Multiplexing and switching
Introduction
A multiplexer receives signals from lots of different sources and can then send the signals along a single communications channel to a single destination using a number of different techniques. At the receiving end, the signals are then separated back out. A switch can be used to make multiple connections between computers and other hardware, as well as being used to 'segment' a network, or split it up into areas, to make communications around a network more efficient.
Multiplexers are used because they greatly increase the amount of data that can be sent across a network in a particular amount of time. This subsequently reduces the cost of the infrastructure of a network.
When a packet is placed on a network, it is broadcast to all computers on the network. If two computers want to send information at exactly the same time, then there is a network collision, the packets are cancelled and they are resent, this time with a small gap between them. With lots of computers on a large network, there could be many collisions, which slows doen the network (because packets have to keep being resent). A switch is used to make multiple, simultaneous connections around a network. This reduces the number of network collisions that occur between packets and improves the efficiency of a network.