Glossary
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BRANCH CABLE—The AUI cable interconnecting the DTE and MAU system
components also known as a drop cable.
BIT TIME—The duration of one bit symbol (1/BR). Ethernet specifies a bit
time of 100 ns.
CARRIER SENSE—In a LAN, an ongoing activity of a data station to detect whether
another station is transmitting.
CARRIER SENSE MULTIPLE ACCESS with COLLISION DETECT (CSMA/
CD)—This is the access method employed by IEEE 802.3 LAN transceivers, by which
multiple stations compete for use of the transmission medium (coax cable) for data
packet transmission and provides for a level of error detection should that transmission
be corrupted or impeded by contention for the transmission medium.
COAX SEGMENT—A segment of Ethernet cable that contains MAU.
COAXIAL CABLE—A two conductor (center conductor, shield system), concentric,
constant impedance transmission line used as the trunk medium in the baseband
system.
COAXIAL CABLE SEGMENT—A length of coaxial cable sections and coaxial
connectors and terminated at each end in its characteristic impedance.
COLLISION—An unwanted condition that results from concurrent transmissions on
the physical medium.
COLLISION PRESENCE—A signal provided by the PLS to the PMA sublayer (within
the physical layer) to indicate that multiple stations are contending for access to the
transmission medium.
COMPATIBILITY INTERFACE—The MDI coaxial cable interface and the AUI
branch cable interface, the two points at which hardware compatibility is defined to
allow connection of independently designed and manufactured components to the
baseband transmission system.
CROSSOVER—Wiring is used when connecting a 10BASE-T MAU to another
10BASE-T MAU or a 10BASE-T hub to another 10BASE-T hub. For example, one
10BASE-T MAU would have the TD pair on the same pins as another 10BASE-T MAU.
If pins were wired straight, there would be two transmitters on one pair with no
receiver. Therefore, the cross-over cable crosses the TD pair with the RD pair of UTP
cable connecting the TD pins on one end to the RD pins at the other end.
D-SUB CONNECTOR—The AUI cable uses 15-pin D-sub connectors. “D” refers to the
shape of the connector shell. Also called miniature D, DB15, or DIX connectors.
DATA COMMUNICATION EQUIPMENT (DCE)—In RS232 specification a module,
such as a modem, for connecting a DTE to other equipment. A repeater connected to a
terminal or workstation for OMEGA LOCAL management use is wired as a DCE.
DATA TERMINAL EQUIPMENT (DTE)—In RS232 specification a module typically
at the end of a segment. The DTE could be an Ethernet workstation, repeater or bridge.
