Computer Terms - Letters I through L
ILECs (incumbent local exchange carriers): a telephone company providing local service when the Telecommunications Act of 1996 was enacted (see CLEC)
ILP (initial loader program): reads an existing file containing database records; also called a boot-loader
Input/output management routines: provide orderly control and flow of information between a computer’s main memory and attached peripheral devices
Interface: point in the system where the rules, control codes, formats, and information direction (as dictated by the protocol) are implemented
Interior protocols: routing protocol used within/interior to an independent/ autonomous system
Internet layer: part of the TCP/IP model that performs the same function as the network layer of the OSI model
Internetworking: connecting one network to another network
Interprocess communication: allows programs to share information dynamically, whether running locally or remotely
I/O (Input/output devices): hardware used to enter and retrieve data from the system
IP (internet protocol): network layer protocol provided with TCP/IP; connectionless, unreliable protocol that provides features for addressing, type or service specification, fragmentation and reassembly, and security
IP address (internet protocol address): logical address assigned to every workstation, server, printer, and router on any interconnected network
IPX/SPX (Internetwork packet exchange/sequenced packet exchange): a networking protocol used by the Novell NetWare operating systems; it is a datagram protocol used for connectionless communications
IRC (Internet relay chat): allows groups to communicate interactively via keyboard and screen display
ISDN (Integrated Services Digital Network): a circuit-switched telephone network system designed to allow digital transmission of voice and data over ordinary copper telephone wires
ISDN PRI: switched-line service from telephone companies that operates over T1 (or E1/J1) facilities
IS-IS (intermediate system-to-intermediate system): an interior gateway protocol (IGP) intended for use within an administrative domain or network
ISPs (Internet service providers): businesses or organizations that provide consumers with access to the Internet and related services
IT (information technology): broad term that can refer to anything from mainframes to PDAs; any technology that moves information (voice, video, or data)
ITU-T (ITU Telecommunication Standardization Sector): coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU)
IXC (interexchange carrier): a telephone company that provides connections between local exchanges in different geographic areas
Jitter: distortion in a digital signal caused by a shift in timing pulses; can cause data interpretation errors
JPEG (Joint Photographics Experts Group): a lossy compression technique for color images; pronounced jay-peg (see Lossy)
Kbps (thousands of bits per second): a measure of data transfer speed
kHz (kilohertz): a unit of measurement of frequency, also known as cycles per second; e.g., one kilohertz equals 1,000 Hz, or cycles per second
LAN (local area network): network that operates within a small geographic area, usually within a building, office, or department
LAPB (link access protocol, balanced): a data link protocol in the X.25 stack
LATAs (local access and transport areas): In the US, refers to a geographic region assigned to one or more telephone companies for providing communication services
Layer 2 switches: interpret and make switching decisions on the LAN hardware adapter address contained in the data link header of MAC frames; forward frames only to the destination hardware address contained in the frame
LCI (logical channel identifier): used to define frequencies in use on M/A-COM EDACS (Enhanced Digital Access Communications System) systems and LTR (logic trunked radio) systems; more commonly known as logical channel number (see LCN); also known as virtual channel
LCN (logical channel number): used to define frequencies in use on M/A-COM EDACS (Enhanced Digital Access Communications System) systems and LTR (logic trunked radio) systems; also known as the logical channel identifier (see LCI); also known as virtual channel
LE (local exchange): a regulatory term in telecommunications for local telephone company
Leased lines: another name for private lines, dedicated lines, or permanent circuits
LEC (local exchange carrier): a public telephone company in the US that provides local service
LGN (logical channel group number): together with the LCN (in the X.25 packet header), identifies the actual logical channel number of the DTE-DCE link; a 4-bit field representing a number between 0 and 15
Line layer: layer of the OSI physical layer that is responsible for synchronizing and multiplexing multiple streams of data into one SONET stream within SONET frames; also monitors and administers SONET multiplexers
LLC (logical link control): standard interface allowing any combination of MAC techniques and physical media to be used simultaneously in the same workstations; shields higher layer protocols from the peculiarities of the physical medium
Logical segmentation devices: allow network designers to maintain separate networks (often for security reasons) that can still communicate with one another
Lossy: data compression method where compressing and then decompressing retrieves data that may well be different from the original, but is "close enough" to be useful in some way
LU (logical unit): identifies an end-user in IBM's Systems Network Architecture (SNA)