In
electronics
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
, a banyan switch is a complex
crossover switch
In electronics, a crossover switch or matrix switch is a switch connecting multiple inputs to multiple outputs using complex array matrices designed to switch any one input path to any one (or more) output path(s). There are blocking and non-block ...
used in electrical or
optical switch An optical transistor, also known as an optical switch or a light valve, is a device that switches or amplifies optical signals. Light occurring on an optical transistor's input changes the intensity of light emitted from the transistor's output ...
es.
It is named for its resemblance to the roots of the
banyan tree which cross over in complex patterns. Logical banyan switches are used in logic or signal pathways to crossover switching of signals onto new pathways.
They can be mechanical
microelectromechanical systems, electrical or
nonlinear optics
Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in ''nonlinear media'', that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typic ...
. Their complexity depends on the topology of the individual switches in a switch matrix (how wide it is by how many 'plies' or layers of switches it takes), to implement a desired crossover logic.
Design
Typical crossover matrices follow this formula: an N×N banyan switch uses (N/2) log
2 N elements.
Other formulas are used for differing number of crossover layers, and scaling is possible, but becomes very large and complex with large N×N arrays.
CAD
Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve co ...
can be used to take the drudgery out of creating these designs. A banyan network is implemented by interconnecting 2×2 switching networks in multiple and recursive stages.
The switches are measured by how many stages, and how many up/down sorters and crosspoints they have. Switches often have buffers built-in for faster switching.
A typical switch may have:
# A 2×2 and 4×4 down sorter
# Followed by an 8×8 up sorter
# Followed by a 2×2 crosspoint banyan switch network
This results in 3 level sorting for a 3-stage banyan network switch.
A simple example
Consider a 2×2 banyan switch, which requires (2/2) log
2 2 = 1 switching element. This switch takes two inputs, numbered 0 and 1, and two outputs, numbered 0 and 1. Every packet that comes in has a header that contains one bit indicating what its destination is (either 0 or 1). If the switch reads the bit and it has value 0, it sends the packet to its higher output (which is 0 in this case), and to its lower output if the routing bit is one. By connecting these switching elements in series and parallel it is possible therefore, to route packets in more complicated ways depending on the desired routes to establish.
Future directions
The future is moving to larger arrays of inputs and outputs needed in a very small space. See
wafer fabrication
Wafer fabrication is a procedure composed of many repeated sequential processes to produce complete electrical or photonic circuits on semiconductor wafers in semiconductor device fabrication process. Examples include production of radio frequ ...
and
VLAs.
See also
*
Crossover switch
In electronics, a crossover switch or matrix switch is a switch connecting multiple inputs to multiple outputs using complex array matrices designed to switch any one input path to any one (or more) output path(s). There are blocking and non-block ...
*
Crossbar switch
*
Clos network
In the field of telecommunications, a Clos network is a kind of multistage circuit-switching network which represents a theoretical idealization of practical, multistage switching systems. It was invented by Edson Erwin in 1938 and first formalize ...
a non blocking crossover switch that needs fewer than N² switches
*
Nonblocking minimal spanning switch
A nonblocking minimal spanning switch is a device that can connect N inputs to N outputs in any combination. The most familiar use of switches of this type is in a telephone exchange. The term "non-blocking" means that if it is not defective, ...
and signal switching
*
Optical computer
Optical computing or photonic computing uses light waves produced by lasers or incoherent sources for data processing, data storage or data communication for computing. For decades, photons have shown promise to enable a higher bandwidth than the ...
References
*
{{DEFAULTSORT:Banyan Switch
Switches