Appendix C. Acronyms/Abbreviations T1 ESF CSU ACE User Manual
56 © 2004 ADTRAN, Inc 61204025L1-1C
FR frame relay
FRAD frame relay access device
FRF frame relay forum
FSU frame relay service unit
HDLC high-speed data link control
IP internet protocol
ISDN integrated services digital network
ITU International Telecommunications Union
KA keep alive
LAN local area network
LED light emitting diode
LLC logical link control
LMI local management interface
LRC lateral redundancy check
MIB management information base
ms millisecond
NRZ non-return to zero
NRZI non-return to zero inverted
OCU office channel unit
OOS out of service
PLAR private line automatic ringdown
PPP point to point protocol
PU physical unit
PVC permanent virtual circuit
RD receive data
RDL remote digital loopback
RFC request for comments
RFECN remote forward explicit congestion notification
RIP routing information protocol
RMA return material authorization
RR receiver ready
RS recommended standard
RTS request to send
Rx receive
SAP service access point
SDLC synchronous data link control
SLIP serial line internet protocol
