Ethernet

Ethernet. It is a family of wired computer networking technologies commonly used in local area networks, metropolitan area networks, and wide area networks. The technology was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. It has largely replaced competing wired LAN technologies such as Token Ring, FDDI, and ARCNET.

History

The original concept was developed at the Xerox PARC research center by Robert Metcalfe and David Boggs in the early 1970s. It was inspired by the ALOHAnet project at the University of Hawaii. The first official specification, known as the "DIX standard" after its corporate sponsors Digital Equipment Corporation, Intel, and Xerox, was published in 1980. This collaboration was crucial in pushing for an open standard, which led to its formal adoption by the Institute of Electrical and Electronics Engineers as part of the IEEE 802 project. Key subsequent developments included the introduction of 10BASE5 (thicknet) and 10BASE2 (thinnet), which used coaxial cable. The shift to twisted pair cabling with 10BASE-T, championed by companies like SynOptics Communications, dramatically simplified installation and fueled widespread adoption in office environments throughout the 1990s.

Technical description

The system operates on the principles of the Carrier-sense multiple access with collision detection protocol for managing data transmission on a shared medium. Modern implementations typically use a star topology centered on a network switch or hub, which has largely supplanted earlier bus topology designs. Frames, the fundamental data units, contain source and destination MAC addresses, payload data, and an error-checking frame check sequence. The physical layer specifications, defined by the IEEE 802.3 working group, govern details like cabling, connectors, and signaling. Common media include unshielded twisted pair cabling, optical fiber, and backplane connections. Speeds have evolved from the original 10 Megabit per second to 100 Megabit per second (Fast Ethernet), 1 Gigabit per second (Gigabit Ethernet), and beyond, with standards like 40 Gigabit Ethernet and 100 Gigabit Ethernet now common in data centers.

Variants and standards

A vast ecosystem of standards exists under the IEEE 802.3 umbrella, each defined by a specific clause. Early standards included 10BASE5 and 10BASE2 for coaxial networks. The ubiquitous 100BASE-TX standard defined 100 Mbit/s operation over Category 5 cable. For Gigabit speeds, 1000BASE-T enabled operation over Category 5e cable, while 1000BASE-SX and 1000BASE-LX specified short and long-range optical fiber links. Higher-speed variants include 10 Gigabit Ethernet (10GBASE-T), 25 Gigabit Ethernet, and 400 Gigabit Ethernet. Specialized standards also exist, such as Power over Ethernet for delivering electrical power alongside data, and Audio over Ethernet for professional audio applications. Industrial applications are served by ruggedized protocols like EtherNet/IP and PROFINET.

Applications and deployment

It is the foundational technology for wired connectivity in enterprise local area networks, connecting devices like personal computers, IP phones, and wireless access points to network switches. In residential settings, it is commonly used to connect routers, game consoles, and smart televisions. Its high reliability and bandwidth make it indispensable in data centers for server-to-switch connections and storage area networks, often using protocols like Fibre Channel over Ethernet. The technology is critical for backhaul connections in telecommunications networks, forming the backbone of the Internet. Industrial automation systems, such as those in General Motors factories, rely on real-time variants for machine control. It also serves as the physical layer for many other protocols, including the Internet Protocol suite.

Comparison with other technologies

Compared to Wi-Fi (IEEE 802.11), it typically offers higher throughput, lower latency, and greater security due to its physical wired medium, but lacks mobility. In the wide area network space, technologies like Synchronous Optical Networking and Asynchronous Transfer Mode were historically used for long-haul telecommunications, though Ethernet-based services like Carrier Ethernet have become dominant. For personal area networks, USB provides a point-to-point connection for peripherals, whereas it is designed for multi-point network communication. Earlier LAN competitors like IBM's Token Ring offered deterministic access but were more complex and costly, leading to their market decline. In storage networking, Fibre Channel was a dedicated high-performance protocol, but converged networks using enhancements like Data Center Bridging have allowed Ethernet to fulfill this role.