protocol that specifies an implementation of the physical layer
and the MAC
sublayer of the data link layer
. IEEE 802.3 uses CSMA/CD
access at a variety of speeds over a variety of physical media. Extensions to the IEEE 802.3 standard specify implementations for Fast Ethernet
Physical variations of the original IEEE 802.3 specification include 10Base2, 10Base5, 10BaseF, 10BaseT, and 10Broad36. Physical variations for Fast Ethernet include 100BaseT, 100BaseT4, and 100BaseX. Also, 802.3 has a substantial analog component for collision detection.
The 802.3 standard is for a 1-persistent CSMA/CD LAN. The origin of 802.3 is the ALOHA system. Carrier sensing was added to ALOHA, and XEROX PARC (who else?) built a 2.94-Mbps CSMA/CD system to connect over 100 workstations on a 1-km cable (Metcalfe and Boggs, 1976).