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).
