LIS 505 - 7. Networking

distributed processing

Running a program on more than one computer or CPU or storing parts of a database on more than one computer. .

digital transmission

Transmission using discrete values, such as bits. . Modern computers generally transmit data digitally.

analog transmission

Transmission using continuous values. . Transmission over the conventional telephone system is considered analog.

asynchronous transmission

Communication in which data can be transmitted intermittently rather than in a steady stream. Typical of communication between computers and other devices. Also called start-stop transmission. .

synchronous transmission

Transmission at regular intervals. Typical of communication along the bus within a computer, which is governed by a clock. .

simplex transmission

Transmission in only one direction. .

half-duplex transmission

Transmission in only one direction at a time. .

full-duplex transmission

Transmission in both directions at once. .

modulation

Blending of data into a carrier signal. The reverse process, separating of data from a carrier signal, is called demodulation. .

modems

external modems

Modems that reside in self-contained boxes outside their computers. .

internal modems

Modems that reside on printed circuit boards inside their computers. .

cable modems

Modems designed to work over cable television lines. .

fax modems

Devices that can be attached to personal computers that enable them to transmit and receive electronic documents as faxes. Often combined with regular modems. .

ISDN

Short for Integrated Services Digital Network. A standard for sending voice, video, and data for short distances over telephone lines. .

DSL

Short for digital subscriber lines. A class of technologies for sending data over regular telephone lines for short distances. Faster than ISDN. .

communications media

UTP

Short for unshielded twisted pair. Cable consisting of two unshielded wires twisted around each other. Commonly used for telephones and in many local area networks. . Also called twisted pair or wire pair, though twisted pair can also be shielded, giving higher bandwidth.

coaxial cable

Cable consisting of a center wire surrounded by insulation and then a shield of braided wire. .

fiber optic cable

Cable consisting of bundles of glass threads, each of which can carry data modulated onto light waves. .

microwave

A form of electromagnetic waves little affected by the atmosphere, commonly used for wireless transmission. whatis.com.

satellites

Wireless receivers/transmitters placed in orbit. whatis.com. Users in remote locations may access the Internet by communicating with a satellite with an antenna (Internet over satellite or IoS). .

bandwidth

The amount of data that can be transmitted in a fixed amount of time. Typically expressed in bits per second or bytes per second. .

noise

Interference that destroys the integrity of signals. .

topology

Shape of a communication system. .

star topology

Topology in which all devices are connected to a central computer. .

ring topology

Topology in which all the devices are connected in a closed loop. .

bus topology

Topology in which all devices are connected to a single cable. .

WANs

Short for wide area networks. Computer networks that span relatively wide geographical areas. A WAN typically consists of several LANs. .

network interface cards

NICs for short. Printed circuit boards that allow computers to communicate over a network. .

dial-up access

Connecting to a network by modem and telephone lines, via a dial-up service or switched service. .

dedicated lines

Channels reserved exclusively for one kind of communication. .

leased lines

Permanent connections between points set up by a telecommunications common carrier. .

multiplexors

Devices that combine several signals for transmission. Also spelled multiplexers. .

bridges

Devices that connect LANs without analyzing and rerouting messages. .

routers

Devices that connect a number of LANs, routing packets of information to appropriate locations. .

gateways

Points on a network that serve to connect to other networks. . In contrast to hosts, which are end points. whatis.com.

downloading

Copying data from a central computer, server, etc., to a local computer, or from a computer to a peripheral device. .

uploading

Copying data to a central computer, server, etc., from a local computer, ,

client/server architecture

A way of arranging a network in which every computer or process running on a computer is either a client or a server, with the clients asking the servers for information or to perform other actions such as printing. ,

peer-to-peer

A communications model in which each party has the same capabilities and either party can initiate a communication session. whatis.com.

CSMA/CD

Short for Carrier Sense Multiple Access / Collision Detection. A set of rules for how points on a network should respond when two of them attempt to use a data channel simultaneously (a collision). After detecting a collision, a device waits a random time and then attempts to re-transmit its message. If it detects a collision again, it waits twice as long again. ,

Ethernet

A widely-used LAN structure, originally developed by Xerox and using a bus topology with CSMA/CD. ,

token ring networks

A type of network with a ring topology in which a special bit pattern (called a token) travels around the ring. To send a message, a device attaches a message to the token. ,

teleconferencing

Holding a conference via telephone or network connections. ,

videoconferencing

Holding a conference by using a computer network to transmit audio and video data. ,

EDI

Short for electronic data interchange. Transfer of data between companies, etc., using networks. ,

electronic funds transfer

EFT for short. Transfer of funds electronically from one bank account to another, initiated from any of various kinds of electronic device. whatis.com.

telecommuting

System in which office workers work using computers at home sending and receiving data over telephone lines.
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Last updated October 23, 2002.
This page maintained by Prof. Tim Craven
E-mail (text/plain only): craven@uwo.ca
Faculty of Information and Media Studies
University of Western Ontario,
London, Ontario
Canada, N6A 5B7