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.