Ch. 2

network media

General term for all forms of pathways that support network communications.

frequency

number of cycles of an electronic signal that occur in 1 second. It is measured in Hertz (Hz)

AWG rating

rating that describes the size of a conductors diameter.

plenum-rated

rating that means a cable has special type of insulation that will not give off toxic gases should the cable be consumed by fire.

1000BaseT

IEEE 802.3 classification that specifies a 1-Gbps data rate using all four pairs of Category 5e cable, a maximum segment length of 100 meter, and a minimum segment length of 0.6 meters. Also know as a Gigabit Ethernet.

1000BaseCX

IEEE 802.3 classification that specifies that specifies a data rate of 1 Gbps, the use of Category 5 cable, a maximum segment length of 25 meters, and a minimum segment length of 0.6 meters.

100BaseTX

IEEE 802.3 classification that specifies that use of Category 5e cable on pairs 1 and 2 only.it is configured in a star topology and has a data rate of 100 Mbps.

10BaseT

IEEE 802.3 classification that specifies the use of Category 3, 4, and 5 UTP cable. It is arranged in a star topology.

10Base2

IEEE 802.3 classification that specifies the use of RG-58 (thinnet) cable and a data rate of 10 Mbps.

10Base5

IEEE 802.3 classification that specifies the use of RG-8 (thicknet) and a data rate of 10Mbps.

10BaseT4

IEEE 802.3 classification that specifies the use of all four pairs of Category 3,4, or 5 cable and a data rate of 100 Mbps.

RG-8

a thick, rigid coaxial cable used in a 10Base5 network. also called thicknet

RG-58

a thin, flexible coaxial cable used in a 10Base2 network. also called thinnet.

twisted pair

a type of cable that consists of four pairs of twisted conductors.

RG-6

a type of coaxial cable that has become the standard for Cable television (CATV) systems and satellite systems.

decibel (dB)

a unit of measurement that expresses the relationship of power between two electrical forces.

amplifier

an electronic device designed to raise a signal's amplitude.

haf-duplex

communication that is bi-directional but can only occur in one direction at a time.

full-duplex

communication that occurs bi-directionally and simultaneously between two devices.

simplex

communication that occurs in one direction only.

termination resistor

electrical device that absorbs transmitted signals when they reach the end of a network segment, preventing the signals from deflecting and distorting.

noise

electromagnetic interference

analog signal

electronic signal that caries in values.

digital signal

electronic signal that has discrete values.

crosstalk

interference that comes form neighboring conductors inside a wire's insulating jacket.

attenuation

loss of signal strength

amplitude

maximum voltage, or height, of an electronic signal.

Equal Level Far-End Crosstalk (ELFEXT)

measurement calculated by subtracting the effects of attenuation.

Far-End Crosstalk (FEXT)

measurement of reflective loss at the end, of a cable.

bandwidth

measurement of the network media's ability to carry data.

Alien Crosstalk (AXT)

measurement of the noise introduced outside the cable jacket, typically caused by other network cables in close proximity.

Near-End Crosstalk (NEXT)

measurement of the reflected loss at the near end, or input end, of a cable.

baseband

method of transmitting data in the form of a digital signal, using the entire bandwidth of a cable.

broadband

method of transmitting data in the form of several analog signals at the same time.

reflected loss

the amount of signal reflected from the end of a cable

latency

the amount of time it takes a signal to travel from its source to it destination.

Time to Live (TTL)

the maximum amount of time a packet is allowed to circulate through a network before it is destroyed.

impendance

the opposition to alternation current.

resistance

the opposition to direct current in a conductor

coaxial cable

type of cable that consists of copper core conductor surrounded by and insulator referred to as dielectric. also called coax.

interference

undesired electromagnetic signal imposed on a desired signal that distorts or corrupts the desired signal.