Overview

Ethernet was originally developed by Xerox and DEC as a way to interconnect their machines without the use of a mainframe network. The original Ethernet protocol was adapted by the Institute of Electrical and Electronics Engineers (IEEE), which made many improvements to the original design. The outcome was the Ethernet standard commonly used today, 802.3, which is called Carrier Sense Multiple Access with Collision Detection (CSMA/CD).

The IEEE also improved on the two protocols used in Ethernet and created another standard called 802.2. This standard deals with the actual packetizing of data and identifies the protocol structure, whereas 802.3 defines the standard used to prevent multiple computers from sending data at the same time (which results in collisions).

Ethernet uses a bus topology. The medium used in early Ethernet networks was coaxial cable. Thin coaxial is referred to as 10BASE2. In both cases, the 10 represents 10 Mbps, which is the bandwidth of Ethernet. The BASE indicates that the network is baseband, which means only one station can transmit at a time. The last number indicates the maximum distance supported by the medium. A 5 indicates 500 meters (m), and the 2 represents 200 m.

This has changed with the introduction of newer cables capable of transmitting data at higher speeds over thin copper wires twisted together (like those used in telephone networks). The difference between this new cable and conventional telephone cable is in the shielding used and the method used for twisting the cable pairs together.