Module 05 Flashcards
A measure of the number of times an electrical signal changes state per second.
Frequency
A measure of the amount of data that could theoretically be transmitted during a given period of time.
Bandwidth
The amount of data that a medium transmits during a given period of time. Throughput is usually measured in Mbps (megabits per second, which is 1,000,000 bits) or Gbps (gigabits per second).
Throughput
The process of altering an analog signal to carry data.
Modulation
The process of converting data into a digital signal for transmission.
Encoding
A measure of the degradation or distortion of a signal.
dB (decibel) loss
The loss of a signal’s strength as it travels away from its source.
Attenuation
A device used to regenerate a digital signal in its original form. Repeaters operate at the physical layer of the OSI model.
Repeater
The delay between the transmission of a signal and its receipt.
Latency
The length of time it takes for a packet to go from sender to receiver, then back from receiver to sender. RTT is usually measured in milliseconds.
RTT (round trip time)
A transmission flaw caused by packets experiencing varying amounts of delay and arriving out of order. Also called PDV (packet delay variation).
Jitter
A type of transmission in which signals may travel in both directions over a medium simultaneously; also called, simply, duplex.
Full-duplex
A type of transmission in which signals may travel in both directions over a medium simultaneously.
Duplex
A problem that occurs when neighboring devices are using different speed or duplex configurations and results in failed transmissions.
Speed and duplex mismatch
A form of transmission that allows multiple signals to travel simultaneously over one medium.
Multiplexing
A method of multiplexing that assigns a time slot in the flow of communications to every node on the network and, in that time slot, carries data from that node.
TDM (time division multiplexing)
A type of multiplexing that assigns time slots to nodes (similar to TDM), but then adjusts these slots according to priority and need.
STDM (statistical time division multiplexing)
A type of multiplexing that assigns a unique frequency band to each communications subchannel. Signals are modulated with different carrier frequencies and then multiplexed to simultaneously travel over a single channel.
FDM (frequency division multiplexing)
A multiplexing technique in which each signal on a fiber-optic cable is assigned a different wavelength, which equates to its own subchannel.
WDM (wavelength division multiplexing)
A type of WDM multiplexing that supports full-duplex light transmissions.
Bidirectional WDM
A multiplexing technique used over single-mode or multimode fiber-optic cable in which each signal is assigned a different wavelength for its carrier wave.
DWDM (dense wavelength division multiplexing or dense WDM)
A multiplexing technique used over single-mode or multimode fiber-optic cable in which each signal is assigned a different wavelength for its carrier wave.
CWDM (coarse wavelength division multiplexing or coarse WDM)
A type of cable that consists of a central metal conducting core, surrounded by an insulator, shielding, and an outer cover. Today coaxial cable, called “coax” for short, is mostly used to connect cable Internet and cable TV systems.
Coaxial cable
A measure of the opposition to a current’s flow through a cable, expressed in ohms.
Impedance
A type of coaxial cable with an impedance of 75 ohms and an 18 AWG core conductor. RG-6 is used for television, satellite, and broadband cable connections.
RG-6
A connector used to terminate coaxial cable that transmits television and cable broadband signals.
F-connector
A coaxial cable connector type that uses a turn-and-lock (or bayonet) style of coupling.
BNC connector
A type of copper cable that looks very similar to coaxial cable but has two or more cores, or conductors, inside the cable. Called twinax for short.
Twinaxial cable
A type of cable similar to telephone wiring that consists of color-coded pairs of insulated copper wires, each with a diameter of 0.4 to 0.8 mm. Every two wires are twisted around each other to form pairs, and all the pairs are encased in a plastic sheath.
Twisted-pair
A type of Ethernet network that is capable of 100-Mbps throughput.
Fast Ethernet
A type of Ethernet network that is capable of 1000-Mbps, or 1-Gbps, throughput. Requires Cat 5e or higher cabling.
Gigabit Ethernet
The number of twists per meter or foot in a twisted-pair cable.
Twist ratio
A form of UTP that contains four wire pairs and supports up to 100-Mbps throughput and a 100-MHz signal rate. Required minimum standard for Fast Ethernet.
Cat 5 (Category 5)
A higher-grade version of Cat 5 wiring that supports a signaling rate of up to 350 MHz and a maximum throughput of 1 Gbps, making it the required minimum standard for Gigabit Ethernet.
Cat 5e (Enhanced Category 5)
A twisted-pair cable that contains four wire pairs, each wrapped in foil insulation. Additional foil insulation can cover the bundle of wire pairs, and a fire-resistant plastic sheath might cover the second foil layer. The foil insulation provides excellent resistance to crosstalk and enables Cat 6 to support a signaling rate of 250 MHz and throughput up to 10 Gbps.
Cat 6 (Category 6)
A higher-grade version of Cat 6 wiring that further reduces attenuation and crosstalk, and allows for potentially exceeding traditional network segment length limits.
Cat 6a (Augmented Category 6)
A twisted-pair cable that contains multiple wire pairs, each separately shielded then surrounded by another layer of shielding within the jacket, allowing throughput up to 100 Gbps at very short distances. Cat 7 is not included in the TIA/EIA standards.
Cat 7 (Category 7)
A higher-grade version of Cat 7 wiring that might support up to 100-Gbps throughput at short distances and up to 1000-MHz signal rate but has not been accepted as a TIA/EIA standard.
Cat 7a (Augmented Category 7)
A twisted-pair cable that relies on improved and extensive shielding and is optimized for short-distance backbone connections within the data center.
Cat 8 (Category 8)
Cabling designed to withstand high temperatures, offers a highly fire-retardant jacket, and burns with less smoke that is nontoxic.
Plenum-grade cable
Cabling coated with a fire-retardant jacket that is thicker than typical network cables to ease the cable’s insertion through risers in buildings or between floors.
Riser-rated cable
The standard connector used with shielded twisted-pair and unshielded twisted-pair cabling.
RJ-45 (registered jack 45)
The standard connector used with unshielded twisted-pair cabling (usually Cat 3) to connect analog telephones.
RJ-11 (registered jack 11)
A standard pinout for RJ-45 plugs required by the federal government on all federal contracts. Also called T568A.
TIA/EIA-568A
A standard pinout for RJ-45 plugs commonly used in homes and businesses. Also called T568B.
TIA/EIA-568B
The pin numbers and color-coded wire assignments used when terminating a cable or installing a jack, as determined by the TIA/EIA standard.
Pinouts