Glossary of Technical Terms (L-P)

(We wish to thank Unicom for their contributions.)

# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



LAN (Local Area Network)* – (1) The network which interconnects all computing devices located within a single end user location; e.g., an integrated token ring / ATM network covering an entire campus. (2) A single layer-two network, which may be connected to other such networks within an end user location; e.g., a single Ethernet segment. To avoid confusing the two definitions, Xylan commonly refers to the former as a “campus” network.


Lay – The length measured along the axis of a wire or cable required for a single strand (in stranded wire) or a conductor (in cable) to make complete turn about the axis of the conductor or cable.


LED* – Light Emitting Diode.


Link* – An end-to-end transmission path provided by the cabling infrastructure. Cabling links include all cables and connecting Equipment and work area cables are not included as part of a link.


Local Exchange Carrier (LEC)* – The local regulated provider of public switched telecommunications services.


Longitudinal Shield – A tape shield, flat or corrugated, applied longitudinally with the axis of the core being shielded.


Loss – Energy dissipated without accomplishing useful work.


Low Loss Dielectric – An insulating material that has a relatively low dielectric loss, such as polyethylene of Teflon.


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MAC (Media Access Control)* – The way LAN workstations share access to a transmission medium. MAC-layer protocols include Ethernet, token ring, and FDDI. This MAC has absolutely nothing to do with the Apple Macintosh computer.


MAC Address* – The layer-two address of a LAN device.


MAU (Media Access Unit)* – In token ring, a hub which interconnects the devices connected to the ring, and in turn connects to other MAUs through Ring-In / Ring-Out connections. Generally, a MAU is not managed via software.


Mbps* – Millions of bits per second.


MDF (Main Distribution Frame)* – In a structured building wiring system, the central point for cabling throughout the building. Typically, multiple IDFs located in wiring closets connect to a central MDF.


Mega (M) – A numerical prefix denoting 1,000,000 (106).


MHz – Megahertz (one million cycles per second). Formerly mc.


Micro – A numerical prefix denoting one-millionth (106)


MII (Media Independent Interface)* – The standard interface for Fast Ethernet. It is similar to the AUI interface for traditional Ethernet.


Mil – A unit in measuring diameter of a wire or thickness of insulation over a conductor. One one-thousandth of an inch (.001″).


MMJ (Modified Modular Jack)* – A six-wire modular jack with the locking tab shifted off to the right side. Used in the DEC wiring system.


Modulation* – The process of modifying a carrier signal to transmit information.


Modulus of Elasticity – The ratio of stress to strain in an elastic material.


Monomer – The basic chemical unit used in building a polymer.


MT-RJ* – A type of dual fiber optic connector: small size, lower cost, more flexible application and easier use. The MT-RJ system supports both Single Mode and Multi-Mode applications, providing a robust solution for both backbone and horizontal needs. About half the size of an SC-based transceiver, the MT-RJ presents significant space savings. The narrower width allows network equipment vendors to achieve the same port density as with modular jacks.


Multi-mode* – A form of fiber optic cabling in which light is able to follow multiple paths as it traverses the cable. Less expensive, and with a lower maximum rate and distance, than single mode fiber optic cable.


Multiplex* – To transmit two or more messages or message streams on a single channel, typically through the use of frequency-division multiplexing, time division multiplexing, or statistical time division multiplexing.


Multiplexer* – A device used for division of a transmission facility into two or more subchannels, either by splitting the frequency band into narrower bands or by allotting a common channel to several different transmitting devices one at a time. Also known as a mux.


Mutual Capacitance – Capacitance between two conductors when all other conductors including ground are connected together and then replaced as an ignored ground.


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Nano (N) – A numerical prefix denoting one-billionth (109)


National Electric Code – A consensus standard published by the National Fire Protection Association (NFPA) and incorporated in OSHA regulations.


NEXT (Near End Crosstalk)* – Signal distortion as a result of signal coupling from one pair to another at various frequencies.


Network* – A number of interconnected systems that, typically, exchange information with one another and share resources that may be distributed among the systems.


NIC (Network Interface Card)* – A physical plug-in module which goes into a workstation or server and provides the connection to a network.


Node* – Any network device (such as a server, workstation, or router) that can communicate across the network.


Noise* – A low-voltage, low-current, high-frequency signal that interferes with normal network transmissions, often data.


N-Way* – See “Auto-Negotiation”.


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OFHC – Abbreviation for oxygen-free, high conductivity copper. It has no residual deoxidant, 99.95% minimum copper content and an average annealed conductivity of 101 %.


Ohm – A unit of electrical resistance.


Oxygen Index – Percentage of oxygen necessary to support combustion in a gas mixture.


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Parallel Detection* – The method of establishing a link between auto-negotiation and non-negotiation devices


Patch Cord* – The connecting cord between the terminal device and the drop.


Patch Panel* – Connecting hardware that typically provides means to connect horizontal or backbone cables to an arrangement of fixed connectors that may be accessed using patch cords or equipment cords to form cross-connections or interconnections.


Percent Conductivity – Conductivity of a material expressed as a percentage of that of copper.


Periodicity – The uniformly spaced variations in the insulation diameter of a transmission cable that result in reflections of a signal, when its wavelength or a multiple thereof is equal to the distance between two diameter variations.


Phase* – The amplitude of a cyclic signal at a specific point in time.


Pick – Distance between two adjacent crossover points of braid filaments. The measurement in picks per inch indicates the degree of coverage.


Pico (P) – A numerical prefix denoting one-millionth of one-millionth (1012).


Pitch – In flat cable, the nominal distance between the index edges of two adjacent conductors


Plant* – The cables that connect computers together in a LAN


Plasticizer – A chemical agent added to plastics to make them softer and more pliable.


Plenum* – A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.


Polymer – A material of high molecular weight formed by the chemical union of monomers.


Polyclefin – Any of the polymers and copolymers of the ethylene family of hydrocarbons.


Port* – An interface of a computer or other transmission device that acts as an input and/or output point.


POTS* – Plain Old Telephone System


Propagation Delay* – The amount of time that passes between when a signal is transmitted and when it is received at the opposite end of a cable or cabling.


Protocols* – The specifications that define procedures used by computers when they transmit and receive data.


Punch Down* – A method for securing wire to a quick clip in which the insulated wire is placed in the terminal groove and pushed down with at special tool.


PVC (Poly-vinyl Chloride)* – The material most commonly used for the insulation and jacketing of cable.


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