ARCHIVED: What is 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). Following are some Ethernet features:

  • Ethernet transmits data at up to ten million bits (i.e., 10 megabits) per second (10 Mbps). Fast Ethernet supports up to 100 Mbps, Gigabit Ethernet supports up to 1,000 Mbps, and 10 Gbps Ethernet supports up speeds matching its name (10 gigabits per second or 10,000 Mbps).

    Buildings at Indiana University are connected to the campus backbone using 1 Gbps Ethernet. At IU, 10 Gbps connectivity is primarily used for backbone links, though some systems in the Data Centers are connected at this speed as well.

  • Ethernet supports networks built with twisted-pair (10BaseT), thin and thick coaxial (10Base2 and 10Base5, respectively), and fiber-optic (10BaseF) cabling. Fast and Gigabit Ethernets can be built with twisted-pair (100/1000BaseT) and fiber-optic (100BaseF/1000BaseLR) cabling. Currently, 10 and 100BaseT Ethernets are the most common for hosts within buildings.
  • Data is transmitted over the network in discrete packets (frames) which are between 64 and 1,518 bytes in length (46 to 1,500 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 protocols, the most common including TCP/IP, UDP, and ICMP (Ping).
  • 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, including quick reference guides, specification overviews, and history, visit Charles Spurgeon's Ethernet web site.

Note: IU uses the Ethernet_II specification, which is older than the IEEE 802.3 standard, and more closely related to the original DIX Ethernet.

This is document aesi in the Knowledge Base.
Last modified on 2013-09-20 00:00:00.

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