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Glossary of Networking Terms |
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A
Amplifier A device such as a repeater or bridge that amplifies or increases the power of electrical signals so that they can travel on additional cable segments at their original strength. Analogue Related to a repeated variable physical property, such as a voltage. An analogue device can represent an infinite number of values within the range the dice can handle. ATM Asynchronous transfer mode. This is an advanced implementation of a packet switching network that provides high-speed data transmissions across LANS to WANS. AUI Attachment unit interface. The connector used with standard Ethernet that often includes a cable running off the main or backbone cable. Also known as a DIX connector AWG American Wire Gauge. A standard for determining wire diameter. The diameter varies inversely to the gauge number. Standard UTP cable is 24AWG. APPLETALK AppleTalk is the Apple Corp. Networking architecture included with all Mac computers and is related to Ethernet. ANSI American Standards Institute. An organisation of American industry and business dedicated to the development of trade and communications standards. B BACKBONE The backbone is the main cable from which all the network traffic propagates (travels). BANDWIDTH In comms, the difference between the highest and lowest frequencies in a given range. In computer networks the greater the bandwidth indicates faster or greater data transfer capability. BAUD A measurement of data transmission, also known as the Baud Rate. BIT A binary digit, 1 or 0 - the smallest data size sent over in packets on a network. BNC British Naval Connector. A connector for coaxial cables that locks when inserted and rotated 90 degrees. BRIDGE A device used to join two LANS together, BROADCAST A transmission sent simultaneously to more than one PC on the network. BUS TOPOLOGY This topology connects each computer or device to a single cable backbone, such cable will be Coax type cable. C CABLE TESTER A device which measures the electrical properties of the cable and also used to certify a network. COAX A conductive centre wire surrounded by an insulating layer (known as the dielectric), a layer of wire mesh (shielding) and used in the construction. CROSSTALK Signal overflow from an adjacent wire. D DAISYCHAIN A set of devices connected in series. Signals on this type of cabling are passed through the chain from one device to the next. DECNET A DEC Limited set of hardware and software products that implement the Digital Network Architecture or DNA. A type of Ethernet standard. DIGITAL LINE A comms line that carries information only in a binary encoded form. An ISDN is a digital (not Analogue) line. DUPLEX TRANSMISSION Comms that take place simultaneously in both directions between the sender and receiver. Fast Ethernet and ATM are examples of Full Duplex operation. The yanks like to call it 4-wire transmission! E ETHERNET A LAN standard developed by Xerox Corp. In 1976 (same year they made Star Wars!). Ethernet became a widely used network and originated on the Bus Topology at that time. F FDDI A standard developed by the ANSI for high speed fibre optic networks. FDDI provides specifications for transmissions at 100Mbits on networks based on the Token Ring theory. FRAME A package of information transmitted on a network as a single unit, this term is most often used in Ethernet networks. A frame is similar to a packet. FRAME RELAY An advanced packet switching network, similar to ATM. G GATEWAY A device, which is used to connect, networks using different protocols so that information can be passed from one system to the other. H HANDSHAKING The way two modems exchange data during communications. HERTZ (Hz) This is the unit of frequency measurement. The higher the Hertz rates the faster the signal, aka Mhz or Ghz! HOP In routing through a mesh environment the transmission of a data packet through a router, the higher the hop count the longer the data gets from the sending PC to the receiving PC, the Internet works on a Mesh routing environment. HUB A connectivity component that provides a common connection among computers in a star-configured network. I IEEE The Institute of Electrical and Electronic Engineers, an American body that defines network standards such as IEEE 802. IMPEDANCE The resistance, measured on ohms of a cable, the Acome cable is 100 Ohms. ISDN Integrated Services Digital Network. A digital communications service offered by BT amongst others, a quicker system to transmit data than plain Analogue circuits but less common now with the rise of broadband. ISO International Standards Organisation. An organisation that does its best to set global standards for comms and networks. IP The Internet protocol for setting the standards for sending data over networks such as the Internet. IP is part of a suit of programs called TCP/IP IPX The Novell equivalent of the IP protocol. J JITTER Instability in a signal wave form over time that could be caused by signal interferance on Token Ring Networks. K KILOBIT (KBIT) One thousand and twenty four bits KILOBYTE (KB) One thousand and twenty four bytes L LAN Local Area Network. A network that spans a single location such as in a building, hence the word Local! M MEGABIT (MB) Usually 1,048,576 bits. MULTIPLEXER (MUX) A device used for division of a transmission facility into two or more channels. N NETWORK ADAPTER CARD (NIC) An expansion card required for connecting a computer to a LAN. NETWORK ANALYSERS A tool for troubleshooting networks, also called protocol analysers. NODE On a LAN, a device that is connected to the networks and is capable of communicating with other network devices NOISE Random electrical signals that can get onto the cable and degrade the data signal so much that they can cause errors on the computers, usually caused by High Voltage devices such as x-ray machines, fruit machines etc., we would use STP or Fibre cable (being non metallic) to stop the noise problems. O OHM A unit of electrical resistance. Acome cable as well as other twisted pair cables is 100 Ohms, Coax cable is usually 50 or 75 Ohms. OPTICAL FIBRE Medium, which carries digital data signals in the form of light, pulses. The cable uses extremely thin cylinders of very pure glass. P PACKET A packet is a unit of information transmitted as a whole from one device to another, also known as a frame. PARITY A mathematical algorithm used by computers to verify the data that has been sent has been received correctly by the receiving computer, the algorithm is in the form (usually) of a CRC (cyclic redundancy check). PROTOCOL A set of rules or standards designed to enable computers to connect with one another. R REPEATER A device that regenerates the data signals so they can travel on additional cable segments so to extend cable distances. RG58 Stranded core coaxial cable. Used in wiring Bus Topology networks. RING TOPOLOGY This topology has computers on a circular network with no terminating ends. The Token Ring network uses this wiring type. RJ11 A 4-wire modular connector used to join a telephone line to a wall plate or a communications peripheral such as a Modem. RJ45 An 8-wire modular connector used to join a PC to a twisted pair network, AMP make these babies. ROUTER A device used to connect networks of different types. Routers determine the best path the data should take over a network (see HOPS), routers keep the Internet running! RS232 An industry standard for serial communication. S SEGMENT The length of a cable on a network between two terminators. STP Shielded Twisted Pair. An insulated cable with wires that are twisted around each other. The shield comes from a metal foil, which covers the entire cable pairs. SHIELDING This is a construction that protects the electrical signal travelling down the cable from external electrical interference. SNMP Simple Network Management Protocol. A TCP/IP monitoring protocol designed to yeild information such as network traffic over SNMP ready hardware, such as a Hub or Switch. STAR TOPOLOGY Structured Cabling systems are based on this design. Each computer is wired using its own 4 pair cable, which travels back to a central point or Hub. T T PIECE A T-shaped coaxial connector that connects two thinnet Ethernet cables while supplying an additional connector for a network interface card (NIC). TAP A connection to a network. TDR A Time domain reflectometer. A device used for measuring cable distance etc. TERMINATOR Resistors used at each end of a BUS topology network to ensure data is not reflected back and thus cause broadcast errors. THICKNET A rigid coaxial cable about half an inch wide. This is a yellow coloured cable and will allow a maximum transmission range of 500 Metres before needing to be repeated. TRANSCEIVER A device that connects a computer to a network. The term comes from transmitter/receiver. It switches the parallel data stream on the computer's bus into a serial data stream used in the cables connecting computers. TWISTED PAIR CABLE A cable, such as Acome or Alcatel that consists of two insulated strands of copper wire twisted together. A number of twisted wire pairs are often grouped together and enclosed in a protective sheath. U UPS A battery backup system used for providing trouble free power supplies to computers and electronic network devices. UTP Unshielded Twisted Pair. Our Acome is standard UTP cable, UTP means that is does not contain an overall shield and drain wire, and should only be used in areas of low electrical interference. V VAMPIRE TAP An Ethernet transceiver housed in a clamp like device with sharp metal 'fangs' that bite into thicknet (10Base5) cable and make contact with the copper core. An AUI cable is then needed to connect the tap to a PC's Network Card. W WAN Wide Area Network. A computer network that uses long-range connections (i.e. Satellite, fibre etc.) to connect networks together, such as from London to Tokyo. WWW World Wide Web. The part of the Internet that uses the HTTP protocol. X X.25 A packet switching network for terminals, used by hole in the wall cash machines, although going out of fashion. |