100Base TX and 100Base FX: Similarities and Differences Offered

Published on Updated on March 15, 2024

Ethernet technologies have evolved over the years. The term Fast Ethernet has been popular since 1995, when it was covered under IEEE802.3u standard. Fast Ethernet is designed to carry the traffic at the rate of 100 mbit/s at the physical layer in the local area networks (LANs). Based on this speed, the cables are termed as 100Base TX. For a long time, these cables were referred to as 100 Base-T cables. The 100Base TX cable has replaced the earlier versions of coaxial cables – 100Base-T and 100Base-2.

Along with these, there are 100Base FX cables available, too. At times, it may be confusing for people to differentiate between 100Base TX and 100Base FX cables.

This post offers insights on these two types of cables and their increasing popularity in various applications and more.

Protection of RS232 Serial Connections

The Meaning of 100Base-TX/FX

Before going through the comparisons between the 100Base-TX and 100Base-FX. We are going to break the "100Base-TX/FX" into parts to make it easier to understand:

100: In 100Base, "100" stands for 100 Mega Hertz or 100 MHz, which translates to 100 mbit/seconds. This 100 mbit/seconds theoretically points to 12 Mbps; however, you may not get more than 4 Mbps in real.

Base: This is the term for Baseband, which is mainly used to depict the communication used by the Ethernet Network. It depicts that the cable is using all the available bandwidth to transmit the data. Against this, in broadband the cable usually shares the bandwidth. This is one of the reasons why users may face some slowdown at times when multiple users are connected to the network. Although Ethernet users may also experience some slowdown, is the frequency is lesser compared to broadband.

TX: The term "TX" is sometimes referred to as "T" is term for Twisted Pair, which is a type of physical signal carried by the cable. This TX shows that the application is utilizing CAT5 UTP cables, where two pairs of copper wires are being used to support speed of 100 mbit/s.

FX: In "FX", the cable uses two pairs of fiber to support more than 100 Mbps. This cable can support a speed up to 2 km.


What is 100BASE-TX?

The 100 Base-TX cables operating over two pairs of copper wires within a cat5 or better cable. It can support data speeds up to 100 meters and must possess minimum recommended node length of 2.5 meters between two cables.


What is 100BASE-FX?

100BASE-FX is a Fast Ethernet standard which supports 100Mbps (Mega bits per second) data speed over fiber optic cables. This cable is ideal choice for long distance applications.

100 Base TX vs. 100 Base FX – Side by Side Comparison Offered

The following pointers will help you understand these two technologies better and how they are similar and dissimilar in many ways

  • Pair of Wires: As said before, 100Base-TX uses two pairs of UTP category 5 wires for signal transmission. At times, it may also use two unshielded twisted pair (STP) type 1 wires. Against this, 100Base FX uses two pairs of optical fibers for data transmission. Both types of wires assure full-duplex transmission, where one pair of wire transmits the frames from the hub to the device, and the other pair from device to the hub.
  • Data Rates: Both these wires possess data rates of 125 Mbps. The maximum value of fundamental frequency of 100Base-T is 31.25 MHz
  • Encoding and Decoding: Of these, 100Base-T uses the MLT-3 scheme for encoding and decoding. They also use 4B/5B block coding.
  • MLT-3 Encoding: MLT-3 encoding refers to the Multi-Level Transmit, which is a popular signaling method that uses three voltage levels - -1, 0, +1, 0. They move through these voltage levels sequentially o 4B/5B block coding contributes to DC equalization and spectrum shaping.

      Against this, 100Base FX uses NRZ-I encoding scheme along with 4B/5B. The NRZ-I encoding refers to non-return-to-zero, which is a line code in binary code. The pulses in this encoding scheme offer high energy than return-to-zero (RZ code).

      100BASE-TX vs. 100BASE-FX, What is the Difference?











      Cat 5








      Device Type

      Media Converter

      Media Converter, Optical Transceiver

      System Cost




      Along with the cables, you need to choose the network devices that are compatible with them. VERSITRON provides various types of conversion devices like 10/100Base TX to 100Base FX Industrial Fast Ethernet to Fiber Media Converter, 10/100 Base TX to 100 Base FX Fiber Optic Media Converter, Multimode SC, and so on. The company also provides industrial switches and several other Ethernet devices, which have been installed in various applications across the world.

      Rich Tull

      Rich Tull
      R.W. Tull is the President of Versitron, a leading technology company specializing in data communication and networking solutions. With expertise in Guiding network switches and media converters, R.W. Tull has played a pivotal role in driving Versitron's success. His deep understanding of these technologies has enabled the company to provide innovative and reliable solutions to clients. As a visionary leader, He ensures that Versitron remains at the forefront of the industry, delivering cutting-edge networking solutions that enhance data communication efficiency.
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