Editing Inverse multiplexer

{{Short description|Breaks a data stream into multiple lower data rate streams}}
{{onesource|date=September 2009}}

[[File:Inverse multiplexing diagram.svg|thumb|250px|A high data rate signal is inverse multiplexed over multiple slower links, then recombined]]

An '''inverse multiplexer''' (often abbreviated to '''inverse MUX''' or '''IMUX''') allows a [[data stream]] to be broken into multiple lower data rate [[communication link]]s.<ref>{{Cite journal |last1=Magalhaes |first1=Luiz |last2=Kravets |first2=Robin |date=2001 |title=End-to-end inverse multiplexing for mobile hosts |url=https://www.scielo.br/j/jbcos/a/F4NWChPCdnsBknLwQ6RXP5D/?lang=en |journal=Journal of the Brazilian Computer Society |language=en |volume=7 |issue=2 |pages=52–62 |doi=10.1590/S0104-65002001000100006 |issn=0104-6500 |archive-url=https://web.archive.org/web/20230201230250/https://www.scielo.br/j/jbcos/a/F4NWChPCdnsBknLwQ6RXP5D/?lang=en |archive-date=2023-02-01 |access-date=2024-08-31}}</ref>  An inverse multiplexer differs from a [[demultiplexer]] because the multiple output streams from the former stay inter-related, whereas those from the latter are unrelated.  An inverse multiplexer is the opposite of a [[multiplexer]]  in that it divides one high-speed link into multiple low-speed links, whereas a multiplexer combines multiple low-speed links into one high-speed link.

This provides an end to end connection of several times the data rate available on each of the low rate data links.  Note that, as with multiplexers, links are often used in bi-directional pairs and, at either end of the link, an inverse multiplexer will be combined with its reverse (an inverse demultiplexer) and still be called an ''inverse MUX''.

Inverse multiplexers are used, for example, to combine a number of [[Integrated Services Digital Network|ISDN]] channels together into one high rate circuit, where a higher rate connection than is available from a single [[Integrated Services Digital Network|ISDN]] connection is needed.   This is typically useful in areas where higher rate circuits are not available.

An alternative to an inverse multiplexer is to use separate links and load sharing of data between them.  In the case of IP, network packets could be sent in [[round-robin scheduling#Data packet scheduling|round-robin]] mode between each separate link.  Advantages of using inverse multiplexing over separate links include:

* Lower link [[Latency (engineering)|latency]] (one single packet can be spread across all links)
* Fairer [[load balancing (computing)|load balancing]] 
* Network simplicity (no [[network switch]] needed between boxes with high-speed [[Network interface controller|interface]]s)

A simple analogy to transport can help explain the distinction between multiplexing and inverse multiplexing.  When small cargoes such as [[pencil]]s are shipped overseas, they are generally not carried one at a time, but are assembled into small boxes, which are grouped into larger cartons, which go into [[intermodal container]]s, which are packed onto a [[container ship]].  Each step is analogous to a multiplexing process.  Conversely a large cargo, for example in [[structure relocation]], may be disassembled for carriage on multiple vehicles and reassembled at the destination. This is analogous to inverse multiplexing.
  
==See also==
*[[Bonding protocol]]
*[[Divide-and-conquer algorithm]]
*[[Inverse Multiplexing for ATM]]
*[[Link aggregation]]
*[[Multiplexer]]
*[[Point-to-Point Protocol#Multilink PPP|Multilink PPP]]
*[[Virtual concatenation]]

==References==
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[[Category:Multiplexing]]