What is 100Base-T4?

Computer EngineeringComputer NetworkMCA

100BASE-T4 is the early implementation of Fast Ethernet over twisted pair cables, carrying data traffic at 100 Mbps (Mega bits per second) in local area networks (LAN). It was launched as the IEEE 802.3u standard in 1995. Here, 100 is the maximum throughput, i.e. 100 Mbps, BASE denoted use of baseband transmission, and T4 denotes use of four twisted pair cables in Fast Ethernet.


  • This has four pairs of unshielded twisted pair of Category 3. i.e. voice grade.

  • Two of these pairs are bi-directional and the other two are unidirectional. The two unidirectional wires are reserved for receiving and sending data respectively. In each direction, three pairs can be used simultaneously for data transmission.

  • Each twisted pair is capable of transmitting a maximum of 25Mbaud data. Thus the three pairs can handle a maximum of 75Mbaud data.

  • It uses the encoding scheme 8B/6T (eight binary/six ternary).

The following diagram shows the use of four wires −

Updated on 02-Jul-2020 13:31:21