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L - length

L/L - long local

L2F - Layer Two Forwarding

L2TP - Layer Two Tunneling Protocol

LA - line amplifier

LAB - logic array block

LAD-GNSS - local area differential global navigation satellite system

LAN (Local Area Network) - A type of high-speed data communications arrangement wherein all segments of the transmission medium (typically coaxial cable, twisted-pair wire or optical fiber) are in an office or campus environment under the control of the network operator.

LANACS - local area network asynchronous connection server

LANE - local area network emulation

LANET - Lucent Limitless ATM Network

LANTDIS - Atlantic Command deployable intelligence terminal

LAPB - link access procedure balanced (protocol)

LAPD - link access procedure direct (protocol)

LAPM - link access procedure for modems

LAS - local area system

LASINT - Laser Intelligence

LAT - local access terminal

LATA - Local Access and Transport Area. The area within which calls are routed by your Local Exchange Carrier (LEC). Under the divestiture of the Bell System calls going outside of this area must be handled by an Interexchange carrier (IEC). With the latest round of de-regulation the usual IEC companies are being allowed to compete in the IntraLATA long distance market and LECs are beginning to be permitted to handle InterLATA calls.

Latching Loopback - A (more) complex method of implementing network loop-in. A complex sequence of NCCs and specific data patterns controls implementation and release of a latching loopback. Latching loopback requires a specific NCC to release or "unlatch" the loop-in, whereas "nonlatching" loopback is released when the network side stops transmitting the loopback code. A latching loopback provides a means to perform more thorough testing because any data pattern can be transmitted between the time the loop-in is "latched" and "unlatched," whereas nonlatching loopback requires that loopback code be transmitted every other byte. Also see nonlatching loopback.

LAW - local authority workstation

LAW - light antitank weapon

LAWN - local area wireless network

lb - pound

LB - local battery

LBA - logical block addressing

LBO - line built out

LBS - local base station

lbs - pounds

LBSS - lightweight battlefield surveillance system

LBT - listen before talk

LBT1 - limited bandwidth T1

LBX - low bandwidth X

LC - line concentrator

LCB - line circuit board

LCC - Land Component Commander

LCC - local control center

LCC - logic control cell

LCC - amphibious command ship

LCC - link communications circuit

LCCES - light contingency communications extension switch

LCCP - light contingency communications package

LCCPS - light contingency communications parent switch

LCCS - Life Cycle Contractor Support (For C4I)

LCD - Liquid Crystal Display

LCDL - low cost data link

LCES - line conditioning equipment scanner

LCMS - Local COMSEC Management System

LCP - link control protocol

LCR - least-cost routing

LCS - large complex systems

LCSE - life cycle software engineering

LCSEC - Life Cycle Software Engineering Center

LCSS - land combat support system

LCSS - life cycle software support

LCT - low cost terminal

LCU - lightweight computer unit

LD - load

LD-CELP - (Low Delay Code Excited Linear Prediction) - A voice compression module which uses a backward-adaptive analysis-by-synthesis algorithm. This voice module offers the advantages of toll quality voice compression while maintaining the ability to transmit group III FAX.

LD-CELP Post-Filter - The Post-Filter is used to add additional voice quality to the decompressed voice signal at end-points in the network.

LDA - logical device address

LDAP - Lightweight Directory Access Protocol

LDC - lightweight deployable communications

LDF - lightweight digital facsimile

LDGPS - local area differential global positioning system

LDI - long dwell imagery

LDI - line driver interface

LDM - limited distance modem

LDMX - Local Digital Message Exchange

LDN - Listed Directory Number. When a number of Telco channels share the same hunt group it is customary to give out only one phonenumber for the group, although generally each channel will have its own number. The number given out is the "Listed Directory Number" since that is the number that would be listed in the Telephone Directory and given to customers. See also Hunt Group.

LDO - limited duty officer

LDR - low data rate

LDR - leader

LDRM - low data rate multiplexer

LDS - long distance service

LDU - local distribution unit

LDV - lock data views

LDVM - legacy PPT/Voice Module

LEA - Law Enforcement Agency

LEAF - law enforcement access field

LEAP - leading edge advanced packages

LEASAT - leased satellite

Leased Line - A dedicated circuit, typically supplied by the telephone company, that permanently interconnects two or more user locations; generally voice-grade in capacity and range of frequencies supported. It is typically analog, though sometimes it refers to DDS subrate digital channels (2.4 to 9.6 kbps); could be point-to-point or multipoint.

Least-Cost Routing - The capability of a switch, either a node or a PBX, to automatically determine an optimal route establishing a circuit; also called automatic route selection.

LEC - Local Exchange Carrier. Your local telephone service provider which is either an RBOC or an Independent. In other words, a traditional phone company. In contrast to CLEC or IEC.

LECP - line ECP

LED - light emitting diode

LEM - language extension module

LEN - low entry networking

LEN - Large Extension Node

LENS - large extension node switch

LEO - Law Enforcement On-Line (FBI)

LEO - low Earth orbit

LES - Leading Edge Services (DISA)

LES - Litton Emulation Software

LF - low frequency

LFB - look ahead for busy

LFI - last file indicator

LFN - long fat network

LFSR - linear-feedback shift-register

LG - loop group

LGDT - load global descriptor table

LGM - Loop Group Multiplexer

LGSM - light ground station module

LH - left hand

LHA - general purpose amphibious assault ship

LHD - general purpose amphibious assault ship (with internal dock)

LIA - Legacy Interface Adapter

LIDT - load interrupt descriptor table

LIFO - last in, first out

LIM - Litton Interface Manager

LIMS - laboratory information management system

LINCS - Leased Interfacility National Airspace Communications System

Line - An electrical connection between a telephone service providerÕs switch (LEC or CLEC) and a telephone terminal or Key system. An electrical connection between a telephone service providerÕs switch and another switch is called a trunk. Note that some type of physical lines offer more than one channel. I.E. a BRI circuit has 2 channels, called B channels. This term is a confusing one. See Channel. See also Station Line

Line Card - The circuit in the Telco switch to which your line is connected. On an ISDN circuit the line card performs a role analogous to the NT1 in adapting and equalizing the circuit.

Line Coding, T1 - The clock signal for T1 is derived at the far end from the data bits themselves. Therefore T1 lines have certain restrictions as to the data allowed. No more than 15 zeros shall be sent in a row; and average density of 12.5% ones must be maintained. The CSU is responsible to ensure that these requirements are met. The line encoding method, AMI or B8ZS determines exactly how these requirements are met while still allowing recovery of the original data at the far end. Your Telco will determine the method used on a specific circuit. B8ZS is preferred. E1 circuits have similar restrictions. HDB3 is preferred for E1 circuits.

Line Format, T1 - Modern T1 circuits usually use either Superframe (sometimes called SF or D4) or Extended Superframe (sometimes called ESF) line formatting. The type of framing used is determined by your Telco. ESF is preferred. See ESF and SF

Line Hit - An incident of electrical interference causing unwanted signals to be introduced onto a transmission circuit.

Link - A circuit or transmission path, including all equipment, between a sender and a receiver. A logical connection between two nodes consisting of one or more T1/T3 trunks.

Link Cost - See routing cost.

Link ID - Links are identified through the Operator Interface by indicating the nodes connected by a link. For example, the link between Nodes 5 and 7 is referred to as N5N7 or N7N5.

LINT - line interface number

LIP - large internet packet

LIPS - logistics information processing system

LIRCM - large (aircraft) infrared countermeasures

Listed Directory Number - See LDN

LITE - Lightweight Integrated Telecommunications Equipment

LITINT - literature intelligence

LIU - LAN interface unit

LIU - line interface unit

LIWA - land information warfare activity

LKG - Loop Key Generator

LKGI - loop key generator interfaces

LKM - local key manager

ll - numbers

LLC - logical link control

LLCSC - lower level computer software component

LLDT - load local descriptor table

LLLTV - low light level television

LLP - lower layer protocol

LM - loop modem

LMD - loop group multiplexer and demultiplexer

LMDS - Local Multi-point Distribution Service

LMF - language media format

LMI - (Local Management Interface) - A protocol used for controlling the connection between the User and the Network.

LMR - land mobile radio

LMRDFS - lightweight man-transportable radio direction finding system

LMS - lightweight modular shelter

LMSS - land mobile satellite system

LMST - lightweight multiband satellite terminal

LMSW - load machine status word

LMU - local management unit

LN - link node

LNA - local network attachment

LNA - low noise amplifier

LNE - Late Net Entry

LNO - Liaison Officer

LNP - Local Number Portability

LNS - leader node switch

LNX - flood search numbering plan prefix

LNX+XXXX - format for a MSE user's telephone number

LO - low

LOAC - Laws of Armed Conflict

Load - Unit - A measure of the processing capability of each processor (PPM and PLM) module.

LOC - lines of code

LOC - local

Local Access and Transport Area - See LATA.

Local Exchange Carrier - See LEC and CLEC.

Local Loop - A diagnostic technique that loops data out to local cable and terminal equipment to isolate failures.

Local UI - A user Interface application resident on the same machine as SSIMP-LR Main.

LOCE - Linked Operations Intelligence Capability-Europe

LOCIS - Library of Congress Information System

LOCK - logical coprocessor kernel

LOF - lowest operating frequency

log - logistics

LOGAIS - logistics automated information system

Logical Slots - A measure of the bandwidth amount required for the operation of a specific module. Each shelf in a node can support a specific number of logical slots.

LOI - loss-of-input

LOICE - Link Operations Intelligence Center-Europe

Long Distance - 1. If your local Telco is a former Bell Operating Company then any call outside of your LATA or any Interstate call is considered long distance and is handled by an IEC 2. If your local phone company is an independent then only interstate and inter-phone company calls are considered long distance. The above is true regardless of whether you are referring to a dedicated line or a dial up call 3. However, under the current state of deregulation, toll calls within a LATA may now be covered by the IEC, and in some cases RBOCs are being permitted to handle InterLATA calls.

LOOP - MUX loop multiplexer

Loop - 1. A diagnostic technique that loops data out or in to the equipment to isolate failures. 2. The telephone circuit from the CO to the customer's premises. Generally refers to a copper cable circuit.

Loop Qualification - Process of actually measuring the loss on a prospective ISDN line to see if it can be used for ISDN service . The actual loss on the line determines whether ISDN service can be offered without a repeater. Generally ISDN is available up to 18,000 feet from the serving Central Office. It may not be available within this range, or may be available further from the CO. Only a loop qualification can tell for sure. Not all Telcos will extend ISDN lines with Repeaters.

Loop Start Line - A plain old telephone line. The telephone terminal signals the "off hook" condition by allowing DC current to flow. See Ground Start Trunk. See also Glare.

Loop Start Trunk - A plain old telephone line connected to a PBX switch. See Loop Start Line. The PBX signals the "off hook" condition by allowing DC current to flow. Ground Start Trunks are generally preferred for use on PBXs to prevent glare. See Ground Start Trunk. See also Glare.

Loop Timing - Loop timing indicates that the transmit and receive frame bits are synchronized. When the operator selects the Loop Timing parameter, the voice card obtains it’s transmit and receive clock from the incoming bit stream.

Loop-in - A transmission capability in which the received signal is returned (looped in) to the network.

Loop-out - A transmission capability in which the received signal is returned (looped out) to the physical interface. In the SDMS port 0 bundle context, the meaning of loop-out is straightforward. In the subrate port context, it is confusing because DSMS ports have no physical interface; data is looped back towards the remote data port. To the remote QSD port, this looks like a loop-in.

Loopback - A transmission capability in which the received signal is returned (looped back) to the sender.

LORAN-C - Long-Range Aid to Navigation

LOS - line of sight

LOS - loss of signal

LOSH - line of sight (high capacity)

LOSL - line-of-sight link

LOSM - line of sight (Marine Corps)

LOW - link orderwire

LOW - link orderwire

LP - linearly polarized (mode)

LP - linear programming

LP - linking protection

LP - log periodic (antenna)

LP - BK loop back

LP - listening point

LPA - linear power amplifier

LPC - linear predictive coding

LPC - longitudinal parity check

LPCK - Loop Clock

LPCS - lateral parent COMSEC switch

LPD - low probability of detection

LPD - Line Printer Daemon (protocol)

LPD - amphibious transport dock

LPE - low probability of exploitation

LPI - low probability of interference (intercept)

LPP - line printer/plotter

LPU - line printer unit

LPVM - legacy PTT voice module

LQA - link quality analysis

LRAU - local radio access unit

LRC - longitudinal redundancy check

LRDM - low rate data multiplexer

LRF - laser rangefinder

LRI - limited range of intercept

LRM - language reference manual

LRM - low rate multiplexer

LRM - low rate modem

LRSU - Long Range Surveillance Unit

LRU - line replaceable unit

LS - LKG selector

LS - light stream

LS (Low Speed) Trunk Module - A bandwidth efficient trunk module primarily used as a low bandwidth trunk.

LS - low speed

LSB - least significant bit

LSB - lower sideband

LSC - least significant character

LSCDM - Low-Speed Cable Driver Modem

LSD - large screen display

LSD - least significant digit

LSD - large screen display

LSD - landing ship, dock

LSDIS - light & special division interim sensor

LSE - local subscriber environment

LSI - Large-Scale Integration

LSL - link support layer

LSMS - local service management system

LSP - Logistics Support Package

LSPR - Low-Speed Pulseform Restorer

LSRD - Loop Start Ringdown

LSRR - loose source and record route

LSSC - Logistics Systems Software Center (Army)

LSTDM - low-speed time division multiplexers

LT - laser transmitter

LT - local terminal

LTBF - Local Timing Buffer

LTC - line traffic coordinator

LTE - Late Traffic Entry

LTG - Local Timing Generator

LTM - Line Termination Module

LTOIV - latest time of intelligence value

LTU - Line Termination Unit

LTU - TCTC transmit cipher text clock, transit case technical control

LU - logical unit

LUA - logical unit application

Lucent Technologies - Company which now makes the former AT&T 5ESS switch, as well as various other pieces of Telco gear and semiconductors. Lucent was split off from AT&T in 1996 and owns Bell Labs. As of approximately 1999 Lucent sold their telephone set manufacturing business (and the right to use the AT&T name on telephone sets) to V-Tech. V-Tech is using the AT&T name and line as their high-end line.

LUF - lowest usable frequency

LUT - look up table

LVDTC - local video display terminal controller

LVM - large voice module

LWIR - long wave infrared

LWIRJ - long wavelength infrared jammer

LWSD - large wall screen display

LWX (LAN/WAN Exchange) Module - This module provides an internetworking connection between geographically separated LANs (local area networks) to connect to a WAN (wide area network).

LZ - landing zone


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