Ethernet

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Ethernet

[′ē·thər‚net]
(computer science)
A protocol for interconnecting computers and peripheral devices in a local area network.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Ethernet

(networking)
A local area network first described by Metcalfe & Boggs of Xerox PARC in 1976. Specified by DEC, Intel and XEROX (DIX) as IEEE 802.3 and now recognised as the industry standard.

Data is broken into packets and each one is transmitted using the CSMA/CD algorithm until it arrives at the destination without colliding with any other packet. The first contention slot after a transmission is reserved for an acknowledge packet. A node is either transmitting or receiving at any instant. The bandwidth is about 10 Mbit/s. Disk-Ethernet-Disk transfer rate with TCP/IP is typically 30 kilobyte per second.

Version 2 specifies that collision detect of the transceiver must be activated during the inter-packet gap and that when transmission finishes, the differential transmit lines are driven to 0V (half step). It also specifies some network management functions such as reporting collisions, retries and deferrals.

Ethernet cables are classified as "XbaseY", e.g. 10base5, where X is the data rate in Mbps, "base" means "baseband" (as opposed to radio frequency) and Y is the category of cabling. The original cable was 10base5 ("full spec"), others are 10base2 ("thinnet") and 10baseT ("twisted pair") which is now (1998) very common. 100baseT ("Fast Ethernet") is also increasingly common.

Usenet newsgroup: news:comp.dcom.lans.ethernet.

http://wwwhost.ots.utexas.edu/ethernet/ethernet-home.html.
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

Ethernet

The network technology that connects computers via cables to each other and to the Internet. Defined by the IEEE as the 802.3 standard, the Ethernet access method is used worldwide. Companies have hundreds and thousands of PCs wired together via Ethernet, and almost every reference to "local network," "LAN," and "network ready" is Ethernet. All new computers have Ethernet built in, and old machines can be retrofitted (see Ethernet adapter). See LAN and 802.3.

Ethernet Is Wired - Wi-Fi Is Wireless
Wired Ethernet and wireless Wi-Fi exist together in virtually every home and office. Desktop computers may be wired, but phones and tablets use Wi-Fi, and a wireless router provides both. See Wi-Fi and wireless router.

10/100/1000 Gigabit Ethernet
All new routers and Ethernet switches are 10/100/1000 "Gigabit" devices because the top speed is 1000 Mbps (1 Gbps). Older networking hardware maxed out at 10 and 100 Mbps. If device speeds are not equal, Ethernet uses the highest common speed between sending and receiving ports. See Gigabit Ethernet.

Above one gigabit, Ethernets do not mix. There is no such thing as a 10/100/1000/10000 port (see 10 Gigabit Ethernet).

Ethernet and TCP/IP Are Global
TCP/IP prepares the data that Ethernet transmits. Together, they comprise the global local area network (LAN) standard and more (see 100 Gigabit Ethernet and automotive Ethernet). See TCP/IP.

History
Invented by Robert Metcalfe and David Boggs at Xerox PARC in 1973, Ethernet first ran at just under 3 Mbps. Metcalfe joined Digital Equipment Corporation where he facilitated a joint venture with Intel and Xerox to collaborate further, and Ethernet Version 1 was finalized in 1980. In 1983, the IEEE approved the 802.3 standard. See Ethernet adapter, Ethernet switch and automotive Ethernet.

MAXIMUM CABLE LENGTHS (Device to Switch)              Speed     DistanceVersion       (Mbps)   Feet/Meters
 TWISTED WIRE PAIR
   10Base-T       10     328/100
  100Base-T      100     328/100
 1000Base-T     1000     328/100

               Speed        DistanceVersion       (Mbps)   Miles/Kilometers
 OPTICAL FIBER
  10Base-FL MM    10       1.2/2
 100Base-FX MM   100       1.2/2
 100Base-FX SM  1000         6/10
  MM=multimode   SM=singlemode


Ethernet Uses a Star Topology
All computers connect to a central switch that lets each sender/receiver pair transmit at full speed (10, 100 or 1000 Mbps). Spare telephone wires are sometimes used, but often at lower speeds. For earlier topologies, see 10Base5 and 10Base2. See Ethernet switch, cable categories and twisted pair.







Ethernet Switch
This earlier Omnitron switch had 16 10/100 ports and, like all Ethernet switches, automatically adjusted to the highest common speed between sender and receiver.







Ethernet Is Everywhere
In the back of a home theater cabinet is a NETGEAR Ethernet switch. It connects the Fire TV, Apple TV and Roku 3 streaming boxes, plus an Oppo Blu-ray player, to the main switch in another part of the house some 60 feet away.
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References in periodicals archive ?
Other networks are installing fast Ethernet hubs, increasing the bandwidth that must be shared to 100 megabits a second and so reducing delays.
Whereas Ethernet wasn't so popular in the early 1970s, neither was networking in general, notes Jeff Martin, vice chair of communications for the Gigabit Ethernet Alliance, a group of 115 companies working on standardizing and promoting the fastest Ethernet to date.
To handle increasing network traffic, some health care organizations have opted to upgrade an Ethernet system to faster speeds, rather than retraining network staff on a totally new networking technology.
Vendors say that once networking staff understand 10 megabit Ethernet, they don't need retraining to understand and manage the faster varieties.
They've got very used to dealing with Ethernet," says Martin, who is also product marketing manager at Bay Networks.
Ethernet shipment data indicate just how popular a technology it is.
"The technology that's going to take a piece out of (10 megabit) Ethernet is not ATM.
In 1995, the first year for which data about fast Ethernet hubs were available, almost 460,000 ports shipped worldwide.
"Fast Ethernet switches and bit Ethernet are all going to enjoy tremendous growth over the next four years," Armstrong predicts.