrent, Inc. in 2006, and further developed within its new owner. It was first introduced in the µTorrent 1.8.x beta branches, and publicized in the alpha builds of µTorrent 1.9.
The implementation of µTP used in µTorrent was later separated into the "libutp" library and published under the MIT license.
The first free software
client to implement µTP was KTorrent
4.0. libtorrent
currently has an incomplete implementation of µTP in a development branch. Azureus (now called Vuze
) Bittorrent Client also implements µTP (since Azureus 4.5.0.5 on Microsoft Windows
and Mac OS X
10.5 or higher only). Transmission implements µTP since version 2.30.
The µTP framing scheme is believed by some to be far from optimal.
LEDBAT has been described in an Internet-Draft,
but the details of the µTP implementation are different from those of the draft.
Open standard
An open standard is a standard that is publicly available and has various rights to use associated with it, and may also have various properties of how it was designed . There is no single definition and interpretations vary with usage....
UDP
User Datagram Protocol
The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring...
-based variant of the BitTorrent peer-to-peer file sharing
Peer-to-peer file sharing
P2P or Peer-to-peer file sharing allows users to download files such as music, movies, and games using a P2P software client that searches for other connected computers. The "peers" are computer systems connected to each other through internet. Thus, the only requirements for a computer to join...
protocol intended to mitigate poor latency and other congestion control issues found in conventional bittorrent over TCP, while providing reliable, ordered delivery.
It was devised to automatically slow down the rate at which packets of data are transmitted between users of peer-to-peer
Peer-to-peer
Peer-to-peer computing or networking is a distributed application architecture that partitions tasks or workloads among peers. Peers are equally privileged, equipotent participants in the application...
file sharing torrents when it interferes with other applications. For example, the protocol should automatically allow the sharing of an ADSL line between a BitTorrent application and a web browser.
Development
µTP emerged from research at Internet2Internet2
Internet2 is an advanced not-for-profit US networking consortium led by members from the research and education communities, industry, and government....
on QoS
Quality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
and high-performance bulk transport, was adapted for use as a background transport protocol by Plicto, which was acquired by BitTorrent, Inc. in 2006, and further developed within its new owner. It was first introduced in the µTorrent 1.8.x beta branches, and publicized in the alpha builds of µTorrent 1.9.
The implementation of µTP used in µTorrent was later separated into the "libutp" library and published under the MIT license.
The first free software
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
client to implement µTP was KTorrent
KTorrent
KTorrent is a BitTorrent client written in C++ for KDE using the Qt user interface toolkit. It is maintained in the KDE Extragear.- Features :*Upload and download speed capping / throttling & scheduling...
4.0. libtorrent
Libtorrent (Rasterbar)
libtorrent is an open source implementation of the BitTorrent protocol. It is written in and has its main library interface in C++. Its most notable features are support for Mainline DHT, IPv6 , HTTP seeds and µTorrent's peer exchange....
currently has an incomplete implementation of µTP in a development branch. Azureus (now called Vuze
Vuze
Vuze is a BitTorrent client used to transfer files via the BitTorrent protocol. Vuze is written in Java, and uses the Azureus Engine. In addition to downloading data linked to by .torrent files, Azureus allows users to view, publish and share original DVD and HD quality video content...
) Bittorrent Client also implements µTP (since Azureus 4.5.0.5 on Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
and Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
10.5 or higher only). Transmission implements µTP since version 2.30.
Operation
µTP consists of two parts: a framing scheme and a congestion control algorithm that is less aggressive than TCP's.µTP framing
µTP stores data within UDP datagrams using its own framing scheme. µTP's framing scheme has functionality roughly equivalent to TCP's (with timestamps and SACK), but it is realised in a completely incompatible manner.The µTP framing scheme is believed by some to be far from optimal.
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. Additionally, information from the µTP congestion controller can be used to choose the transfer rate of TCP connections.LEDBAT has been described in an Internet-Draft,
but the details of the µTP implementation are different from those of the draft.
See also
- µTorrent
- BitTorrent
- TCP congestion avoidance algorithmTCP congestion avoidance algorithmTransmission Control Protocol uses a network congestion avoidance algorithm that includes various aspects of an additive increase/multiplicative decrease scheme, with other schemes such as slow-start in order to achieve congestion avoidance....
External links
- Official uTP protocol page
- BitTorrent Enhancement Proposal 29 - µTorrent transport protocol
- TCP-LP