Ethernet is a form of Local Area Network (LAN) widely used for interconnecting computers and standardized in IEEE 802.3, allowing a wide variety of manufacturers to produce compatible interfaces and extend capabilities – repeaters, bridges, etc. The data transmission rate is 10, 100 Mb/s up to 1 and 10 Gb/s, but overheads in packaging data and packet separation mean actual throughput is less than the ‘wire speed’ bit rate.

There are many connection methods for Ethernet varying from copper to fiber optic. Currently the three most common are:

10 Base-T The standard for 4-wire twisted pair cable using RJ connectors. This gives extremely low cost-per-node network capabilities.

100 Base-T (a.k.a. Fast Ethernet) 100 Mb/s 4-wire twisted pair cable using RJ connectors is now becoming very popular. Similar technology to 10 Base-T but uses Cat. 5 cable.

Gigabit Ethernet (GigE) Development of existing Ethernet technology to support 1,000 Mb/s. This is specified for both fiber and copper Cat. 5e.

10 Gigabit Ethernet (10GigE) only functions over copper for short distances – 15 meters using twinax cable. Using augmented cat. 6 (Cat 6A) cable it may travel twice that distance. For longer range optical fiber is the only answer. This only operates in full-duplex mode – so collision detection protocols are unnecessary. But the packet format and other current Ethernet capabilities are easily transferable to 10GigE.

100 Gigabit Ethernet (100GigE) continues the x10 steps of Ethernet data speed evolution. Destined to travel over optical fiber, it is at the development stage but will doubtless emerge into the commercial world sometime soon.

See also: Hub, CSMA/CD
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