Chapter 9. 100 Mb/s Ethernet

This chapter describes the signaling and media components used in the 100BASE-TX and 100BASE-FX systems. The 100 Megabit per second “Fast Ethernet” media systems were first defined in the 802.3u supplement to the Ethernet standard in 1995. These systems are still in wide use, providing high-speed service at low cost to desktop computers and other devices.

The most widely used 100 Mb/s media standards are based on specifications first developed in the 1990s for the Fiber Distributed Data Interface (FDDI) network standard. After the development of 100 Mb/s Ethernet technology, equipment based on the FDDI standard lost market share and is no longer sold, but FDDI technology lives on in the 100BASE-X Ethernet standards, which include twisted-pair and fiber optic cable types.

100BASE-X Media Systems

The 100BASE-X system includes 100BASE-TX twisted-pair and 100BASE-FX fiber optic segments based on FDDI technology. Although multiple 100 Mb/s copper media systems were developed, the 100BASE-X media segments became the most widely adopted, and the other systems are no longer sold.

The systems that are no longer sold include:

Designed to use four pairs of Category 3 or better twisted-pair cabling.
Designed to use two pairs of Category 3 or better cabling.

Fast Ethernet Twisted-Pair Media Systems (100BASE-TX)

The 100BASE-TX twisted-pair media system is based on the ANSI FDDI TP-PMD (Twisted-Pair Physical Medium Dependent) standard. The system ...

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