Glossary
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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. It provides for a level of error detection should that
transmission be corrupted or impeded by contention for the transmission medium.
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, terminated at each end in its characteristic impedance.
COLLISION—An unwanted condition that results from concurrent transmissions on
the physical medium.
COLLISION PRESENCE—Provides the ability to detect simultaneous occurrence of
Manchester-encoded data on the DI and DO and to report such an occurrence as a
collision.
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 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 has
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 and no receiver. As a solution, the crossover
cable crosses the TD pair with the RD pair, to connect the TD pins on one end to the RD
pins at the other end.
CYCLIC REDUNDANCY CODE (CRC)—An algorithm used to check for and correct
bit errors in data transmission.
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 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.
EMULATED LOCAL AREA NETWORK (ELAN)—See LAN Emulation.
FOIRL — A fiber optic standard that allows up to 1,000 meters (3,280 ft.) of multimode
duplex fiber optic cable in a point-to-point link.
HARMONICA ADAPTER—This adapter provides a simple way to convert the 50-pin
Telco connection to RJ-45 connections.
HEARTBEAT—See SQE
HOT SWAPPING— The process of replacing a module without interrupting the
network. This process occurs by sliding an active module into a fully powered up unit,
replacing a failed module.
HOUSE WIRING—House wiring is the existing wiring inside a building. This wiring
generally originates from one or more wiring closets, such as a telephone room. Some
older buildings may have wiring unsuitable for 10 megabit data rates. In these
circumstances, it is recommended that the wiring be tested with a 10Base-T signal/wire
tester.
