Cnna Final Exam Review Edition 7 Chapter 5

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1000BaseLX

Back 1

APhysical layer standard for networks that specifies 1-Gbpstransmission over fiber-optic cable using baseband transmission.1000Base-LX is a common fiber version of Gigabit Ethernet and can runon either single-mode or multimode fiber. The LX represents itsreliance on long wavelengths of 1300 nanometers.

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1000BaseTX

Back 2

APhysical layer standard for networks that achieves 1 Gbps over Cat 6or better cabling using only two pairs of wires.

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10BaseT

Back 3

APhysical layer standard for networks that specifies basebandtransmission, twisted-pair media, and 10-Mbps throughput. 10Base-Tnetworks have a maximum segment length of 100 meters and rely on astar topology.

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10GBaseER

Back 4

APhysical layer standard for achieving 10-Gbps data transmission oversingle-mode, fiber-optic cable. In 10GBase-ER, the ER stands forextended reach. This standard specifies a star topology and segmentlengths up to 40,000 meters.

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Amplitude

Back 5

Ameasure of a signal’s strength at a given point in time.

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AnalogSignal

Back 6

Asignaling method in which electromagnetic waves vary infinitely andcontinuously, and appear as a wavy line when graphed over time.

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DigitalSignal

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Asignaling method composed of pulses of precise, positive voltages andzero voltages. Unlike analog signals, there is nothing infinite orcontinuous about a digital signal because it is inherently either onor off.

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Attenuation

Back 8

Theloss of a signal’s strength as it travels away from its source.

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Bandwidth

Back 9

(1)The amount of traffic, or data transmission activity, on a network.(2) A measure of the difference between the highest and lowestfrequencies that a medium can transmit.

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CableInternet

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(BroadbandCable) A method of connecting to the Internet over a cable network.In broadband cable, computers are connected to a cable modem thatmodulates and demodulates signals for transmission and reception viacable wiring.

Front 11

CAT

Back 11

(category)A term used to refer to a type of twisted-pair cable. All of thecategory cables fall under the TIA/EIA 568 standard

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CAT5e

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(EnhancedCategory 5) A higher-grade version of Cat 5 wiring that containshigh-quality copper, offers a high twist ratio, and uses advancedmethods for reducing cross-talk. Enhanced Cat 5 can support asignaling rate of up to 350 MHz, more than triple the capability ofregular Cat 5, and a maximum throughput of 1 Gbps, making it therequired minimum standard for Gigabit Ethernet.

Front 13

CAT6

Back 13

Atwisted-pair cable that contains four wire pairs, each wrapped infoil insulation. Additional foil insulation can cover the bundle ofwire pairs, and a fire resistant plastic sheath might cover thesecond foil layer. The foil insulation provides excellent resistanceto cross-talk and enables Cat 6 to support a signaling rate of 250MHz and throughput up to 10 Gbps.

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Cladding

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Theglass or plastic shield around the core of a fiber-optic cable.Cladding reflects light back to the core in patterns that varydepending on the transmission mode. This reflection allows fiber tobend around corners without impairing the light-based signal.

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Demux

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Adevice that separates multiplexed signals once they are received andregenerates them in their original form.

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DSL

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(digitalsubscriber line) A dedicated WAN technology that uses advanced datamodulation techniques at the Physical layer to achieve highthroughput over regular phone lines. DSL comes in several differentvarieties, the most common of which is Asymmetric DSL (ADSL).

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DWDM

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(densewavelength division multiplexing) A multiplexing technique used oversingle-mode or multimode fiber-optic cable in which each signal isassigned a different wavelength for its carrier wave. In DWDM, littlespace exists between carrier waves to achieve extraordinary highcapacity.

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FDM

Back 18

(frequencydivision multiplexing) A type of multiplexing that assigns a uniquefrequency band to each communications subchannel. Signals aremodulated with different carrier frequencies, then multiplexed tosimultaneously travel over a single channel.

Front 19

FEXT

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(farend cross-talk) Cross-talk measured at the far end of the cable fromthe signal source.

Front 20

Fiberoptic (cabling, connectors)

Back 20

Aform of cable that contains one or several glass or plastic fibers inits core. Data is transmitted via a pulsing light sent from a laseror light-emitting diode (LED) through the central fiber (or fibers).Fiber-optic cables offer significantly higher throughput than copperbased cables. They may be single-mode or multimode and typically usewave-division multiplexing to carry multiple signals.

Front 21

Frequency

Back 21

Thenumber of times that a wave’s amplitude cycles from its startingpoint, through its highest amplitude and its lowest amplitude, andback to its starting point over a fixed period of time, expressed incycles per second, or hertz (Hz).

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FullDuplex

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Atype of transmission in which signals may travel in both directionsover a medium simultaneously; also called, simply, duplex.

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Half-duplex

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Atype of transmission in which signals may travel in both directionsover a medium, but in only one direction at a time.

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Impedance

Back 24

Theresistance that contributes to controlling an electrical signal.Impedance is measured in ohms

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Latency

Back 25

Thedelay between the transmission of a signal and its receipt.

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LoS

Back 26

(lineof sight) A wireless signal or path that travels directly in astraight line from its transmitter to its intended receiver. Thistype of propagation maximizes distance for the amount of energy usedand results in reception of the clearest possible signal.

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Modem

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Adevice that modulates digital signals from a computer into analogsignals at the transmitting end for transmission over telephonelines, and demodulates analog signals into digital signals at thereceiving end so a computer can read the received transmission

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Multimode

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(multimodefiber) A type of fiber-optic cable containing a core that is usually50 or 62.5 microns in diameter, over which many pulses of lightgenerated by a laser or light emitting diode (LED) travel atdifferent angles.

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Multiplexing

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Aform of transmission that allows multiple signals to travelsimultaneously over one medium.

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NEXT

Back 30

(nearend cross-talk) Cross-talk that occurs between wire pairs near thesource of a signal.

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Phase

Back 31

Apoint or stage in a wave’s progress over time.

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Repeater

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Adevice used to regenerate a digital signal in its original form.Repeaters operate at the Physical layer of the OSI model.

Front 33

RG-6

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Atype of coaxial cable characterized by a 50-ohm impedance and a 10AWG core conductor. RG-8 provided the medium for the first Ethernetnetworks and was called Thicknet.

Front 34

RJ-11

Back 34

(registeredjack 11) The standard connector used with unshielded twisted-paircabling (usually Cat 3) to connect analog telephones.

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RJ-45

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(registeredjack 45) The standard connector used with shielded twisted-pair andunshielded twisted-pair cabling.

Front 36

Rolled cable

Back 36

Thecolored wires at one end of the cable are in the reverse sequence ofthe colored wires at the other end of the cable.

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Shortcircuit

Back 37

Anunwanted connection, such as when exposed wires touch each other.

Front 38

Simplex

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Atype of transmission in which signals may travel in only onedirection over a medium.

Front 39

Singlemode

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(singlemode fiber) A type of fiber-optic cable with a narrow core of 8 to 10microns in diameter that carries light pulses along a single pathfrom one end of the cable to the other end. Data can be transmittedfaster and for longer distances on single mode fiber than onmultimode fiber. However, single mode fiber is more expensive

Front 40

STP

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(shieldedtwisted pair) A type of copper-based cable containing twisted-pairwires that are not only individually insulated, but are alsosurrounded by a shielding made of a metallic substance such as foil.

Front 41

Telephonespeech ranges?

Back 41

300to 3300Hz

Front 42

Thinnet

Back 42

Anoutdated IEEE Physical layer standard for achieving 10-Mbpsthroughput over coaxial copper cable. Thinnet was also known as10Base2. Its maximum segment length is 185 meters, and it relies on abus topology.

Front 43

Throughput

Back 43

Theamount of data that a medium transmits during a given period of time.Throughput is usually measured in megabits (1,000,000 bits) persecond, or Mbps

Front 44

UTP

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(unshieldedtwisted pair) A type of copper-based cable that consists of one ormore insulated twisted-pair wires encased in a plastic sheath. As itsname implies, UTP does not contain additional shielding for thetwisted pairs. As a result, UTP is both less expensive and lessresistant to noise than STP.

Front 45

Wavelength

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Thedistance between corresponding points on a wave’s cycle, expressedin meters or feet. Wavelength is inversely proportional to frequency

Front 46

WDM

Back 46

(wavelengthdivision multiplexing) A multiplexing technique in which each signalon a fiber-optic cable is assigned a different wavelength, whichequates to its own subchannel. Each wavelength is modulated with adata signal. In this manner, multiple signals can be simultaneouslytransmitted in the same direction over a length of fiber.