100Base-T Definition

100Base-T is an Ethernet wiring standard for LANs (local area networks) that supports data transfer rates up to 100Mbps (100 megabits per second) over unshielded twisted pair copper wire cable or optical fiber cable.

Ethernet is by far the most commonly used LAN architecture as a result of its high speeds, robustness (i.e., high reliability), low cost and adaptability to new technologies.

100Base-T is based on the older 10Base-T Ethernet standard, which supports transfer rates of 10Mbps. Because it is ten times faster than its predecessor, it is often referred to as fast Ethernet. Its official name is IEEE 802.3u.

The network segment length for a 100BASE-T cable is limited to 100 meters, as with 10Base-T and gigabit Ethernet (which supports a speed of one billion bits per second). Likewise, it also uses the CSMA/CD (carrier sense multiple access/collision detection) LAN access method.

There are versions of 100Base-T for three different cabling schemes: 100Base-TX for two pairs of high-quality twisted pair wires, 100Base-T4 for four pairs of normal-quality twisted pair wires and 100Base-FX for multimode optical fiber cables.

100Base-T is the most widely used Ethernet standard, and the vast majority of common implementations or installations of 100Base-T are 100Base-TX.

Created October 31, 2005.
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