Glossary - 10
FORE Systems ES-2810 Ethernet Switch User's Manual
Glossary
cport - a FORE program that monitors and changes the state of ports on a ForeRunner switch
running asxd.
Cross Connection - a mapping between two channels or paths at a network device.
Customer Premise Equipment (CPE) - equipment that is on the customer side of the point of
demarcation, as opposed to equipment that is on a carrier side. See also point of demarcation.
Cut Through - Establishment of a complete path for signaling and/or audio communications.
Cyclic Redundancy Check (CRC) - an error detection scheme in which a number is derived
from the data that will be transmitted. By recalculating the CRC at the remote end and com-
paring it to the value originally transmitted, the receiving node can detect errors.
D3/D4 - Refers to compliance with AT&T TR (Technical Reference) 62411 definitions for coding,
supervision, and alarm support. D3/D4 compatibility ensures support of digital PBXes, M24
services, Megacom services, and Mode 3 D3/D4 channel banks at DS-1 level.
D4 Channelization - refers to compliance with AT&T Technical Reference 62411 regarding DS1
frame layout (the sequential assignment of channels and time slot numbers within the DS1).
D4 Framed/Framing Format - in T1, a 193-bit frame format in which the 193rd bit is used for
framing and signaling information (the frame/framing bit). To be considered in support of D4
Framing, a device must be able to synchronize and frame-up on the 193rd bit.
Data Communications Equipment (DCE) - a definition in the RS232C standard that describes the
functions of the signals and the physical characteristics of an interface for a communication
device such as a modem.
Data Country Code (DCC) - This specifies the country in which an address is registered. The
codes are given in ISO 3166. The length of this field is two octets. The digits of the data country
code are encoded in Binary Coded Decimal (BCD) syntax. The codes will be left justified and
padded on the right with the hexadecimal value âFâ to fill the two octets.
Data Link - Communications connection used to transmit data from a source to a destination.
Data Link Connection Identifier (DLCI) - connection identifier associated with frame relay pack-
ets that serves the same functions as, and translates directly to, the VPI/VCI on an ATM cell.
Data Link Layer - Layer 2 of the OSI model, responsible for encoding data and passing it to the
physical medium. The IEEE divides this layer into the LLC (Logical Link Control) and MAC
(Media Access Control) sublayers.
Data Set Ready (DSR) - an RS-232 modem interface control signal (sent from the modem to the
DTE on pin 6) which indicates that the modem is connected to the telephone circuit. Usually a
prerequisite to the DTE issuing RTS.
Data Terminal Equipment (DTE) - generally user devices, such as terminals and computers, that
connect to data circuit-terminating equipment. They either generate or receive the data carried
by the network.
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