Chapter 12. Glossary

1000Base-LX: Gigabit Ethernet transmitted over fiber using long wave laser transmitters
1000Base-SX: Gigabit Ethernet transmitted over fiber using short wave laser transmitters
1000Base-T: Gigabit Ethernet over twisted pair.
100Base-FX: 100 Mbps Fast Ethernet system based on 4B/5B signal encoding transmitted over fiber optic cable.
100Base-T: Term used for the entire 100 Mbps Fast Ethernet system, including both twisted-pair and fiber optic media types.
10Base2: 10 Mbps Ethernet system based on Manchester signal encoding transmitted over thin coaxial cable. Also called Thin Wire and Cheapernet
10Base5: 10 Mbps Ethernet system based on Manchester signal encoding transmitted over thick coaxial cable. Also called Thick Net
10Base-F: 10 Mbps Ethernet system based on Manchester signal encoding transmitted over fiber optic cable.
10Base-T: 10 Mbps Ethernet system based on Manchester signal encoding transmitted over Category 3 or better twisted-pair cable
802.1: IEEE Working Group for High Level Interfaces, Network Management, Inter-networking, and other issues common across LAN technologies
802.3: IEEE Working Group for Carrier Sense Multiple Access/Carrier Detect Local Area Networks.
802.11, 802.15, 802.16, 802.17, 802.20: IEEE standards for low power, short range wireless LAN. Also referred to as Wi-Fi.
Address: A unique identification of a device attached to a network. The address can used to identify either a specific location such as a port on a switch, or a specific device.
ADSL: Asymmetric Digital Subscriber Line. Most common form of DSL where the data rate being transmitted to the subscriber is high than the data rate transmitted from the subscriber.
Aerial Cable: A cable suspended in the air on poles or other overhead structures
Alternating Current (AC): Electric current that continually reverses its direction. It is expressed in cycles per second (hertz or Hz).
Analog: A signal that varies continuously such as a sound wave. Analog signal have frequency and bandwidth measured in hertz.
ANSI: American National Standards Institute
APPA: American Public Power Association.
ASTM: American Society of Testing and Materials.
ATM: Asynchronous Transfer Mode. A digital transmission switching format with cells (packets) of a fixed length to help facilitate voice and video transmission.
Attenuation: Power loss in an electrical or telecommunications system. In cables, expressed in dB per unit length, usually dB per 1000 feet, or per kilometer. This term is also used to express loss in fiber optic cable.
AWG: Abbreviation for American Wire Gauge. Based on a circular mil system. 1 mil equals .001 inch. Used to determine the size of conductors.
Backbone: A transmission network that carries high speed telecommunications between locations. This is normally the main portion of a telecommunication network, with branches going to individual buildings. In a local area network, this is usually the link between routers, switches, and bridges.
Balun: An adapter for connecting an unbalanced coaxial transmission line to a balanced two-wire system.
Band Marking: A continuous circumferential band applied to a conductor at regular intervals for identification.
Bandwidth: The information carrying capacity of the system. In analog systems, this is also the highest frequency that can be carried.
Baud: The number of signal level transitions per second in digital data. The term is often confused with bits per second. Telecommunications specialists prefer to use "bits-per-second" to provide an accurate description.
BER: Bit Error Rate. The number of bit errors that occur within the space of one second. This measurement is one of the prime considerations in determining signal quality. The higher the data transmission rate the greater the standard. A DS-1 signal is considered acceptable with a BER of 10-6, but an OC-3 signal requires a BER of no more than 10-12.
Bps: Bytes per second. Term used by software engineers to describe bandwidth.
bps: Bits per second. Term used by telecommunication engineers to describe bandwidth.
Bridge: A device that allows multiple communication circuits to use a common circuit. Only one circuit can be connected to the common at any given moment
Broadband: Generally used to describe data transmission requirements of greater than 128 Kbps.
Broadcast Transmission: Sending the same signal to many locations.
Building Wire: Insulated single conductors, 600 volts, used for supplying power for lighting, operating machinery, controls, etc. Usually installed through conduits/trays inside buildings.
Bundle: A group of wires (or fiber strands) contained within a single wrapper.
Bus: An electrical transmission path for carrying information, usually serving a shared connection for multiple devices.
Byte: Eight bits of data.
Cable: A group of individually insulated conductors in twisted or parallel configuration, with an overall outer jacket.
Carrier Hotel: A large building where communication carriers place equipment to provide connections between their respective systems.
Carrier Sense: Carrier Sense is the process used by devices on Ethernet to determine whether the cable is currently being used by a transmitting station. If electrical signals are detected on the cable, then carrier has been detected and a station is currently transmitting on the cable
Category 5: Commonly referred to as "Cat 5". A type of twisted pair copper cable that meets standards for transmitting high speed signals.
CATV: An acronym for Community Antenna Television.
CCITT: International Consultative Commission on Telephone and Telegraph, an arm of the ITU (International Telecommunications Union) a standards setting body.
CCTV: Closed Circuit Television.
Central Office: Commonly referred to as a "CO". A telephone company facility for switching signals among local telephone circuits. Also called a "Switching Office".
Certificate of Compliance (C of C): A certificate showing that the product being shipped meets customer's specifications.
Certified Test Report (CTR): A report providing actual test data on a cable. Tests are normally run by a Quality Control Department, which shows that the product being shipped conforms to test specifications.
Coaxial Cable: A cable consisting of two conductors with a common axis, separated by a dielectric.
Collision: A collision is a condition where two devices detect that the network is idle and end up trying to send packets at exactly the same time (within 1 round-trip delay). Since only one device can transmit at a time, both devices must back off and attempt to retransmit again.
Color Code: A system for circuit identifications through use of solid color insulations and/or contrasting tracers.
Composite Cable: A cable containing more than one gauge size or a variety of circuit types, e.g., pairs, triples, quads, coaxials, etc.
Conduit: A tube through which insulated wires and cables are run.
Connector: A device mounted on the end of copper, or fiber optic cables to facilitate link of the cables.
Control Cable: A multiconductor cable made for operation of control or signal circuits.
Cord: A small, flexible insulated cable.
Core: In cables, a component or assembly of components over which additional components (shield, sheath, etc.) are applied.
CPE (Construction Term): Jacketing compound based on chlorinated polyethylene.
CPE (Network Term): Customer Premise Equipment – a term used by telephone companies to identify equipment owned by a customer
Crosstalk: Signal interference between nearby conductors caused by pickup of stray energy. It is also called induced interference.
Crosstalk: The unwanted transfer of a signal from one circuit to another.
CSMA/CD: Carrier Sense Multiple Access/Collision Detect. The formal name for the medium access control (MAC) protocol used in Ethernet.
CWDM: Coarse Wave Division Multiplexing
Cycles Per Second: CPS. The frequency of a wave, or the number of oscillations it makes persecond. One cycle per second equals one hertz.
Dark Fiber: Optical fiber installed without a transmitter or receiver. These fibers are the un-used fibers in a cable. Some fibers are held in reserve for future requirements. Others are often leased to different carriers (or large customers) for use in their individual systems.
Data Link: A data communications connection between two points.
Data Link Layer: Layer 2 of the OSI reference model. This layer takes data from the network layer and passes it on to the physical layer. The data link layer is responsible for transmitting and receiving Ethernet frames, 48-bit addressing, etc. It includes both the media access control (MAC) protocol and logical link control (LLC) layers.
dBm: Decibels below 1 mW (milliwatt)
dBu: Decibels below 1 µW (microwatt)
DCE: Data Communications Equipment. Any equipment that connects to Data Terminal Equipment (DTE) to allow data transmission between DTEs. A modem is a type of DCE.
Decibel (dB): A unit to express differences of power level. Used to express power gain in amplifiers or power loss in passive circuits or cables. Also, a logarithmic comparison of two power levels, defined as ten times the base ten logarithm of the ratio of the two power levels.
Dielectric: Nonconductive material
Dielectric Strength: The voltage which an insulation can withstand before breakdown occurs. Usually expressed as a voltage gradient (such as volts per mil).
Digital: An encoded signal. Normally encoded in discrete levels to represent a binary signal of ones and zeros.
Digital Subscriber Line: DSL. A service that transmits digital signals (to homes and small offices) via the existing copper wire used for voice transmissions.
Direct Burial Cable: A cable installed directly in the earth.
Direct Current (DC): An electric current which flows in only one direction.
Drain Wire: In a cable, the uninsulated wire in intimate contact with a shield to provide for easier termination of such a shield to a ground point.
DSSS: Direct Sequence Spread Spectrum – One of two types of spread spectrum radio transmission
DTE: Data Terminal Equipment. Any piece of equipment at which the communication path begins or ends. A PC is DTE.
Duct: An underground or overhead tube through which electrical conductors are pulled. Gives mechanical protection.
Duplex: A bi-directional transmission of the transmit and receive elements of a communication signal occurring simultaneously.
DWDM: Dense Wave Division Multiplexing
EIA: Electronic Industries Association.
EIA/TIA 568: This is the color-code connection standard for an RJ-45 (8 conductor) connector. There are two wiring standards: 568A and 568B. The only difference between the two is that two pairs of colors are swapped. The 568B is an older standard defined by AT&T. All new installations are supposed to use 568A. What really is important is that everything be consistent in all your wiring. Otherwise, you'll get yourself confused. Note that the difference is only in what color is used for what pin, not what signal is on what pin, so in a patch cable with both ends pre-wired, it doesn't matter.
Electricity: The energy produced by the flow of "free" or valance electrons moving from one atom to another in a conductor.
E&M Signaling: Ear (receive) and Mouth (transmit), a signal outside of the voice frequency range that can be used to activate a fuction in a telephone switch.
EMI: Electromagnetic Interference. The noise generated when stray electromagnetic fields induce currents in electrical conductors.
Encoding: A means of combining clock and data information into a self synchronizing stream of signals.
Ethernet: A local area network standard.
F.D.D.I.: Fiber Distributed Data Interface.
Facilities: Term used by telecommunication engineers to indicate communications systems
FHSS: Frequency-Hopping Spread Spectrum – One of two types of spread spectrum radio transmission
Fiber Optics: A light wave or optical communications system in which electrical information is converted to light energy, transmitted to another location through optical fibers, and is there converted back into electrical information.
Figure 8 Cable: An aerial cable configuration in which the conductors and the steel strand which supports the cable are integrally jacketed. A cross section of the finished cable approximates the figure 8.
Filled Cable: A cable construction in which the cable core is filled with a gel material that will prevent moisture from entering or passing through the cable.
Frame: A packet of transmitted information. The frame contains all of the necessary information to indicate the origin and destination, control information and the actual data.
Frequency Division Multiplexing: FDM. Combining analog circuits by assigning each a different carrier frequency and merging them into a single communication signal.
FTTC: Fiber-to-the-Curb
FTTH: Fiber-to-the-Home
Full Duplex: Transmitters and receivers simultaneously send and receiver signals in both directions on the same pair of wires.
FXO: Foreign Exchange Office
FXS: Foreign Exchange Station
Gauge: A term used to denote the physical size of a wire.
Gbps: Giga bits per second, or Gbit/s. One billion bits persecond.
GHz: Giga Hertz. One billion hertz, or cycles per second.
Ground: A conducting connection between an electrical circuit and the earth or other large conducting body to serve as an earth thus making a complete electrical circuit.
Half Duplex: Transmitters and receivers send or receive on the same pair of wires.
HDTV: High definition (or high resolution) television
Hertz: Frequency in cycles per second
Hierarchy: A set of transmission speeds arranged to multiplex a successively higher number of circuits.
Homerun: A cable run that goes directly from a jack in a wall plate to a centralized position (patch panel). There are no stops or interruptions between the 2.
Hub: Hubs act as the center of a "star" topology. They have between 4 and 20+ ports. Internally, hubs are "dumb" devices that just resend information they receive. All devices attached utilize a part of the rated speed, be it 10 or 100Mbit/sec. Hubs know nothing about a packet's destination. Therefore, hubs are generally the cheapest connecting device in a star topography, although for a busier network, switches are more robust.
Hybrid Cable: A cable design to meet many requirements. Most commonly, hybrid cables will contain a mixture of twisted-pair and coaxial, or coaxial and fiber.
IAEI: International Association of Electrical Inspectors.
IBEW: International Brotherhood of Electrical Workers.
ICEA: Insulated Cable Engineers Association (Formerly IPCEA).
IEC: Independent Electrical Contractors association.
IEEE: Institute of Electrical and Electronics Engineers.
IMSA: International Municipal Signal Association. Publishes specifications for cables and wires used in municipal, county, and state Traffic Signal, Communication and Fire Alarm systems.
Inside Plant: Telecommunications facilities placed inside a building.
Insulation: A material having high resistance to the flow of electric current. Often called a dielectric.
Internet: The worldwide collection of networks based on the use of TCP/IP network protocols.
Intranet: A collection of networks supporting a single site or corporate entity.
IP: Internet protocol. Standard format for transmitting data via the internet.
ISA: Instrument Society of America.
ISDN: Integrated Services Digital Network. A digital transmission standard using 144 kbps containing two 64 kbps voice channels and one 16 kbps data channel.
ISO: International Standards Organization.
ITE: Institute of Transportation Engineers
IUEW: International Union of Electrical Workers.
Jacket: An outer covering, usually nonmetallic, mainly used for protection against the environment.
Jitter: Also called phase jitter, timing distortion, or inter-symbol interference. The slight movement of a transmission signal in time or phase that can introduce errors and loss of synchronization. The amount of jitter will increase with longer cables, cables with higher attenuation, and signals at higher data rates.
LAN: Local Area Network. Integration of computer and communication systems that wire computers, peripheral equipment and telephones together so they can all "talk" to each other.
LASER: Light Amplification by Stimulated Emission of Radiation.
LED: Light Emitting Diode. A semiconductor that emits light.
Light Guide: An optical fiber bundle.
Longitudinal Shield: A tape shield, flat or corrugated, applied lengthwise with the axis of the core being shielded.
Loose Tube: A protective tube loosely surrounding fiber strands. The tube may be filled with gel to protect against moisture infiltration.
Loss: Attenuation of an optical or electrical signal, normally measure in decibels
Loss Budget: An accounting of overall attenuation in a system. The budget is the amount of acceptable loss.
MAC: Media Access Control. A portion of the Ethernet frame.
MAN: Metropolitan Area Network. Backbone system deployed in metropolitan areas to connect Telephone Companies, Carriers, Carrier Hotels, and large office buildings.
Margin: Allowance for attenuation (or loss) in addition to that explicitly accounted for in a system design.
Mbps: Megabits per second. Also expressed as Mbit/s.
Messenger Cable: The linear supporting member, usually a high strength steel wire, used as the supporting element of a suspended aerial cable. The messenger may be an integral part of the cable, or exterior to it.
Microbending: Tiny bends in fiber that allow light to leak out and increase loss. microbending occurs during installation and is usually unavoidable. Loss budget margins should account for microbending.
Mil: A unit used in measuring the diameter of a wire or thickness of insulation over a conductor. One one-thousandth of an inch. (.001")
Modal Dispersion: Dispersion arising from differences in the times that different modes take to travel through multimode fiber.
Mode: An electromagnetic field distribution that satisfies theoretical requirements for propagation in a waveguide. Light has modes in a fiber.
MODEM: Modulator-Demodulator
Modem: A device used to convert signals from one form to another. It can be used to convert the output of a computer to a voice channel equivalent, or an electrical signal to an optical signal.
Multimode: Transmits multiple modes of light.
Multiplexer: A device that combines many communication circuits into one circuit
MUX: Abbreviation for Multiplexer
NAED: National Association of Electrical Distributors.
Nanometer: A unit of measurement, 10-9 meters. Light wave frequencies are stated in nanometers.
NAPE: National Association of Power Engineers.
NEC: National Electric Code. A standard published by the National Fire Protection Association (NFPA) and incorporated in OSHA (Occupational Safety and Health Act) regulations.
NECA: National Electrical Contractors Association.
NEMA: National Electrical Manufacturers Association.
Network: A system of cables or wireless pathways that link communication nodes.
NFPA: National Fire Protection Association.
NIC: Network Interface Card. This is the interface between a computer (or other device) and the Ethernet network.
Node: A communication point usually comprised of communication devices.
NRECA: National Rural Electric Cooperative Association.
NRZ: Non-Return-to-Zero. An electrical communication signal which uses a "low" signal for zero and a "high" signal for one. The electrical signal value never reaches zero.
NTSC: National Television System Committee. Analog video broadcast standard used in North America.
O.D.: Outside diameter.
OC-x: Optical Carrier rate specified for SONET; OC-3, OC-12, OC-48, etc.
OFDM: Orthogonal Frequency Division Multiplexing – a frequency division modulation technique for transmitting large amounts of digital data over a radio wave. OFDM works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver.
Ohm: Unit of resistance such that a constant current of one ampere produces a force of one volt.
OSI: Open Standards Integration
OTDR: Optical Time-Domain Reflectometer. An instrument that measures transmission characteristics by sending a short pulse of light down a fiber and measures the reflected light pattern.
Outside Plant: Telecommunication facilities that are placed outside of a building.
P.O.P.: Point of Presences - A location of telecommunication carrier equipment
P.O.T.S.: "Plain Old Telephone Service" - a reference to basic voice telephone service
Packet: A technique used to break large quantities of data into small groups, or packets, to facilitate transmission with very few errors.
Packet Switch: A switch that moves data packets from multiple transmissions and provide for efficient sharing of communication facilities.
Patch Cable (Cord): A twisted-pair, or fiber optic jumper cable used to make a connection between a network interface, or network port, and a media segment, or to directly connect stations and hub ports together.
PCS: Personal Communications Service. A group of frequencies in the 1.8 to 2.0 GHz range reserved for cellular telephone communications.
PE: Polyethylene.
PHY: Physical Layer Device. The name used for a transceiver in Fast Ethernet and Gigabit Ethernet systems.
Physical Address: The 48-bit MAC address assigned to a station interface, identifying that station on the network.
Plenum: The air return path of a central air handling system, either ductwork or open space over a dropped ceiling.
Plenum Cable: Cable approved by Underwriters Laboratories for installation in plenums without the need for conduit because the insulation and jacket compounds used have low flame-spread and low smoke characteristics.
Point-to-Point Transmission: Carrying a communication signal between two locations without branching to other locations.
Polyethylene: A thermoplastic material having the chemical identity of polymerized ethylene.
Polyvinyl Chloride (PVC): A thermoplastic material composed of polymers of vinyl chloride which may be rigid or flexible depending on specific formulation.
Port: A connection point on a hub, router, bridge, switch, etc.
Protocol: A set of agreed upon rules and message formats for exchanging information among devices on a network.
Pulling Eye: A device fastened to a cable to which a hook may be attached in order to pull the cable through a duct.
PVC (Construction Term): Polyvinyl chloride.
PVC (Network Term): Permanent Virtual Circuit
REA: Rural Electrification Administration of the U.S. Dept. of Agriculture. Publishes telephone cable and wire specifications and a list of approved manufacturers of cable, wire and related installation supplies.
Receiver: A device that detects a communication signal and converts it into sound, data, or video.
Regenerator: A receiver-transmitter device that detects a weak signal, converts it to its original state, and then transmits is as a strong signal. Most problems in the received signal are corrected.
Repeater: A receiver-transmitter device that detects a weak signal and boosts its power for continued transmission. This device is also called an amplifier. Any problems in the received signal are simply retransmitted.
Resistance: In DC circuits, the opposition a material offers to current, measured in ohms. In AC circuits, resistance is the real component of impedance, and may be higher than the value measured at DC.
RF: Radio Frequency. A general term used to indicate a radio system.
RG/U: Abbreviation for Radio Grade, Universal. RG is the military designation for coaxial cable and U stands for "general utility".
Ribbon Cable: A cable in which many conductors (copper or fiber) are embedded in a plastic material in parallel, forming a flat, ribbon like structure.
RJ-11: RJ-11 is standard modular phone connector. There are 3 different types: 2, 4, and 6 conductor connectors. They're all the same, except that contacts or wires are missing. Ordinary phone connectors are 4-conductor (2 pairs = 2 phone lines). Sometimes you get a phone wire that only has 2 conductors in it; this will screw you up if you're trying to run more than 1 phone line. There's also a little-bitty version of this connector that only has 2 conductors on it. It will fit in the same socket.
RJ-45: RJ-45 is the 8-conductor version of an RJ-11. It looks like a regular modular phone connector, only it's wider. You need to use RJ-45 for Ethernet, because the connection standard puts the Ethernet on some of the outer connectors not in RJ-11. RJ-11 plugs will fit into an RJ-45 socket, but because the plastic plug is smaller, some of the contacts will get bend back a little
Router: A device that has enough intelligence to be connect one, or many, devices to other devices. Typically used in Local Area Networks to connect desktop computers to printers or file servers.
SDH: Synchronous Digital Hierarchy. The international version of the SONET digital hierarchy.
Segment: A segment is a piece of network wire bounded by bridges, routers, repeaters or terminators.
Sheath: The outer covering of a communication cable.
Shield: A metallic layer placed around a conductor or group of conductors to prevent electrostatic interference between the enclosed wires and external fields.
Signal-to-Noise Ratio: The ratio of signal to noise measured in decibels. An indication of signal quality in analog communication systems.
Simplex: Simple uni-directional transmission. Transmitter on one end and a receiver on the other.
Single Mode: Normally referring to commonly used type of fiber optic cable.
SNMP: Simple Network Management Protocol. A protocol specified by the Internet Engineering Task Force (IETF) for exchanging network management information between network devices and network management stations.
SONET: Synchronous Optical Network.
STP: Shielded Twisted Pair
Subscriber Loop: The part of the telephone network that runs from the central office to individual subscribers.
Switch: A device that direct electricity, or light, along different physical paths.
Switch: Switches act as the center of a "star" topology, much like hubs. They have between 4 and 20+ ports. Internally, switches are different that hubs due to their intelligent design. Switches "remember" what device is attached to what port, and will relay packets only to the proper destination port. Because of this, all devices attached are able to utilize their maximum rated speed, be it 10 or 100Mbit/sec/port. This cleaver design makes switches more expensive, but in a busy network, switches can keep the traffic flowing.
T - Carrier: Normally refers to a T-1 transmission system, but can be any of standard North American Digital Hierarchy transmission rates.
TDM: Time Division Multiplexing
Telemetering Cable: Cable used for transmission of information from instruments to the peripheral recording equipment.
Temperature Rating: The maximum temperature at which an insulating material may be used in continuous operation without loss of its basic properties.
Tensile Strength: The pull stress required to break a given specimen.
TIA/EIA: Telecommunications Industry Association/Electronics Industry Association. An organization that sets telecommunications standards for buildings, cables, and connectors. Also sets practices and standards for construction of telecommunication systems.
Tight Buffered: A type of fiber optic communication cable where the fiber strands are tightly wrapped by the covering sheath.
Tinned Copper: Tin coating added to copper to aid in soldering and inhibit corrosion.
Tray: A unit or assembly of units or sections, and associated fittings, made of metal or other noncombustible materials forming a rigid structural system used to support cables. Includes ladders, troughs, channels, solid bottom trays, and similar structures.
Trunk: Trunk Line. A communication link running between telephone company central offices. Also a communication link that connects a customer location to a telephone company central office, but is not directly connected to a switch.
Twisted Pair: Pair of copper wires wrapped around each other.
UL: Abbreviation for Underwriters Laboratories, a nonprofit independent organization, which operates a testing and listing service for electrical and electronic materials and equipment.
UTP: Unshielded Twisted Pair.
Watt: A unit of electrical power. One watt is equivalent to the power represented by one ampere of current under a pressure of one volt in a DC circuit.
Waveguide: A structure that guides electromagnetic waves along its length.
Wavelength: The distance an electromagnetic wave travels in the time it takes to oscillate through a complete cycle.
WDM: Wavelength-Division Multiplexing. Multiplexing of signal by transmitting them at different light frequencies through the same fiber.
WEP: Wired Equivalent Privacy – a security protocol for wireless local area networks
Wicking: The flow of a liquid in a wire or cable due to capillary action.
Wi-Fi: Wireless Fidelity
Wi-Max: Broadband Wireless
WPA: Wi-Fi protected access – a Wi-Fi standard that was designed to improve upon the security features of WEP.