Ethernet: The Definitive Guide, 2nd Edition

Chapter 10. Gigabit Ethernet

The IEEE standard uses both “1000 Mb/s” and “Gigabit Ethernet” to describe this variety of Ethernet media system, which operates over both twisted-pair and fiber optic cabling.

The specifications for the 1000BASE-X system for fiber optic media were developed in the 802.3z supplement to the IEEE standard, which was adopted in 1998 as Clauses 34–39 of the standard. The specifications for the 1000BASE-T twisted-pair media system were developed in the 802.3ab supplement to the IEEE standard, which was adopted in 1999 as Clause 40 of the standard.

Gigabit Ethernet Twisted-Pair Media Systems (1000BASE-T)

Supporting 1 billion bits per second over unshielded twisted-pair (UTP) cable was a remarkable achievement at the time that this standard was developed. To make it happen, the 1000BASE-T media system uses a mix of signaling and encoding techniques that were originally developed for the 100BASE-TX, 100BASE-T2, and 100BASE-T4 media standards. While 100BASE-T2 and 100BASE-T4 were not widely adopted in the marketplace, their technology was essential to developing the 1000BASE-T standard.

The 100BASE-T2 Fast Ethernet standard is based on a signal encoding system that could send 100 Mb/s Ethernet signals over two pairs of Category 3 cable. These signaling techniques were adopted and extended by the 1000BASE-T standard for use over four pairs of twisted-pair cable rated at Category 5 or better.

From the 100BASE-T4 system, the 1000BASE-T standard adopted the technique ...