Glossary

A

A

Ampere.

asynchronous

An operation that proceeds independently of any timing mechanism. In comunications, for example, two modems communicating asynchronously rely upon each sending the other start and stop signals in order to pace the exchange of information.

Attachment Unit Interface (AUI)

In a local area network, the interface between the medium attachment unit and the data terminal equipment within a data station.

AUI

Attachment Unit Interface.

bridge

A device that interconnects multiple LANs (locally or remotely) that use the same logical link control protocol but that can use different medium access control protocols. A bridge forwards a frame to another bridge based on the Medium Access Control (MAC) address.

bridging

In LANs, the forwarding of a frame from one LAN segment to another. The destination is specified by the Medium Access Control (MAC) sublayer address encoded in the destination address field of the frame header.

coaxial cable

A cable consisting of a central conductor surrounded by an insulator and then by another grounded conductor. The outer cable acts as a shield to prevent interference from reaching the inner conductor.

configuration

(1) The manner in which the hardware and software of an information processing system are organized and interconnected.
(2) The devices and programs that make up a system, subsystem, or network.

connection

In data communications, an association established between functional units for exchanging information.

Data Circuit-terminating Equipment (DCE)

In a data station, the equipment that provides the signal conversion and coding between the DTE and the line. The DCE can be separate equipment or an integral part of the DTE or of the intermediate equipment. A DCE can perform other functions that are usually performed at the network end of the line.

Data Terminal Equipment (DTE)

That part of a data station that serves as a data source, data sink, or both.

Data Terminal Ready (DTR)

A signal to the modem used with the EIA 232 protocol.

DCE

Data Circuit-terminating Equipment.

Device

(1) A shared boundary between two functional units, defined by functional characteristics, signal characteristics, or other characteristics, as appropriate. The concept includes the specification of the connection of two devices having different functions. (2) Hardware that links systems, programs, or devices.

DTE

Data Terminal Equipment.

EIA

Electronic Industries Association.

EIA 232

In data communications, a specification of the Electronic Industries Association (EIA) that defines the interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE), using serial binary data interchange.

Electronic Industries Association (EIA)

An organization of electronics manufacturers that advances the technological growth of the industry, represents the views of its members, and develops industry standards.

Ethernet

A 10-Mbps baseband local area network that allows multiple stations to access the transmission medium at will without prior coordination. Avoids contention and resolves contention by using Carrier Sense Multiple Access with Collision Detection (CSMA/CD).

frame relay

(1) An interface standard describing the boundary between a user's equipment and a fast-packet network. In frame relay systems, flawed frames are discarded; recovery comes end-to-end rather than hop-by-hop. (2) A technique derived from the Integrated Services Digital Network (ISDN) D channel standard. It assumes that connections are reliable and dispenses with the overhead of error detection and control within the network.

IBD

See Integrated Boot Device.

IEEE

Institute of Electrical and Electronics Engineers.

Integrated Boot Device (IBD)

Banks of memory in routers storing configuration files.

Integrated Services Digital Network (ISDN)

A digital end-to-end telecommunication network that supports multiple services including, but not limited to, voice and data. ISDNs are used in public and private network architectures.

interface

A logical entity that represents a source of data packets routed by a forwarding protocol (IP, IPX, or AppleTalk).

International Organization for Standardization (ISO)

An organization of national standards bodies from various countries established to promote development of standards to facilitate international exchange of goods and services and to develop cooperation in intellectual, scientific, technological, and economic activity.

internet

A collection of networks interconnected by a set of routers that allow the networks to function as a single, large network. See Internet.

Internet

The internet administered by the Internet Architecture Board (IAB), consisting of large national backbone networks and many regional and campus networks all over the world. The internet uses the internet suite of protocols.

ISDN

Integrated Services Digital Network.

ISO

International Organization for Standardization

ITU

International Telecommunication Union. An international organization that sets standards for interconnection of telephone equipment (for example, modems) and networks.

kVA

kilovolt amperes.

LAN

Local Area Network.

link

The combination of the link connection (the transmission medium) and two link stations, one at each end of the link connection. A link connection can be shared among multiple links in a multipoint or token-ring configuration.

local

Pertaining to a device accessed directly without use of a telecommunication line.

Local Area Network (LAN)

(1) A computer network located on a user's premises within a limited geographical area. Communication within a local area network is not subject to external regulations; however, communication across the LAN boundary may be subject to some form of regulation. (2) A network in which a set of devices are connected to one another for communication and that can be connected to a larger network.

MAC

Medium Access Control. A medium-specific access control protocol within IEEE-802. MAC provides a set of services to ensure proper operation of the token ring including detection of and recovery from error conditions.

Management Information Base (MIB)

(1) A collection of objects that can be accessed by means of a network management protocol. (2) A definition for management information that specifies the information available from a host or gateway and the operations allowed. (3) In OSI, the conceptual repository of management information within an open system.

modem (modulator/demodulator)

A functional unit that modulates and demodulates signals. One of the functions of a modem is to enable digital data to be transmitted over analog transmission facilities.

network

(1) A configuration of data processing devices and software connected for information interchange. (2) A group of nodes and the links interconnecting them.

network architecture

The logical structure and operating principles of a computer network. The operating principles of a network include services, functions, and protocols.

network management

The process of planning, organizing, and controlling a communication-oriented data processing or information system.

OSI

Open Systems Interconnection. The ISO architecture for internetworking.

OSI Reference Model

The seven layer model specified by ISO which lists the specifics of particular network functions.

port

(1) A physical access point for data entry or exit. (2) A connector on a device to which cables for other devices such as display stations and printers are attached. (3) The representation of a physical connection to the link hardware. (4) In the Internet suite of protocols, a 16-bit number used to communicate between TCP or the User Datagram Protocol (UDP) and a higher-level protocol or application. (5) An abstraction used by transport protocols to distinguish among multiple destinations within a host machine.

remote

Pertaining to a device accessed through a telecommunication line.

route

(1) An ordered sequence of nodes and Transmission Groups (TGs) that represent a path from an origin node to a destination node traversed by the traffic exchanged between them. (2) The path that network traffic uses to get from source to destination.

router

(1) A computer that determines the path of network traffic flow. The path selection is made for several paths based on information obtained from specific protocols, algorithms that attempt to identify the shortest or best path, and other criteria such as metrics or protocol-specific destination addresses. (2) An attaching device that connects two or more network segments, which use similar or different architectures, at the reference model network layer. Contrast with bridge. (3) In OSI terminology, a function that determines a path by which an entity can be reached.

routing

The assignment of the path by which a message is to reach its destination.

Simple Network Management Protocol (SNMP)

In the Internet suite of protocols, a network management protocol that is used to monitor routers and attached networks. SNMP is an application layer protocol. Information on devices is defined and stored in the application's Management Information Base (MIB).

SNMP

Simple Network Management Protocol.

source route bridging

In LANs, a bridging method that uses the routing information field in the IEEE 802.5 Medium Access Control (MAC) header of a frame to determine which rings or token-ring segments the frame must transit. The routing information field is inserted into the MAC header by the source node. The information in the routing information field is derived from explorer packets generated by the source host.

STP

Shielded Twisted Pair. Twisted-pair cable that has shielding to provide protection against external crosstalk.

synchronous

(1) Pertaining to two or more processes that depend upon the occurrence of specific events such as common timing signals.
(2) Occurring with a regular or predictable time relationship.

TCP

Transmission Control Protocol.

TCP/IP

Transmission Control Protocol/Internet Protocol.

Telnet

A TCP/IP protocol that enables remote access and control of one workstation from another workstation on the IP network.

TFTP

Trivial File Transfer Protocol.

token

(1) In a local area network, the symbol of authority passed successively from one data station to another to indicate the station temporarily in control of the transmission medium. Each data station has an opportunity to acquire and use the token to control the medium. A token is a particular message or bit pattern that signifies permission to transmit. (2) In LANs, a sequence of bits passed from one device to another along the transmission medium. When the token has data appended to it, it becomes a frame.

Token Ring

According to IEEE 802.5, network technology that controls media access by passing a token (special packet or frame) between media-attached stations.

Transmission Control Protocol (TCP)

A protocol in the TCP/IP protocol suite that implements transport functions on the internet.

transparent bridging

In LANs, a method for tying individual local area networks together through the MAC level. A transparent bridge stores the tables that contain MAC addresses so that frames seen by the bridge can be forwarded to another LAN if the tables indicate to do so.

Trivial File Transfer Protocol (TFTP)

A simplified version of the File Transfer Protocol (FTP) that provides unreliable file transfers.

UTP

Unshielded Twisted Pair. Twisted-pair cable that has no shielding and is commonly used in the telephone network.

V.24

In data communications, a specification of the ITU that defines the list of definitions for interchange circuits between DTE and DCE. Also known as EIA232, formerly RS-232.

V.25

In data communications, a specification of the ITU that defines the automatic answering equipment and parallel automatic calling equipment on the General Switched Telephone Network, including procedures for disabling of echo controlled devices for both manually and automatically established calls.

V.35

In data communications, a specification of the ITU that defines the list of definitions for interchange circuits between DTE and DCE at various data rates.

V.36

In data communications, a specification of the ITU that defines the list of definitions for interchange circuits between DTE and DCE at various data rates.

Vac

Volts alternating current.

WAN

Wide Area Network.

Wide Area Network (WAN)

(1) A network that provides communication services to a geographic area larger than that served by a local area network or a metropolitan area network, and that may use or provide public communication facilities. (2) A data communications network designed to serve an area of hundreds or thousands of miles; for example, public and private packet-switching networks, and national telephone networks.

X.21

An ITU recommendation for a general-purpose interface between data terminal equipment and data circuit-terminating equipment for synchronous operations on a public data network.

X.25

An ITU recommendation for the interface between data terminal equipment and packet-switched data networks.