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Monster Media 1993 #2
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LAN GLOSSARY EDITED BY BONNY HINNERS
1 BASE5 An implementation of the StarLAN IEEE Standard on a
baseband medium at 1 megabit per second. The maximum segment
length is 500 meters.
10BASE2 An implementation of the Ethernet IEEE standard on thin
coaxial cable, a baseband medium, at 10 megabits per second. The
maximum segment length is just under 200 meters.
10BASE5 An implementation of the Ethernet IEEE standard on
twinaxial cable, a baseband medium, at 10 megabits per second.
The maximum segment length is 500 meters.
10BASE-T An implementation of the Ethernet IEEE standard on 24
gauge unshielded twisted-pair wiring, a baseband medium, at 10
megabits per second.
3+3COM Corporation's networking system implementing parts of
Xerox's XNS (Xerox Network Systems) and microsoft/IBM PC LAN
protocols.
802.3 Defined by the IEEE, these standards govern the use of
CSMA/CD (Carrier Sense Multiple Access/Collision Detection)
network access method used by Ethernet networks.
802.4 Defined by the IEEE, these standards govern the use of the
token bus network access method.
802.5 Defined by the IEEE, these standards govern the use of the
token ring network access method.
AC (Access Control) On Token Ring networks, this byte contains
the token indicator and frame priority.
ACCESS METHOD set of rules by which networks arbitrate their use.
ACCOUNTING MANAGEMENT reports costs for network resources
requested by users and groups. It is also one of five categories
of network management defined by the ISO.
ACSE (Association Control Service Element) An application-level
protocol. active/passive device A device such as a Token Ring MAU
(Multistation Access Unit) that supplies current for the loop is
considered active. One that does not supply current is considered
passive.
ADDRESS a unique identifier assigned to networks and stations so
that each device can be separately designated to receive and
reply to messages.
AFP (Apple Talk Filing Protocol) In an AppleTalk network, this
presentation-level protocol governs remote file access.
ALAP (AppleTalk Link Access Protocol) In an AppleTalk network,
this link access layer (or data link layer) protocol governs
packet transmission on LocalTalk.
ANALOG a transmission scheme that continually varies the waveform
over an infinite range of voltage.
ANOLOG RECORDING transfer method that converts data from digital
to analog format.
ANSI (American National Standards Institute) Principal group in
the U.S. for defining standards. ANSI represents the U.S. in the
ISO.
API (Application Program Interface) A set of programming
functions and routines that provides access between protocol
layers, such as between an application an dnetwork services.
APPC (Advanced Program-to-Program Communications) Primarily for
personal computers in an SNA (System Network Architecture)
network to communicate with a mainframe host, this implementation
of LU (Logical Unit) 6.2 uses high-level program interaction.
APPLESHARE apple computers network system implementing the
AppleTalk protocols.
APPLETALK PROTOCOL suite defined by Apple Computer for connecting
computers and peripherals using shielded twisted-pair wiring and
transfer rates of about 230.4 kilobytes per second. The network
and transport-level protocols include Datagram Delivery Protocol
(DDP), AppleTalk Transaction Protocol (ATP), AppleTalk Session
Protocol (ASP), and the Name Binding Protocol (NBP).
APPLICATION LAYER the seventh layer of the OSI (Open Systems
Interconnection) model for data communications. It defines
protocols for user or application programs,
ARCnet A 2.5 megabit per second baseband, token-passing network
designed by Datapoint Corporation that supports up to 255 nodes.
ARP (Address Resolution Protocol) TCP/IP protocol for determining
a DLC (data-link control) address from an IP (Internet Protocol)
address.
ARPA (Advanced Research Projects Agency) The group within the
U.S. Department of Defense that developed ARPANET, the first
major packet-switched network.
ASCII (American Standard Code for Information Interchange) A
seven-bit binary code standardized by ANSI for use by personal
computers and some mainframes to represent alphanumeric and
graphical characters. An additional bit is included to for an
eight-bit character byte.
ASYNCHRONOUS TRANSMISSION a data transmission technique
controlled by start and stop bits at each end of a character and
characterized by an undetermined time interval between
characters.
AUDIT TRAILS a record of events on the network including when
users requested specific resources.
AUI (Attachment Unit Interface) Connector used with thick
Ethernet that often includes a drop cable.
BACK-END Database server functions and procedures for
manipulating data.
BACKBONE CABLE on which two or more stations or networks may be
attached.
BACKUP OFF-LINE copies of data for protection against system
failures.
BALUN (balance, unbalance) Device for matching impedance between
a balanced and an unbalanced line, usually twisted-pair wire and
coaxial cable respectively.
BANDWIDTH used to indicate transmission capacity in Hertz, this
represents the difference between the highest and lowest
frequencies available for signals.
BASEBAND A network in which the entire bandwidth of the
transmission medium is used by a single digital. Unlike
broadband, no modulation techniques are used.
BAUD MEASUREMENT of signaling speed indicating line changes per
second, where line changes can represent one or more bits. Only
for line changes representing a single bit, baud is equal to bits
per second.
BINDARY NETWARE database of user names, passwords, groups, and
accounting information.
BNC Standardized connector used with Thinnet and coaxial cable.
BOOT PROM (Boot Programmable Read-Only Memory) A processor chip
usually mounted on the network interface card that enables a
personal computer to load the operating system from the network.
BRIDGE A device operating at the data link layer to connect local
or wide-area networks that use the same protocol.
BROADBAND A network in which the bandwidth can be shared by
multiple simulations signals that are encoded with radio-
frequency modulation.
BROADCAST The address for all nodes in a network or the message
sent to all nodes.
BROUTER A device that can route specific protocols and bridge
others, thus combining the capabilities of bridges and routers.
BUFFER A temporary storage location that provides uninterrupted
data flow between devices as keyboards and processors or
processors and printers until the data from one be accepted by
the other.
BUS TOPLPOGY A network topology in which nodes are connected to a
single cable with terminators at each end.
CACHE MEMORY location set aside to store frequently accessed data
for improved system performance.
CASCADED STARS Topology in which a centralized multiport repeater
serves as the focal point for many other multiport repeaters.
CCITT (Consultstive Committee for International Telegraphy and
Telephony) Group within the international Telecommunications
Union (ITU) that defines data communications standards.
Cheapernet See Thinnet
CLIENT A node that requests network services from a server.
CLIENT-SERVER computing A technique with which processing can be
distributed between nodes requesting information (clients) and
those maintaining data servers.
CMIP/CMIS (Common Management Information Protocol/Services)
Standards described by the OSI (Open System Interconnection) for
managing heterogeneous networks.
COAXIAL CABLE data transmission medium with a single-wire
conductor insulated from EMI/RFI (Electromagnetic
Interference/Radio Frequency Interference).
COMMON CARRIER a licensed, private utility company that supplies
data and voice communications services.
CONCURRENCY CONTROL rules that regulate data access to multiple
users on a database server.
CONTENTION NETWORK access method in which nodes compete for
transmission by sending signals at will.
CPU (Central Processing Unit) A personal computer's primary
microprocessor chip.
CRC (Cyclical Redundancy Check) Error checking technique in which
bytes at the end of a packet are used by the receiving node to
detect transmission problems. The bytes represent the result of
a calculation performed on the data portion of the packet before
transmission. If the results for the same calculation on the
received packet are not equal to the transmitted results, the
receiving node can request that the packet be resent.
CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)
Network access method using contention similar to CSMA/CD used by
LocalTalk networks. Unlike CSMA/CD, in this method the sending
node requests permission to send from the intended receiving
node. If the receiving node responds with a clear to send
signal, transmission begins.
CSMA/CD (Carrier Sense Multiple Access/Collision Detection)
Network access method in which nodes contend for the right to
send data. If two or more nodes attempt to transmit at the same
time, they abort their transmission until a random time period of
microseconds has transpired and then attempt to resend.
DAT (Digital Audio Tape) Medium for storing digital rather than
analog data.
DATA INTEGRITY a measure of accuracy based on error detection.
DATA LINK LAYER2, Layer2 of the OSI (Open Systems
Interconnection) model; it defines protocols governing data
packetizing and transmission into and out of each node.
DATABASE SERVER a computer that stores data centrally for network
users and managers and often uses client-server software to
distribute the processing of that data between itself and nodes
requesting information.
DATAGRAM IN THE INTERNET PROTOCOLS (IP), this refers to a packet
containing destination address and data.
DB-9 a standardized connector with 9 pins for token ring and
serial connections.
DB-15 a standardized connector with 15 pins for Ethernet
transceivers.
DB-25 a standardized connector with 25 pins for parallel or
serial connections.
DCE (Data Communications Equipment) A device that establishes,
maintains, and terminates a data communications session and
provides encoding or conversion if necessary.
DDD (Direct Distance Dialing) A telephone service with which a
subscriber can call someone outside the area without requiring
operator assistance.
DECNET Digital Equipment Corporation's network system and
protocols.
DEDICATED SERVER a node on which applications are limited to
maintaining network resources; no user applications are
available.
DES (Data Encryption Standard) U.S. government standard for data
encryption.
DID (Direct Inward Dialing) A telephone service with which
subscribers can have calls within a system routed to a specified
telephone without switchboard assistance.
DISK DUPLEXING fault tolerance method in which two disk
controllers are used in a single server.
DLC (Data Link Control) Protocols governing packet information
including destination address, source address, and control
information.
DMA CHANNEL (Direct Memory Access Channel) Memory access method
independent of the CPU (Central Processing Unit).
DNS (Domain Name Service) A TCP/IP protocol for discovering and
maintaining network resource information distributed among
different servers.
DOS (Disk Operating System) The operating system developed by
Microsoft and often ported by computer manufactures such as IBM
to run specifically on their computers.
DOWN TIME Period when the network is unavailable to users.
DQDB (Distributed Queue Dual Bus A communication technique
proposed for MANS (Metropolitan Networks).
EBCDIC (Extended Binary Coded Decimal Intercharge Code) An eight-
bit binary code standardized by IBM for use by its mainframes to
represent alphanumeric and graphical characters.
EEHLLAPI (Entry Emulator High Level Language Applications
Programming Interface) An IBM API Subset of HLLAPI.
EISA (Expanded Industry Standard Architecture) Compaq's improved
bus architecture that is backwards compatible with ISA (Industry
Standard Architecture).
ELECTRONIC MAIL (e-mail) An application with which users can send
information to other users with whom they share a data
communication connection.
EMI/RFI (Electromagnetic Interference/Radio Frequency
Interference) A form of "noise" on data transmission mediums that
can reduce data integrity and increase transmission errors.
EMULATION The imitation of one device by another.
ENTERPRISEWIDE NETWORK Internetwork connecting all sites of a
single corporation worldwide.
ESDI (Enhanced Small Device Interface) Interface type for
computer adapter and controller boards.
ETHERNET a 10 megabits per second baseband, CSMA/CD network
originally designed by Xerox Corporation.
ETHERNET TALK Apple Talk protocol governing Ethernet
transmissions. Also the apple computer ethernet adapter and
drivers. The first implementation, Phase 1, was replaced by
Phase 2 in 1989.
ETHERTYPE a two-byte code indicating protocol type in an
Ethernet packet.
FAULT MANAGEMENT DETECTS, isolates and corrects network faults.
It is also one of five categories of network management defined
by the ISO.
FAULT TOLERANCE The ability of a system to perform fault
management and continue operating in the event of system
failures.
FC (Frame Control) On token Ring networks, this data supplies the
frame type.
FCC (Federal Communications Commission) Government agency that
supervises, licenses, and controls standard for all forms of
radio and electromagnetic transmissions.
FDDI (Fiber-Optic Data Distribution Interface) A 100 megabits per
second data transfer interface for fiber optic cable.
FIBER OPTIC CABLE glass or plastic fibers over e=which modulated
light pulses from laser or LED (Light Emitting Diode) can
transmit data. It is not subject to interference or electronic
eavesdropping.
FILE LOCKING Method of data management which reserves a file for
the first user that requests it, thus locking out other users.
FILE SERVER A computer that stores data centrally for network
users and managers access to that data. File servers can be
dedicated so that no processes other than network management can
be executed while the network is available, or nondedicated so
that standard user applications can run while the network is
available.
FLAGS signals passed between processes.
FLOW CONTROL hardware or software mechanism such as a buffer that
manages data transmissions when the receiving device cannot
accept data.
FRONT-END Client application for presenting, entering, and
updating data.
FTAM (File Transfer Access and Management) An application level
protocol governing file access.
FTP (File Transfer Protocol) A TCP/IP application protocol
governing file transfer.
GATEWAY a device connecting two or more networks that may use
different protocols and media. Gateways can connect locally or
over wide areas.
GOSIP (Government OSI Profile) A version of the OSI (Open System
Interconnection) Model designed specifically for the U.S.
government.
HDLC (High-level Data Link Control) An ISO protocol for X.25
international communications.
HELICAL SCAN storage method that increases media capacity by
laying data out in diagonal strips.
HETEROGENEOUS NETWORKS, networks composed of hardware and
software from multiple vendors usually implementing multiple
protocols.
HUB a concentrator or repeater in a star topology at which node
connections meet.
IEEE (Institute of Electrical and Electronics Engineers) a
professional organization within the ISO that assists with the
creation of networking standards.
IMPEDANCE MEASUREMENT of resistance to current that a
transmission medium offers. It is measured in ohms.
INTERFACE AREA of connection through which information can be
exchanged.
INTERNET connected networks including those of the National
Science Foundation and the advanced projects research agency.
INTERNETWORK a collection of two or more connected networks that
may be dissimilar.
INTEROPERABILITY The ability to operate and exchange information
in a heterogeneous network.
I/O ADDRESS (Input/Output address) Starting address for data
input and output.
IP (Internet Protocol) TCP/IP protocol governing packet
forwarding.
IPC (Interprocess Communications) a protocol for data exchange
between applications or threads.
IPX (Internetwork Packet eXchange) NetWare protocol similar to IP
(Internet Protocol).
IRQ (Interrupt Request) The method by which hardware devices
request processor attention.
ISA (Industry Standard Architecture) The popular architecture for
personal computer buses, such as the IBM PC, XT, and AT.
ISDN (Integrated Services Digital Network) Protocol proposed for
carrying voice, data, facsimile, and video signals across a
network.
ISO (International Standards Organization) An international
organization that creates networking standards including the OSI
(Open System Interconnections) model.
JABBER NETWORK error caused by an interface card continually
sending corrupted data onto the network.
LAN (Local Area Network) A system of software and hardware
connected by a common data transmission medium and limited to a
geographical area less than about 10 kilometers.
LAN-AWARE applications that have file and record locking for use
on a network.
LAN-IGNORANT applications written for single users only. These
are not recommended for use on LAN's.
LAN-INSTINSIC applications written for client-server networks.
LAN MANAGER MICROSOFT'S network operating system based on OS/2.
LAN SERVER IBM'S implementation of LAN manager.
LAP (Link Access Protocol) Apple Talk protocols including ELAP
for Ethernet and LLAP for LocalTalk.
LAT (Local Area Transport) DECnet protocol governing
communications between terminals and hosts.
LEASED LINE a private telephone line reserved for the leasing
customers use.
LED LIGHT emitting diode.
LLC (logical link control) A layer 2 protocol governing
transmission, also known as the IEEE 802.2 standard.
LOCAL TALK a 230 kilobits per second baseband network using the
CSMA/CA access method.
LOOPBACK a diagnostic test in which a signal is transmitted
across a medium while the sending device waits for tits return.
LOOSELY COUPLED A multiprocessor computer in which the CPUs
(Central Processing Units) have separate memory and system buses.
LU (Logical Unit) An IBM protocol suite primarily for SNA (System
Network Architecture) network.
LU 6.2 (Logical Unit 6.2) An IBM protocol suite governing peer-
tp-peer communications in an SNA (System Network Architecture)
network.
MAC (Medium Access Control) A layer 2 protocol governing access
to transmission media.
MAN (Metropolitan Area Network) A network capable of high-speed
data communications over distances up to about 80 kilometers.
MANCHESTER ENCODING a digital encoding method that describes a
bit value by transition between two signals and that is self-
clocking.
MAP (Manufacturing Automation Protocol) a version of the OSI
(Open System Interconnection) model for manufacturing
environments developed by General Motors.
MAPPING REDIRECTING local resources to network resource.
MAU (Multistation Access Unit) A concentrator or transceiver for
attracting nodes to a transmission medium.
MCA (Microchannel Architecture) IBM's proprietary bus
architecture that offers improved performance over ISA (Industry
Standard Architecture) and is used primarily in PS/2 computer
system.
MIB (Management Information Base) a database of network
management information used by CMIP (Common Management
Information Protocol) and SNMP (Simple Network Management
Protocol).Mirroring a fault tolerance method in which a backup
data storage device maintains data identical to that on the
primary device and can replace the primary if it fails.
MODEM (Modulator-demodulator) a device that converts digital and
analog signals.
MODULATION The alternation of a signal's frequency, phase, or
amplitude.
MOUNT The method in NFS and other networks by which nodes access
network resources.
MULTICAST An address for a selection of nodes in a network, or
the message sent to a selection of nodes.
MULTIPROCESSOR A computer with more than one Central Processing
Unit (CPU) that can be accessed simultaneously by an operating
system adapted to this architecture.
MULTITASKING The process of swapping from one task to another
without losing track of either. Usually accomplished by time
slicing any shared resources.
MULTI-USER SOFTWARE An application designed for simultaneous
access by two or more network nodes. It typically employs file
and/or record locking.
NBP (Name Binding Protocol) AppleTalk protocol for translating
device names to addresses.
NDIS (Network Driver Interface Specification) Specification for a
generic device driver for network interface cards that is
independent of hardware and protocol.
NETBIOS (Network Basic Input/Output System) A widely-used
protocol governing data exchange and network access.
NETWARE Novell's network operating system using IPX (Internetwork
Packet Exchange) and SPX (Sequential Packet Exchange) protocols.
NETWORK A system of software and hardware connected in a manner
to support data transmission.
NETWORK ARCHITECTURE A description of data formats and procedures
used for communication between nodes.
NETWORK LAYER, Layer 3 of the OSI (Open Systems Interconnection)
model; it defines protocols governing data routing.
NETWORK LOADABLE MODULE (NLM) An application or driver that
resides on a netware server to provide additional resource
management capabilities.
NETWORK TOPOLOGY The arrangement of nodes usually forming a star,
ring, tree, or bus pattern.
NFS (Network File System) Sun microsystem's network operating
system based on TCP/IP protocols.
NIC (Network Interface Controller) Adapter board that provides
the physical connection between a computer and the network
medium. Also called network interface card.
NODE any device including servers and workstations connected to a
network; also the point where devices are connected.
NONDEDICATED SERVER a node on which user applications are
available while network resource maintenance applications execute
in the background.
NOS (Network Operating System) Controlling software for a
network, which may run on top of DOS, that oversees resource
sharing and often provides security and administrative tools.
OS/2 Microsofts multi-threaded, multitasking, single-user
operating system.
OSI Model (Open System Interconnection) The seven-layer protocol
model defined by the OSI for data communications.
PACKET a collection of bits comprising data and control
information formatted for transmission from one node to another.
PACKET FILTER the ability to search a packet to determine its
destination and to then route it accordingly. This ability helps
to control network traffic.
PACKET FORWARDING copying the packet to another node without
looking at destination address.
PACKET SWITCHING a data transmission method that routes packets
along the most efficient path and allows a communications to be
shared by multiple connections.
PAD (Packet Assembler/Disassemble) a device for connecting a
terminal or computer to an X.25 network.
PAP (Printer Access Protocol) An appletalk protocol governing
transmissions between workstations and printers or similar
devices.
PCF (Physical Control Fields) The AC (Access Control) and FC
(Frame Control) bytes in a token Ring header.
PEER-TO-PEER a system in which two or more nodes or processes
can initiate communications with each other. Usually describes a
network in which all nodes have the ability to share resources
with other nodes so that a dedicated server can be implemented
but is not required.
PERFORMANCE MANAGEMENT measures and records resource utilization.
It is one of the categories of network management defined by the
ISO.
PHASE MODULATION altering a characteristic of a sine wave,
specifically its phase.
PHYSICAL LAYER, layer 1 of the OSI (Open System Interconnection)
model; it details protocols governing transmission media and
signals.
PINOUTS pin configurations for cabling.
PIPE a device that acts as an interface or buffer between
applications and devices.
POINT-TO-POINT LINK a direct connection between only two nodes.
POLLING an access method with which a hub asks each node in turn
if it has data to transmit.
PRESENTATION LAYER, layer 6 of the OSI (Open System
Interconnection) model; it defines protocols governing data
formats and conversions.
PRINT SERVER a computer that manages printers and print requests
from other nodes.
PRINT SPOOLER an application that manages print requests or jobs
so that one job can be processed while other jobs are placed in a
queue until the printer has finished with preceding jobs.
PROPAGATION DELAY the time required for data to travel from
transmission point to destination.
PROTECTED MODE CPU (Central Processing Unit) mode in which
application must request memory allocations from the operating
system, and these allocations are then protected from other
applications requests.
PROTOCOL a standardized set of rules that specify the format,
timing, sequencing, and/or error checking for data transmission.
PROTOCOL STACK A representation of the hierarchical nature of
protocol suite.
PROTOCOL SUITE a hierarchical set of related protocols.
PUBLISHING making resources available to network users.
QBE (Query By Example) a database front-end that requests the
user to supply an example of the type of data to be retrieved.
QUREY LANGUAGE a programming language that permits users to
retrieve information from the database.
QUEUE an ordered list of items waiting to be processed.
RAM (Random Access Memory) Memory in which data is temporarily
stored processing.
RAM BASE ADDRESS (Random Access Memory Base Address) Starting
address for memory dedicated to a specific task.
RARP (Reverse Address Resolution Protocol) A TCP/IP protocol
governing the translation of a DLC (Data Link Control) address to
an IP (Internet Protocol) address.
REAL MODE CPU (Central Processing Unit) mode in h=which
applications have direct access to physical memory of the
computer.
RECORD LOCKING a method a managing shared data on a network by
preventing more than one user from accessing the same segment of
data at the same time.
REDIRECTOR an application that intercepts request for resources
local to a node on the network and redirects those request
elsewhere on the network.
REPEATER a device that regenerates and often amplifies signals to
extend transmission distance. It is independent of protocol and
media.
RESPONSE TIME the time required between transmission of the last
character of message and reception of the first reply character.
RFC request for comment
RG-58 Coaxial cable with 50-ohm impedance used by Thinnet.
RG-62 Coaxial cable with 93-ohm impedance used by ARCnet.
RING TOPOLOGY a network topology in which nodes are connected to
a closed loop no terminators are required because there are no
unconnected ends.
RJ-11 Four-wire modular connectors for phone lines.
RJ-45 Eight-wire modular connectors for Star Lan networks and
some phone lines.
ROUTE DISCOVERY process through which a router can learn LAN
topology by passing information about its address and the LANs it
connects and receiving the same information from others.
ROUTER a device that connects networks and supports the required
protocols for packet filtering.
RPC (Remove Procedure Call) A protocol governing the method with
which an application activates processes on other nodes and
retrieves the results.
SCSI (Small Computer System Interface) an interface type for
computer adapters and controller boards.
SDLC (Synchronous Data Link Control) A protocol for SNA (systems
network architecture) networks similar to LLC (Logical Link
Control).
SECURITY MANAGEMENT protects a network from invalid accesses. It
is one of the management categories defined by the ISO.
SEF (Source Explicit Forwarding) Security feature that allows
transmissions only from specified stations to be forwarded by
bridges.
SEMAPHORE a method with which multiple applications can
coordinate related operations using messages.
SERVER a computer that provides shared resources, such as files
and printers, to the network.
SESSION an active communications connection between nodes or
applications.
SESSION LAYER, layer 5 of the OSI (Open Systems Interconnection)
model; it defines protocols governing communications between
applications.
SHARED MEMORY portion of memory accessible to multiple processes.
SHEILDED WIRING protected from electromagnetic and radio
frequency interference by metal-backed mylar foil and plastic ar
PVC.
SMTP (Simple Mail Transfer Protocol) governing electronics mail
transmissions.
SNA (Systems Network Architecture) IBM's protocols governing
mainframe communications.
SNMP (Simple Network Management Protocol) TCP/IP protocol
governing network monitoring.
SOCKETS IN API (Application Program Interface) for communications
between Unix and TCP/IP.
SPOOL (Simultaneous Peripheral Operation On-Line) See print
spooler
SPP (Sequenced Packet Protocol) XNS (Xerox Network Systems)
protocol governing sequenced data.
SPX (Sequential Packet Exchange) Novells implementation of SPP
(Sequential Packet Protocol).
SQL (Structured Query Language) a widely used programming
language for manipulating database information.
STA (Spanning Tree Algorithm) A technique for determining the
most desirable path between segments of a multiloop, bridged
network.
STAR LAN AT&T's network operating system implementing CSMA/CD.
STAR TOPOLOGY a network topology in which nodes are connected to
a common device such as a hub or concentrator.
STORE-AND-FORWARD a message switching technique in which messages
are temporarily stored at intermediate points before being
retransmitted to the next destination.
STREETTALK VINES (Virtual Network Software) protocol for
discovering and maintaining network resource information
distributed among different servers.
SYNCHRONOUS TRANSMISSION a data transmission scheme in which the
interval between transmitted characters is fixed so that start
and stop bits are not required.
T1 A 1.544 megabits per second multichannel transmission system
for voice or data provided by long distance carriers.
T-CONNECTOR a T shaped device with two female and one male BNC
connectors.
TCP (Transmission Control Protocol) TCP/IP protocol governing
sequenced data.
TCP/IP (Transmission Control Protocol/Internet Protocol) A
protocol suite developed by ARPA (Advanced Research Projects
Agency).
TELNET TCP/IP protocol governing character-oriented terminal
data.
THICKNET CABLING scheme using twinaxial cable.
THINNET CABLING scheme using 50 ohm coaxial cable.
THREADS Individual processes within a single application.
TIE LINES (Terminal Interface Equipment Lines) long-distance
leased lines reserved for the leasing company.
TIGHTLY COUPLED a multiprocessor computer in which the CPU's
(Central Processing Units) share memory and one system bus.
TOKEN the character sequence passed among nodes in sequence to
indicate which one has permission to transmit.
TOKEN BUS a bus topology network using a token passing access
method.
TOKEN PASSING a network access method that requires nodes to wait
for their turn before transmitting data. Turns are indicated by
a character sequence that passes from one node to the next.
TOKEN RING a 4 megabit per second or 16 megabit per second
network using a ring topology and a token passing access method.
TOP (Technical Office Protocol) a version of the OSI (Open System
Interconnection) model for the office developed by Boeing.
TRANSCEIVER An AUI (Attachment Unit Interface) device for
receiving and transmitting data that often provides collision
detection as well.
TRANSPORT LAYER, layer 4 of the OSI (Open System Interconnection)
model; it defines protocols governing message structure and some
error checking.
TREE TOPOLOGY a network topology in which nodes are connected by
cables to a trunk cable with a central retransmission facility.
TRIGGERS uncompiled code residing on an intelligent database
server.
TWISTED PAIR CABLE a wiring scheme with one or more pairs of 18
to 24 gauge copper strands. The strands are twisted to improve
protection against electromagnetic and radio frequency
interference. Cable may be either shielded or unshielded.
TYPE 1 CABLE Shielded two-pair cable.
TYPE 3 CABLE unshielded twisted pair cable
UNINTERRUPTIBLE POWER supply battery backup system to provide
power in the event of power failures or fluctuations.
Particularly important for network servers, bridges, and
gateways.
UNITY GAIN refers to the balance between signal loss on a
broadband network and signal gain through amplifiers.
UNSHEILDED WIRING not protected from electromagnetic and radio
frequency interference, but covered with plastic and/or PVC.
VALUE ADDED PROCESS (VAP) An application designed to load and run
automatically on a NETWARE server in order to help manage
resources.
VINES (Virtual Network Software) Banyan's network operating
system based on Unix and its protocols.
VIRTUAL CIRCUIT a communications link that appears to be
dedicated circuit and passes sequential packets between devices
usually in a packet switching network.
VTAM (Virtual Telecommunications Access Method) On an SNA
(Systems Network Architecture) network, this application provides
access to shared information.
WAN (Wide Area Network) a network capable of transmissions over
large geographic areas that uses transmissions lines provided by
a common carrier.
WORKSTATION a networked computer typically reserved for end-user
applications.
WORM (Write Once Read Many) Optical disk to which data may be
written once and not altered, but from which data can be
retrieved as often as necessary.
X.25 CCITT protocol governing packet-switched networks using
virtual circuits.
X.400 CCITT protocol governing international electronic mail
transmissions.
X.500 CCITT protocol governing the maintenance of files and
directories on multiple systems.
XNS (Xerox Network Systems) Xerox's data communications
protocols.
ZONE one or more connected AppleTalk networks grouped according
to network usage.