Inverse multiplexer
Encyclopedia
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 from the former stay inter-related, whereas those from the latter are unrelated. An inverse multiplexer is the opposite of a multiplexer
which divides one high speed link into multiple low speed links.
| low rate link #1 |
Tx — high rate data — inverse mux. — | low rate link #2 | — inverse demux. — rx
| low rate link #3 |
This example provides an end to end connection of 3 times the data rate available on each of the low rate data links. Note that, as with multiplexers, links are almost always bi-directional and, at either end of the link, an inverse mux will be combined with its reverse (an inverse demux) and still be called an inverse mux.
Inverse multiplexers are used, for example, to combine a number of ISDN
channels together into one high rate circuit, where a higher rate connection than is available from a single ISDN
connection is needed. This is typically useful in areas where higher rate circuits are not available.
An alternative to an inverse mux. is to use three separate links and load sharing of data between them. In the case of IP, network packets could be sent in round robin mode between each separate link. Advantages of using inverse multiplexing over separate links include:
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. Rather, they are assembled into small boxes, which are grouped into larger cartons, which go into intermodal container
s, which join multiple containers aboard a container ship
. Each step is a multiplexing. Conversely a large cargo, for example in structure relocation
, may be disassembled for carriage on multiple vehicles and then reassembled in the correct order at the destination. This is inverse multiplexing.
Data stream
In telecommunications and computing, a data stream is a sequence of digitally encoded coherent signals used to transmit or receive information that is in the process of being transmitted....
to be broken into multiple lower data rate communication links. 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
Multiplexer
In electronics, a multiplexer is a device that selects one of several analog or digital input signals and forwards the selected input into a single line. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output...
which divides one high speed link into multiple low speed links.
| low rate link #1 |
Tx — high rate data — inverse mux. — | low rate link #2 | — inverse demux. — rx
| low rate link #3 |
This example provides an end to end connection of 3 times the data rate available on each of the low rate data links. Note that, as with multiplexers, links are almost always bi-directional and, at either end of the link, an inverse mux will be combined with its reverse (an inverse demux) and still be called an inverse mux.
Inverse multiplexers are used, for example, to combine a number of ISDN
Integrated Services Digital Network
Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...
channels together into one high rate circuit, where a higher rate connection than is available from a single ISDN
Integrated Services Digital Network
Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...
connection is needed. This is typically useful in areas where higher rate circuits are not available.
An alternative to an inverse mux. is to use three separate links and load sharing of data between them. In the case of IP, network packets could be sent in round robin mode between each separate link. Advantages of using inverse multiplexing over separate links include:
- Lower link latencyLagLag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
(one single packet can be spread across all links) - Fairer load balancingLoad balancing (computing)Load balancing is a computer networking methodology to distribute workload across multiple computers or a computer cluster, network links, central processing units, disk drives, or other resources, to achieve optimal resource utilization, maximize throughput, minimize response time, and avoid...
- Network simplicity (no router needed between boxes with high speed interfaceNetwork interfaceNetwork interface may refer to:* Network interface controller, the device a computer uses to connect to a computer network* Network interface device, a demarcation point for a telephone network...
s)
A simple analogy to transport can help explain the distinction between multiplexing and inverse multiplexing. When small cargoes such as pencil
Pencil
A pencil is a writing implement or art medium usually constructed of a narrow, solid pigment core inside a protective casing. The case prevents the core from breaking, and also from marking the user’s hand during use....
s are shipped overseas, they are generally not carried one at a time. Rather, they are assembled into small boxes, which are grouped into larger cartons, which go into intermodal container
Intermodal container
An intermodal container is a standardized reusable steel box used for the safe, efficient and secure storage and movement of materials and products within a global containerized intermodal freight transport system...
s, which join multiple containers aboard a container ship
Container ship
Container ships are cargo ships that carry all of their load in truck-size intermodal containers, in a technique called containerization. They form a common means of commercial intermodal freight transport.-History:...
. Each step is a multiplexing. Conversely a large cargo, for example in structure relocation
Structure relocation
A structure relocation is the process of moving a structure from one location to another. There are two main ways for a structure to be moved: disassembling and then reassembling it at the required destination, or transporting it whole. For the latter, the building may be pushed on temporary rails...
, may be disassembled for carriage on multiple vehicles and then reassembled in the correct order at the destination. This is inverse multiplexing.
See also
- Bonding protocolBonding protocolBonding protocol is a generic name for a method of bonding or aggregation of multiple physical links to form a single logical link....
- Inverse Multiplexing for ATMInverse Multiplexing for ATMIMA is a standardized technology used to transport ATM traffic over a bundle of T1 or E1 cables, also known as IMA Group. This allows for gradual increase in line capacity, where implementing a high-capacity solution is not deemed feasible...
- Link aggregationLink aggregationLink aggregation or trunking or link bundling or Ethernet/network/NIC bonding or NIC teaming are computer networking umbrella terms to describe various methods of combining multiple network connections in parallel to increase throughput beyond what a single connection could sustain, and to provide...
- Multiplexer-demultiplexer
- Multilink PPP
- Virtual concatenationVirtual concatenationVirtual concatenation is an inverse multiplexing technique creating a large capacity payload container distributed over multiple smaller capacity TDM signals. These signals may be transported or routed independently...