Network Terms

7/30/2019 Network Terms

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32-bit - Refers to number of bits used by an operating system to perform an operation. Is

based on the microprocessor that the OS is designed to run on.

access method - Technique for moving data between main storage and input/output

devices. In a Systems Network Architecture (SNA) environment, it is the software that

controls the flow of information in a network.

adapter - Hardware installed in a PC or other computer and used to connect the computer

to other hardware.

address - Identifier assigned to networks, stations and other devices so that each device

can be separately designated to receive and reply to messages.

Address Resolution Protocol (ARP) - Internet protocol that dynamically maps Internet

addresses to physical (hardware) addresses on local area networks. ARP is limited to

networks that support hardware broadcast.

Advanced Program-to-Program Communications (APPC) - Part of the SNA protocol that

establishes the conditions that enable programs to communicate across the network. Thiscapability, involving LU6.2 and its associated protocols, allows communication between

two or more processes in an SNA network without the involvement of a common host

system or of terminal emulation.

agent - The part of a networked system that performs information preparation and

exchange on behalf of a software entity.

algorithm - A prescribed set of well-defined rules or processes for arriving at a solution to

a problem.

American National Standards Institute (ANSI) - ANSI is responsible for the

establishment of many standards, including a number of data communications and

terminal standards. ANSI is the recognized U.S. representative within CCITT and ISO.See also CCITT and ISO.

American Standard Code for Information Interchange (ASCII) - A 7-bit code, intended as

a U.S. standard for the interchange of information among communications devices.

AppleShare - AppleShare is Apple Computer's networking solution. It requires a

dedicated Macintosh as a network server and includes both server and workstationsoftware. It uses the AppleTalk Filing Protocol (AFP).

AppleTalk - AppleTalk is a set of communications protocols (such as IPX/SPX and NCP)used to define networking on an AppleShare network. On the OSI model, AppleTalk is

comparable to communications protocols, in that both protocols specify communications,

ranging from application interfaces to media access.



AppleTalk Filing Protocol (AFP) - Allows distributed file sharing across an AppleTalk

network.

application - A software program or program package that makes calls to the operating

system and manipulates data files, thus allowing a user to perform a specific job (such as

accounting or word processing). application binary interface (ABI) A specificationdefining the interface between an operating system and a certain hardware platform,

particularly the calls between applications and the operating system.

application interface - A set of software routines and associated conventions that permits

application programmers to use that interface as a part of any application. In general, an

application interface is used to access system or networking services that would

otherwise require significant development effort to create from scratch. For example, theManageWise application interface lets a programmer use ManageWise file structures and

services within an application. See also application programming interface.

application programming interface (API) - A means by which an application gains accessto system resources, usually for the purpose of communication (the sending and receiving

of data), data retrieval or other system services. In the specific area of terminal emulation,an API provides for the simulation of keystrokes and for writing into and reading from

the presentation space (device buffer). It may also provide for the sending and receiving

of structured fields.

application server - A server in a client-server network which runs one or more

applications that can be shared by client stations and which also shares the data

processing burden with client stations. This shared application and shared data processingmodel contrasts with the model used for other servers, such as file servers, that simply

send, receive, and store files, requiring client stations to run all applications and process

all data. Either model can be most advantageous, depending on circumstances. In manycircumstances the application server model allows for faster data processing, faster

throughput to client stations, greater data reliability, and increased data security.

architecture - The manner in which a system, such as a network, computer or program is

structured.

archive - To create a redundant copy of computer file data, typically to create a backupcopy of that data to protect it if the original copy is damaged or otherwise irretrievable.

By some definitions, an archive is required to contain copies of every version of a

particular file. In this case, to archive means to save a copy of every object in a filesystem with a separate copy of all changes made to that file. In addition to protecting files

from loss, this approach also permits any previous version of a file to be restored,

typically by date and time.

ARCnet (Attached Resource Computing Network) - A proprietary token-bus networking

architecture developed by Datapoint Corporation in the mid-1970s. Currently, ARCnet is

widely licensed by third-party vendors and is a popular networking architecture,



especially in smaller installations. It is relatively fast (2.5 Mbit/s) and reliable, and it

supports coaxial, twisted pair and fiber optic cable-based implementations.

ASCII - See American Standard Code for Information Interchange.

asynchronous - A data transmission method in which each character is sent one bit at atime. Each character has a start and stop bit to synchronize signals between the sending

device and receiving device. This allows a character to be sent at random after the

preceding character has been sent. See also synchronous.

autoauthentication - In a client-server environment, a utility that lets users access

unrestricted network resources without password verification. Only when a user attempts

to access a restricted resource does the utility prompt for a password.

autologin - In a network environment, a utility that regulates user login attempts.

automount - A graphical utility that provides an iconical tree structure to simplify theuser's task of locating and using a server, filesystem, or volume.

backbone network - Primary connectivity mechanism of a hierarchical, distributed

network. Ensures that all systems that have connectivity to an intermediate system on the

backbone have connectivity to one another.

bad block table - A list kept on a hard disk of storage locations on the disk that are

damaged or physically unable to hold data reliably. The bad block table is usually

duplicated on a label on the outside of the disk housing. Also called 'media defect list.'See also Hot Fix, read-after-write verification.

bandwidth - Carrying capacity of a circuit, usually measured in bits per second for digitalcircuits, or hertz for analog circuits.

baseband - Network technology that uses a single carrier frequency and requires that allstations attached to a network participate in every transmission.

basic input/output system (BIOS) - A set of programs, usually in firmware, that enables

each computer's central processing unit to communicate with printers, disks, keyboards,consoles and other attached input and output devices.

beaconing - In token-ring networks, the state that results when an error condition occurs, preventing communication until the error condition is resolved.

Berkeley Software Distribution (BSD) - A UNIX operating system version developed atthe University of California, Berkeley.

binary - Numbering system using only zeros and ones.



bindery - A network database, in versions of the network operating system earlier than

4.0, that contains definitions for entities such as users, groups, and workgroups.

BIOS - See basic input/output system. bit Binary digit; either a one or a zero.

bit/s - The rate at which data is transferred over a serial interface.

block - Set of continuous bits or bytes that make up a definable quantity of information

such as a message.

bridge - See router.

broadcast - Packet delivery service in which all nodes on a network receive a copy of anyframe that is designated for broadcast or, when used as a verb, sending the message to all

nodes.

broadband - Characteristic of any network that multiplexes multiple, independentnetwork carriers on a single cable. Allows several networks to coexist on a single cable.

Traffic from one network does not interfere with traffic from another network becauseconversations happen on different frequencies.

buffer - Memory area or electronic register where data is stored temporarily whileawaiting disposition. It compensates for differences in data-flow rates (for example,

between a terminal and its transmission line). Also used as a data backup mechanism,

holding data that may be retransmitted if an error is detected during transmission.

burst - Method of data transfer in which information is collected and sent as a large unit

in one high-speed transmission. LAN traffic is usually considered bursty traffic because it

has short intervals of intense activity with lulls between. byte Group of eight binary digitsoperated on as a unit; also known as a character or octet.

cache - High-speed memory section that holds blocks of data that the CPU is currentlyworking on; designed to minimize the time the CPU spends accessing memory.

central processing unit (CPU) - Main processing unit of a computer.

CCITT recommendations - The CCITT is a committee that recommends standards for

communications equipment interfaces, communications protocols, modem modulation

methods and so on.

channel - Path for transmitting electromagnetic signals; synonym for line or link.

channel service unit (CSU) - Digital signal processor that performs transmit and receive

filtering, signal shaping, longitudinal balance, voltage isolation, equalization, and remote

loopback testing for digital transmission. It functions as a guaranteed safe electrical

circuit, acting as a buffer between the customer's equipment and a public carrier's wide



area network. CSUs prevent malfunctioning digital service units (DSUs) or other

customer premises equipment from disabling a public carrier's transmission system. The

design of a CSU must be certified by the FCC.

character - Group of eight binary digits operated on as a unit; also called a byte or octet.

circuit - Any path that can carry an electrical current.

client - 1.) Node or workstation (computer) on a computer network that requests servicesfrom a network server. Client stations run client software. 2). An executing software

program or set of programs through which a client station sends a request to a server and

waits for a response (for example, the Novell NetWare Client for DOS/MS Windows). 3.)

The user end of a client-server connection.

client-server model - 1.) Data communication model that relies on distributed, intelligent

interaction between network servers and individual (client) workstations. Clients request

services from servers. Servers receive client requests and return requested data or results.Clients and servers may be any class of computer, but often the client is a desktop

computer and servers are powerful microcomputers, 'workstation class' computers or minicomputers. 2.) Data communication model in which there is (1) server software that

starts execution before communication begins and, after communication begins,

continually accepts requests from and returns responses to clients, and (2) client softwarethat periodically sends requests for services to the server and accepts server responses.

client-server network - A network consisting of client nodes (workstations) which have

client capabilities only and server nodes which have (usually) server capabilities only. Ona client-server network, communication and data sharing between clients is, in most

cases, arbitrated by the network servers. Each client runs client software and each server

runs a client-server operating system (see client-server operating system below). Asimple network with only one server, a file server, is a classic example of a client-server

network.

client-server operating system - An operating system which runs on a server in a client-

server network and which is responsible for coordinating the use (by clients) of all

resources available from that server. Server resources include hardware such as hard

disks, Random Access Memory (RAM), printers and equipment used for remotecommunications, such as modems. Resources also include logical systems such as the

network file system and network directory services, and the information (data) therein.

cluster controller - An IBM or IBM-compatible device for the attachment of 3270 or

3270-class terminals. May be channel-attached to a host system or may communicate

with the host via an SDLC or, in some cases, a bisynch link to a host-attachedcommunications controller.

coaxial - A type of cable that uses two conductors: a central, solid wire core, surrounded

by insulation, which is then surrounded by a braided wire conductor sheath. This cable is



particularly well suited for networking because it can accommodate high bandwidth but

is relatively resistant to interference.

collision - What happens when two devices transmit data at the same time, resulting in a

loss of data.

compression - Method of compacting data into a smaller number of bits for more efficient

transmission or storage.

concentrator - Device with a single bus and multiple connections to computers; provides

a star-wired physical layout.

configuration - The way in which a system or part of a system, such as a piece of software, is set up, based on a number of possible choices.

configuration management - Refers to the management of networked applications and

their related user access.

connectionless - Model of interconnection in which communication takes place withoutfirst establishing a connection.

Connectionless Network Protocol (CLNP) - Open Systems Interconnection (OSI) protocol that provides the OSI Connectionless Network Service (delivery of data).

Connectionless Transport Protocol (CLTP) - Provides end-to-end transport data

addressing and error detection, but does not guarantee delivery or provide flow control.The Open Systems Interconnection (OSI) equivalent of the User Datagram Protocol

(UDP) datagram service.

connection-oriented - Model of interconnection in which communication proceeds

through three well-defined phases: connection establishment, data transfer, and

connection release.

connectivity - The ability to connect to and communicate with multiple architectures on a

single network.

console - The monitor and keyboard from which you actually view and control server or

host activity.

controller board - See adapter.

data - Data are entities that convey meaning. Computer data is stored as a series of (electrical) charges arranged in patterns to represent information. In other words, data

refers to the form of the information (the electrical patterns). It is not the information

itself.



database - Set of logically connected files that have a common access. All data entities

that exist for several related systems. A database can have several data items that can be

assembled into many different record types.

data compression devices - Equipment that compresses data into a smaller number of bits,

allowing more data to be transmitted per second than the link speed otherwise allows.

Data Encryption Standard (DES) - A standard encryption technique that scrambles data

into a code for transmission over a public network.

datagram - One packet of information and associated delivery information that is routed

through a packet-switching network.

data rate - Speed at which data bits are transmitted and received. Usually measured in bits

per second.

DECnet - A set of networking protocols developed by Digital Equipment Corporationand used in its VAX family of computers to exchange messages and other data. Although

DECnet is currently a proprietary protocol, DEC is merging its protocols with OSI protocols for the upcoming DECnet Phase V. When this process is complete, DECnet

protocols should interoperate with any OSI-compliant network node.

decryption - Unscrambling or decoding of encrypted data.

dedicated - A device that has only one function. For example, a dedicated server cannot

be used as a workstation. See also nondedicated.

dedicated line - Leased or private communications line. See also dial-up line.

demodulation - Process of recovering information from a previously modulated carrier

frequency by converting analog signals into digital signals.

desktop computer - A small-scale computer that fits on a desktop and that has a

microprocessor system. Also called a microcomputer or personal computer. Contrast with

minicomputer and mainframe computer.

developer - One who develops software, either for internal use or for commercial sale.

device driver - Software or firmware that translates operating system requests (such asinput/output requests) into a format that is recognizable by specific hardware, such as

adapters.

dial-up line - Communications line accessible via dial-up facilities, typically the public

telephone network. See also dedicated line.



digital - Representation of information using ones and zeros. It is discretely variable as

opposed to continuously variable. Data characters are coded in discrete separate,

electrical pulses or signal levels. Contrast with analog.

digital service unit (DSU) - Device between a user's data terminal equipment (DTE) and

a common carrier's digital circuits. It formats data for transmission on public carrier widearea networks and ensures that the carrier's requirements for data formats are met.

directory caching - Feature to improve performance. In directory caching, copies of thefile allocation table and the directory entry table are written into the network server's

memory. A file's location can then be read from memory, which is faster than reading it

from a disk.

directory hashing - Feature to improve performance. Directory hashing is a method of

indexing file locations on a disk so the time needed to locate a file is reduced.

directory rights - Restrictions specific to a particular directory.

directory services - Network service that provides information about an entity of interest.It is like an electronic phone book to help network clients find services. There are several

designs, including the X.500 standard, the Domain Name System and Novell's NetWare

Directory Services.

directory structure duplication - Feature that protects data from failures in network

hardware. A hard disk's directory and file allocation tables contain the address

information the operating system needs to determine where to store or retrieve data. Toreduce the possibility of losing this information, the network operating system (NOS)

maintains duplicate copies of both the directory table and the file allocation table on

separate areas of the hard disk. If the primary copy is lost or destroyed, the NOS uses thesecondary copy.

directory verification - Feature that protects data from failures in network hardware. Eachtime the server is turned on, the network operating system performs a consistency check

on duplicate sets of directory and file allocation tables to verify that the two copies are

identical.

disk duplexing - Feature that protects data from failures in network hardware. In disk

duplexing, all data on one hard disk is duplicated on a second hard disk on a separate

channel. Disk writes made to the original disk are also made to the second disk. If theoriginal disk or channel fails, the duplicate disk takes over automatically.

disk mirroring - Feature that protects data from failures in network hardware. In disk mirroring, all data on one hard disk is duplicated on a second hard disk on the same

channel. Disk writes to the original hard disk are also written to the second hard disk. If

the original disk fails, the duplicate disk takes over automatically.



distributed application - An application that operates in a distributed computing

environment, where application modules may run on different systems.

distributed computing - A computer operating environment that may involve computers

of differing architectures and data representation formats that share data and system

resources.

distributed network - A computer network on which processing is shared by many

different parts of the network. Processing may be shared by client (local) computers, fileservers, print servers and application servers such as database servers. Distributed

processing enables the most efficient use of processing power because available

processors can be dynamically assigned as either general or job specific processors,

depending on the type of work to be done and the existing work load. Distributed processing also enables duplication and distribution of key services, such as directory

services, so that full services remain available regardless of the failure of individual parts

of the network.

distributed processing - A technique to enable multiple computers to cooperate in the

completion of tasks, typically in a networked environment. Each computer thatcontributes to the completion of the total task actually does so by completing one or more

individual subtasks independently of its peers, reporting the results from its subtasks as

they are completed.

domain - In the Internet, a part of a naming hierarchy. Syntactically, an Internet domain

name consists of a sequence of names separated by periods. In the network operating

system and OSI, it is generally used as an administrative partition of a complexdistributed system.

Domain Name System (DNS) - Distributed name/address database used on the Internet.

DOS - A generic term to refer to those operating systems that use commands rather than

having a graphical user interface. The most common of these are DR DOS, MS-DOS andPC DOS.\

downsizing - The trend to off-load some applications from proprietary mainframe

systems to smaller, less expensive, networked microcomputers.

downtime - Time when a system or network is unavailable.

drag-and-drop function - A mouse pointer operation in which you select an object and

place it in a new location. For example, to print a document, you drag its icon to the

printer icon and drop it there.

driver - See device driver.



dumb terminal - Simple CRT and keyboard with limited capabilities such as display and

edit functions.

elevator seeking - Feature to improve performance. Elevator seeking allows the disk

read-write head to pick up files in the direction it is traveling across the disk rather than

picking them up in the order they were requested.

E-mail (electronic mail) - A method of file transfer and message sending among

workstations.encryption Scrambling or coding of data for security.

engine - The core of a database or of an application.

error detection - Process of determining whether one or more bits have changed from aone to a zero, or vice versa, during transmission.

Ethernet - A network cable and access protocol scheme originally developed by DEC,

Intel and Xerox but now marketed primarily by DEC and 3Com.

EtherTalk - AppleTalk packets encapsulated to run on Ethernet cables.

expansion - Increasing the capability of a microcomputer by adding hardware that

performs a task that cannot be done with the basic system.

Extended Binary Coded Decimal Interchange Code (EBCDIC)

Eight-bit code defined by IBM. Includes values for control functions and graphics.

FCONSOLE - Utility used to access information from the network server and fine-tune

its performance. It is a virtual console utility that allows the operator to control a server

from any station on the network.

fiber-optic cable - High-bandwidth transmission medium that allows data to be

transmitted by modulating a light wave through a special glass or plastic fiber.

file allocation table (FAT) - A FAT keeps track of file locations in a particular volume.

The network operating system (NOS) divides each volume into blocks and stores files on

the volume in these blocks. If the file consists of one or more blocks, the file may bestored in blocks that are not adjacent. The FAT keeps track of the block numbers where

different parts of the file are located. To retrieve a file, the NOS searches through the

FAT until it finds the FAT entries and corresponding block numbers for the requestedfile.

file sharing - An important feature of networking that allows more than one user to accessthe same file at the same time.

File Transfer, Access, and Management (FTAM) - The Open System Interconnection

(OSI) remote file service and protocol.



firmware Set of software instructions that are set, permanently or semipermanently, into

integrated circuitry.

gateway - A hardware/software package that runs on the OSI application layer and allows

incompatible protocols to communicate; includes X.25 gateways. Usually connects PCsto a host machine, such as an IBM mainframe.

gigabyte (GB) - A unit of measure for memory or disk storage capacity. Ten to the ninth power (one billion) bytes.

groupware - A type of software that supports concurrent use of objects (such as

documents, calendars and spreadsheets) by multiple LAN users.

Hierarchical File System (HFS) - Attached to AFP in the Macintosh operating system. It

manages files and directories.

High-Level Data Link Control (HDLC) - Communications protocol defined for high-

level, synchronous connections to X.25 packet networks. Similar in almost all respects toSDLC. See also synchronous.

High-Level Language/Application Program Interface (HLLAPI) - Application programming interface designed for use with high-level languages.

host - A computer, attached to a network, that provides services to another computer

beyond simply storing and forwarding information. Usually refers to mainframe andminicomputers.

Hot Fix - Feature that protects data from failures in network hardware. When the Hot Fixfeature is activated, a small portion of a hard disk's storage space is set aside as a Hot Fix

redirection area. When read-after-write verification determines that there is a bad data

block on the disk, Hot Fix redirects data that was to be stored in the bad block to the HotFix redirection area. Hot Fix marks the defective block as bad, and the server will not

attempt to store data there again.

hub - Concentrator or repeater at which node connections meet in a star physical layout.

hypertext - A method for storing, retrieving and presenting information based on the

processing power of computers. Allows computerized linking and almost instantaneousretrieval of information based on a dynamic index.

Institute of Electrical and Electronic Engineers (IEEE) - Creates networking standards for cabling, electrical topology, physical topology and access schemes.

intelligent hub - Unit combining the function of a hub with processing capabilities.



Integrated Services Digital Network (ISDN) - A CCITT standard that covers a wide

range of data communications issues but primarily the total integration of voice and data.

Already having major effects on exchange and multiplexer design.

interface - Point at which a connection is made between two elements so that they can

work together.

International Standards Organization (ISO) - Based in Paris, this organization develops

standards for international and national data communications.

Internet - Collection of networks and gateways that use the TCP/IP suite of protocols.

Lowercase, it is an abbreviation for internetwork.

internetwork - Two or more networks connected by an internal or external router.

Internetwork Packet Exchange (IPX) - A protocol that allows the exchange of message

packets on an internetwork.

interoperability - Ability for devices on a heterogeneous network to transmit and sharedata.

jabber - State of a network adapter in which a network device continuously transmits.

journaling - The process of logging system activity to facilitate a fast restart when

needed.

kernel - The core of an operating system that is responsible for managing system

resources.

kilobits per second (kbit/s) - Unit of measure for data transfer rates; two to the 10th

power (1,024) bits per second.

kilobyte (KB) - A unit of measure for memory or disk storage capacity; two to the 10th

power (1,024) bytes.

kilobytes per second (kbyte/s) - One thousand twenty-four bytes per second. Unit of measure commonly used for transfer rates to and from peripheral devices.

local area network (LAN) - A system that links computers together to form a network,usually with a wiring-based cabling scheme. LANs connect personal computers and

electronic office equipment, enabling users to communicate, share resources such as data

storage and printers, and access remote hosts or other networks.

LocalTalk - Shielded twisted-pair cable introduced by Apple.



logical unit (LU) - Terminal emulation program or application in an SNA network. LUs

can communicate with host systems and applications (LU Type 0, 1, 2, 3, 4 and 7) or

with other LUs of the same type (LU Type 6.0, 6.1 and 6.2 only).

login script - A set of instructions that directs your workstation to perform specific

actions when you log in to the network. The network supervisor can create a system-widelogin script (which is the same for all users on the network) that instructs all workstations

to perform the same actions upon login. Your individual login script executes after the

system-wide login script. It specifies your individual drive mappings.

mainframe computer - A large-scale computer (such as those made by Burroughs,

Control Data, IBM, Univac and others) normally supplied complete with peripherals and

software. Also called a host or CPU. Contrast with minicomputer and desktop computer.

media - Plural of medium. Physical paths over which communications flow, such as

copper wires, coaxial cable or optical fiber.

megabits per second (Mbit/s) - Unit of measure for data transfer rates; two to the 20th

power (1,048,576) bits per second.

megabyte (MB) - A unit of measure for memory or disk storage capacity; two to the 20th

power (1,048,576) bytes.

message - Logical grouping of information at the application layer.

minicomputer - A small-scale or medium-scale computer (such as those made by DataGeneral, DEC, Hewlett-Packard and others) that usually services dumb terminals.

Contrast with mainframe computer and desktop computer.

modem - Literally modulator/demodulator. Converts digital data into analog (waveform)

signals for transmission along media that carry analog signals and converts received

analog signals back into digital data for use by the computer. With the advent of digitallines, there is a also a new kind of modem, called a digital modem, that doesn't actually

modulate or demodulate signals but is merely responsible for their transmission over

digital lines.

multicast - Special form of broadcast in which copies of the packet are delivered to

multiple stations, but only a subset of all possible destinations.

multiple name space support - The method that allows various workstations running

different operating systems to create their own familiar naming conventions. Different

operating systems have different conventions for naming files, but with multiple namespace support, the name spaces supported on a volume are configurable so that each file

on a given volume has a name that any workstation can recognize.

Multiple Virtual Storage (MVS) - IBM operating system for large host systems.



multiplexer - Device that allows a single communications circuit to take the place of

several parallel ones; often used to allow remote terminals to communicate with front-end processor ports over a single circuit.

multitasking - The ability to run two or more programs (tasks) on one computer at thesame time. The tasks take turns using available I/O and CPU cycles.

multivendor network - Network comprised of components from different vendors.

NetBIOS (Network Basic Input/Output System) - A programmable entry into the network

that allows systems to communicate over network hardware using a generic networking

API that can run over multiple transports or media.

NetView - IBM network monitoring software for SNA networks.

network - A system that sends and receives data and messages, typically over a cable. Anetwork enables a group of computers to communicate with each other, share peripherals

(such as hard disks and printers), and access remote hosts or other networks.

network adapter - The hardware installed in workstations and servers that enables them to

communicate on a network. See also adapter.

network computing - A multivendor computing environment that integrates local and

wide area network technologies to provide enterprise-wide connectivity.

Network File System (NFS) - A distributed file system network protocol developed by

Sun Microsystems.

node - Device that is connected to a network and is capable of communicating with other

network devices.

noise - Unwanted changes in waveform that occur between two points in a transmission

circuit.

nondedicated - A device that performs multiple simultaneous functions. For example, anondedicated network server runs the network functions and performs as a workstation.

See also dedicated.

open architecture - An architecture that is compatible with hardware and software from

any of many vendors.

OPEN LOOK - AT&T's non-proprietary GUI standard for 2-D and 3-D graphics,

implemented by Sun Microsystems; includes a window manager and a toolkit.



Operation, Administration and Management (OA&M) package - A UnixWare menu-

based interface to a suite of system administration and maintenance utilities.

operating system (OS) - Software that manages a computer system. It controls data

storage, input and output to and from the keyboard and other peripheral devices, and the

execution of compatible applications.

OS/2 - An operating system that uses a graphical user interface and was designed by

IBM.

OSF/Motif - The Open Software Foundation's non-proprietary GUI standard; includes a

window manager and a toolkit.

OSI (Open Systems Interconnection) reference model - A model for network

communications consisting of seven layers that describe what happens when computers

communicate with one another.

packet - The unit of information by which the network communicates. Each packet

contains the identities of the sending and receiving stations, error-control information, arequest for services, information on how to handle the request and any necessary data that

must be transferred.

packet assembler/ disassembler (PAD) - Device or program used to create packets of data

for transmission over a CCITT X.25 packet data network and to remove data from the

received packets. The most common is a CCITT X.29 PAD, used for packetizing and

depacketizing asynchronous ASCII data.

peer-to-peer communication - Communication directly between devices that operate on

the same communications level on a network, without the intervention of anyintermediary devices such as a host or server. A peer-to-peer communication method (or

protocol) defines only the basic mechanisms used to transfer data; it need not specify

when or why peer application programs or nodes interact or how communication betweensuch applications or nodes should be organized in a distributed environment. The latter

problems fall into the domain of the peer-to-peer operating system (see peer-to-peer

network below).

peer-to-peer network - A network consisting of nodes (computers) which all have both

client and server capabilities and on which communication and data sharing is carried on

directly between nodes, rather than being arbitrated by an intermediary node. On a peer-to-peer network all nodes run the same peer-to-peer operating system, which gives them

both client and server capabilities.

performance tuning - Monitoring and analyzing the net performance of a system and

adjusting its configuration to obtain optimum performance.

physical address - Data-link layer address of a network device.



physical unit (PU) - A node in an SNA network supporting one or more logical units

(LUs).

pkgadd - A UnixWare command that simplifies the process of installingoperating system

extensions and third-party software.

platform - Term used as a generic reference to all possible choices for some specific part

of the computing environment. For example: desktop operating system platform (couldinclude DOS, OS/2, and so on) or network operating system platform (NetWare, LAN

Manager, and so on).

port - For hardware, a connecting component that allows a microprocessor tocommunicate with a compatible peripheral. For software, a memory address that

identifies the physical circuit used to transfer information between a microprocessor and

a peripheral.

protocol - Set of rules that allow computers to connect with one another, specifying the

format, timing, sequencing and error checking for data transmission.

protocol suite - A collection of networking protocols that provides the communications

and services needed to enable computers to exchange messages and other information,typically by managing physical connections, communications services and application

support.

query - Process of extracting data from a database and presenting it for use.

queue - A line or list formed by items waiting for service, such as tasks waiting to be

performed, stations waiting for connection, or messages waiting for transmission.

read-after-write verification - Feature that protects data from failures in network

hardware. When the network operating system writes data to a block on the hard disk, it

reads back the data and compares it to the original data still in memory. If the data fromthe disk matches the data in memory, the data in memory is released. If the data does not

match, Hot Fix marks that block on the disk as bad and redirects the data to another

location on the hard disk.

real-time - An on-line computer that generates output nearly simultaneously with the

corresponding inputs. Often, a computer system whose outputs follow its inputs by only a

very short delay.

record locking - This feature on the network operating system prevents two users from

writing simultaneously to the same record.

redundancy - A duplicate capacity that can be called upon when a failure occurs; having

more than one path to a signal point.



remote dialback - Dials number back to confirm user's number. It is a security method

procedure.

rights - Security feature. Rights control which directories and files a user can access and

what the user is allowed to do with those directories and files. Rights are assigned to

directories and files by the network supervisor.

router - A software and hardware connection between two or more networks, usually of

similar design, that permits traffic to be routed from one network to another on the basisof the intended destinations of that traffic. A router, formerly known as an internal or

external bridge, can connect networks that use different network adapters or transmission

media as long as both sides of the connection use the same protocols. If a router is located

in a server, it is called an internal router; if located in a workstation, it is called anexternal router.

Sequenced Packet Exchange (SPX) - A protocol by which two workstations or

applications communicate across the network. SPX uses IPX to deliver the messages, butSPX guarantees delivery of the messages and maintains the order of messages on the

packet stream.

server - A computer on the network capable of recognizing and responding to client

requests for services. These services can range from basic file and print services tosupport for complex, distributed applications. For example, a distributed database

management system can create a single logical database across multiple servers.

Service Advertising Protocol (SAP) - A feature that advertises the services available onthe Applications Server.

shielded cable - Cable that has a layer of insulation to reduce electromagnetic interface.

spanning - A technique for improving I/O performance by placing frequently-used

segments of a file system or database on separate disks.

standalone - A computer that is not connected to a network.

store-and-forward - Message-switching technique in which messages are temporarilystored at intermediate points before being transmitted to the next destination.

striping - A technique for improving I/O performance by interleaving file systems or data bases across multiple disks.

supervisor - The person responsible for the administration and maintenance of a network or database. A supervisor has access rights to all volumes, directories and files.

synchronous - A data transmission mode in which synchronization is established for an

entire block of data (message). See also asynchronous.



Synchronous Data Link Control (SDLC) - IBM-defined link-control protocol that is

code-independent.

System Application Architecture (SAA) - A set of IBM-defined standardsdesigned to

provide a consistent environment for programmers and users across a broad range of IBMequipment, including microcomputers, minicomputers and mainframes.

System Fault Tolerance (SFT) - Duplicating data on multiple storage devices so that if one storage device fails, the data is available from another device. There are several

levels of hardware and software system fault tolerance. Each level of redundancy

(duplication) decreases the possibility of data loss.

System Network Architecture (SNA) - IBM network architecture, defined in terms of its

functions, formats and protocols.

TCP/IP (Transmission Control Protocol/Internet Protocol) - A protocol suite and relatedapplications developed for the U.S. Department of Defense in the 1970s and 1980s

specifically to permit different types of computers to communicate and exchangeinformation with one another. TCP/IP is currently mandated as an official U.S.

Department of Defense protocol and is also widely used in the UNIX community.

telephony - Generic term to describe voice telecommunications.

Telnet - Protocol in the TCP/IP suite that governs character-oriented terminal traffic.

terminal - A device, usually equipped with a keyboard and display, capable of sending

and receiving data over a communications link.

terminal emulation - Software that allows a microcomputer to function as a dumb

terminal.

throughput - Net data transfer rate between an information source and an information

destination.

topology - The physical layout of network components (cable, stations, gateways, hubsand so on). There are three basic interconnection topologies-star, ring and bus networks.

transaction - A specific delimited amount of processing, intended to be an indivisibleaction.

Transaction Tracking System (TTS) - Feature that protects data from failures in network hardware. TTS protects the integrity of databases by backing out of incomplete

transactions that result from a failure in a network component.

transparent - Function that operates without being evident to the user.



twisted-pair wiring - Two wires, usually loosely spun around each other to help cancel

out any induced noise in balanced circuits.

uninterruptible power supply (UPS) - A backup power unit that provides continuous

power even when the normal power supply is interrupted.

UNIX - Operating system developed by AT&T Bell Laboratories. Allows a computer to

handle multiple users and programs simultaneously.

UnixWare operating system (OS) - Novell's UNIX operating system for 80xxx

processors.

UPS monitoring - Feature that protects data from failures in network hardware. A third-

party uninterruptible power supply (UPS) provides power to the server during power

fluctuations and outages. The network operating system's UPS monitoring feature

monitors the status of the UPS attached to the server.

user - Any person who attaches to a server or host.

user accounts - Security feature. Each user on a network has a user account. This account

determines what name the user uses to log in to the network, the groups the user belongsto and what trustee assignments the user has. User accounts are maintained by the

network supervisor.

value-added process (VAP) - An application that runs on top of network operatingsystems. VAPs tie in with the network operating system so that print servers, archive

servers and database servers can provide services without interfering with the network's

normal operation.

VAX - A Digital Equipment Corporation minicomputer.

vector graphics (images) - Graphics displayed using a technology that specifies how an

image is represented by using vector notation; for example, a starting point, a length and

the direction that the line to be drawn from the starting point is to take. From a

mathematical perspective, a vector graphics image is simply a collection of individuallines or vectors.

vertical application - An application that is specific to one area of use. For example: anaccounting application or a legal application.

virtual - Conceptual or appearing to be, rather than actually being.

VMS (Virtual Memory System) - Operating system for DEC VAXs.



wide area network (WAN) - A WAN is two or more LANs in separate geographic

locations connected by a remote link.

Windowing Korn Shell (WKSH) - A UNIX tool for developing windowing applications

that incorporates the MoOLIT toolkit. It provides a comprehensive prototyping facility

for exercising the application early in the development cycle.

workgroup - Two or more individuals on a LAN who share files, databases and other

resources.

workstation - Any individual personal computer that is connected to a network.

X11 - X Windows System, version 11.

X.25 - A CCITT standard that defines the communications protocol for access to packet-

switched networks.

X.400 - Open Systems Interconnection (OSI) standard that defines how messages are to

be encoded for the transmission of electronic mail and graphics between dissimilar computers and terminals; defines what is in an electronic address and what the electronic

envelope should look like. The X.400 standards are a subset of, and conform to, the X.25

standard approved by the Consultative Committee for International Telegraphy andTelephony (CCITT).

X Windows - Standard set of display-handling routines developed at MIT for UNIX

workstations; they allow the creation of hardware-independent graphical user interfaces.

zone - On a local area network such as AppleTalk, a subgroup of users within a larger

group of interconnected networks.

Documents

Network Terms