Inverse Multiplexing for
ATM (IMA) is a standardized technology used to transport ATM traffic over a bundle of
T1 or
E1 lines, which is called an ''IMA Group''. This allows for gradual increase in
data link
A data link is the means of connecting one location to another for the purpose of transmitting and receiving digital information ( data communication). It can also refer to a set of electronics assemblies, consisting of a transmitter and a rece ...
capacity where implementing a higher capacity solution like T3/E3 or
SONET/SDH
Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting ...
is not deemed feasible. The maximum number of lines in an IMA Group is 32, bringing the total data rate to roughly 64 Mbit/s. The standard specification was initially approved by The ATM Forum in July 1997, and was later updated to version 1.1 in March 1999.
ATM cell insertion happens in the
round robin fashion and is transparent for the
terminal equipment on the ends of the link. IMA inverse multiplexing functionality requires some overhead (ICP or ''IMA Control Protocol'' cells, typically one ICP cell in every IMA frame—commonly 128 cells in length—and in CTC or ''Common Transmit Clock'' mode, an ICP ''stuff'' cell must be inserted after every 2048 cells), and an IMA sublayer on the
physical layer
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer; The layer most closely associated with the physical connection between devices. This layer may be implemented by a PHY chip.
Th ...
.
See also
*
Inverse multiplexing
An inverse multiplexer (often abbreviated to inverse MUX or IMUX) allows a data stream to be broken into multiple lower data rate communication links. An inverse multiplexer differs from a demultiplexer because the multiple output streams fr ...
External links
* The ATM Forum IMA specification, version 1.1, https://web.archive.org/web/20100616001651/http://broadband-forum.org/ftp/pub/approved-specs/af-phy-0086.001.pdf
* http://www.cisco.com/en/US/tech/tk39/tk356/technologies_configuration_example09186a0080174992.shtml
Multiplexing
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