Glossary
16
BIT TIME
—The duration of one bit symbol (1/BR). Ethernet specifies a bit
time of 100 ns.
COAX SEGMENT
—A segment of Ethernet cable that contains MAU.
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.
CARRIER SENSE
—In a LAN, an ongoing activity of a data station to
detect whether another station is transmitting.
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.
CROSS-OVER
—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 unit, 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 unit
typically at the end of a segment. The DTE could be an Ethernet workstation,
repeater, or bridge.
