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Glossary
GL-10
Issue 1
December 1997
I
IAO LAN
IntrAOffice Local Area Network
IC
Internal Clock. Used in synchronization messaging.
ID
Identifier. See shelf ID and site ID.
IEC
International Electrotechnology Commission
IMF
Infant Mortality Factor
INC
Incoming Status
I/O
Input/Output
IP
Internet Protocol
IR
Intermediate Reach. A term used to describe distances of from 15 to 40 km between
optical transmitter and receiver without regeneration. See long reach.
IS
In Service — One possible state of a DS1, DS3, or EC-1 port. Other possible states are
"auto" (automatic) and "nmon" (not monitored).
ISCI
Intershelf Control Interface
ISI
Intershelf Interface
ISDN
Integrated Services Digital Network
IS-3
An intraoffice short reach proprietary interface provided by the 21D/21D-U and 22D-U
optical line interface units.
ISO
International Standards Organization. See OSI.
IVHS
Intelligent Vehicle Highway System