IBM Books

Introduction and Planning Guide

Glossary


This glossary includes terms and definitions from:

The following cross-references are used in this glossary:

Contrast with:
This refers to a term that has an opposed or substantively different meaning.

Synonym for:
This indicates that the term has the same meaning as a preferred term, which is defined in its proper place in the glossary.

Synonymous with:
This is a backward reference from a defined term to all other terms that have the same meaning.

See:
This refers you to multiple-word terms that have the same last word.

See also:
This refers you to terms that have a related, but not synonymous, meaning.

A

A
Ampere.

ac
Alternating current.

active
(1) Operational.
(2) Pertaining to a node or device that is connected or is available for connection to another node or device.

Advanced Peer-to-Peer Networking (APPN) network node
A node that offers a broad range of end-user services and that can provide the following:

agent
A system that assumes an agent role.

analog
(1) Pertaining to data consisting of continuously variable physical quantities. (A)
(2) Contrast with digital.

AMI
Alternate Mark Inversion.

ANSI
American National Standards Institute.

AppleTalk
A network protocol developed by Apple Computer, Inc. This protocol is used to interconnect network devices, which can be a mixture of Apple and non-Apple products.

APPN node
Advanced Peer-to-Peer Networking (APPN) node.

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. (I) (A)

AUI
Attachment unit interface.

autonomous system (AS)
A group of networks and routers that use the same interior gateway protocol and for which one administrative authority has responsibility.

B

Bc
Committed burst size.

Be
Excess burst size.

bootstrap
(1) A short program that is permanently resident or easily loaded into a computer and whose execution brings a larger program, such as an operating system or its loader, into memory. (A)
(2) To execute a bootstrap. The term "bootstrapping" is also used for translating a compiler by using itself or a previous version as the translator. (A)
(3) Synonym for initial program load.

bps
Bits per second.

bridge
A functional unit 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.

broadband
A large frequency band allowing different kinds of transmissions, such as coded voice, video, and data, at the same time.

BSC
Binary synchronous communication.

C

CAS
Channel associated signaling.

CCITT
International Telegraph and Telephone Consultative Committee. This was an organization of the International Telecommunication Union (ITU). On 1 March 1993 the ITU was reorganized, and responsibilities for standardization were placed in a subordinate organization named the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-TS). "CCITT" continues to be used for recommendations that were approved before the reorganization.

CCS
(1) common channel signaling (2) change control server.

CDB
Configuration database.

CES
Circuit emulation service.

channelization
The process of breaking the bandwidth on a communication line into a number of channels, possibly of different size. Also called time division multiplexing (TDM).

CIR
Committed information rate.

circuit
(1) One or more conductors through which an electric current can flow. See physical circuit and virtual circuit.
(2) A logic device.

circuit switching
(1) A process that, on demand, connects two or more data terminal equipment (DTEs) and permits the exclusive use of a data circuit between them until the connection is released. (I) (A)
(2) Synonymous with line switching.

CMIP
Common Management Information Protocol.

CMIS
Common Management Information Services.

CMOT
CMIP over TCP/IP.

CNM
Communication network management.

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

connection
In data communication, an association established between functional units for conveying information. (I) (A)

CP
Control point.

CPCI
Compact peripheral component interconnect.

CRC
Cyclic redundancy check.

CSU
Channel Service Unit.

D

data circuit
(1) A pair of associated transmit and receive channels that provide a means of two-way data communication. (I)
(2) See also physical circuit and virtual circuit.

Notes:

  1. Between data switching exchanges, the data circuit may include data circuit-terminating equipment (DCE), depending on the type of interface used at the data switching exchange.

  2. Between a data station and a data switching exchange or data concentrator, the data circuit includes the data circuit-terminating equipment at the data station end, and may include equipment similar to a DCE at the data switching exchange or data concentrator location.

data circuit-terminating equipment (DCE)
In a data station, the equipment that provides the signal conversion and coding between the data terminal equipment (DTE) and the line. (I)

Notes:

  1. The DCE may be separate equipment or an integral part of the DTE or of the intermediate equipment.

  2. A DCE may perform other functions that are usually performed at the network end of the line.

data link control (DLC)
A set of rules used by nodes on a data link (such as an SDLC link or a token ring) to accomplish an orderly exchange of information.

data link switching (DLSw)
A method of transporting network protocols that use IEEE 802.2 logical link control (LLC) type 2. SNA and NetBIOS are examples of protocols that use LLC type 2. See also encapsulation and spoofing.

data terminal equipment (DTE)
That part of a data station that serves as a data source, data sink, or both. (I) (A)

data terminal ready (DTR)
A signal to the modem used with the EIA 232 protocol.

dc
Direct current.

DCD
DC distribution (module).

DCE
Data circuit-terminating equipment.

DC48
DC power input type -48V.

dependent LU requester (DLUR)
An APPN end node or an APPN network node that owns dependent LUs, but requests that a dependent LU server provide the SSCP services for those dependent LUs.

device
A mechanical, electrical, or electronic contrivance with a specific purpose.

digital
(1) Pertaining to data that consist of digits. (T)
(2) Pertaining to data in the form of digits. (A)
(3) Contrast with analog.

DLCI
Data link connection identifier.

DLS
Data link switching.

DLUR
Dependent LU requester.

DTE
Data terminal equipment. (A)

DTMF
Dual-tone modulation frequency.

DTR
Data terminal ready.

E

E&M
Earth & mark.

EIA
Electronic Industries Association.

EIA unit
A unit of measure, established by the Electronic Industries Association, equal to 44.45 millimeters (1.75 inches).

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.

encapsulation
In communications, a technique used by layered protocols by which a layer adds control information to the protocol data unit (PDU) from the layer it supports. In this respect, the layer encapsulates the data from the supported layer. In the Internet suite of protocols, for example, a packet would contain control information from the physical layer, followed by control information from the network layer, followed by the application protocol data. See also data link switching (DLSw).

ESF
Extended status flags.

Ethernet
A 10-Mbps baseband local area network that allows multiple stations to access the transmission medium at will without prior coordination, avoids contention by using carrier sense and deference, and resolves contention by using collision detection and transmission. Ethernet uses carrier sense multiple access with collision detection (CSMA/CD).

ELS
Event Logging System

F

FAT
File allocation table.

fax
Hardcopy received from a facsimile machine. Synonymous with telecopy.

FDL
Facility Data Link.

flash memory
A data storage device that is programmable, erasable, and does not require continuous power. The chief benefit of flash memory over other programmable and erasable data storage devices is that it can be reprogrammed without being removed from the circuit board.

FR
Frame relay.

FRAD
Frame relay access device.

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.

frequency
The rate of signal oscillation, expressed in hertz.

FRFH
Frame relay frame handler.

FRTE
Frame relay terminal equipment.

FRU
Field replaceable unit.

FTP
File Transfer Protocol.

FXO
Foreign Exchange Office.

FXS
Foreign Exchange Station.

G

gateway
(1) A functional unit that interconnects two computer networks with different network architectures. A gateway connects networks or systems of different architectures. A bridge interconnects networks or systems with the same or similar architectures. (T)
(2) In the IBM Token-Ring Network, a device and its associated software that connect a local area network to another local area network or a host that uses different logical link protocols.

Gbps
Gigabits per second (1 000 000 000 bits per second).

GUI
Graphical user interface.

H

HDLC
High-level data link control.

high-level data link control (HDLC)
An access service used over data networks. It uses a non-real-time connection.

HDLC-like data link control, for example:

high-performance file system (HPFS)
In the OS/2 operating system, an installable file system that uses high-speed buffer storage, known as a cache, to provide fast access to large disk volumes. The file system also supports the coexistence of multiple, active file systems on a single personal computer, with the capability of multiple and different storage devices. File names used with the HPFS can have as many as 254 characters.

high-performance routing (HPR)
An addition to the Advanced Peer-to-Peer Networking (APPN) architecture that enhances data routing performance and reliability, especially when using high-speed links.

hot pluggable
Refers to an hardware component that can be installed or removed without disturbing the operation of any other resource that is not connected to, or dependant on, this component.

HPDT
High-Performance Data Transfer.

HPFS
High-performance file system.

hub (intelligent)
A wiring concentrator, such as the IBM 8260, that provides bridging and routing functions for LANs with different cables and protocols.

I

IDNX
Integrated Digital Network Exchange.

IEEE
Institute of Electrical and Electronics Engineers.

impedance
The combined effect of resistance, inductance, and capacitance on a signal at a given frequency.

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

interface
(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. (T)
(2) Hardware, software, or both, that links systems, programs, or devices.

Intermediate Session Routing (ISR)
A type of routing function within an APPN network node that provides session-level flow control and outage reporting for all sessions that pass through the node but whose end points are elsewhere.

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 develop cooperation in intellectual, scientific, technological, and economic activity.

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

Internet
A worldwide network connecting users through autonomous networks in industry, education, government, and research. The Internet network uses Internet Protocol (IP). The major Internet services include electronic mail, FTP, telnet, World Wide Web, and electronic bulletin boards (Usenet). For network interconnection and routing, and Transmission Control Protocol (TCP) for end-to-end control. (A)

Internet Protocol (IP)
A connectionless protocol that routes data through a network or interconnected networks. IP acts as an intermediary between the higher protocol layers and the physical network. However, this protocol does not provide error recovery and flow control and does not guarantee the reliability of the physical network.

Internetwork Packet Exchange (IPX)
The network protocol used to connect Novell's servers, or any workstation or router that implements IPX, with other workstations. Although similar to the Internet Protocol (IP), IPX uses different packet formats and terminology.

IP
Internet Protocol.

IPX
Internetwork Packet Exchange.

ISDN
Integrated services digital network.

ISM
IBM Solution Manager.

ISMD
IBM Software Manufacturing and Delivery.

ISO
International Organization for Standardization.

ISR
Intermediate session routing.

ITU-T
International Telecommunication Union - Telecommunication (replaces CCITT).

K

Kbps
Kilobits per second (1024 bits per second).

kVA
kilovolt amperes.

L

LAN
Local area network.

LAPD
Link access procedure for D-channel.

LBO
Line build out.

LCS
Logical channel station.

LED
Light-emitting diode.

LIC
Line interface coupler.

Line build out
The voltage level on the RJ-45 connector that terminates your ISDN line at the IBM 2212. LBO accounts for the distance between the IBM 2212 and the telco, the quality of the line, and the intermediate amplification as specified in dB.

line switching
Synonym for circuit switching.

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.

link connection
The physical equipment providing two-way communication between one link station and one or more other link stations; for example, a telecommunication line and data circuit-terminating equipment (DCE). Synonymous with data circuit.

LMI
Local management interface.

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. (T)
(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. See also Ethernet and token ring.
(3) Contrast with metropolitan area network (MAN) and wide area network (WAN).

M

MAN
Metropolitan area network.

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.

MB
Megabyte (1 048 576 bytes).

Mbps
Megabits per second (1 048 576 bits per second).

metropolitan area network (MAN)
A network formed by the interconnection of two or more networks which may operate at higher speed than those networks, may cross administrative boundaries, and may use multiple access methods. (T) Contrast with local area network (LAN) and wide area network (WAN).

MIB
(1) MIB module.
(2) Management Information Base.

modem (modulator/demodulator)
(1) 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. (T) (A)
(2) A device that converts digital data from a computer to an analog signal that can be transmitted on a telecommunication line, and converts the analog signal received to data for the computer.

MPC
Multi-Path Channel.

MPC+
High-Performance Data Transfer (HPDT) Multi-Path Channel.

ms
Millisecond (1/1000 second).

N

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. (T)
Note:The operating principles of a network include those of services, functions, and protocols.

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

NIC
Network Information Center.

NMS
Network management station.

NNI
Network-to-network interface.

non-return-to-zero change-on-ones recording (NRZ-1)
A recording method in which the ones are represented by a change in the condition of magnetization, and zeros are represented by the absence of change. Only the one signals are explicitly recorded. (Previously called non-return-to-zero inverted, NRZI, recording.)

NRZ-1
Non-return-to-zero change-on-ones recording.

NSAP
Network service address point.

NSC
Network Support Center.

NVDM
NetView Distribution Manager/6000.

O

OSI
Open systems interconnection.

P

packet loss ratio
The probability that a packet will not reach its destination or not reach it within a specified time.

packet mode operation
Synonym for packet switching.

packet switching
(1) The process of routing and transferring data by means of addressed packets so that a channel is occupied only during transmission of a packet. On completion of the transmission, the channel is made available for transfer of other packets. (I)
(2) Synonymous with packet mode operation. See also circuit switching.

PBX
Private branch exchange.

PCM
Pulse code modulation.

PDH
Plesiochronous digital hierarchy.

permanent virtual circuit (PVC)
In X.25 and frame relay communications, a virtual circuit that has a logical channel permanently assigned to it at each data terminal equipment (DTE).

physical circuit
A circuit established without multiplexing. See also data circuit. Contrast with virtual circuit.

PM
Presentation Manager.

PMF
Parameter Management Frame.

PNP
Private numbering plan.

Point-to-Point Protocol (PPP)
A protocol that provides a method for encapsulating and transmitting packets over serial point-to-point links.

port
(1) An 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. Synonymous with socket.
(3) The representation of a physical connection to the link hardware. A port is sometimes referred to as an adapter; however, there can be more than one port on an adapter. There may be one or more ports controlled by a single DLC process.
(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. Some protocols, such as File Transfer Protocol (FTP) and Simple Mail Transfer Protocol (SMTP), use the same well-known port number in all TCP/IP implementations.
(5) An abstraction used by transport protocols to distinguish among multiple destinations within a host machine.

PPP
Point-to-Point Protocol.

private branch exchange (PBX)
A private telephone exchange for transmission of calls to and from the public telephone network.

problem determination
The process of determining the source of a problem; for example, a program component, machine failure, telecommunication facilities, user or contractor-installed programs or equipment, environmental failure such as a power loss, or user error.

PRS
Primary reference source.

PSN
Public switched network.

PSTN
Public switched telephone network.

PTM
Packet transfer mode.

PVC
Permanent virtual circuit.

Q

QoS
Quality of service.

R

rack
A metallic structure, with a standard 19-inch width, that houses Nways Switch hardware elements: logic subrack with modules, fan boxes, and power subrack with power units.

real-time processing
The manipulation of data that are required, or generated, by some process while the process is in operation. Usually the results are used to influence the process, and perhaps related processes, while it is occurring.

RETAIN
Remote Technical Assistance Information Network.

ring
See ring network.

ring network
(1) A network in which every node has exactly two branches connected to it and in which there are exactly two paths between any two nodes. (T)
(2) A network configuration in which devices are connected by unidirectional transmission links to form a closed path.

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 from 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 LAN segments, which use similar or different architectures, at the reference model network layer. Contrast with bridge and gateway.
(3) In OSI terminology, a function that determines a path by which an entity can be reached.

routing
(1) The assignment of the path by which a message is to reach its destination.
(2) In SNA, the forwarding of a message unit along a particular path through a network, as determined by parameters carried in the message unit, such as the destination network address in a transmission header.

RSC
Remote Support Center.

RSF
Remote Support Facility.

RT
Real time.

S

s
Second.

SDH
Synchronous digital hierarchy.

SDLC
Synchronous Data Link Control.

SDT
Structured data transfer.

SF
Super Frame.

Serial Line Internet Protocol (SLIP)
A TCP/IP protocol used on a point-to-point connection between two IP hosts over a serial line (for example, an RS/EIA-232 connection into a modem over a telephone line).

In an NBBS network, the SLIP is used over a connection between an Nways Switch administration station (NAS) and an IBM Network Support Center (NSC).

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 managed is defined and stored in the application's Management Information Base (MIB).

SLA
Serial link architecture.

SLIP
Serial Line Internet Protocol.

SNA
Systems Network Architecture.

SNMP
Simple Network Management Protocol.

socket
The abstraction provided by the University of California's Berkeley Software Distribution (commonly called Berkeley UNIX or BSD UNIX) that serves as an endpoint for communication between processes or applications.

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.

spoofing
For data links, a technique in which a protocol initiated from an end station is acknowledged and processed by an intermediate node on behalf of the final destination. In IBM 6611 data link switching, for example, SNA frames are encapsulated into TCP/IP packets for transport across a non-SNA wide area network, unpacked by another IBM 6611, and passed to the final destination. A benefit of spoofing is the prevention of end-to-end session timeouts.

SRC
System reference code.

STM-1
Synchronous transport module-1.

SW
Switch (module).

SWRD
Switch redrive (module).

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

Synchronous Data Link Control (SDLC)
A discipline conforming to subsets of the Advanced Data Communication Control Procedures (ADCCP) of the American National Standards Institute (ANSI) and High-level Data Link Control (HDLC) of the International Organization for Standardization, for managing synchronous, code-transparent, serial-by-bit information transfer over a link connection. Transmission exchanges may be duplex or half-duplex over switched or nonswitched links. The configuration of the link connection may be point-to-point, multipoint, or loop. (I) Contrast with binary synchronous communication (BSC).

system
In data processing, a collection of people, machines, and methods organized to accomplish a set of specific functions. (I) (A)

Systems Network Architecture (SNA)
The description of the logical structure, formats, protocols, and operational sequences for transmitting information units through, and controlling the configuration and operation of, networks. The layered structure of SNA allows the ultimate origins and destinations of information, that is, the end users, to be independent of and unaffected by the specific SNA network services and facilities used for information exchange.

T

TCP
Transmission Control Protocol.

TCP/IP
Transmission Control Protocol, Internet Protocol.

TDM
Time division multiplexing.

Telnet
In TCP/IP, an application protocol that allows a user at one site to access a remote system as if the user's display station were locally attached. Telnet uses the Transmission Control Protocol as the underlying protocol.

TFTP
Trivial File Transfer Protocol.

time division multiplexing (TDM)
See channelization.

TN3270
An informally defined protocol for transmitting 3270 data streams over Telnet.

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. (T)
(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
(1) According to IEEE 802.5, network technology that controls media access by passing a token (special packet or frame) between media-attached stations.
(2) A FDDI or IEEE 802.5 network with a ring topology that passes tokens from one attaching ring station (node) to another.
(3) See also local area network (LAN).

Transmission Control Protocol (TCP)
A communications protocol used in Internet and in any network that follows the U.S. Department of Defense standards for internetwork protocol. TCP provides a reliable host-to-host protocol between hosts in packet-switched communications networks and in interconnected systems of such networks. It assumes that the Internet protocol is the underlying protocol.

Transmission Control Protocol/Internet Protocol (TCP/IP)
A set of communications protocols that support peer-to-peer connectivity functions for both local and wide area networks.

Transmission Control Protocol/Internet Protocol (TCP/IP)
A set of communication protocols that support peer-to-peer connectivity functions for both local and wide area networks.

transparent bridging
In LANs, a method for tying individual local area networks together through the medium access control (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)
In the Internet suite of protocols, a protocol for file transfer that requires minimal overhead and minimal capability. TFTP uses the connectionless datagram delivery services of the User Datagram Protocol (UDP), which allows hosts that have no disk storage to implement TFTP in read-only memory (ROM) and use it to boot themselves.

U

UDP
User Datagram Protocol.

UNI
User network interface (protocol).

UTP
Unshielded twisted pair.

V

V ac
Volts alternating current.

V.24
In data communications, a specification of the CCITT that defines the list of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-terminating equipment (DCE).

V.25
In data communications, a specification of the CCITT 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.34
In data communications, an ITU-T standard model serial line protocol using signalling rates of up to 28 800 bps for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits.

V.35
In data communications, a specification of the CCITT that defines the list of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) at various data rates.

V.36
In data communications, a specification of the CCITT that defines the list of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) at rates of 48, 56, 64, or 72 kilobits per second.

version
A separately licensed program that usually has significant new code or new function.

virtual circuit
(1) In packet switching, the facilities provided by a network that give the appearance to the user of an actual connection. (T) See also data circuit. Contrast with physical circuit.
(2) A logical connection established between two DTEs.

virtual connection
In frame relay, the return path of a potential connection.

VoFR
Voice over Frame Relay.

VPD
Vital product data.

W

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. (T)
(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. Contrast with local area network (LAN) and metropolitan area network (MAN).

X

X.21
An International Telegraph and Telephone Consultative Committee (CCITT) 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 International Telegraph and Telephone Consultative Committee (CCITT) recommendation for the interface between data terminal equipment and packet-switched data networks. See also packet switching.

[ Top of Page | Previous Page | Next Page | Table of Contents | Index ]