Crossover Switches are complex array matrixes to switch any one input path to any one(or more) output path(s). There are blocking and non-blocking types of cross-over switches. They are used in electronics and fiber optic circuits, as well as some optical computers. They can be mechanical MEMS, electrical or optical NLO. A banyan switch is one type of cross-over switch. 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 your desired crossover logic.
Typical crossover matricies follow the formula: an N×N Banyan switch uses (N/2) log N elements.
Other formulas are used for differing number of cross-over layers and scaling is possible, but becomes very large and complexwith large NxN arrays. CAD and AI can be used to take the drugery out of these designs.
The switches are measured by how many stages, and how many up/down sorters and crosspoints. Switches often have buffers built in to speed up switchiong speeds.
- A typical switch may have a 2x2 and 4x4 down sorter,
followed by a 8x8 up sorter,
followed by a 2x2 crosspoint Banyan switch network,
resulting in a 3 level sorting for a 3 stage banyan network switch.
The future is moving to larger arrays of inputs and outputs needed in a very small space. See Wafer Fabrication and VLA's.