10BaseT

The IEEE 802.3 specification for Ethernet over unshielded twisted pair copper wire.

56K(bps) Service

This service, provided by local telephone companies or long-distance carriers, offers customers digital circuits capable of transmitting voice, data, or video at data rates of 5,000 bits per second. It is a dedicated 56K service connecting two points permanently with a monthly line charge. The switched 56K service allows the customer to dial up the circuit on demand and pay a per minute rate based on actual monthly usage.

Analog Transmission

A continuous wave transmission expressed by bandwidth, or range of frequencies. Telephones turn voice vibrations into electrical vibrations of the same shape. Analog implies continuous operation in contrast with digital, which is broken up into numbers. By converting analog signals into digital, the original audio data can be preserved.

ANSI

American National Standards Institute. The coordinating body for voluntary standards groups within the United States. ANSI is a member of the International Organization for Standardization (ISO).

Archive

A file that contains copies of one or more other files. An archive, which is often used for backup purposes may or may not be compressed. The popular unix archival utility.tar does not compress files.

ARP

Address Resolution Protocol. A member of the TCP/IP protocol suite used to resolve a destination host's hardware address from its knows IP address.

ASCII

American Standard Code for Information Interchange. A standard numeric encoding (ranging from 0 to 255) of characters widely used in the computer industry.

ATM

Asynchronous Transfer Mode. The standard for cell relay wherein information for multiple types of services (voice, video, data) is conveyed in small, fixed-size cells.

Backbone

The part of a network used as the primary path for transporting traffic between network segments.

Bandwidth

A measure of the information-carrying capacity of a communications channel. The higher (wider) the bandwidth, the greater the information-carrying capacity. The bandwidth is generally described as the range of frequencies in a signal, which is measured in cycles per second, or hertz, for analog signals, and bits per second for digital signals.

Baseband

The technique of transmitting a digital signal over a single medium. The entire bandwidth is used to transmit the single digital signal.

Baud

A measure of a computer modem's transmission speed, equal to bits per second.

Bit

Short for binary digit, the smallest unit of information in a computer. A binary digit has two possible values, one or zero.

Bridge

A device that connects or links two or more network segments or channels of voice or data.

Broadband

refers to a great bandwidth of frequencies, adequate for TV transmission or multiple audio circuits. Fiber optic or coaxial cable has broadband capability. A telephone line (twisted pair) does not.

Broadcast

A message sent to all network destinations.

Buffer

A storage area used for handling data in transit. Buffers often are used to compensate for differences in processing speed between network devices.

Byte

A group of bits, usually eight, handled as a unit, that stores a piece of information such as a character. Computer memory is measured in bytes; "64K" means a computer has 64 kilobytes (64,000 bytes) or 512,000 bits of memory.

C-Band

Satellites transmit most programming in one of two bands of frequencies, either C-Band or KU-Band. A C-Band satellite is one which operates in the 4/6 gigahertz band.

Channel

A communication path between two points; also commonly called a circuit, line, or link.

Circuit Switching

Switching system in which a dedicated physical circuit path must exist between sender and receiver for the duration of the call. Circuit switching is used heavily in the telephone-company network. This method of communication establishes an electrical connection between calling and called parties, on demand, and for the exclusive use of the parties until the connection is broken.

Coaxial Cable

Cable consisting of a center conductor (wire) and surrounding circular shield which is generally capable of greater bandwidth than twisted-pair copper but less than fiber optic cable.

CODEC

Coder/DECoder - A device that converts an analog (voice or video) signal into a digital signal for transmission, and converts it back to analog for display at the remote site. CODECs used for videoconferencing compress the analog video signal, allowing it to be transmitted over a less expensive channel such as copper (as opposed to full-motion video which requires more expensive channels).

Common Carrier

FCC class of regulated transmission systems, such as telephone, telegraph, and certain satellites, which offer services to the public at uniform fees. System owners are divorced from content control. For example, broadcast television is not a common carrier.

Compressed Video

Type of video signal which has been compressed (using a CODEC) in preparation for transmission. In the past, compressed video has been inferior in quality to full-motion video because of the reduced number of frames per second (<30) capability. However, there has been rapid advances made in compression methods (and CODECs) allowing for near-full-motion video quality being transmitted over the less expensive copper wiring.

Compression

Methods used to substantially reduce the amount of picture information sent in a video, audio, or data signal. A video CODEC compresses a video signal by only transmitting information about areas of a television picture than change over time or space.

CSU - Channel Service Unit

A device used to make a digital connection, such as a T-1 line being delivered from the phon company, to either a multiplexer, channel bank, or other device that accepts digital signals.

Cyberspace

Meanings include the universe of networked computers, programs, and data; perceiving and inhabiting this universe as a virtual reality; or society from the perspective. Cyberspace inhabitants include cybernauts, cyberpunks, etc.

DCE - Data Communications Equipment

The equipment providing functions that establish, maintain, and terminate a data transmission connection (such as a modem or printer).

Dedicated

Characteristic of a machine or system used only for one function.

Digital Transmission

While an analog signal is a continuous wave, digital transmission is a code of discrete binary signals (on and off, zero and one, etc). Digital transmission is expressed by numbers of bits per second.

Downlink

The ground facility which receives electronic communication from a satellite.

DS-1

Digital system 1 or digital signal level 1. Term used to refer to the 1.44 Mbps digital signal carried on a T1 facility. (See also T1)

DS-3

Digital signal level 3. Term used to refer to the 45 Mbps digital signal carried on a T3 facility. (See also T3)

DSU - Data Service Unit

The terminal interface, located between terminal equipment (such as a multiplexer and the CSU. DSUs and CSUs usually work in conjunction with each other and may be combined in a single unit.

EIA

Electronic Industries Association - A group that specified electrical transmission standards.

Encryption

A process applied to a digital signal to ensure secure communications between computers.

Ethernet

A baseband protocol and technology invented by Xerox Corporation and developed jointly by Xerox, Intel, and Digital Equipment Corporation. Ethernet networks operate at 10 Mbps over coaxial cable and allows terminals, workstations, and hosts to communicate with each other.

FDDI - Fiber Distributed Data Interface

An ANSI-defined standard specifying a special type of 100 Mbps network using fiber optic cable.

Fiber Optics

Communications medium based on a laser transmission that uses a glass fiber which carries light to transmit video, audio, or data signals. These optical waves being transmitted over a fine glass fiber allows for the transmission of digitized data around curves and at high speeds without loss. Each fiber can carry from 90 to 150 megabits of digital information per second or 1,000 voice channels.

Firewall

A means of securing an internal network from unwelcome intrusions from an external network, typically in the case of a business or research computer network by protecting its data and operations from hackers.

Forwarding

The process of sending a frame toward its ultimate destination by an internetworking device.

Frame

A frame is an individual image from television, film or video. Television sends images at 30 frames-per-second (fps), while film (movies) used 24 fps. Videoconferencing systems typically send between 8 and 30 fps., depending on the transmission bandwidth offered.

Frame Switch

A device similar to a bridge that forwards data frames based on the frame's address. LAN switches such as Ethernet and FDDI switches are examples of frame switches.

FTP - File Transfer Protocol

A common file transfer format used on the internet.

Full-Duplex Audio

An audio channel which allows conversation to take place interactively and simultaneously between the various parties, without electronically cutting off one or more participants if someone else is speaking. With half-duplex, only one party can speak at a time without cutting the other off.

Full-Motion Video

A standard video signal of 30 frames per second and 525 horizontal lines per frame which is capable of complete action (the data is not compressed).

Fully Interactive Audio/Video

This allows for two or more videoconferencing sites to interact with one another via audio and video signals. Full-motion is not a requirement to being fully interactive.

Gateway

A gateway is a device used to relay data transmission on one network to other networks or to points separate from the network.

Gigahertz

An analog signal with the range of frequency of one billion cycles per second.

GIF - Graphics Interchange Format

A compressed graphics file format common on the Internet.

Hardware Address

also called physical address. The hardware address is associated with a particular network device.

Hosts

Computers, not terminals, that act as data sources or destinations in a communications network.

HTML HyperText Markup Language

A simple text-based generic markup language for representing the design and contents of documents that World-Wide Web browsers can display.

HTTP HyperText Transport Protocol

A fast, stateless information-retrieval protocol designed to distribute information quickly to as many users as possible. Addresses for documents on the World Wide Web usually begins with http:// before the server computer's name, as in
http://www.cameron.edu

Hub

A central point of a network, usually providing some level of network-wide coordination.

ICMP - Internet Control Message Protocol

An Internet protocol that provides message packets to report errors and other information relevant to IP processing.

IEEE - Institute of Electrical and Electronic Engineers

Professional organization that defines network standards. IEEE LAN standards are the predominant LAN standards today, including protocols similar or virtually equivalent to Ethernet or Token Ring.

Information Superhighway

The ultimate interaction of computer networks. An evolving communications medium which links the entire world through video, sound, and digital communications. The Internet is also known as the Information Superhighway.

Interactive

Refers to technologies which permit user participation.

Interface

A connection between two systems or devices.

Internet

The global system of networks interconnected by TCP/IP (and IP-related protocols), which include over 30 million users from the private sector, educational institutions, government, nonprofits, and individuals. Internet users gain access to e-mail, file transfer, remote login, gopher, news, World Wide Web, and other related services.

Internet Access Provider (IAP)

An organization that provides connectivity to the Internet from a central location or locations. This organization usually markets their services to end users in a specific community.

Internet Address

Also called an IP address, it is a 32-bit address assigned to hosts using TCP/IP. The address is written as four octets separated with periods (ex: CU's Internet address is 198.17.223.2).

Internet Service Provider (ISP)

An organization that offers access to the Internet through dial-up or dedicated lines. An ISP supports customers to various degrees in the areas of special services, such as domain name registration, listservers, FTP site creation and maintenance, and Web page creation and maintenance.

IP - Internet Protocol

A protocol that contains addressing information and some control information that allows outgoing messages to be routed and recognizes incoming messages.

IP Address

See Internet Address.

Internetwork

A collection of networks interconnected by routers that functions (generally) as a single network. Sometimes called an internet, which is not to be confused with the Internet.

ISDN - Integrated Services Digital Network

An international telecommunications standard that allows a communications channel to simultaneously carry voice, data, and video (digitally). Narrow-band ISDN is copper-based with speeds up to 1.544 Mbps. Broadband ISDN has data speeds of 100 Mbps or greater.

ISDN TA Terminal Adapter

An interface between your computer and an ISDN connection. TAs can be internal or external devices. Think of a TA as a cross between a network interface card and a modem.

ITFS - Instructional Television Fixed Service

Local (up to 25 mile radius and line-of-sight) one-way, over-the-air block of TV channels operating at microwave frequencies reserved for educational purposes. ITFS can be received only by TV installations equipped with a converter to change signals back to those used by a television set, and is one-way audio and full-motion video.

JFIF

A generic form of JPEG that allows the exchange of JPEG-compressed images across platforms; also known as JIF.

JPEG - Joint Photographic Experts Group

A compression format designed to compress either full-color or gray-scale digital images.

Kb kilobits

A measurement that represents 1,024 bits of information in computer applications.

KB kilobytes

A measurement that represents 1,024 bytes of information in computer applications. There are 8 bits to a byte.

Kbps kilobits per second

A measurement that represents 1,024 bits of information per second. However, in telephone applications such as modem communications and ISDN, Kbps represents 1,000 bits per second.

Kilohertz

Analog signal with the range of frequency of one thousand cycles per second.

KU-Band

Satellite which operates in the 12/14 gigahertz band. See also C-Band.

LAN - Local Area Network

A communications facility covering a relatively small geographic area (usually measured in buildings or blocks, not miles) which interconnects communications devices such as terminals, personal computers, servers, and host computers.

LAN Switching

See frame switching.

LASER - Light Amplification by Stimulated Emission of Radiation

A device that emits an extremely narrow beam of light, used in fiber optics.

Latency

The delay between the time a device receives data and the time the data is forwarded out to the destination port.

Leased line

A communications line, from one point to another, leased from the telephone company for the exclusive use of a customer. See also point-to-point.

MB megabyte

A measurement representing 1,024 kilobits.

Mbps

Megabits per second - 1 million bits per second.

Media

Plural of medium. The physical environment through which transmission signals pass. Common network media include twisted pair, coaxial and fiber optic cable, and the atmosphere (through which microwave and infrared transmission occurs).

Megahertz

Analog signal with the range of frequency of one million cycles per second.

MODEM - Modulator-DEModulator

A type of computer equipment that connects computers through analog links (e.g. telephone lines) by converting data signals to analog signals and back again.

MPEG Moving Pictures Experts Group

An organization that maintains a digital video format allowing movies to play on a computer.

Multimode Fiber

Optical fiber supporting propagation of multiple frequencies of light.

Multiplexer

Hardware that brings together several low-speed communications lines, transforms them into one high-speed channel, and reverses the operation at the other end.

Multiplex

Transmission of two or more information streams over a single physical channel at the same time. Multiplexing allows a number of simultaneous transmissions over a single circuit.

Network

A collection of computers and other devices that are able to communicate with each other over some medium.

Network Address

Also called a protocol address, which refers to a logical rather than a physical network device.

Node

Any point within an internetwork which has an address, either physical or logical. Examples include a PC or a printer.

Open Systems Interconnect (OSI)

The OSI is a reference model that serves as a framework for the development of communications protocols. The model is intended to provide guidance for the establishment of common standards to facilitate communications between different vendors' products.

Packet

A collection of data and control characters in a specified format, sent through a network as a single unit.

Packet Switching

Communications technique that breaks down messages into smaller units called packets, which are individually addressed and routed through a network. The network link is occupied only during packet transmission.

PBX - Private Branch Exchange

A private telephone system serving an individual organization with connections to a public telephone system. A PBX is a computerized version of the telephone switchboard but with an expanded range of voice and data services and administrative features.

Peer-to-Peer

In networking, communications between equals with no central system or device providing coordination.

Physical Address

Term sometimes used to refer to the hardware address of a network device. See also hardware address.

Ping - Packet Internet Groper

Refers to the ICMP echo message and its reply. Ping is often used to test the reachability of a network address.

PKZIP/PKUNZIP

PKZIP is a popular DOS-based shareware program that archives files and compresses them to a fraction of their size. You can identify a compressed file by its ZIP extension. The PKUNZIP program restores the information from a ZIP file to its original uncompressed state. PK stands for Phil Katz, the programs' creator.

PPP Point-to-Point Protocol

A newer protocol that supports an Internet connection over a dial-up line. Similar to SLIP, PPP is better designed to handle multiple networking protocols. Allows communication from one location to several locations simultaneously.

Protocol

A formal description of a set of rules and conventions that govern how devices on a network exchange information.

QuickTime

A time-based technology designed to acquire and deliver digitized audio and video information quickly and efficiently.

Repeater

A device that regenerates and propagates electrical signals between two network segments.

RJ-45

An eight wire jack that is typically used for data transmission over twisted pair copper wires.

Route

A path through an internetwork.

Router

A device that can decide which of several paths network traffic will follow based on some routing metric. Also called a gateway (although this definition of gateway is becoming increasingly outdated), routers forward packets from one network to another based on addressing information.

Routing

The process of finding a path to the destination host. Routing is very complex in large networks because of the many potential intermediate destinations a packet might traverse before reaching its destination host.

Routing Metric

The method by which a routing algorithm determines that one route is better than another. Metrics include reliability, delay, bandwidth, load, communication costs, and others.

Segment

A bounded section of the network. A segment is usually bounded by bridges, routers, or switches.

Server

Central computer whose software (applications and/or data) are shared by one or more workstations. A server can also be computers that accept messages from a node or workstation and perform a specific function (e.g. file servers, print servers, etc.).

Single-Mode Fiber

Also called monomode fiber. Single-mode fiber has a narrow core that allows light to enter at only a single angle. Such fiber has higher bandwidth than multimode fiber, but requires a special light source with a narrow spectral width (for example, a laser).

SLIP - Serial Line Internet Protocol

A communications protocol that supports an Internet connection over a dial-up line.

SMTP - Simple Mail Transport Protocol

Defines the standard for naming and transferring mail across a network. Addresses in SMTP are in the form of: user@host.network (example: debbieg@cameron.edu).

Smart

as in a "smart" terminal, having built-in data processing ability. A "smart" building is wired for communications and computer services. Without such wiring, it is "dumb".

SNMP - Simple Network Management Protocol

The Internet network management protocol which provides a means to monitor and set network configuration and runtime parameters.

SONET - Synchronous Optical Network

A set of standard fiber-optic-based serial standards planned for use with ATM in North American which was developed by Bellcore.

Star Topology

A topology where devices are connected to a central point.

Store and Forward

Switching technique where frames, packets or messages are temporarily received and buffered at intermediate points between the source and destination. Bridges, routers and ATM switches are all based on store and forward technology.

Switch

In the context of frame or LAN switching, this refers to a device which filters and forwards frames based on the frame's destination address.

T1

Bell system terminology referring to a digital carrier facility used for transmission of data through the telephone hierarchy. The rate of transmission is 1.544 Mbps. T1 is often used for compressed video teleconferencing networks. Each T1 circuit can accommodate 24 voice channels. See also DS-1.

T3

A digital carrier service that operates at 45 Mbps. One T3 channel can carry 28 T1 channels. T3 is commonly used for digital video transmissions or for major PBX interconnections. See also DS-3.

TA terminal adapter

An interface between your computer and an ISDN connection. Tas can be internal or external devices. Think of a TA as a cross between a network interface card and a modem.

TAPI - Telephone Application Programming Interface

Software jointly introduced by Microsoft and Intel. TAPI lets a PC communicate directly with telephone systems.

TAR tape archive

A common utility used on most unix systems to archive (backup) files and folders.

TCP/IP - Transmission Control Protocol/Internet Protocol

The common name for the suite of protocols developed by the US Department of Defense in the 1970's to support the construction of world-wide internetworks. TCP and IP are the two best-knows protocols and provides for the reliable transmission of data.

TELNET

Standard Internet terminal emulation protocol.

Terminal Emulation

A very popular network application in which a computer runs software that makes it appear to a host (or a mainframe computer) across the network as a directly attached dumb terminal.

TFTP - Trivial File Transfer Protocol

A simplified version of FTP allowing the transfer of files from one computer to another over a network.

TN3270

A variant of the TELNET program that allows one to attach to IBM mainframes and use the mainframe as if you had an IBM 3270 or similar terminal.

Transponder

Those components of the satellite installed expressly to accept, route, amplify, and translate the frequency assignment to/from the satellite. There are 24 transponders on a satellite.

Twisted Pair

A voice or data link consisting of two copper wires continuously twisted to enhance transmission characteristics. Telephone wire is a type of one pair twisted copper wire which 10BaseT wire consists of several twisted pairs combined.

Uplink

The ground facility which transmits electronic communication to a satellite.

URL Uniform Resource Locator

A pointer to a file, Web page or server, or nearly any other type of resource available through the Internet. URLs usually begin with some identifier or prefix that identifies the type of resource. The following table lists common URL types and prefixes you will encounter on the Internet.

Type of resource	Prefix
World Wide Web	http://
Telnet	telnet://
FTP	ftp://
Gopher	gopher://
E-mail	mailto:

UTP - Unshielded Twisted Pair

Four-pair wire medium used in the transmission of many different protocols such as Ethernet and 10BaseT.

Virtual Circuit

A logical circuit set up to ensure reliable communication between two network devices. Physical resources are not permanently allocated as in a switched circuit on a circuit switch network.

Voice Processing

Any one of several industries that combine computers with the telephone system to provide automated services. Voice processing systems can understand touch tone digits entered by a user at their telephone. Some can even understand the spoken word and can speak themselves. Examples are voice mail and banking by phone.

WAN - Wide Area Network

An integrated network spanning a large geographical area, typically used to describe microwave and satellite networks.

Web Page

Refers to either the HTML source document or the hypermedia image that is interpreted by a Web browser such as Netscape or Mosaic.

Workgroup

A group of workstations and servers that commonly exchange data. This term is also used to describe a group of people who work together, sharing software and data.

WWW - World-Wide Web (Web, WWW, W3)

A graphical, interactive, hypertext information system that is cross-platform and can be run locally or over the global internet. The Web consists of Web servers offering pages of information to Web browsers who view and interact with the pages. Pages can contain formatted text, background colors, graphics, as well as audio and video clips. Simple links in a Web page can cause the browser to jump to a different part of the same page or to a page on a Web server halfway around the world. Web pages can be used to send mail, read news, and download files. A Web address is called a URL.

Zmodem

A fast file-transfer protocol common to many communications packages. Other similar file transfer protocols include ymodem, ymodemg, and xmodem. Of these, zmodem is the fastest and most efficient.

General | Technical | Glossary

This page is maintained by Julie A. Duncan, Computer Support Specialist.