What Does 100BASE-T Mean?

100BASE-T is an enhanced form of Ethernet 10BASE-T and a network standard used for fast data transfer rates up to 100 Mbps. 100BASE-T is 10 times faster than standard Ethernet and, like standard Ethernet, it follows the Carrier Sense Multiple Access/Collision Detection (CSMA/CD) technique to avoid collision.


100BASE-T is an official IEEE 802.3u standard that is used to connect nodes when establishing a local area network. In 1998, 100BASE-T’s signal speed was superseded by Gigabit Ethernet.

100BASE-T is officially known as fast Ethernet.

Techopedia Explains 100BASE-T

Smart network administrators always use multi-adapter network switches and hubs that simultaneously support 10BASE-T and 100BASE-T. 100BASE-T is used primarily with star topology because it requires a centralized hub, which is used for port communication.

100BASE-T has three major standard versions in copper and fiber mediums:

  1. 100BASE-TX: Used for full-duplex point-to-point communication with two twisted cable pairs. One pair receives signals while the other sends them. 100BASE-TX uses an RJ-45 cable for physical connection and supports segment lengths of up to 100 meters.
  2. 100BASE-T4: One of the earliest Fast Ethernet versions. It uses CAT-3 twisted pair cables, and requires four cable pairs for communication. One pair receives and one pair sends signals. The two remaining pairs are reserved and used as required.
  3. 100BASE-FX: This optical fiber cable standard uses thin infrared light wavelengths for communication via two twists of cable. The two strands are used to transmit and receive signals; one sends and the other receives to provide full-duplex communication. 100BASE-FX allows for a distance of up to six miles between two stations. A repeater is required every 165 yards over long haul distances.

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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…