Ethernet
Ethernet (the name commonly used for IEEE 802.3 CSMA/CD) is the dominant cabling and low level data delivery technology used in local area networks (LANs). First developed in the 1970s, it was published as an open standard by DEC, Intel, and Xerox (or DIX), and later described as a formal standard by the IEEE. Following are some Ethernet features:
- Ethernet transmits data at up to ten million bits per
second (10Mbps). Fast Ethernet supports up to 100Mbps and Gigabit
Ethernet supports up to 1000Mbps. Many buildings on the Indiana
University campus are wired with Fast Ethernet and the campus backbone
is Gigabit Ethernet.
- Ethernet supports networks built with twisted-pair (10BaseT), thin
and thick coaxial (10Base2 and 10Base5, respectively), and fiber-optic
(10BaseF) cabling. Fast Ethernets can be built with twisted-pair
(100BaseT) and fiber-optic (100BaseF) cabling. Currently, 10BaseT
Ethernets are the most common.
- Data is transmitted over the network in discrete
packets (frames) which are between 64 and 1518
bytes in length (46 to 1500 bytes of data, plus
a mandatory 18 bytes of header and CRC information).
- Each device on an Ethernet network operates independently and
equally, precluding the need for a central controlling device.
- Ethernet supports a wide array of data types, including
TCP/IP, AppleTalk, and IPX.
- To prevent the loss of data, when two or more devices attempt to send packets at the same time, Ethernet detects collisions. All devices immediately stop transmitting and wait a randomly determined period of time before they attempt to transmit again.
For more information, including quick reference guides, specification overviews, and history, visit Charles Spurgeon's Ethernet web site at:
http://www.ethermanage.com/ethernet/ethernet.html
Also read the newsgroups
comp.dcom.lans.ethernet and
comp.dcom.cabling.
IU uses the Ethernet_II specification, which is older than the IEEE 803.2 standard, and more closely related to the original DIX Ethernet.
