ARCHIVED: What is Ethernet?

  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


  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


  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.