Ethernet, Fast Ethernet, Gigabit Ethernet

Ethernet is the name used for a particular version of a communications system where multiple devices that are connected together on a common cable can send and receive information.  Because the connections are to a single cable (or segment), if two devices try to send data at the same time (an event known as a collision), corruption will occur.  For this reason devices check first before transmitting.  If a collision does occur, then the conflicting devices wait for a short random time before transmitting again.

Ethernet operates at 10 Megabits per second (MPBS).  Fast Ethernet is an upgraded form that operates at 100MBPS, and is rapidly becoming the standard connection speed for PCs and other devices.  Gigabit Ethernet provides another ten-fold increase to 1000MBPS (or 1 Gigabit per second).  This will gradually become used as the core of medium-sized networks, and also to link to network server systems.  As the performance has increased, new standards for operating at the higher speeds have had to be developed to work over different media.  The standards for operating Ethernet are known by names like 10BaseT, 100BaseTX, 1000BaseT, 100BaseSX, etc.  where the number represents the speed in MBPS.

Some devices can work at more than one speed, usually shown in the form 10/100MBPS, and some will automatically configure themselves to operate at the optimum speed, a feature known as Autonegotiation.

There are various rules for connecting Ethernet devices, and these vary depending upon the speed and the media type.  Need to know more?  .

See also: Half / Full Duplex