Published : 01-01-2015 by : Pawan Janorkar

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Ethernet is a family of frame-based computer networking technologies for local area networks (LANs). The name comes from the physical concept of the ether. It defines a number of wiring and signaling standards for the Physical Layer of the OSI networking model, through means of network access at the Media Access Control protocol (a sub-layer of Data Link Layer), and a common addressing format.

Ethernet is standardized as IEEE 802.3. The combination of the twisted pair versions of Ethernet for connecting end systems to the network, along with the fiber optic versions for site backbones, is the most widespread wired LAN technology. It has been in use from around 1980[1] to the present, largely replacing competing LAN standards such as token ring, FDDI, and ARCNET

destination and source address fields specified a "packet type", but, as the paper says, "different protocols use disjoint sets of packet types". Thus the original packet types could vary within each different protocol, rather than the packet type in the current Ethernet standard which specifies the protocol being used.
Metcalfe left Xerox in 1979 to promote the use of personal computers and local area networks (LANs),

forming 3Com. He convinced DEC, Intel, and Xerox to work together to promote Ethernet as a standard, the so-called "DIX" standard, for "Digital/Intel/Xerox"; it specified the 10 megabits/second Ethernet, with 48-bit destination and source addresses and a global 16-bit type field. The first standard draft was first published on September 30, 1980 by the Institute of Electrical and Electronics Engineers (IEEE). It competed with two largely proprietary systems, Token Ring and Token Bus. To get over delays of the finalization of the Ethernet "Carrier sense multiple access with collision detection" (CSMA/CD) standard due to the difficult decision processes in the "open" IEEE, and due to the competitive Token Ring proposal strongly supported by IBM, support of CSMA/CD in other standardization bodies

(i.e. ECMA, IEC and ISO) was instrumental to its success. The proprietary systems soon found themselves buried under a tidal wave of Ethernet products. In the process, 3Com became a major company. 3COM built the first 10 Mbit/s Ethernet adapter (1981). This was followed quickly by DEC's Unibus to Ethernet adapter, which DEC sold and used internally to build its own corporate network, reaching over 10,000 nodes by 1986, far and away the largest then extant computer network in the world.

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