Transit
Means to issue signals along a network medium (such as a cable).
Transmission
Refers to either the process of transmitting or the progress of signals after they have been transmitted.
Transciever
Device that transmits and receives signals.
Volts
Measurment used to describe the degree of pressure an electrical current exerts on a conductor.
Voltage
The pressure (sometimes referred to as Strength) of an electrical current.
Analog
Signal that uses variable voltage to create continuous waves resulting in an inexact transmission.
Amplitude
Measure of a signals strength.
Frequency
The number of times that a wave's amplitude cycles from it's starting point through it's highest amplitude and it's lowest amplitude and back to it's starting point over a fixed period. (expressed in cycles/sec or Hertz-Hz)
Wave Length
Distance between corresponding points on a wave's cycle. Ex. between one peak and the next. (expressed in meters or feet and is inversely proportional to it's frequency).
Phase
Refers to the progress of a wave over time in relationship to a fixed point.
Digital
Composed of pulses of precise positive voltages(1) and zero voltages(0).
Bit
Aka-Binary Digit. Equals a single pulse in the digital encoding system and may have only one of two values: 0 or 1.
Byte
8 bits of information.
Binary
System founded using 1's and 0's to encode information.
Modem
Device that modulates analog signals into digital signals at the transmitting end for transmission and demodulates digital signals to analog at the receiving end.
Modulation
Technique for formatting signals in which one property of a simple carrier wave is modified by the addition of a data signal during transmission.
Simplex
Type of transmission in which signals may travel in only one direction over a medium.
Half-Duplex
Type of transmission in which signals may travel in both directions over a medium but in only one direction at a time.
Full-Duplex (aka Duplex)
Type of transmission in which signals may travel in both directions ove a medium simultaneously.
Channel
Distinct communication path between nodes.
Multiplexing
Form of transmission that allows multiple signals to travel simultaneously ove one medium.
SubChannel
One of many distinct communication paths established when a channel is multiplexed or modulated.
Multiplexer (mux)
Device that separates a medium into multiple channels and issues signals to each of those subchannels.
Demultiplexer (demux)
Device that separates multiplexed signals once they are received and regenerates them in their original form.
Time Division Multiplexing (TDM)
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.
Statistical Multiplexing
Method of multiplexing in which each node on a network is assigned a separate time slot for transmission, based on the node's priority and need.
Frequency Division Multiplexing (FDM)`
Method of multiplexing that assigns a unique frequency band to each communication subchannel. Signals are modulated with different carrier frequencies then multiplexed to simultaneously travel over a single channel.
Wavelength Division Multiplexing (WDM)
Multiplexing technique in which each signal on a fiber-optic cable is assigned a different wavelength, which equates to it's own subchannel.
Dense Wavelength Division Multiplexing (DWDM)
Multiplexing technique used over a single-mode or multimode fiber-optic cable in which each signal is assigned a different wavelength for its carrier wave.
Point-to-Point (PTP)
Data transmission that involves only one transmitter and one receiver.
Point-to-Mulitpoint
Data transmission that involves one transmitter and multiple receivers. Can be separated into 2 types: Broadcast and Nonbroadcast.
Broadcast
Transmission that involves only one transmitter and multiple, undefined receivers.
Nonbroadcast
A communications arrangement in which a single transmitter issues signals to multiple, derfined recipients.
Throughput
The measure of how much data is transmitted during a given period of time.
Bandwith
A measure of the difference between the highest and lowest frequencies that a medium can transmit.
Baseband
Form of transmission in which digital signals are sent through direct current pulses applied to wire. Requires exclusive use of a wire's capacity so it can only transmit one signal or one channel at a time. Every device shares a single channel on this sys
Broadband
Form of transmission in which signals are modulated as radiofrequency analog pulses with different frequency ranges. This technology does not use binary encoding and can operate over several channels.
Noise
Unwanted signals, or interference, from sources near network cabling such as electrical motors, power lines, etc.
Electromagnetic Interference (EMI)
Type of interference that may be caused by motors, power lines, TV's, or other sources of electical activity.
Cross Talk
Type of itnerference caused by signals traveling on nearby wire pairs infringing on another pair's signal.
Alien Cross Talk
EMI interference induced on one cable by signals traveling over a nearby cable.
Near End Cross Talk (NEXT)
Cross talks, or the impingement of the signal carried by one wire onto a nearby wire, that occurs between wire pairs near the source of the signal.
Attenuation
The extent to which a signal has weakened after traveling a given distance.
Amplifier
A device that boosts, or strengthens, an analog signal.
Regeneration
The process of retransmitting a digital signal.
Repeater
A device used to regenerate a signal.
Latency
The delay between the transmission of a signal and it's receipt.
Round Trip Time (RTT)
the length of time it takes for a packet to go from sender to receiver, then back from receiver to sender. Usually measured in milliseconds.
Populated Segment
A network segment that contains end nodes, such as workstations.
Unpopulated Segment
A network segment that does not contain end nodes, such as workstations. Also called Link Segments.
Connectors
The pieces of hardware that connect the wire to the network device.
Media Converter
A device that enables networks or segments using different media to interconnect and exchange signals.
Coaxial Cable
Type of cable that consists of a central metal core, which might be solid or stranded and is often made of copper, surrounded by an insulator, braided metal shielding called braiding, and an outer cover called the sheath or jacket.
F-Type Connector
A connector used to terminate coaxial cable used for transmitting TV and broadband cable signals.
BNC Connector
A coaxial cable connector type taht uses a twist-and-lock (or bayonet) style of coupling.
Twisted Pair Cable
A type of cable similar to telephone wiring that consists of color-coded pairs of insulated copper wires, each with a diameter of 0.4-0.8 mm, twisted around each other and encased in plastic coating.
Twist Ratio
The number of twists per meter or foot in a twisted pair cable.
Shielded Twisted Pair (STP)
A type of cable containing twisted-wire pairs that are not only individually insulated but also surrounded by a shielding made of metallic substance such as foil.
Ushielded Twisted Pair (UTP)
A type of cable that consists of one or more insulated wire pairs encased in a plastic sheath. Does not contain additional shielding and is less resistant to noise.
Cat 3
Form of UTP that contains 4 wire pairs and can support up to 10 Mbps, with a possible bandwith of 16MHz. Typically used for 10Mbps Ethernet or 4Mbps token ring networks
Cat 4
Form of UTP that contains 4 wire pairs and can support up to 16 Mbps throughput and is guaranteed for data transmission up to 20 MHz. May be used for 16 Mbps token ring or 10Mbps Ethernet networks.
Cat 5
Form of UTP that contains 4 wire pairs and supports up to 100 Mbps throughput and a 100 MHz signal rate.
Cat 5e
A higher grade version of Cat 5 wiring that contains high quality copper, offers high twist ratio, and uses advanced methods for reducing cross talk. Can support a signaling rate of up to 350 MHz more than triple that of Cat 5.
Cat 6
Twisted pair cable that contains 4 wire pairs, each wrapped in foil insulation. The foil insulation provides excellent resistance to cross talk and can support a signaling rate of 250 MHz and at least six times the throughput supported by Cat 5.
Cat 6e
A higher grade version of Cat 6 wiring that further reduces attenuation and cross talk. Is capable of 550MHz signaling rate and can reliable transmit data at multi-gigabit/sec rates.
Cat 7
Twisted pair cable that contains multiple wire pairs, each separately shielded then surrounded by another layer of shielding within the jacket. Can support up to a 1GHz signal rate but is less flexible that other forms of twisted pair wiring.
Patch Cable
Relatively short cable (usually 3-25ft) witgh connectors at both ends.
Straight Through Cable
A twisted pair patch cable in which the wire terminations in both connectors follow the same scheme.
Crossover Cable
A twisted pair patch cable in which the termination locations of the transmit and receive wires on one end of the calbe are reversed.
Fiber Optic Cable
Form of cable that contains one or several glass or plastic fibers in its core. Data is transmitted via pulsing light sent from a laser or LED through the the central fiber(s). Offers a high throughput and may be single-mode or multimode and typically use
Cladding
The glass or plastic shield around the core of a fiber optic cable. It reflects light back to the core in patterns that vary depending on the transmission mode. This reflections allos fiber to bend around corners w/o impairing the light-based signal.
Single Mode Fiber (SMF)
A type of fiber optic cable with a narrow core that carries light pulses along a single path data from one end of the cable to the other end.
Multimode Fiber
A type of fiber optic cable that contains a core with a diameter between 50-100 microns, through with many pulses of light generated by the LED travel at different angles.
Data Terminal Equipment (DTE)
Any end user device such as a workstation, terminal, or console (essentially a monitor w/little to no independent data processing capability).
Data Circuit-Terminating Equipment (DCE)
A device, such as a multiplexer or modem, that processes signals.
Serial
Style of data transmission in which the pulses that represent bits follow one another along a single transmission line. They are issued sequentially not simultaneously.
Serial Cable
Cable that contains serial transmissions.
Rollover Cable
Type of cable in which ther terminations on one end are exactly reverse of the terminations at the other end. Used for serial connect between routers and consoles and other devices.
Cable Plant
The hardware that makes up the enterprise-wide cabling system.
Structured Cabling
Method for uniform, enterprise-wide, multivendor cabling systems.
RG-6
Type of coaxial cable with an impedance of 75 ohms and contains an 18 AWG core conductor. Used for TV, satelite, and broadband cable connections.
RG-8
Type of coaxial cable characterized by a 50 ohm impedance and a 10 AWG core. Provided the medium for the first Ethernet netowrks wich followed the now obsolete 10base-5 standard.
RG-58
Type of coaxial cable characterized by a 50 ohm impedance and a 25 AWG core. Was a popular medium for Ethernet in the 1980s, used the now obsolete 10base-2 standard.
RG-59
Type of coaxial cable characterized by a 75 ohm impedance and a 20 or 22 AWG core.
RJ-11
The standard connector used with unshielded twisted pair cabling (usually Cat 3 or Level 1) to connect analog telephones.
RJ-45
The standard connector used with shielded twisted pair and unshielded twisted pair cabling.