electronics Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield ...

, 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 inputs to outputs such that each output is connected to only one input, but usually inpu ...

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 A banyan, also spelled banian ( ), is a Ficus, fig that develops accessory trunks from Aerial root#"Stranglers" (prop-root), adjacent prop roots, allowing the tree to spread outwards indefinitely. This distinguishes banyans from other trees ...

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 MEMS (micro-electromechanical systems) is the technology of microscopic devices incorporating both electronic and moving parts. MEMS are made up of components between 1 and 100 micrometres in size (i.e., 0.001 to 0.1 mm), and MEMS devices ...

, electrical or

nonlinear optics Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in Nonlinearity, 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 ...

. 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) log₂ 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 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) log₂ 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 a semiconductor device fabrication process. Examples include production of radio f ...

and

VLAs Vlas is both a surname and a given name. Notable people with the name include: * Adrian Vlas (born 1982), Romanian footballer * Valeriu Vlas (born 1971), Moldovan long-distance runner * Vlas Chubar (1891–1939), Ukrainian Bolshevik and Soviet poli ...

References

* {{DEFAULTSORT:Banyan Switch Switches

Design

A simple example

Future directions

See also

References