What is 100Base-FX?

Computer EngineeringComputer NetworkMCA

100BASE-FX is the technical name of Fast Ethernet over fiber optic cables. It is a version of Fast Ethernet 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 FX denotes use of optical fibers in Fast Ethernet.

The 100BASE-FX Physical Medium Dependent (PMD) sublayer is defined by Fiber Distributed Data Interface (FDDI).


  • This has two pairs of optical fibers. One pair transmits frames from hub to the device and the other from device to hub.

  • Maximum distance between hub and station is 2000m.

  • It has a data rate of 125 Mbps.

  • It uses NRZ-I encoding scheme along with 4B/5B block coding.

  • In most Fast Ethernet applications, fiber optics is used for the long haul transmission, which the individual devices are connected by twisted pair copper wires, i.e. 100BASE-TX. This requires a convertor between the connections. The following diagram shows the set up required −

Updated on 02-Jul-2020 13:33:36