Gigabit Ethernet: From 100 to 1000 Mbps

the family of high-speed Ethernet technologies. It extends the operating speed of the world's most deployed LAN to 1 billion bits per second while maintaining compatibility with the installed base of 10 Mbps and 100 Mbps Ethernet equipment. T he installed base for Ethernet ranges from PCs and servers to printers , test equipment, telephone switches, cable TV set-top boxes, process control systems, and even high-end theatrical lighting systems. In short, Ethernet is ubiquitous—which is to say, consumers can't get enough of it. The great value of Ethernet is not that one size fits all, but that common protocols and models are available at a wide range of price/performance points. Originally standardized and deployed at 10 megabits per second, Ethernet has always been considered a high-speed network. The newest standard, Gigabit Ethernet, 1 scales up two orders of magnitude to 1,000 Mbps, while maintaining compatibility with systems deployed in the early 1980s. The Ethernet supplier community has consistently led the technical developments underlying ever-faster operating speeds on the installed base of network cabling—whether it was coaxial cable, Unshielded Twisted Pair, multimode fiber, or single-mode fiber. Each media type presents unique challenges. In this tutorial, we describe the operation of Gigabit Ethernet over fiber-optic cabling and the emerging IEEE standards project known as 1000Base-T, which addresses operation over Category-5 UTP cabling. Any tutorial concerning a network interface and access protocol standard must refer first to the ISO seven-layer reference model. Like most specifications produced by the IEEE 802 LAN/MAN standards committee, Giga-bit Ethernet (IEEE802.3z) addresses the two lowest layers of the model: s Layer 2, the Data-link layer, which describes how data are organized into frames and sent over the network, and s Layer 1, the Physical layer, which describes the network medium and signaling specifications.