Understanding the network.pdf - Back to Home

Ethernet
The original Ethernet protocol was developed by Dr. Robert Metcalfe and his
development team at Xerox PARC (Palo Alto Research Center) in Palo Alto,
California, in 1972. Ethernet's media access mechanism, Carrier Sense Multiple
Access Collision (CSMA/CD), was based on work done by Dr. Norman Abramson at
the University of Hawaii on the radio transmission WAN known as the ALOHA system.
Metcalfe's experimental Ethernet network, called ALOHA ALTO, supported 100
nodes on 1km length of 50-ohm coaxial cable and operated at a rate of 2.94Mbps.
The nodes were connected to the cable with transmitter-receivers (transceiver) and
a cable tap. The combination of the cable tap and transceiver is known as an MAU
(media access unit).
In 1979, the Ethernet DIX consortium was formed between Digital Equipment
Corporation, Intel, and Xerox. The following year (1980), the DIX "Blue Book"
Ethernet V 1.0 specification was published (based largely on the experimental ALTO
Ethernet). Then in 1982, the DIX specification was updated to Ethernet Version 2.0
(commonly referred to a the Ethernet II specification). Then in 1981, the IEEE
subcommittee 802.3 began the process of developing a draft standard based on the
DIX Ethernet specifications. In 1983, the IEEE finalized the first standards-based
Ethernet version, 10Base-5, which was based on the DIX V2 or Ethernet II
specification. The following year 3Com (Computers, Communication, and
Compatibility) and Hewlett-Packard submitted the "Thin-Net" standard to the IEEE
802.3. Their standard, 10Base-2, operated over a thinner grade of 50-ohm coaxial
cable, and the transceiver was integrated into the Network Interface Card (NIC).
Instead of using the cable tap and AUI drop cable approach (between the NIC and
the transceiver) used by 10Base-5, 10Base-2 used BNC (British Navel Connectors)
and T-barrel connectors to connect the end-stations to the bus cable. The IEEE
formally approved 10Base-2 in 1989.