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1000Base-LX/FX
Gigabit Ethernet over fibre optic cable

1000Base-T
1000Mbps, 1 billion bits per second over copper cabling. All four pairs of Cat6 cable utilised at 250Mbps per pair

100Base-FX
100 Mbps Ethernet data transmissions over Fibre Optic cable

100Base-LX
1300nm - Long wavelength fibre optic transmissions at 100 Mbps

100Base-SX
850nm - Short wavelength fibre optic transmissions at 100 Mbps

10BaseT
10 Mbps Ethernet running baseband signalling over twisted pair copper cable

9/125 micron
The common size of Single-Mode fibre optic cables

50/125 micron
One of two common sizes of Multimode fibre optic cables

62.5/125 micron
One of two common sizes of Multimode fibre optic cables

ACR
Attenuation to Crosstalk Ratio. The level of cross talk in relationship to the attenuated signal at the far end of the cable. Critical in Full Duplex mode

ADSL
Asymmetric Digital Subscriber Line. A digital connection with higher bandwidth for downloading than uploading

Attenuation
Loss of signal strength and integrity over a given length of cable

AWG
American Wire Gauge. The larger the number, the smaller the wire diameter

Bandwidth
The capacity of a medium to carry data bits. Measured in Hz

Baseband
The raw data is transmitted using the full bandwidth of the cable with no modulation

BNC
Bayonet connector used with RG58 coaxial cable networks. Thin Ethernet

bps
Bits per second

Broadband
The bandwidth of the cable is split into multiple modulated channels. Guard bands are used to separate the channels

Broadcast
To send data to more than one device at a time

Bus Network
A network with all devices sharing one common cable

CAT5
100 MHz Category 5 data cabling as specified by the EIA/TIA standards authority

CAT5 E
Enhanced Cat 5 data cabling with more stringent tests and headroom. Still 100Mhz

Category 5, Cat5
UTP 100 ohm for frequencies up to 100Mbs defined by TAI/EIA 568-A specifications

Category 5E, Cat5E
Enhanced Cat5. Similar to Cat5 with improved specifications including PSELFEXT, ACR and attenuation. Defined by EIA/TIA 568-A-5

Category 6,Cat6
Proposed cabling standard to support up to 250 MHz over UTP. Not yet ratified

Category 7, Cat7
Proposed cabling standard to support up to 600 MHz over UTP

Coax
Coaxial cable with a copper screen carrying unbalanced signals

Core
Centre of a fibre optic cable

Crosstalk
interference picked up from an adjacent wire pair within the same cable (see also alien crosstalk)

D' Type D'
Shaped connector with an array of pins in 9, 15 and 25

EIA
Electronics Industry Association in America

EIA 568
UTP commercial building specifications from the EIA

EIA 568B
Now the most common UTP cable colour codes and pin allocation

ELFEXT
Equal Level Far End Cross Talk

EMI
Electro Magnetic Interference. Unwanted noise from a source such as fluorescent lighting and electric motors

Ethernet
A LAN protocol in which computers access the network through CSMA/CD protocols defined by the IEEE 802.3 standards. Invented by Rank Xerox

Fast Ethernet
100Mbps CSMA/CD Ethernet

FDDI
Fibre Distributed Data Interface as defined by (ANSI X3T12) for 100Mbs token passing over Fibre

Full duplex
Allows data transmissions in two directions at once. Transmit and receive simultaneously

Gbps
Giga bits per second. 1 billion or 1,000,000,000 bits per second

Gigabit Ethernet
1000Mbps, 1 Billion bits per second over copper cabling

Half Duplex
Single way transmission. Is capable of both Transmitting and Receiving but not simultaneously

Headroom
The amount by which a network cable ACR exceeds 10dB above the specification

Horizontal Cabling
The structured cabling which connects the wall sockets to the network cabinet or wiring closet

Hub
The centre of a star wired network. May be passive or active in re-transmissions of network traffic

Hz
Frequency per second

IEEE
Institute of Electrical & Electronic Engineers

Impedance
Measurement of the opposition to the flow of electrons in a cable. The combination of Resistance, Capacitance & Inductance

Infrastructure
The collection of communication components (excluding active equipment) that together provide support for the distribution of information within a building or campus

Insertion Loss
The attenuation of a signal as it passes through a connector

Intranet
A large private company network often spanning many countries

IP
Internet Protocol. Along with TCP is used to track and deliver data packets over a network

ISDN
Integrated Digital Network Services. High speed data transfer over the PSN

ISO
International Standards Organisation

ISP
Internet Service Provider. The company who provides a connection to the internet

LAN
Local Area Network

MAN
Metropolitan Area Networks, Spanning a Town or City

Media
The physical wire of fibre for the transmission of signals

Miss-Wire
Where the single wires in a UTP cable have been attached to the connector in the wrong sequence

Mode
A single wave travelling in an optical fibre

Modem
A device which modulates & demodulate the signals between digital to analogue circuits

Multi mode
Fibre optic cable which supports the propagation of multiple wavelengths Diameter of 50 to 100 microns with a stepped refractive index. Can use inexpensive LED light sources

N Connector
Connectors used for thick Ethernet 10Base-5 coax cable

NEXT
Near End Cross Talk. The effect of one cable pairs signal on the adjacent pairs

Numerical Aperture
The angle at which a fibre will gather light and propagate it down the core

OTDR
Optical Time Domain Reflectometer. A device for finding breaks in fibre optic cables or measuring the length

PABX
Private Automatic Branch Exchange, A switchboard, (PBX)

Packet
A string of bits containing command information, destination and source addresses and data

Patch Cable
The cable connecting the network panel and the active switch or hub.

Patch panel
An array of connectors in the network cabinet to allow circuit rearrangements by plugging in patch cords

Physical layer
Layer one of the seven OSI layers. This layer is responsible for the transmission of signals between computers

POP
Point of Presence. The connection point to the internet

Premises cabling
The complete cabling infrastructure for the transmission of voice, data and video through out a given building

Propagation delay
The time for a signal to travel from input to the output of a device

Protocol
A data transfer mode using Bit codes, Start Stop bits, Parity. Both transmitter and receiver must use the same protocols

PSELFEXT
Power Sum Equal Level Far End Cross (X) Talk. Measures the summed cross talk from 3 pairs on the remaining pair having compensated for the known attenuation of the cable

PSNEXT
Power Sum Near End Cross Talk. The effect on one pair of the summed crosstalk of the three other pairs

Reflection
The return of electromagnetic energy that occurs when components are mismatched in network cabling. These reflections can cause data errors

Reversed Pairs
The most common miss wire where the single wires in a pair have been reversed

RFI
Radio Frequency Interference

RG 58
The specification of the coaxial cabled used for thin Ethernet networks


Ring Topology
Describes a network in a complete ring. Now the fastest and most resilient network

RJ11
Registered Jack number 11. Small line plug and socket used on telephone handsets and modem connections

RJ45
Registered Jack number 45. 8 pin plug and socket

RS232
Robust but outdated signalling protocol using 2 pairs

RX
Receive

SC connector
A connecter for terminating fibre optic cables. Can be snapped together to form a duplex connector for RX and TX transmissions

Shielded
Cable with a braided or foil shield to keep out RFI and EMI

Single-Mode
An optical fibre that supports only one mode of light propagation above the cutoff wavelength. The core diameters are usually between 5 and 10 microns

Skew
The differential delay between two adjacent cables carrying data transmitted simultaneously

Split Pairs
Where the single wires from two different pairs have been swapped. If the same at both ends will not affect short cable transmissions, but will fail over longer distance. A common fault

ST connector
Straight Tip. A connector registered to AT&T for fibre optic terminations

Star Topology
All devices are attached to a central hub in a star configuration

STP
Shielded Twisted Pair copper cable

Structured cabling
The fixed solid core cabling which makes up the building wiring

Switch
An Ethernet active repeater which reads MAC addresses and routes data to the individual node or network hub. Switches split up networks into smaller individual collision domains. A switch can route data at wire speed through all it's ports simultaneously

TCP
Transmission Control Protocol. Used with IP to track and deliver packets of data over a network

TDR
Time Domain Reflectometer. A device for measuring the length of cables by "bouncing" a signal off the far end. The NVP must be known and programmed into the machine

Terminator
An electrical connector attached to the end of a cable to reduce signal reflections and unwanted noise

TIA
Telecommunication Industry Association

TIA 568A-4
The TIA Category 5E Specifications

Token Ring
A network where a single token is passed around a network between computers. A computer must grab and hold onto the token before it can transmit. After transmission it releases the token back onto the network

Topology
Network architecture, circuit design and transmission protocols

Transceiver
An electronic circuit designer to transmit and receive data over a network. A NIC contains a transceiver as does a hub and a switch

Twisted Pair
Pairs of 26 AWG wires twisted together the reduce RFI and Crosstalk

TX
Transmit

UTP
Unshielded Twisted Pair. 4 twisted pairs in one sheath

WAN
Wide Area Network