AA Auto Answer AAB All-to-All Broadcast AAL Asynchronous Transfer Mode Adaption Layer AAP Applications Access Point [DEC] AAS All-to-All Scatter AASP ASCII Asynchronous Support Package AAT Average Access Time ABC Atanasoff-Berry Computer (First digital calculating mac ABEND Abnormal End ABI Application Binary Interface ABIOS Advanced BIOS ABS Absolute ABT Abort AC Automatic Computer ACC Accumulator ACD Automated Call Distribution ACDI Asynchronous Communications Device Interface ACE Advanced Computing Environment [SCO] ACF Access Control Field ACH Automated Clearing House ACIAS Automated Calibration Internal Analysis System ACIS American Committee for Interoperable Systems ACK Acknowledgment ACL Access Control List ACM Association for Computing Machinery ACMS Application Control Management System ACP Ancillary Control Program ACROSS Automated Cargo Release and Operations Service System ACS Access ACTS Automated Computer Time Service ACTT Advanced Communication and Timekeeping Technology [Seik ACU Automatic Calling Unit ADA Automatic Data Acquisitions ADC Adaptive Data Compression (protocol) [Hayes] ADCCP Advanced Data Communication Control Procedures ADD Automatic Document Detection [WordPerfect] ADF Automatic Document Feed ADI AutoCad Device Interface (driver) ADL Address Data Latch ADLAT Adaptive Lattice Filter ADMD Administrative Management Domain [X.400] ADP Automatic Data Processing ADPCM Adaptive Differential Pulse Code Modulation ADR Address ADS Application Development Solutions [AT&T] ADSC Address Status Changed ADSL Asymmetrical Digital Subscriber Line ADSR Attack, Decay, Sustain, Release ADT Application Data Types ADU Automatic Dialing Unit AE Above or Equal AEB Analog Expansion Bus [Dialogic] AF Auxiliary carry Flag AFC Automatic Font Change AFD Automatic File Distribution AFII Association for Font Information Interchange AFP Appletalk Filing Protocol [Macintosh] AGC Automatic Gain Control AI Analog Input AIA Applications Integration Architecture [DEC] AIF Audio Interchange Format AIIM Association for Information and Image Management AIN Advanced Intelligent Network [Bell Atlantic] AIP Application Integration Program AISB Association of Imaging Service Bureaus AISP Association of Information Systems Professionals AIX Advanced Interactive Executive [IBM] ALC Arithmetic and Logic Circuits ALE Address Latch Enable ALGOL Algorithmic Oriented Language (see IAL) ALR Advanced Logic Research, Inc. ALT Alternate (mode) ALU Arithmetic Logic Unit AMANDDA Automated Messaging and Directory Assistance AMD Active Matrix Display AMMA Advanced Memory Management Architecture [Everex Systems AMPS Advanced Mobile Phone Service ANCOVA Analysis of Covariance ANI Automatic Number Identification ANN Artificial Neural Network ANOVA Analysis Of Variance ANSI American National Standards Institute AO Analog Output AOCE Apple Open Collaboration Environment AOE Application Operating Environment [AT&T] AOL America Online AOS Add Or Subtract AP Adjunct Processor APA Adaptive Packet Assembly APAR Authorized Program Analysis Report [IBM] APAREN Address Parity Enable [IBM] APC Asynchronous Procedure Call APCUG Association of PC User Groups API Application Program Interface APIC Advanced Programmable Interrupt Controller [Intel] APL A Programming Language (Mathematics) APM Advanced Power Management [IBM OS2] APPC Advanced Program-to-Program Communications [IBM] APPI Advanced Peer-to-Peer Internetworking APPN Advanced Peer-to-Peer Networking [IBM] APS Asynchronous Protocol Specification APSE ADA Programming Support Environment APT Address Pass Through ARA Apple Remote Access ARCA Advanced RISC Computing Architecture ARCnet Attached Resource Computer Network ARL Adjusted Ring Length ARLL Advanced Run Length Limited ARM Advanced RISC Machine (processor) ARMA Association of Records Managers and Administrators ARP Address Resolution Protocol [Novell] ARPA Advanced Research Projects Agency ARPL Adjust Requested Privilege Level ARQ Automatic Repeat Request ARTIC A Real-Time Interface Copressor [IBM] ARTS Asynchronous Remote Takeover Server ARTT Asynchronous Remote Takeover Terminal ARU Audio Response Unit AS Autonomous System [Internet] AS3AP ANSI SQL Standard Scalable and Portable ASAP As Soon As Possible ASCII American Standard Code for Information Interchange ASIC Application-Specific Integrated Circuit ASIT Advanced Security and Identification Technology ASL Adaptive Speed Levelling ASN Abstract Syntax Notation ASP Association of Shareware Professionals ASPI Advanced SCSI Programming Interface [Adaptec] ASPS Advanced Signal Processing System ASR Automatic Send-Receive AST AST Research, Inc. (named from first initials of the fo ASYNC Asynchronous AT Advanced Technology ATA Advanced Technology Attachment ATDP Attention Dial Pulse ATDT Attention Dial Tone ATE Automated Test Equipment ATG Advanced Technology Group ATH Attention Hang-Up ATM Adobe Typeface Manager ATR Automatic Terminal Recognition ATS Administrative Terminal System ATTN Attention ATTRIB Attribute (also ATR) AT&T American Telephone and Telegraph AUDIT Automated Data Input Terminal AUI Attachment Unit Interface AUP Acceptable Use Policy [Internet] AUTO Automatic AUTOEXE Automatic Execution AUX Auxiliary AVA Audio Visual Authoring [IBM] AVC Audio Visual Connection [IBM] AVG Average AVI Audio Visual Interleaved [Microsoft] AVR Automatic Voice Recognition AWG American Wire Gage AWK (Unix language named after its authors... Al Aho, Peter AWS Advanced Workstations and Systems (group) [IBM] AX Architecture Extended A/D Analog to Digital A/P Accounts Payable A/R Accounts Receivable B2X Binary To Hexadecimal [REXX] BAK Binary Adaption Kit [Microsoft] BAL Basic Assembly Language BAM Boyan Action Module BARTS Bell Atlantic Regional Timesharing BASIC Beginner's All-purpose Symbolic Instruction Code BASM Built-In Assembler BBS Bulletin Board System BCC Blind Carbon Copy BCD Binary Coded Decimal BCL Batch Command Language BCP Bulk Copy Program BCPL Basic Computer Programming Language BCR Byte Count Register BDOS Basic Disk Operating System BE Below or Equal BEL Bell BELLCOR Bell Communications Research BER Basic Encoding Rules [HP] BERT Bit Error Rate Test/Tester BF Bad Flag BFT Binary File Transfer BGE Branch if Greater or Equal BGP Border Gateway Protocol BGT Branch if Greater Than BHI Branch if Higher BHIS Branch if Higher or Same BI Binary Input BiDi Bidirectional BIM Beginning of Information Marker BINAC Binary Automatic Computer BIOS Basic Input/Output System BIS Business Information System BISDN Broadband Integrated Services Digital Network BiSYNC (See BSYNC) BIT Binary Digit BITNET Because It's Time Network BITNIC Bitnet Network Information Center BIU Bus Interface Unit BIX Byte Information Exchange (BBS) BKSP Backspace BL Backlit BLAST Blocked Asynchronous Transmission (protocol) [Communica BLE Branch if Less or Equal BLK Block BLMC Buried Logic Macrocell BLOB Binary Large Object BLOS Branch if Lower Or Same BMI Branch if Minus BMIC BusMaster Interface Controller [Intel] BMP Batch Message Processing Program BNE Branch if Not Equal BO Binary Output BoB Break-out Box BOM Beginning Of Message BOOTP Bootstrap Protocol [Internet] BORPQU Borland Pro Quattro BORQU Borland Quattro BOS Basic Operating System BOT Beginning Of Table BP Base Pointer BPB BIOS Parameter Block BPI Bits Per Inch BPL Branch if Plus BPS Bits Per Second BR Bad Register BRGC Binary Reflected Gray Code BRI Basic Rate Interface BSAM Basic Sequential Access Method BSC Binary Synchronous Communication BSCS Bachelor of Science (Degree) in Computer Science BSD Berkely Software/Standard Distribution BSF Bit Scan Forward BSI British Standards Institute BSR Bit Scan Reverse BSS Block Started by Symbol BSV BASIC Bsave Graphics (file name extension) BSY Busy BSYNC Binary Synchronous Communications (protocol) BT Bit Test BTAM Basic Telecommunications Access Method [IBM] BTB Branch Target Buffer BTC Bit Test and Complement BTP Batch Transfer Program BTR Bit Test and Reset BTS Bit Test and Set BU Branch Unit BUF Buffer BWM Block-Write Mode BYTE Binary Element String B/F Background/Foreground C C Programming Language C2D Character To Decimal [REXX] C2X Character To Hexadecimal [REXX] CA Collision Avoidance CAD Computer Aided Design CADD Computer Aided Design and Drafting CAE Common Applications Environment CAG Column Address Generator CAI Computer Aided Instruction CAL Calendar CAM Common Access Method CAN Cancel CAP Central Arbitration Point CAPD Computing To Assist Persons With Disabilities [Johns Ho CAPS Capitals (Upper Case Letters) CARL Colorado Alliance of Research Libraries [Internet] CAS Column Address Select CASE Computer Aided Software Engineering CASL Crosstalk Application Scripting Language [DCA] CASS Computer Assisted Search Service CASSIS Classified and Search Support Information System CAT Computer Aided Testing CAT SCAN Computerized Axial Tomography Scan CATS Computer Assisted Training System CATV Community Antenna Television CAU Controlled Access Unit CAV Constant Angular Velocity CBC Cipher Block Chaining CBCR Channel Byte Count Register CBEMA Computer and Business Equipment Manufacturers Associati CBI Computer Based Instruction CBL Computer Based Learning CBMS Computer-Based Mail System CBR Constant Bit Rate CBT Computer Based Training CBW Convert Byte to Word CBX Computer-Controlled Branch Exchange CC Cluster Controller CCD Charged-Coupled Device CCFT Cold Cathode Fluorescent Tube CCITT Consultative Committee for International Telegraph and CCP Console Command Processor CCS Common Communications Support CD Carrier Detect CDA Compound Document Architecture [DEC] CDC Control Data Corporation CDDI Copper Distributed Data Interface CDE Common Desktop Environment CDL Computer Design Language CDMA Code Division Multiple Access CDOS Concurrent Disk Operating System CDPD Cellular Digital Packet Data CDR Call Detail Record CDRL Contract Data Requirements List CDS Current Directory Structure CD-I Compact Disk - Interactive CD-MO Compact Disk - Magneto Optical CD-R Compact Disk - Recordable CD-RDx Compact Disk - Read Only Memory Data Exchange Standard CD-ROM Compact Disk - Read Only Memory CD-RTOS Compact Disk - Real Time Operating System CD-V Compact Disk - Video CD-WO Compact Disk - Write Once CD-XA Compact Disk - Extended Architecture CD_CHRD Card Channel Ready [IBM] CE Cache Enable CEG Continuous Edge Graphics CEI Conducted Electromagnetic Interference CEPT Commission Europ‚enne Postal et Telephonique CERT Computer Emergency Response Team CFB Cipher Feedback CFV Call For Votes [Bitnet] CGA Color Graphics Adapter CGI Computer Generated Images CHAP Challenge Authentication Protocol (protocol) CHAR Character CHAT Conversational Hypertext Access Technology [Internet] CHCK Channel Check CHCP Change Code Page CHDIR Change Directory CHGRP Change Group CHKDSK Check Disk CHMOD Change Mode CHOWN Change Owner CHP Chapter CHR Character CHRP Common Hardware Reference Platform [Apple; IBM] CICS/VS Customer Information Control System/ Virtual Storage [I CID Configuration/Installation/Distribution CIM CompuServe Information Manager CIO Chief Information Offier CIOCS Communication Input/Output Control System CIP Command Interface Port CIRC Circular Reference CIS Card Information Structure CISC Complex Instruction Set Computing CIX Commercial Internet Exchange CJLI Command Job Language Interpreter CKD Count Key Data (device) CLAR Channel Local Address Register CLASS Client Access to Systems and Services CLC Clear Carry Flag CLD Clear Direction Flag CLI Call-Level Interface CLIST Command List CLK Clock CLNP Connectionless Network Protocol CLS Clear Screen CLTS Clear Task Switch Flag CLUI Command Line User Interface CLUT Color Look-Up Table [Macintosh] CLV Constant Linear Velocity CM Centimeter CMA Concert Multi-thread Architecture CMC Common Mail Calls CMIP Common Management Information Protocol CMIS Common Management Information System CML Computer Mananged Learning CMMS Computerized Maintenance Management Software CMMU Cache/Memory Management Unit [Motorola] CMOS Complementary Metal-Oxide Semiconductor CMP Compare CMPS Compare word String CMS Code Management System CMY Cyan-Magenta-Yellow (color model) CMYK Cyan-Magenta-Yellow-Black (color model) CNA Certified NetWare Administrator [Novell] CNC Computerized Numerical Control CNE Certified NetWare Engineer CNG Call Negotiation Tone CNIDR Clearinghouse for Network Information and Discovery and CNIDR Clearinghouse for Networked Information and Retrieval CNSS Core Nodal Switching Subsystem [Internet] CNV Conventional (pertaining to Memory) CNVT Convert CNX Certified Network Expert CO Central Office COBOL Common Business-oriented Language (See HLL) CODASYL Conference on Data System Languages (Group that designe CODEC Coder/Decoder COEM Commercial Original Equipment Manufacturer COFF Common Object File Format [Unix] COGO Coordinate Geometry (Programming Language) COL Collision COLD Computer Output to Laser Disk COM Commercial (organization Domain name) [Internet] COM1 First serial Port (asynchronous port) COM2 Second serial Port COM3 Third serial Port COM4 Fourth serial Port COMDEX Computer Dealers Exposition COMET Cornell Macintosh Terminal Emulator COMP Compare COMSAT Communications Satellite Corporation CON Console (includes Keyboard and Screen) CONFIG Configuration CONTONE Continuous Tone CORBA Common Object Request Broker Architecture CoREN Corporation for Research and Enterprise Network COS Compatible Operating System COSE Combined Office Standard Environment COSMIC Computer Software Management and Information Center [NA COSMOS Computer System for Mainframe Operations COTS Commercial Off-The-Shelf CP Copy Protected CPA Certified Public Accountant CPCS Check Processing Control System [IBM] CPE Central Processing Element CPG Clock Pulse Generator CPI Characters Per Inch CPI-C Common Programming Interface for Communications [IBM] CPL Current Privilege Level CPS Characters Per Second CPT Command Pass Through CPU Central Processing Unit CP/M Control Program for Microcomputers CR Carriage Return CRC Cyclic Redundancy Check CREN Computer Research Education Network CRF Cable Retransmission Facility CROM Control Read Only Memory CRT Cathode Ray Tube CRTC CRT Controller CR/LF Carriage Return/Line Feed CS Chip Select CSAR Channel System Address Register CSD Corrective Service Diskette [IBM] CSDS Packet Switched Data Service CSE Certified System Engineer CSG Constructive Solid Geometry CSL Computer Sensitive Language CSLIP Compressed Serial Line Interface Protocol [Internet] CSM Communications Services Manager CSMA/CD Carrier Sense Multiple Access/with Collision Detection CSNET Computer Science Network CSP Commercial Subroutine Package CSPDN Circuit Switched Public Data Network CSS Continuous System Simulator (Language) CSTA Computer-Supported Telephony Applications CSU Channel Service Unit CSV Comma-Separated Values/Variables CTB Cipher Type Byte CTI Computer-Telephone Integration CTOS Computerized Tomography Operating System CTPA Coax-to-Twisted-Pair Adapter CTRL Control CTS Clear To Send CTSS Compatible Time Sharing System CUA Common User Access [IBM] CUB Cursor Backward CUD Cursor Down CUE Custom Updates and Extras (card) [Egghead Software] CUF Cursor Forward CUI Character-Oriented User Interface CUP Cursor Position CUPID Completely Universal Processor I/O Design [AST] CUTE Clarkston University Terminal Emulator CUU Cursor Up CVF Compressed Volume File CVGA Color Video Gaphics Array CVIA Computer Virus Industry Association CVT Convert CVW CodeView for Windows CWD Convert Word to Double Word CWIS Campus Wide Information Service/System [Internet] CYL Cylinder CYMK Cyan-Yellow-Magenta-Black (color model) C&T Chips and Technologies C/D Control Data C/S Client/Server D2C Decimal To Character [REXX] D2T2 Dye Diffusion Thermal Transfer (printing) D2X Decimal To Hexadecimal [REXX] DAA Data Access Arrangement DAC Data Acquisition and Control DAD Desktop Application Director [Borland] DAL Data Access Language [Apple Computer] DAM Data Acquisition and Monitoring DAO Data Access Objects [Microsoft] DAP Data Access Protocol [DEC] DARI Database Application Remote Interface [IBM] DAS Decimal Adjust for Subtraction DASD Direct Access Storage Device DAT Digital Audio Tape DATACOM Data Communications dB Decibel DB Data Base DB2 Database 2 dBA Adjusted Decibel DBCS Double-Byte Character Set DBM Data Base Manager DBMS Data Base Management System DBS Data Base Server DC Data Collection DCA Digital Communications Associates DCAF Distributed Console Access Facility [IBM] DCB Disk Coprocessor Board [Novell] DCC Digital Command Control DCD Data Carrier Detect DCE Data Communications Equipment DCF Data Communication Facility [IBM] DCI Display Control Interface DCL Declaration DCS Data Collection System DCT Discrete Cosine Transform DD Day DDA Domain-Defined Attribute DDB Device Dependent Bitmap DDC Digital Data Channel [VESA] DDCMP Digital Data Communications Message Protocol [DEC] DDCS Distributed Database Connection Services [IBM] DDD Direct Distance Dialing DDE Direct Data Entry DDEML Dynamic Data Exchange Manager Library [Microsoft] DDF Dynamic Data Formatting [IBM] DDK Device Driver Kit [Microsoft Windows] DDL Data Definition Language DDM Distributed Data Management DDN Defense Data Network DDS Digital Dataphone Service [AT&T] DEC Decrement DEF Desktop Functional Equivalent [Compaq] DEFRAG Defragment DEK Data Encryption Key DEL Delete DELSTR Delete String [REXX] DES Data Encryption Standard DET Device Execute Trigger DEV Device DF Data Field DFC Data Flow Control DFS Distributed File System DFT Diagnostic Funtion Test DFU Data File Utility DGIS Direct Graphics Interface Standard DHCP Dynamic Host Configuration Protocol DI Data In DIA Document Interchange Architecture [IBM] DIB Device Independent Bitmap DIBOL DEC Business Oriented Language DID Direct Inward Dialing DIF Data Interchange Format DIFFSEN Differential Sense DIIP Direct Interrupt Identification Port DIN Deutsche Industrie Norm (German equivalent of EIA) DIO Data Input-Output DIP Digital Imaging Processing DIR Directory (file) DIS Dynamic Impedance Stabilization [CompuCom] DISP Displacement (offset) DIT Directory Information Tree DIV Divide DIW D-Inside Wire [AT&T] DL Download (also D/L) DLC Data Link Control (protocol) [IBM] DLE Data Link Escape DLL Dynamic Link Library DLM Dynamic Link Module DLR DOS LAN Requester DLT Digital Linear Tape DL/1 Data Manipulation Language 1 [IBM] DM Distributed Memory DMA Direct Memory Access/Addressing DMAC DMA Controller DMD Digital Micromirror Device [Texas Instruments] DME Distributed Management Environment DMI Desktop Mangement Interface DML Data Manipulation Language DMM Digital Multimeter DMMS Dynamic Memory Management System DMOS Double-diffused Metal-Oxide Semiconductor DMP Dot Matrix Printer DMPC Distributed Memory Parallel Computer DMQS Display Mode Query and Set [IBM] DMS Data Management Software DMSD Digital Multistandard Decoding DMTF Desktop Management Task Force DMY Day Month Year DN Down DNC Direct Numerical Control DNIC Data Network Identification Code DNIS Dialed Number Identification Service DNS Domain Naming System DO Data Out DOE Distributed Objects Everywhere DOMF Distributed Object Management Facility DOS Disk Operating System DOSEM DOS Emulation DOW Day Of Week DO-IT Disabilities, Opportunities, Internetworking and Techno DP Data Processing DPA Demand Protocol Architecture [3Com] DPAM Demand Priority Access Method DPAREN Data Parity Enable [IBM] DPB Drive Parameter Block DPC Direct Program Control DPI Dots Per Inch DPL Descriptor Privilege Level DPM Digital Panel Meter DPMA Data Processing Management Association DPMI DOS Protected Mode Interface [Microsoft] DPO Data Phase Optimization DPS Document Processing System DPSK Differential Phase Shift Keying DPtoTP Display Coordinates to Tablet Coordinates (converting) DQL DataEase Query Language [DataEase International] DR Data Received DRAM Dynamic Random Access Memory DRAW Direct Read After Write DRDA Distributed Relational Database Architecture [IBM] DRDW Direct Read During Write DRI Digital Research Incorporated DRO Data Request Output DRV Drive DR.BOND Dial-up Router Bandwith On Demand [NEC] DS Data Segment DSA Directory System Agent [HP] DSAP Destination Service Access Point DSDD Double Sided, Double Density (diskette) DSE Data Storage Equipment DSEA Display Station Emulation Adapter DSECT Dummy Control Section DSHD Double Sided, High Density (diskette) DSIS Distributed Support Information Standard DSL Dynamic Simulation Language DSMA Digital Sense Multiple Access DSOM Distributed System Object Model DSP Digital Signal Processing DSQD Double Sided, Quad Density (diskette) DSR Data Set Ready DSS Decision Support System DSTN Double Supertwisted Nematic DSU Data Service Unit DSW Data Status Word DTA Disk Transfer Area DTD Document Type Definition DTE Data Terminal Equipment DTL Diode-Transistor Logic DTMF Data Tone Multiple Frequency DTP Desktop Publishing DTR Data Terminal Ready DTS Distributed Time Service [HP] DTV Desktop Video DTVC Desktop Video Conferencing DU Disk Usage DUA Directory User Agent [HP] DUAT Direct User Access Terminal DVI Digital Video Interactive DVMRP Distance Vector Multicast Routing Protocol [Internet] DWG Drawing DXC Data Exchange Control DXF Drawing Exchange Format D/A Digital to Analog D/R Direct or Reverse EA Extended Attribute [OS/2] EARN European Academic Research Network EAROM Electrically Alterable Read Only Memory EARS Electronic Access to Reference Services EATA Enhanced AT Bus Attachment EBC EISA Bus Controller EBCDIC Extended Binary Coded Decimal Interchange Code [IBM] EBI Equivalent Background Input EBT Electronic Benefits Transfer ECAL Enjoy Computing And Learn ECB Electronic Codebook ECC Error Check Code ECD Enhanced Color Display ECHO European Commission Host Organization [Internet] ECL Emitter Coupled Logic ECMA European Computer Manufacturers Association ECNE Enterprise Certified NetWare Engineer [Novell] ECP Enhanced Capabilities Port [Microsoft] ECTL Electronic Communal Temporal Lobe ED Erase Display EDA Embedded Document Architecture [Go Corporation] EDC Enhanced Data Correction EDDC Extended Distance Data Cable EDGAR Electronic Data Gathering, Analysis and Retrieval EDI Electronic Data Interchange EDIFACT EDI for Administration Commerce and Transport EDLC Ethernet Data Link Control EDLIN Editor (Line Text) EDM Engineering Data Management EDO Extended Data Out EDOS Enhanced DOS for Windows EDP Electronic Data Processing EDPM Electronic Data Processing Machine EDR Extended Distinctive Ring EDRAM Extended Dynamic Random Access Memory EDSAC Electronic Delay Storage Automatic Computer EDSI Enhanced Small Device Interface EDU Education (organization Domain name) [Internet] EDVAC Electronic Discrete Variable Automatic Computer (First EEC Extended Error Correction EEG Electroencephalogram EEM Extended Memory Management EEMS Enhanced Expanded Memory Specification EEPROM Electrically Erasable Programmable Read-Only Memory EES Escrow Encryption Standard EFA Extended File Attribute EFF Electronic Frontier Foundation EFI Electromechanical Frequency Interference EFL Emitter Follower Logic EFTS Electronic Funds Transfer System EGA Enhanced Graphics Adapter EGP Exterior/External Gateway Protocol EHLLAPI Emulator High Level Language Application Programming In EIA Electronic Industries Association EIS Executive Information System EISA Extended Industry Standard Architecture EL Electroluminescent (display) ELF Extremely Low Frequency ELS Entry Level System EM Electronic Mail EMA Electronic Mail Association EMACS Editing Macros [Unix] EMB Extended Memory Block [LIM/AST] EMBARC Electronic Mail Broadcast to a Roaming Computer [Motoro EMC Electromagnetic Compatibility EMI Electromagnetic Interference EMM Expanded Memory Manager EMR Electro-Magnetic Radiation EMS Electronic Mail System ENDS Ends Segment ENIAC Electronic Numerical Integrator Analyzer and Computer ( ENQ Enquiry ENSS Exterior Nodal Switching Subsystem [Internet] EOA End of Address EOB End of Block EOC End of Conversion EOF End of File EOI End or Identify EOJ End of Job EOL End of Line EOM End of Message EOR Exclusive OR (Also XOR) EOS Earth Observing System [NASA] EOSDIS Earth Observing System Data and Information System [NAS EOT End Of Table EP Evolutionary Programming EPL Effective Privilege Level EPLD Electrically Programmable Logic Device EPM Enhanced Editor for Presentation Manager [IBM] EPP Enhanced Parallel Port EPROM Electrically Programmable Read Only Memory EPSF Encapsulated PostScript Files EPV Entry Point Vector [HP] ERAS Electronic Routing and Approval System [Hughes Aircraft ERIC Educational Resources Information Center [Internet] ERLL Enhanced Run Length Limited EROM Erasable Read Only Memory ERR Error ES Extra Segment ESA Enterprise Systems Architecture [IBM] ESC Escape ESCM Extended Services Communications Manager [IBM] ESCON Enterprise System Connection (Architecture) [IBM] ESC/P Epson Standard Code for Printers ESD Electronic Software Distribution ESDI Enhanced Small Device Interface ESI Enhanced Serial Interface (specification) [Hayes] ESN Electronic Security Number ESP Emulation Sensing Processor ESS Electronic Switching System ESU Electro-Static Unit ETANN Electrically Trainable Analog Neural Network (chip) [In ETB End of Transmission Block ETC Enhanced Throughput Cellular (modem protocol) [AT&T] ETPL Endorsed Tempest Products List ETS Econometric Time Series ETX End of Text EU Execution Unit EVE Extensible VAX Editor EVGA Extended Video Graphics Array EWAN Emulator Without A Good Name [Internet] EWS Employee Written Software [IBM] ExCA Exchangeable Card Architecture [Intel] EXE2BIN Program used to convert an (.EXE) file to binary format EXP Exponent EXT External EXTRN External Reference E-MAIL Electronic Mail FAB Computer-Chip Fabrication Plant FAC File Access Code FAMOS Floating Gate Avalanche MOS FAP File Access Protocol FAPI Family Application Program Interface FAQ Frequently Asked Question FARNET Federation of American Research Networks [Internet] FAT File Allocation Table FAX Facsimile FCB File Control Block FCC Federal Communications Commission FCCSET Federal Coordinating Council for Science, Engineering a FCI Flux Changes per Inch FCS Frame Check Sequence FD Floppy Disk FDC Floppy Disk Controller FDDI Fiber Digital Device Interface FDISK Fixed Disk FDM Frequency-Division Multiplexing FDX Full Duplex FEFO First-Ended, First-Out FEP Front End Processor FESDK Far East Software Development Kit [Microsoft] FET Field Effect Transistor FF Flip-Flop FFST First Failure Support Technology [IBM] FFT Fast Fourier Transform FIF Fractal Image Format FIFO First-In, First-Out FILO First-In, Last-Out FIP File Processor Buffering FIPS Federal Information Processing Standard FIR Finite Impulse Response FLC Ferro-electric Liquid Crystal FLD Field FLDB Fileset Location Database [HP] FLL FoxPro Link Library [Microsoft Fox Pro] FLOPS Floating Point Operations Per Second FMS Forms Management System FMT Format FNT Font FOCUS Forum of Control Data Users FOG First Osborne Group FOIRL Fiber Optic Inter Repeater Link [IEEE] FORTH (Programming Language)(See HLL) FORTRAN Formula Translator (Programming Language)(See HLL) FOSE Federal Office Systems Exposition FOSSIL Fido/Opus/Seadog Standard Interface Layer FPGA Field Programmable Gate-Array FPLA Field Programmable Logic-Array FPP Fixed Path Protocol FPS Favorite Picture Selection FPU Floating Point Unit FQDN Fully Qualified Domain Name [Internet] FRAG Fragment FRAM Ferroelectric Random-Access Memory FRED Frame Editor FRPI Flux Reversals Per Inch FS File Separator FSD File System Driver [OS/2] FSE Full Screen Editor FSF Free Software Foundation [Internet] FSK Frequency Shift Keying FSN Full Service Network FSR Free System Resources FTAM File Transfer, Access and Management FTM Flat Tension Mask [Zenith] FTP File Transfer Protocol [Internet] FTPD File Transfer Protocol Daemon FTS Federal Telecommunication System FUI File Update Information FUNC Function FVT Full Video Translation FYI For Your Information F/T Full Time GA General Availability GAAP Generally Accepted Accounting Principles GAL Generic Array Logic GAPI Gateway Application Programming Interface Gb Gigabit (1,000 megabits) GB Gigabyte (1,000 megabytes) GCR Group Code Recording GDA Global Data Area GDDM Graphics Data Display Manager GDI Graphics Device Interface GDP Graphic Draw Primitive GDS Global Directory Service [HP] GDT Geometric Dimensioning and Tolerancing GECOS General Electric Comprehensive Operating System GEIS General Electric Information Service (company) GEM Graphics Environment Manager (DRI Program) GENIE General Electric Network for Information Exchange GEOS Graphic Environment Operating System [Geoworks] GET Get Execute Trigger GHZ Gigahertz GIGO Garbage In, Garbage Out GIS Geographic Information System GIX Global Internet Exchange [Internet] GKS Graphical Kernal System GLIS Global Land Information System [US Geological Survey] GLM General Linear Models GLOBE Global Learning by Observations to Benefit the Environm GMS Global Messaging Service [Novell] GMT Greenwich Mean Time GND System Ground GNN Global Network Navigator [Internet] GNU Gnu's Not Unix (operating system) GOSIP Government Open Systems Interconnection Profile GOV Government (organization Domain name) [Internet] GP Gas Plasma GPF General Protection Fault GPI Graphics Programming Interface GPIB General Purpose Interface Bus GPS Global Positioning System GPSS General Purpose Systems Simulator (language) GRE Graphics Engine GREP Global Regular Expression Print GS Group Separator GSM Global System for Mobiles GUI Graphical User Interface GW-BASI Gee Whiz BASIC G/L General Ledger HACMP High Availability Cluster Multi-Processing [IBM] HAL Hard Array Logic HAL Heuristically Programmed Algorithmic (computer) [from 1 HASP Houston Automatic Spooling Priority (System) HBA Host Bus Adapter HD Hard Disk HDA Head Disk Assembly HDCD High Definition Compatible Digital HDF Hierarchical Data Format [NCSA] HDI Head to Disk Interference HDLC High-Level Data Link Control HDR Header HDSC High Density Signal Carrier [DEC] HDSL High-rate Digital Subscriber Link HDTV High Definition Television HDW Hardware HDX Half Duplex HERC Hercules HEX Hexadecimal HFS Hierarchical File System [Macintosh] HGA Hercules Graphics Adapter HGCP Hercules Graphics Card Plus HH Hour HIFD High-Density Floppy Disk HIL Human Interface Link [HP] HLCO High Low Close Open HLL High Level Language HLLAPI High Level Language Application Programming Interface HLQ High Level Qualifier HLS Hue, Luminance, Saturation (color model) HLT Halt HMA High Memory Area [Microsoft] HMD Head Mounted Display HMI Host Micro Interface [CompuServe] HMOS High Density Metal Oxide Semiconductor HOTT Hot Off The Tree (electronic newsletter) HP Hewlett-Packard (Company) HPCC High Performance Computing and Communications HPDJ Hewlett-Packard Desk Jet HPFS High-Performance File System HPG Hewlett-Packard Graphics HPGL Hewlett-Packard Graphics Language HPIB Hewlett-Packard Interface Bus HPLJ Hewlett-Packard Laser Jet HPPA Hewlett-Packard Precision Architecture HPPI High Performance Parallel Interface HPUX Hewlett-Packard Unix HPW High Performance Workstation [Sun] HRG High Resolution Graphics HRIS Human Resource Information System HRMS Human Resource Management System HS High Speed HSC High Speed Channel HSI Hue Saturation Intensity HSM Hierarchical Storage Management HSP High Speed Printer HSSI High Speed Serial Interface HST High Speed Technology [U.S. Robotics] HSV Hue Saturation Value HTML HyperText Markup Language HTTP HyperText Transport Protocol HTTPD Hypertext Transfer Protocol Deamon [UNIX] HUT Hopkins Ultraviolet Telescope HVP Horizontal & Vertical Position HWCP Hardware Code Page HWD Height-Width-Depth HYTELNE Hypertext-browser for Telnet Accessible Sites Hz Hertz H/V Horizontal/Vertical H/W Hardware IAB Internet Architecture Board [Internet] IAC Interapplication Communication IAL International Algebraic Language (ALGOL was first calle IANA Internet Assigned Numbers Authority [Internet] IAP Internet Access Provider [Internet] IAT Import Address Table IAUP Internet User Account Provider [Internet] IBC Instrument Bus Computer IBM International Business Machines (Corporation) IBM-GL IBM Graphics Language IC Input Circuit ICA Intra-application Communications Area ICAS Intel Communicating Applications Specifications ICCP Institute for the Certification of Computer Professiona ICE In-Circuit Emulator [Intel] ICI Image Component Information ICL Interface Clear ICLID Incomming-Call Line Identification ICM Image Color Matching [Kodak] ICMP Internet Control Message Protocol [Novell] iCOMP Intel Comparative Microprocessor (index) [Intel] ICP Integrated Channel Processor ICR Intelligent Character Recognition ICS Intuitive Command Structure ID Identification IDA Integrated Digital Access IDAPI Integrated Database Application Programming Interface IDE Imbedded Drive Electronics IDF Intermediate Distribution Frame IDIV Integer Divide IDL Interface Definition Language IDMS Integrated Data Base Management System IDP Integrated Data Processing IDT Interrupt Descriptor Table IEEE Institute of Electrical and Electronics Engineers IEF Information Engineering Facility IEMSI Interactive Electronic Mail Standard Identification IETF Internet Engineering Task Force [Internet] IEU Instruction Execution Unit IFD Image File Directory IFF Interchangeable File Format [Amiga] IFG Incoming Fax Gateway IFS Installable File System IFSM Information Systems Management IGA Integrated Graphics Array IGC Integrated Graphics Controller IGES Initial Graphics Exchange Standard IGS Internet Go Server [Internet] IIF Immediate IF IIR Immediate Impulse Response IITF Information Infrastructure Task Force IMAP Internet Message Access Protocol [Internet] IMAX Maximum Image IMDS Image Data Stream (format) [IBM] IME Input Method Editor IMG Image IMP Information/Interface Message Processor IMPA Intelligent Multi-Port Adapter [DCA] IMR Internet Monthly Report [Internet] IMS Information Management System IMTV Interactive Multimedia Television IMUL Integer Multiply IN Input INC Increment INIT Initialization INM Integrated Network Management INS Input String INT Integer INTA Interrupt Acknowledge InterNI Internet Network Information Center [Internet] INTO Interrupt if Overflow occurs IOCS Input/Output Control System IOCTL Input/Output Control IOPL Input/Output Priviledge Level IOSGA Input/Output Support Gate Array IP Instruction Pointer IPC Instructions Per Clock IPDS IBM Personal Dictation System [IBM] IPF Information Presentation Facility IPL Initial Program Load/Loader IPL Information Programming Language IPM Interpersonal Message IPSE Integrated Project Support Environment IPX Internetwork Packet Exchange [Novell] IQL Interactive Query Language IR Infrared IRC Internet Relay Chat [Internet] IRD Integrated Receiver/Descrambler IRDS Information Resource Dictionary System IRET Interrupt Return IRF Inheritance Rights Filter [Novell] IRL Interactive Reader Language IRLED Infrared Light Emitting Diode IRM Information Resource Management IRP I/O Request Packet IRQ Interrupt Request IRTF Internet Research Task Force [Internet] IRX Information Retrieval Experiment IS Information System ISA Industry Standard Architecture ISAM Indexed Sequential-Access Management/Method ISBN International Standard Book Number ISC Instruction Set Computer ISD Image Section Descriptor ISDN Integrated Services Digital Network ISH Information Super Highway ISI Internally Specified Index ISIS Integrated Systems and Information Services ISL Interactive System Language ISMF Interactive Storage Management Facility ISO/OSI International Standards Organization/Open Systems Inter ISP Internet Service Provider [Internet] ISPF Interactive System Programming Facility ISR Information Storage and Retrieval ISSN International Standard Serial Number ISV Independent Software Vendor ITB Information Technology Branch ITC International Typeface Corporation ITN Identification Tasking and Networking ITU International Telecommunication Union ITUG International Telecommunications User Group ITV Interactive Television ITX Intermediate Text Block IU Integer Unit IUAP Internet User Account Provider [Internet] IUS/ITB Interchange Unit Separator/Intermediate Transmission Bl IVIS Interactive Video Information System IVL Intel Verification Lab IVR Interactive Voice Response IVS Interactive Videodisk System IVT Interrupt Vector Table IV&V Independent Verification & Validation I-WAY Information Highway I/F Interface I/O Input/Output JA Jump Address JAD Joint Application Design JAE Jump if Above or Equal JANET Joint Academic Network JBE Jump if Below or Equal JC Jump if Carry set JCL Job Control Language JE Jump if Equal JEDEC Joint Electronic Devices Engineering Council JEIDA Japanese Electronics Industry Development Association JES Job Entry System JFET Junction Field Effect Transistor JFIF JPEG File Interchange Format JG Jump if Greater JGE Jump if Greater or Equal JL Jump if Less JLE Jump if Less than or Equal to JMP Jump JNA Jump if Not Above JNAE Jump if Not Above or Equal JNB Jump if Not Below JNBE Jump if Not Below or Equal JNG Jump if Not Greater JNGE Jump if Not Greater or Equal JNLE Jump if Not Less or Equal JNO Jump if No Overflow JNP Jump if No Parity JNS Jump if No Sign JNZ Jump if Not Zero JPE Jump if Parity Even JPEG Joint Photographic Experts Group JPL Jet Propulsion Laboratory JPO Jump if Parity Odd JS Jump if Sign JUGHEAD Jonzy's Universal Gopher Hierarchy Excavation and Displ JZ Jump if Zero Kb Kilobit KB Keyboard KBD Keyboard (also KEYB) KBD$ Keyboard [OS/2] KBPS Kilobytes Per Second KDT Key Definition Table KEYBBE Foreign language KEYBoard program - Belgium KEYBBR Foreign language KEYBoard program - Brazil KEYBCF Foreign language KEYBoard program - Canadian-French KEYBCZ Foreign language KEYBoard program - Czechoslovakia (Cze KEYBDF Foreign language KEYBoard program - Denmark KEYBFR Foreign language KEYBoard program - France KEYBGR Foreign language KEYBoard program - Germany KEYBHU Foreign language KEYBoard program - Hungary KEYBIT Foreign language KEYBoard program - Italy KEYBLA Foreign language KEYBoard program - Latin America KEYBNL Foreign language KEYBoard program - Netherlands KEYBNO Foreign language KEYBoard program - Norway KEYBPL Foreign language KEYBoard program - Poland KEYBPO Foreign language KEYBoard program - Portugal KEYBSF Foreign language KEYBoard program - Swiss-French KEYBSG Foreign language KEYBoard program - Swiss-German KEYBSL Foreign language KEYBoard program - Czechoslovakia (Slo KEYBSP Foreign language KEYBoard program - Spain KEYBSU Foreign language KEYBoard program - Finland KEYBSV Foreign language KEYBoard program - Sweden KEYBUK Foreign language KEYBoard program - United Kingdom KEYBUS Foreign language KEYBoard program - United States KEYBYU Foreign language KEYBoard program - Yugoslavia kHz Kilohertz KIS Knowbot Information Service [Internet] KPI Kernal Programming Interface KRS Knowledge Retrieval System KSH Korn Shell [UNIX] KSPH Keystrokes Per Hour KSR Keyboard Send Receive K-12 Kindergarten through 12th Grade [US Education System] LADDR Layered Device Driver Architecture [Microsoft] LALL Longest Allowed Lobe Length LAN Local Area Network LANACS Local Area Network Asynchronous Connection Server LAPB Link Access Procedure Balanced (protocol) LAPD Link Access Procedure Direct (protocol) LAPM Link Access Procedure for Modems LAR Load Access Rights LASTpor Local Area Storage Transport (protocol) [DEC] LAT Local Access Terminal LAVC Local Area VAX Cluster LAWN Local Area Wireless Network LB Left Button (of 2 or 3 button Mouse) LBA Logical Block Addressing LBL Label LBR Librarian LBT Listen Before Talk LCC Leadless Chip Carrier LCD Liquid Crystal Display LCF Low Cost Fiber LCK Library Construction Kit [Mircrosoft FoxPro] LCP Link Control Protocol (protocol) LCU Last Cluster Used LDA Logical Device Address LDAP Lightweight Directory Access Protocol LDC Lotus Development Corporation LDM Long Distance Modem LDT Local Descriptor Table LE Less or Equal LEA Load Effective Address LEAF Law Enforcement Access Field LEC Local Exchange Carrier LED Light Emitting Diode LEL Link, Embed and Launch-to-edit [Lotus] LEM Language Extension Module LEN Low Entry Networking LEX Lexicon LF Line Feed LFI Last File Indicator LFS Local File System [HP] LFU Least Frequently Used LGDT Load Global Descriptor Table LICS Lotus International Character Set [LDC] LIDT Load Interrupt Descriptor Table LIEP Large Internet Exchange Packet [Novell] LIF Low Insertion Force LIFO Last In, First Out LILO Last In, Last Out LIM Lotus/Intel/Microsoft LIMA Lotus/Intel/Microsoft/AST LIMS Library Information Management System LIP Large Internet Packet LIPS Logical Inferences Per Second LISP List Processing (Language)(See HLL) LISTSER List Server [Internet] LLC Logical Link Control LLDT Load Local Descriptor Table LLF Low Level Format LMBCS Lotus Multibyte Character Set [Lotus] LMI Local Management Interface LMSW Load Machine Status Word LM/X LAN Manager for Unix LN Logarithm (Natural) LNDI Lotus Notes:Document Imaging LOC Loop On-Line Control LOCIS Library of Congress Information System LODSB Load String Byte LOG Logarithm (Base 10) LOGO (Programming Language)(See HLL) LOOPE Loop while Equal LOOPNE Loop while Not Equal LOOPNZ Loop while Not Zero LOOPZ Loop while Zero LORE Line Oriented Editor LPC Local Procedure Call LPD Line Printer Daemon (protocol) [Berkley] LPI Lines Per Inch LPL Lotus Programming Language [Lotus 1-2-3] [LDC] LPM Lines Per Minute LPN Logical Page Number LPS Low-Power Schottky LPT Line Printer LPT1 First Parallel Printer Port LPT2 Second Parallel Printer Port LPT3 Third Parallel Printer Port LQ Letter Quality LQM Link Quality Monitoring (protocol) LRC Local Register Cache LRL Least Recently Loaded LRM Language Reference Manual LRU Least Recently Used LSA Line Sharing Adapter LSAPI License Services Application Program Interface LSB Least Significant Bit LSC Least Significant Character LSD Least Significant Digit LSI Large Scale Integration LSL Link Support Layer LST List LTR Left-To-Right LU Logical Unit (Also LUN) LUA Logical Unit Application (interface) LUI Local User Input LUT Lookup Table LZ Lazy Write LZW Lempel-Ziv-Walsh (algorithm) mA Milliampere Mac Macintosh (Apple Macintosh Computer) MAC Media/Medium Access Control MACH Multilayer Actuator Head [Epson] mAh Milliampere-Hour MAN Manual MANPAGE Manual Page [Unix] MAP Maintenance Analysis Procedures MAPI Mail/Messaging Applications Programming Interface [Micr MAPICS Manufacturing, Accounting and Production Information Co MARVEL Machine-Assisted Realization of the Virtual Electronic MASM Macro Assembler [Microsoft] MASS Maximum Availability and Support Subsystem [Parallan] MAU Media Access Unit MAVDM Multiple Application VDM MAX Maximum MB Megabyte (1,000 kilobytes) MBASIC Microsoft BASIC [Microsoft] MBONE Multicast Backbone [Internet] MBPS Megabytes Per Second MBR Master Boot Record MBX Mailbox MCA Micro Channel Architecture [IBM] MCAD Mechanical Computer Aided Design MCB Memory Control Block MCGA Multicolor Graphics Array MCI Media Control Interface [Microsoft] MCI MAIL (name from original company Microwave Communicatio MCL Microsoft Compatibility Labs [Microsoft] MCM Multi-Chip Module MCU Multi-Chip Unit [DEC] MD Make Directory MDA Monochrome Display Adapter MDI Multiple Document Interface MDIC Manchester Decoder and Interface Chip [AT&T] MDK Multimedia Developers Kit [Microsoft] MDLP Modile Data Link Protocol MDR Minimum Design Requirement MDY Month Day Year MEB Memory Expansion Board MEG Megabyte MEM Memory MESI Modified Exclusive Shared and Invalid (protocol) MFC Microsoft Foundataion Class [Microsoft] MFFS Microsoft Flash File System [Microsoft] MFLOPS Million Floating Point Operations Per Second MFM Modified Frequency Modulation MFP Multifunction Peripheral MFS Macintosh File System [Macintosh] MFT Multiprogramming with a Fixed number of Tasks MGA Monochrome Graphics Adapter MGE Modular GIS Environment MGR Manager MHS Message Handling Service MHz Megahertz MIB Management Information Base MICRO One-millionth MICS Macro Interpretive Commands MIDI Musical Instrument Digital Interface MIDL Microsoft Interface Definition Language MIF Management Information Format MII Microsoft/IBM/Intel MIL Machine Interface Layer [Go Corporation] MIM Metal-Insulator-Metal (screen) MIMD Multiple Instruction Multiple Data Stream (processor) MIME Multipurpose Internet Mail Extension [Internet] MIN Minimum MINUET Minnesota Internet Users Essential Tool [Internet] MIPS Million Instructions Per Second MIS Management Information System MISC Miscellaneous MIX Member Information Exchange MKDIR Make Directory ML Machine Language MLAPI Multilingual Application Programming Interface MLC Multilevel Cell (program) [Internet] MLID Multi-Link Interface Driver MM Minutes MMA Microcomputer Managers Association MMC Matched Memory Cycle MMIS Materials Manager Information System MMPM Multi Media Presentation Manager MMU Memory Management Unit MNOS Metal Nitride Oxide Semiconductor MNP Microcom Networking Protocol [Microcom] MO Magneto-Optical (disk drive) MOD Modem MODEM Modulator Demodulator MOHLL Machine Oriented High Level Language MOM Microsoft Office Manager [Microsoft] MOP Maintenance Operations Protocol MOS Metal Oxide Semiconductor MOSFET Metal Oxide Semiconductor Field Effect Transistor MOV Metal Oxide Varistor MOV Move MOVS Move String MOVS Move String MP Multiple Processors MPC Multimedia Personal Computer MPCS Mission Planning and Control Station (Software) MPEG Moving Picture Experts Group MPI Multiprecision Integer MPP Massively Parallel Processing MPR Multipart Repeater MPS Multiprocessor Specification MPU Microprocessor Unit MR Magnetoresistive MRCF Microsoft Realtime Compression Format MRCI Microsoft Realtime Compression Interface MRI Magnetic Resonance Imaging MRO Multi-Region Operation MRP Materials Requirement Planning MRPL Main Ring Path Length MRS Media Recognition System MRT Mean Repair Time MS Memory System MSACM Microsoft Audio Compression Manager [Microsoft] MSAU Multi-Station Access Unit MSAV Microsoft Anti Virus [Microsoft] MSB Most Significant Bit MSCDEX Microsoft Compact Disc Extensions [Microsoft] MSD Mass Storage Device MSDR Multiplexed Streaming Data Request MSDS Microsoft Developer Support [Microsoft] MSG Message MSI Medium Scale Integration MSL Map Specification Library MSN MicroSoft Network MSO Multiple-Systems Operator MSW Machine Status Word MS-DOS Microsoft - Disk Operating System [Microsoft] MTA Message Transfer Agent MTBB Mean Time Between Breakdowns MTBF Mean Time Between Failures MTBJ Mean Time Between Jams MTF Microsoft Tape Format [Microsoft] MTS Message Transfer Service/System MTTF Mean Time To Failure MTTR Mean Time To Repair MUD Multi-User Domain [Internet] MUL Multiply MUMPS Massachusetts General Hospital Utility Multi-Programmin MUSE Multi-User Shared Environment MUX Multiplexer mV Millivolt MVB Multimedia Viewer Book MVC Multimedia Viewer Compiler MVDM Multiple Virtual DOS Machines MVGA Monochrome Video Graphics Array MVP Multimedia Video Processor MVS Multiple Virtual Storage MVT Multiprogramming with a Variable number of Tasks MX Mail Exchanger [Internet] NAC Network Adapter Card NACD National Association of Computer Dealers NACS National Advisory Committee on Semiconductors NAE Not Above or Equal NAK Negative Acknowledgment NAM Number Assignment Module NANO One thousand-millionth NAP Network Access Point NAPLPS North American Presentation Level Protocol Syntax (grap NAS Network Application Support [DEC] NASA National Aeronautics and Space Administration NASDAQ National Association of Securities Dealers Automatic Qu NASI NetWare Asynchronous Services Interface [Novell] NAU Network Addressable Unit NBE Not Below or Equal NBI Nothing But Initials NBS National Bureau of Standards NC No Carry NCA Network Communications Adapter NCC Network Control Center NCGA National Computer Graphics Association NCIC National Crime Information Center NCMT Numerical Control for Machine Tools NCP NetWare Core Protocol NCR National Cash Register (Company) NCSA National Center for Supercomputing Applications NCSI Network Communications Services Interface [Novell] NDDK Network Device Development Kid [Microsoft] NDEF Not to be Defined NDIS Network Device/Driver Interface Specification NDP Numeric Data Processor NDR Network Data Representation [HP] NDRO Non-Destructive Read Out NDS NetWare Directory Service [Novell] NEC Nippon Electric Company NED NASA Extragalactic Database [NASA] NEG Negative NEMP Nuclear Electro Magnetic Pulse NES National Education Supercomputer NET Network (organization Domain name) [Internet] NetBEUI NetBIOS Extended User Interface [IBM] NetBIOS Network Basic Input/Output System [IBM] NEWS NetWare Early Warning System [Frye Computer] NEXT Near-End Crosstalk NFF No Fault Found NFS Network File System NG No Good NGE Not Greater or Equal NHC National Hurricane Center NIC Network Information Center [Internet] NICAD Nickel Cadmium NICOLAS Network Information Center OnLine Aid System [NASA] NID New Interactive Display [NEC] NII National Information Infrastructure NIMH Nickel-Metal Hydride NIPS Network I/Os Per Second NIR Network Information Retrieval NIS Network Information Service [Unix] NISO National Information Standards Organization NISP Networked Information Services Project NIST National Institute for Standards and Technology NITC National Information Technology Center NJE Network Job Entry (protocol) [IBM] NL New Line NLE Not Less or Equal NLM NetWare Loadable Module [Netware] NLQ Near Letter Quality NLSFUNC National Language Support Function NMI Non-Maskable Interrupt NMM NetWare Management Map [NetWare] NMOS Negative Channel Metal-Oxide Semiconductor NMS Network Management System [Novell] NN No News [Internet] NNI Network-Network Interface NNTP Network News Transfer Protocol [Internet] NOC Network Operations Center NOP No Operation NOR Not Or NOS Network Operating System NPA Network Printer Alliance NPI Network Printer Interface NPL Nonprocedural Language NPTN National Public Telecomputing Network NPU Natural Processing Unit NPX Numeric Processor Extension NREN National Research and Education Network NRZ Not Return to Zero NRZI Non Return to Zero Inverted NS Nanosecond NSA POLY National Security Agency Polygraph NSF National Science Foundation NSFNET National Science Foundation Network NSI NASA Science Internet NSP Network Service Provider NSSC NASA Standard Spacecraft Computer NSTC National Science and Technology Council NSTL National Software Testing Labs NT New Technology [Microsoft] NTAS NT Advamced Server [Microsoft] NTF No Trouble Found NTFS NT File System [Microsoft] NTIA National Telecommunications and Information Administrat NTIS National Technical Information Service NTP Network Time Protocol [HP] NTRAS NT Remote Access Services [Microsoft] NTSA NetWare Telephony Services Architecture [Novell] NTSC National Television Standards Committee NUI Network User Identification NUL Null NV No Overflow NVM Non-Volatile Memory NVP Nominal Velocity of Propagation NVRAM Non-Volatile Random Access Memory NVT Novell Virtual Terminal [Novell] N/I Non-Interlaced OAB One-to-All Broadcast OAG Official Airline Guide OAI Open Applications Interface OAS One-to-All Scatter OBEX Object Exchange [Borland] OBJ Object OC Optical Carrier OCE Open Collaborative Environment [Apple] OCL Operation Control Language OCR Optical Character Recognition OCT Object Class Table [HP] ODA Office Document Architecture ODAPI Open Database Application Programming Interface [Borlun ODBC Open Data Base Connectivity [Microsoft] ODBMS Object-Oriented Database Management System (also see OO ODI Open Datalink Interface [Novell] ODS Open Data Services [Microsoft] ODSI Open Directory Service Interfaces [Microsoft] ODT Open Desktop OEM Original Equipment Manufacturer OF Overflow Flag OFMT Output Format for Numbers OFS Output Field Separator OH Off Hook OIDL Object Interface Definition Language OIS Office Information Systems OLAP On-Line Analytical Processing (software) OLE Object Linking and Embedding [Microsoft] OLI Optical Line Interface [AT&T] OLMC Output Logic Macrocell OLTP On-Line Transaction Processing OM Object Manager OME Open Messaging Environment (protocol0 OMF Object Module Format [Microsoft] OMG Object Management Group OMI Open Messaging Interface [Lotus] OMNS Open Network Management System OMR Optical Mark Recognition ONC Open Network Computing [Sun] OODB Object-Oriented Database OODMS Object-Oriented Database Management System (also see OD OOL Object-Oriented Language OOPL Object-Oriented Programming Language OOPS Object Oriented Programming and Systems OOS Object-Oriented Systems OOUI Object Oriented User Interface OP Operation OPAC Online Public Access Catlog [Internet] OPC Optical Photoconductor OPCODE Operational Code OPD Operand OPI Open Prepress Interface OPM Operations Per Minute OPS Operations OPT Open Protocol Technology OPUS Octal Program Updating System ORACLE On-Line Inquiry and Report Generator (UNIX DB program) ORG Organization (organization Domain name) [Internet] ORS Output Record Separator OS Operating System OSA Open System Architecture OSF Open Software Foundation OSI Open Systems Interconnection OSM Off-Screen Model OSP Optical Storage Processor OSPF Open Shortest Path First OSQL Object Structured Query Language OS/2 Operating System/2 [IBM] OS/E Operating System/Environment OT Object Technology OTF Open Token Foundation OTP One-Time Programmable OURS Open Users Recommended Solutions OUTS Output String OV Overflow OWL Object Windows Library [Borlund] PABX Private Automatic Branch Exchange PAC Privilege Attribute Certificate [HP] PACS-L Public Access Computer Systems List [Internet] PAD Packet Assembler/Disassembler PADS Pen Application Development System [Slate Corporation] PAIH Public-Access Internet Host [Internet] PAIS Public-Access Internet Site [Internet] PAL Paradox Applications Language [Borlund] PALC Plasma-Addressed Liquid Crystal (display) PALS Principles of the Alphabet Literacy System PAP Passwork Authentication Protocol (protocol) PAR Parallel PARA Paragraph PARC Palo Alto Research Center [XEROX] PASCAL (Programming Language named for Blaise Pascal) PAX Portable Archive Exchange [Unix] PBE Prompt By Example PBX Private Branch Exchange PC Personal Computer PCB Printed Circuit Board PCD Photo Compact Disk PCI Peripheral Component Interconnect [Intel] PCL Printer Command Language [HP] PCM Personal Computer Manufacturer PCMCIA Personal Computer Memory Card International Association PCMIM Personal Computer Media Interface Module PCN Personal Computer Network PCNFS Personal Computer Network File System PCS Patchable Control Store PC-DOS Personal Computer - Disk Operating System [IBM] PC-I/O Program Controlled I/O PD Public Domain PDA Personal Digital Assistant PDD Physical Device Driver PDF Portable Document Format PDIAL Public Dialup Internet Access List [Internet] PDL Page Description Language PDM Process Data Management PDN Public Data Network PDP Programmable Data Processor PDS Packet Driver Specification PDSS Post Development and Software Support PDT Programmable Drive Table PDU Plug Distribution Unit PE Parity Even PEA Pocket Ethernet Adapter PEL Picture Element [IBM] PEM Privacy-Enhanced Mail [Internet] PEN SDK Pen Computing Software Development Kit PEP Packetized Ensemble Protocol [Telebit] PERL Practical Extraction and Report Language [Unix] PERT Program Evaluation and Review Technique PES Positioning Error Signal PET Print Enhancement Technology [Compaq] PFR Power-Fail Restart PGA Pin Grid Array PGDN Page Down PGM Program PGP Pretty Good Privacy (name of encryption program) PGUP Page Up PHIGS Programmers' Hierarchial Interactive Graphics Standards PI Program Interruption PIA Peripheral Interface Adapter PIC Personal Intelligent Communicator PICT Picture PID Process Identification Number PIF Picture Interchange Format File PILOT Programmed Inquiry Learning Or Teaching PilotAC Pilot Automatic Computing Engine PIM Personal Information Manager PIN Personal Identification Number PINE Pine Is Not Elm [Unix] PING Packet Internet Groper PIO Parallel Input/Output PIP Picture In Picture PIPO Parallel In, Parallel Out PIT Programmable Interval Timer PIXEL Picture Element PL Plus PLA Programmable Logic-Array PLATO Programmed Logic for Automatic Teaching Operations PLC Programmable Logic Controller PLCC Plastic Leadless Chip Carrier PLD Programmable Logic Device PLDS Pilot Land Data System [NASA] PLL Phase Locked Loop PLS Primary Link Station PLV Production Level Video PL/1 Programming Language One PL/M Programming Language for Micros PM Presentation Manager [IBM] PMMU Paged Memory Management Unit PMOS Positive Channel Metal Oxide Semiconductor PMS Policy Management System PN Processing Node PNP Plug And Play PO Parity Odd POC Point Of Contact POL Problem Oriented Language POP Point Of Presence [MCI] POPA Pop All Registers POPF Pop Flags POS Point Of Sale POSIX Portable Operating System Interface POST Power-On Self Test POSTNET Postal Numeric Encoding Technique POWER Performance Optimization with Enhanced RISC [IBM] PPDS Personal Printer Data Stream [IBM] PPM Pages Per Minute PPP Point-to-Point Protocol [Internet] PPS Packets Per Second PRACSA Public Remote Access Computer Standards Association PRAM Parallel Random-Access Machine PRAM Parameter Random Access Memory PReP Power PC Reference Platform [IBM/Motorola] PRF Pulse Repetition Frequency PRMD Private Mangement Domain [X.400] PRMD Private Management Domain PRN Printer PROC Procedure PROFS Professional Office System [IBM] PROG Program PROLOG Programming In Logic (Programming Language)(See HLL) PROM Programmable Read Only Memory PRTSC Print Screen PS Proportional Spacing PSAP Presentation Service Access Point [HP] PSC Print Server Command PSDN Packet-Switched Data Network PSDS Packet-Switched Data Service PSERVER Print Server [NetWare] PSF Permanent Swap File PSID PostScript Image Data PSN Packet Switching Network PSP Personal Software Products (group) [IBM] PSPDN Packet-Switched Public Data Network PSTN Public Switch Telephone Network PSW Program Status Word PS/2 Programming System 2 [IBM] PT Page Table PTD Parallel Transfer Disk Drive PTE Page Table Entry PUB Public (directory) [Internet] PUS Processor Upgrade Socket PUSHA Push All Registers PUSHF Push Flags PVC Permanent Virtual Circuit PVM Parallel Virtual Machine PW Password PWB Printed Wire Board PWD Print Working Directory [Unix] PWR Power PWSCS Programmable Worstation Communication Services [IBM] P-SRAM Pseudo-Static Random Access Memory P/T Part Time QA Quality Assurance QAM Quadrature Amplitude Modulation QBE Query By Example QBF Query by Form QC Quality Control QDOS Quick and Dirty Operating System QEMM Quarterdeck Expanded Memory Manager [Quarterdeck Corp.] QFA Quick File Access QFP Quad Flat Pack QIC Quality Information Using Cycle Time [Hewlett-Packard] QPSK Quadrature Phase Shift Keying RA Return Authorization RACF Resource Access Control Facility RAD Rapid Application Development RAG Row Address Generator RAID Redundant Arrays of Independent Disks RALU Register Arithmetic Logic Unit RAM Random Access Memory RAMDAC Random Access Memory Digital-to-Analog Converter [Sierr RAMP Remote Access Maintenance Protocol [Internet] RAND Random RAP Rapid Application Prototyping RARP Reverse Address Resolution Protocol RAS Random Access Storage RASAPI Remote Access Service Application Programming Interface RB Right Button (of 2 or 3 button Mouse) RBBS Remote Bulletin Board System RCL Rotate Carry Left RCP Remote Copy [Internet] RCR Rotate Carry Right RCS Records Communications Switching System RD Receive Data RDA Remote Database Access RDB Receive Data Buffer RDBMS Relational Database Mangement System RDCLK Received Timing Clock RDN Relative Distinguished Name [HP] RDSR Receiver Data Service Request REG Register REGAL Rigid Epoxy Glass Acrylic Laminate RELSECT Relative Sector REM Remark REN Rename REP Repeat REPE Repeat while Equal REPNE Repeat while Not Equal REPNZ Repeat while Not Zero REPZ Repeat while Zero REQ Request RES Remote Execution Service RET Resolution Enhancement Technology [HP] REX Relocatable Executable REXEC Remote Execution REXX Restructured Extended Executor (language) [IBM] RF Radio Frequency RFC Request For Comments [Internet] RFI Radio Frequency Interference RFP Request for Proposal RFQ Request for Quotation RFS Remote File Sharing RFT Revisable Form Text RFU Reserved For Future Use RGB Red-Green-Blue (color model) RI Referential Integrity RIFF Resource Interschange File Format [Microsoft] RIM Remote Installation and Maintenance [Microsoft] RIME RelayNet International Message Exchange RIP Raster Image Processor RISC Reduced Instruction Set Computer RJE Remote Job Entry RLE Run Length Encoded RLL Run Length Limited RLN Remote LAN Node [DCA] RLOGIN Remote Login RLSD Received Line Signal Detected RLSI Ridiculously Large-Scale Integration RM Reset Mode RMA Return Material Authorization RMDIR Remove Directory RMON Remote Monitor/Monitoring RMP Remote Maintenance Processor [IBM] RMS Record Management Services RN Read News [Internet] RND Random RNG Random Number Generator ROL Rotate Left ROM Read Only Memory ROP Raster Operation ROR Rotate Right RPC Real Procedure Call RPG Report Program Generator (Programming Language) RPL Resident Programming Language RPPROM Reprogrammable PROM RPQ Request for Price Quotation RPRINTE Remote Printer [NetWare] RPT Repeat RQBE Relational Query By Example [Fox Pro] RR Real Reality RS Radio Shack RSA129 (129 digit cryptographic security number named after it RSCS Remote Spooling Communications System RSH Remote Shell RSL Request-and-Status Link RSP Required Space Character RST Reset RSTS Resource Sharing Time Sharing [Digital] RSX Real Time Resource Sharing Executive RT Real Time RTAM Remote Terminal Access Method RTC Real-Time Clock RTDM Real-Time Data Migration RTEL Reverse Telnet [Internet] RTF Rich Text Format RTL Register Transfer Language RTM Response Time Monitor RTOS Real-Time Operating System RTS Remote Takeover System RTTY Radio Teletypewriter (Communications) RTV Real Time Video RVA Relative Virtual Address RVI Reverse Interrupt RWM Read-Write Memory RX Receiver RXD Received Data R&D Research and Development R-O Read Only R/T Receive/Transmit R/W Read/Write SA Simulated Annealing SAA Systems Application Architecture [IBM] SADL Synchronous Data Link Control [Racal-Vadic] SAINT Symbolic Automatic Integrator SAL Shift Arithmetic Left SAM Serial Access Memory SAP Second Audio Program SAP Symbolic Assembly Program SAR Shift Arithmetic Right SAS Sales Accounting System SAVDM Single Application VDM SB Sound Board SBA Scene Balance Algorithms [Kodak] SBB Subtract With Borrow SBC Single-Board Computer SBCS Single-Byte Character Set SCAS Scan String SCB Subsystem Control Block [IBM] SCC Serial Communications Controllers SCCS Source Code Control System SCD Standard Color Display SCF System Control Facility SCM Software Configuration Management SCO Santa Cruz Operation (Software Company) SCOPE Simple Communications Programming Enironment [Hayes] SCP Save Cursor Position SCR Silicon Controlled Rectifier SCRN Screen (video display) SCSA Signal Computing System Architecture [Dialogic] SCSI Small Computer Systems Interface SD Send Data SDA Software Disk Array SDB Symbolic Debugger [Unix] SDF Space Delimited File SDI Selective Dissemination of Information SDK Software Developer's Kit [Microsoft] SDLC Synchronous Data Link Control (protocol) SDN Software Defined Network [AT&T] SDNS Secure Data Network Service SDR Streaming Data Request SDRAM Synchronous Dynamic Random Access Memory SDS Sysops Distribution System SD_STB Streaming Data Strobe [IBM] SEA Standard Extended Attribute [OS/2] SEAC Name of first computer to use transistors, built by Sta SEAL Segmentation and Reassembly Layer (protocol) SEC Single Error Correction SECAM Sequentiel Couleur Avec Memoire (Sequential Color With SED Stream Editor SEG Segment SEL Select SEM Scanning Electron Microscope SER Serial SET Softwave Engineering Technology SETEXT Structure Enhanced Text [Internet] SEU Smallest Executable Unit SF Sign Flag SFQL Structured Full-text Query Language SFT System Fault Tolerance SFX Sound Effect(s) SGDT Store Global Descriptor Table SGEN Signal Generator SGML Standard Generalized Markup Language SGR Set Graphics Rendition SHAR Shell Archive SHG Segmented Hypergraphics SHL Shift Logical Left SHR Shift Logical Right SI Source Index SID Serial Input Data SIDF System Independent Data Format SIDT Store Interrupt Descriptor Table SIG Special Interest Group SIGCAT Special Interest Group on CD-ROM Applications and Techn SIGGRAP Special Interest Group on Graphics Applications SIM Simulator SIMD Single Instruction Multiple Data Stream (processor) SIMM Single In-line Memory Module SIMULA Simulation (language) SIO Serial Input/Output (communications driver) SIP Single In-line Package SIPO Serial In, Parallel Out SIPP Single In-line Pin Package SIR Serial Infrared [Hewlett-Packard] SIT Special Information Tones SI/SO Serial In/Serial Out SLDT Store Local Descriptor Table SLIP Serial Line Interface Protocol SLMR Silly Little Modem Reader SLOSH Sea, Lake and Overland Surge from Hurricane (program) SLSI Super Large-Scale Integration SLSS Systems Library Subscription Service [IBM] SM Set Mode SMB Server Message Block (protocol) [MII] SMD Surface Mounted Device SMDS Switched Multi-Megabit Data Service SMF System Manager Facility [Compaq] SMI System Management Interrupt [Intel] SMIF Standard Mechanical Interface SMIT System Management Interface Tool [IBM] SMK Software Migration Kit [Microsoft] SMM System Mangement Mode [Intel] SMP Simple Management Protocol SMPC Shared Memory Parallel Computer SMPS Switching Mode Power Supply SMRAM System Management Random Access Memory SMS Storage Management Services [NetWare] SMSW Store Machine Status Word SMT Surface-Mount Technology SMTP Simple Mail Transfer Protocol SMU System Management Utility SN Serial Number SNA Systems Network Architecture [IBM] SND Sound SNMP Simple Network Management Protocol [Internet] SNOBOL String Oriented Symbolic Language (Progamming Language) SNP Serial Number/Password [Omen Technology] SNR Signal-to-Noise Ratio SOC System On a Chip SOCKS Socket Secure (server) [Internet] SOE Standard Operating Environment SOH Start of Header SOL Simulation Oriented Language SOM Start of Message SONET Synchronous Optical Network SOP Standard Operating Procedures SOS Silicon On Sapphire SOTA State Of The Art SOX Sound Exchange SP Service Pack [IBM] SPA Software Publishers Association SPAN Space Physics Analysis Network SPARC Scalable Processor Architecture SPC Small Peripheral Controller SPCL Spectrum Cellular Corporation SPEC Systems Performance Evaluation Cooperative SPF Shortest Path First SPI Service Provider Interface SPIKE Science Planning Intelligent Knowledge-Based Environmen SPL Spooler SPM System Performance Monitor [IBM] SPOOL Simultaneous Peripheral Operations On Line SPP Sequenced Packet Protocol SPS Standby Power System SPSS Statistical Package for the Social Sciences SPT Sectors Per Track SPX Sequenced Packet Exchange [Novell] SQ Squeezed (files) SQL/DS Structured Query Language/Data System [IBM] SQRT Square Root SR Shift Register SRAM Shadow Random Access Memory SRB Source-Route Bridge SRD Screen Reader System SRM Security Reference Monitor SRO Sharable and Read Only SRPI Server-Requester Programming Interface SRQ Service Request SRR Serially Reusable Resource SRT Structure Rule Table [HP] SS Stack Segment SSAP Source Service Access Point SSEC Selective Sequence Electronic Calculator [IBM] SSGA System Suppport Gate Array SSI Small Scale Integration SST Spread-Spectrum Technology STA Spanning Tree Algorithm STB Strobe STC Set Carry Flag STD Set Direction Flag STDA StreetTalk Directory Assistance [Banyan] STDAUX Standard Auxillary STDERR Standard Error STDIN Standard Input STDIO.H Standard Input/Output Header [C] STDM Statistical Time Division Multiplexer STDOUT Standard Output STDPRN Standard Printer STI Set Interrupt Flag STN Super-Twist Nematic STOS Store String STP Shielded Twisted Pair (cable) STR Store Task Register STRESS Structural Engineering System Solver (Programming Langu STRUDL Structural Design Language (Programming Language) STScI Space Telescope Science Institute STT Secure Transaction Technology STX Start of Text SUB Subroutine SVC Switched Virtual Circuit SVGA Super Video Graphics Array SVM System Virtual Machine [Microsoft] SVR# System V Release Number [AT&T] SWAIS Simple Wide Area Information Server [Internet] SYLK Symbolic Link SYNC Synchronous SYS System SYSGEN System Generator SYSLOG System Log SYSMOD System Modification SYSOP System Operator SYSREQ System Request S-VHS Super VHS S/H Sample and Hold S/N Signal-to-Noise (Ratio) S/W Software TAD Telephone Answering Device TAPCIS The Access Program for the CompuServe Information Servi TAPI Telephony Applications Programming Interface TAS Telephone Access Server TASM Turbo Assembler [Borland] TAXI Transparent Asynchronous Tranceiver/Receiver Interface TB Terabyte (1,000 gigabytes) TBBS The Bread Board System (BBS) TC Test Control TCL Tool Command Language TCM Trellis-Coded Modulation TCP/IP Transmission Control Protocol/Internet Protocol TD Transmit Data TDD Telecommunications Device for the Deaf TDE Terminal Display Editor TDF Time Differential Factor [HP] TDI Transport Driver Interface TDM Time Division Multiplexing TDMA Time Division Multiple Access TDMS Terminal Display Management System TDR Time Domain Reflectometry TDSR Transmitter Data Service Request TDtoDP Tablet Coordinates to Display Coordinates (converting) TEB Thread Environment Block TEC Tokyo Electronics Corporation TED Tiny Editor TEML Turbo Editor Macro Language [Borlund] TEMP Temporary TER Thermal Eclipse Reading [Sony] TERMPWR Terminator Power TE/2 Terminal Emulator/2 [Oberon] TFDD Text File Device Driver TFEL Thin-Film Electroluminescent TFT Thin-Film Transistor (screens) TFTP Trivial File Transfer Protocol THD Total Harmonic Distortion THOR Tandy High-Performance Optical Recording THR Transmit Holding Register TI Texas Instruments, Inc. TIA Telecommunications Industry Association TID Target ID TIES Time Independent Escape Sequence TIFF Tagged Image File Format TIGA Texas Instruments Graphics Architecture TIGER Topologically Integrated Geographic Encoding and Refere TIIAP Telecommunications and Information Infrastructure Assis TIP Terminal Interface Processor TIPS The Internet Protocol Suite (TCP,UDP,IP,FTP,SMTP,SNMP.. TLA Three-Letter Acronym TLB Translation Lookaside Buffer TLI Transport Layer Interface TLU Table Lookup TM Trademark TMP Temporary TN Twisted Nematic TNC Terminal Node Controller ToC Table Of Contents TOP Technical and Office Protocol TPC Transaction Processing Performance Council TPI Tracks Per Inch TPL Table Producing Language TPM Transactions Per Minute TPORT Twisted Pair Port Transceiver [AT&T] TPS Transactions Per Second TPW Turbo Pascal for Windows TQM Total Quality Management TR Terminal Ready TRADIC Transistorized Airborne Digital Computer (Name of first TRN Threaded Read News [Internet] TRON The Real-Time Operating System Nucleus TS Top Secret TSA Technical Support Alliance TSAPI Telephony Services Application Program Interface [AT&T TSB Termination Status Block TSO Time Sharing Option TSR Terminate and Stay Resident TSS Task State Segment TSTN Triple Supertwisted Nematic TSV Tab Separated Values TS/SI Top Secret/Sensitive Information TTL Transistor-Transistor Logic TTS Text-To-Speech TTY Teletype TUI Text-Based User Interface [WordPerfect] TVF Table of contents Verbosely from File [UNIX] TVI Television Interference TWX Teletypewriter Exchange Service TXD Transmitted Data TXT Text TXT2STF Text To Structured File [Lotus Agenda] T/B Top and Bottom T/R Transmit/Receive UA User Agent UAE Unrecoverable Application Error UART Universal Asynchronous Receiver/Transmitter UCL Universal Communications Language UCS Universal Character Set UDC User Defined Commands UDE Universal Data Exchange UDF User Defined Functions UDP User Datagram Protocol UFS Unix File System UG User Group UI Unix International UID User Identifier UL Underwriters Laboratories ULA Uncommitted Logic Array ULN Universal Link Negotiation ULSI Ultra Large Scale Integration UMB Upper Memory Block [LIM/AST] UNC Universal Naming Convention UNCOL Universal Computed Oriented Language UNI User-Network Interface UNICOM Universal Integrated Communication (System) UNICOS Universal Compiler FORTRAN compatible UNIVAC Universal Automatic Computer UNIX (AT&T Bell Laboratories Operating System) UNMA Unified Network Management Architecture UPC Universal Product Code UPL User Program Language UPM Unix Programmer's Manual UPS Uninterruptible Power Supply UREP Unix RSCS Emulation Protocol (protocol) URL Uniform Resource Locator URN Uniform Resource Number US Unit Separator USART Universal Synchronous-Asynchronous Reciever/Transmitter USENET User's Network [Internet] USERID User Identification USQ Unsqueezed (files) USR US Robotics (corporation) USRT Universal Synchronous Receiver/Transmitter USSA User Supported Software Association (United Kingdom) UT User Terminal UTC Coordinated Universal Time UTI Universal Text Interchange UTP Unshielded Twisted-Pair (cable) UTS Update Time Stamp UU Uuencode/Uudecode UUCP Unix-To-Unix Copy Program UUD UUDecoding [Unix] UUE UUEncoding [Unix] UUI User-To-User Information [AT&T] UUID Universal Unique Identifier UV Ultraviolet VA Virtual Address VAD Value Added Dealer VADD Value Added Disk Driver VAL Value VAM Virtual Access Method VAN Value Added Network VAP Value Added Process VAR Value Added Reseller VAX/VMS Virtual Address Extension/Virtual Memory System [DEC] VB Variable Block VBA Visual Basic for Applications [Microsoft] VBE/AI Vesa Bios Extension/Audio Interface VBR Variable Bit Rate VBRUN Visual Basic Runtime VCD Virtual Communications Driver VCPI Virtual Control Program Interface VCR Video Cassette Recorder VDD Virtual Device Driver VDDM Virtual Device Driver Manager VDE Video Display Editor VDISK Virtual Disk VDM Virtual DOS Machine [IBM] VDS Virtual DMA Services VDT Video Dial Tone VDU Video Display Unit VEGA Video-7 Enhanced Graphics Adapter [Video-7, Inc.] VEMM Virtual Expanded Memory Manager VER Verify VERONIC Very Easy Rodent-Oriented Network Index to Computer Arc VERR Verify Read Access VERW Verify Write Access VESA Video Electronics Standards Association VF Virtual Floppy VFAT Virtual File Allocation Table [Microsoft] VFD Vacuum Fluorescent Display VFS Virtual File System VGA Video Graphics Array VGC Video Graphics Controller VHDL VHSIC Hardware Description Language VHS Very High Speed VHSIC Very High Speed Integrated Circuit VI Visual Interactive (editor) [UNIX] VIE Virtual Information Environment VIF Virtual Interface VIM Vendor Independent Mail VINES Virtual Network Operating System [Banyan] VIO Video Input/Output VIP Variable Information Processing VIPER Verifiable Integrated Processor for Enhanced Reliabilit VIS Video Information System [Tandy] VLF Very Low Frequency VLIW Very Long Instruction Word VLM Virtual Loadable Module VLSI Very Large Scale Integration VLSIPS Very Large Scale Immobilized Polymer Synthesis VLT Variable List Table VL-BUS Vesa Local-Bus [VESA] VM Virtual Machine VMA Virtual Memory Address VMB Virtual Machine Boot VME Virtual Memory Environment VMM Virtual Machine/Memory Manager VMOS Vertical MOS VMS Virtual Memory System VMS Virtual Memory System VMT Virtual Memory Technique VNA Virtual Network Architecture VOD Video On Demand VOL Volume VOM Volt Ohm Meter VOS Verbal Operating System VPD Virtual Printer Device VPDS Virtual Private Data Service [MCI] VR Virtual Reality VRAM Video Random Access Memory VRML Virtual Reality Markup Language VROOMM Virtual Real-time Object Oriented Memory Manager [Borlu VRU Voice Response Unit VS Virtual Storage VSAM Virtual Storage Access Method VSAT Very Small Aperture Terminal VSE Virtual Storage Extended VSF Vertical Scanning Frequency VSIO Virtual Serial Input Output VSLI Very Large Scale Integration VSM Virtual Shared Memory VSN Volume Serial Number VSOS Virtual Storage Operating System VSYNC Vertical Sync VTAM Virtual Telecommunications Access Method [IBM] VUE Visual User Environment [HP] VUI Video User Interface VUP VAX Unit of Performance VWB Visual WorkBench [Microsoft] VxD Virtual Extended Driver [Microsoft] W3 (see WWW) W4 What-Works-With-What WABI Windows Application Binary Interface [Sun] WAIS Wide Area Information Server WAITS Wide Area Information Transfer System WAN Wide Area Network WATS Wide Area Telecommunications Service WC Word Count WDL Windows Driver Library [Microsoft] WELL Whole Earth 'Lectronic Link (BBS) WFW Windows For Workgroups [Microsoft] WGS Work Group System WHAM Waveform Hold and Modify [Microsoft] WINE Windows Emulator WINForu Wireless Information Networks Forum WinHEC Windows Hardware Engineering Conference WINSOCK Windows Open Systems Architecture [Microsoft] WINWORD Word For Windows [Microsoft] WISE WordPerfect Information System Environment WM Work Manager [HP] WNIC Wide-Area Network Interface Co-Processor WNIM Wide-Area Network Interface Module WORM Write Once, Read Many WOS Workstation Operating System WOSA Windows Open Services/Systems Architecture [Microsoft] WOW Windows On Win32 [Microsoft] WP WordPerfect WPHD Write-Protect Hard Disk WPM Words Per Minute WPOS Workplace Operating System WPS Windows Printing System [Microsoft] WS WordStar WT Write Through WWIS World Wide Information System [Internet] WWW World-Wide Web [Internet] WYSBYGI What You See Before You Get It WYSIWYG What You See Is What You Get W/ With W/O Without X2B Hexadecimal to Binary [REXX] X2C Hexadecimal to Character [REXX] X2D Hexadecimal to Decimal [REXX] XA Extended Architecture XAPIA X.400 Application Program Interface Association XBM X Windows Bitmap XCHG Exchange XCMD External Command XCOPY Extended Copy XDF Extended Density Format [IBM] XDR Extended/External Data Representation XDS X/Open Directory Service [HP] XFCN External Function XGA Extended Graphics Array [IBM] XID Exchange Identifier XIOS Extended Input/Output System XLAT Translate XLM Excel Macro Language [Microsoft] XMIT Transmit XMM Extended Memory Manager [LIM/AST] XMS Extended Memory Specification [LIM/AST] XNS Xerox Network System (protocol) [Xerox] XOFF Transmitter Off XOM X/Open Object Management [HP] XON Transmitter On XOR Exclusive OR (Also EOR) XSMD Extended Storage Module Drive (interface) XTAL Crystal XTCLK External Transmit Clock YACC Yet Another Compiler Compiler YAM Yet Another Modem [Omen Technology] ZBR Zone Bit Recording ZDL Zero Delay Lockout ZDS Zenith Data Systems ZIF Zero-Insertion Force (socket) ZIP Zigzag In-Line Package ZSL Zero Slot LAN Z-CAV Zoned Constant Angular Velocity * Wildcard character (asterisk) *.* Star-Dot-Star (represents Any file name.Any file name e .ADB Appointment Book [HP] .ADE cc:Mail Local Address Book update .ADF Adapter Description File (file name extension) [IBM] .ADN Add In Utility (file name extension) [Lotus 1-2-3] [LDC .AFM Adobe Font Metrics (file name extension) [Adobe Systems .ANN Annotations (file name extension) [IBM] .APP Application (file name extension) [R:Base] .APR Lotus Approach Database .APT Lotus Approach Database File .ARC Archive (file name extension) .ARJ Compressed File (file name extension) [Jung] .ASC ASCII text (file name extension) .ASM Assembler Source Language (file name extension) .ATT cc:Mail message attachment .AU Sound File .BAK Backup (file name extension) .BAS Basic Language (file name extension) .BAT Batch Processing (file name extension) .BGI Borland Graphic Interface (file name extension) .BIB Bibliography (file name extension) .BIN Binary (file name extension) .BK! Backup (file name extension) [WordPerfect] .BLD BASIC Bload Graphics (file name extension) .BMP Bitmap Picture (file name extension) .BSC Boyan Script (file name extension) [Boyan Communication .C C source code (file name extension) [C] .CAP Capture (file name extension) .CAT Catalog (file name extension) .CBL COBOL source code (file name extension) .CCM cc:Mail inbox .CDF Comma Delimited Format (file name extension) .CDX Compound Index (file name extension) [Fox Pro] .CFG Configuration (file name extension) .CFL Cash Flow Lists [HP] .CGM Computer Graphics Metafile (file name extension) .CHK CHKDSK (file name extension) .CLP Clipboard (file name extension) [Windows] .CMD Command (file name extension) .CNF Configuration (file name extension) .CNT Help Contents File [Microsoft] .COB COBAL source code (file name extension) .COD Code List (file name extension) .COM Command (file name extension) .CPI Code Page Information (file name extension) [MS-DOS] .CRD Cardfile (file name extension) .CTF Character translation files [HP] .CUR Cursor (file name extension) .DAT Data (file name extension) .DBF Database (file name extension) .DCF Datacomm Configuration File [HP] .DCT Dictionary (file name extension) .DEF Definitions .DEM Demonstration (file name extension) .DES Description (file name extension) .DHP Dr. Halo PIC (file name extension) .DIC Dictionary (file name extension) .DOC Document .DOT Microsoft Word Template .DRS Driver Resource (file name extension) [WordPerfect] .DRV Device Driver (file name extension) (Also see .DVR) .DRW Draw .DTA Data (file name extension) .DV DESQview Script (file name extension) .DVI Device Independent (file name extension) .DVR Device Driver (file name extension) (Also see .DRV) .DXB Drawing Interchange Binary (file name extension) [AutoC .EML Electronic Mail (file name extension) .ENC Encoded (file name extension) .ENV Environment files .EPS Encapsulated PostScript (file name extension) .EQN Solver equation lists [HP] .EXE Executable (file name extension) .EXM System Manager compliant Programs [HP] .FAX Fax (file name extension) .FCF Filer configuration files [HP] .FLD cc:Mail folder .FON Font Format files [DOS] .FOR FORTRAN source code (file name extension) .FRS WordPerfect Graphics Driver (file name extension) .GDB General Data Base [HP] .GIF Graphics Interchange Format (file name extension) .GLY Glossary (file name extension) [Microsoft Word] .GRF Graph (file name extension) .GRP Group (file name extension) .gz Compressed file (compressed filename extension - using .H Header (file name extension) [C] .HLP Help (file name extension) .HPJ Help Project File [Microsoft] .HST History .HT Hyper Terminal File [Microsoft] .HTM Hypertext Markup File (HTML) .HYP Hyphenation (file name extension) .ICO Icon (file name extension) .IDF MIDI Instrument Definition .IDX Index (file name extension) .INF Information (file name extension) .INI Initialize (file name extension) .JNK Junk (file name extension) .KIT Keyboard information table [DOS] .LBR Library (file name extension) .LCF Datacomm Script files [HP] .LET Letter (file name extension) .LIB Library (file name extension) .LOG Log File .LRS Language Resource (file name extension) [WordPerfect] .LST List (file name extension) .MAC MacPaint (file name extension) .MAI Mail (file name extension) .MAP Linker Map (file name extension) .MAS Freelance Presentation SmartMaster File [Lotus] .MDF Menu Definition File (file name extension) .ME Opening Information (file name extension) (As in READ.M .MEN Menu (file name extension) .MET Metafile (file name extension) .MID MIDI Sequence .MNU Menu (fine name extension) .MSG Program Message (file name extension) .MSP Microsoft Paint (file name extension) [Microsoft] .MWP WordPro Wordprocessor File [Lotus] .NCF Netware Command File [Novell] .NDB Note Taker Data Base [HP] .NDX Index (file name extension) .NEW New Information (file name extension) .OLD Old version (file name extension) .OPT Options (file name extension) .ORI Original (file name extension) .OUT Outlines (file name extension) .OVL Program Overlay (file name extension) .OVR Program Overlay (file name extension) .PAK Packed (compressed file name extension) [NoGate Consult .PAS PASCAL source code (file name extension) .PAT Patch (file name extension) .PCF Printer Configuration File [HP] .PCT Picture (file name extension) .PCX Picture Image (file name extension) .PDB Phone Book [HP] .PDF Printer Description (file name extension)[Borlund,Lotus .PDT Pocket Quicken Data file .PDX Paradox files (file name extension) [Borlund] .PFM Printer Font Metrics (file name extension) [Windows] .PGL Graphics (file name extension) [Hewlett-Packard] .PGP ProGram Parameter (file name extension) [AutoCAD] .PHO Phone List (file name extension) .PLL Prelinked Library (file name extension) [Clipper] .PRD Printer Driver (file name extension) [Word] .PRE Freelance Presentation File [Lotus] .PRF Preferences (file name extension) [Grammatik IV] .PRG Program (file name extension) .PRO Profile (file name extension) .PRS Printer (file name extension) [WordPerfect] .PS PostScript (file name extension) .ps.Z Compressed PostScript (file name extension) [Unix] .PUB Publication (file name extension) [Ventura] .PX Primary Index (file name extension) [Paradox] .QDI Dictionary (file name extension) [Quicken] .QDT Data (file name extension) [Quicken] .QIC Backup Set for Microsoft Backup .QIF Quicken Interchange Format (file name extension) .QMT Memorized List (file name extension) [Quicken] .QNX Indexes to Data (file name extension) [Quicken] .REC Recorder (file name extension) .REF Reference (file name extension) .RES Resource (file name extension) .SAM AmiPro Wordprocessor File [Lotus] .SAV Saved (file name extension) .SC Script (file name extension) .SCR Script (file name extension) .SDF Standard Data Format (file name extension) .SEA Self Extracting Archive (file name extension) [Macintos .SET Driver Set (file name extension) [Lotus 1-2-3] [LDC] .SIT Stuff-It (compressed file name extension) [Macintosh] .SMP Sample (file name extension) .SND Sound File .SPL Spell Checker (file name extension) .SRC Source (file name extension) .STA Calculator Statistics List [HP] .STF Structured File (file name extension) [Lotus Agenda] .STY Style (file name extension) [Ventura, Word, WordPerfect .SUP Supplemental Dictionary (file name extension) [WordPerf .SWP Swap (file name extension) .SYM Symbols (file name extension) .SYN Synonym (file name extension) .SYS System Configuration (file name extension) .tar Tape Archive (archived file name extension) [Unix] .tar.Z Compressed Archived files (file name extension) [Unix] .TBK Toolbook (file name extension) .TDF Trace Definition File (file name extension) [OS/2] .TFM Tagged Font Metric (file name extension) .THD Thread (file name extension) .THS Thesaurus (file name extension) .TIF Tagged Image File (filename extension) .TLX Telex (file name extension) .TRM Terminal (file name extension) .TST Test (file name extension) .TTF TrueType Font (file name extension) .TUT Tutorial (file name extension) .UC2 Compressed File (file name extension) [UltraCompressor] .VAL Validity Checks (file name extension) [Paradox] .VBX Visual Basic Extension (file name extension) .VRS WordPerfect Graphics Driver (file name extension) .WAV Waveform Audio (file name extension) .WDB World Time Data Base [HP] .WK1 Worksheet (file name extension) [Lotus 1-2-3] [LDC] .WK3 Worksheet File [Lotus] .WK4 Worksheet File [Lotus] .WKB Workbook (file name extension) [WordPerfect] .WKE Worksheet (file name extension) [Lotus 1-2-3] [LDC] .WKQ Spreadsheet (file name extension) [BORQU] .WKS Worksheet (file name extension) [Lotus 1-2-3] [LDC] .WKZ Compressed Spreadsheet (file name extension) [BORQU] .WMF Windows Metafile Format (file name extension) [Microsof .WPG Graphics (file name extension) [WordPerfect] .WPK Keyboard (file name extension) [WordPerfect] .WPM Macro (file name extension) [WordPerfect] .WQ1 Spreadsheet (file name extension) [BORPQU] .WQ! Compressed Spreadsheet (file name extension) [BORPQU] .WR1 Worksheet File [Lotus] .WRI Write (file name extension) .WRK Worksheet File [Lotus] .z Packed file (file name extension - using Pack/Unpack pr .Z Compressed file (file name extension - using Compress/U .ZIP Compressed File (file name extension) [PKWare] .ZOO Compressed File (file name extension) [Dhesi] Glossary 0VR zero volt return 10Base-2 10Base-2 is Ethernet 50 RG-58 coaxial cable with a 0.2 inch diameter. It is also known as thinwire Ethernet. 10Base-5 10Base-5 is standard Ethernet 50 coaxial cable with a 0.4 inch diameter. It is also known as thickwire Ethernet. 10Base-F 10Base-F is the Ethernet standard (IEEE 802.3) for transmission over fibre optic cables. 10Base-T 10Base-T is the Ethernet standard (IEEE 802.3) for transmission over unshielded twisted pair. 10BaseFL 10BaseFL is a standard fibre-optic interface for Ethernet/IEEE 802.3 at 10 Mb/s that supports transmission over distances up to two kilometres. 23B+D 23 bearer channels plus data channel For T1, each bearer channel provides 64 kb/s. The data channel provides 64 kb/s for out-of-band signalling. 2601, 2602, 2603, Each of these DTUs can connect to one or two data 2701, 2702, 2703 devices. The 2601 and 2701 MainStreet DTUs connect to and 2704 RS-232/V.24 devices; the 2602 and 2702 MainStreet DTUs MainStreetDTUs connect to X.21 (RS-449/422) devices; the 2603 and 2703 MainStreet DTUs connect to V.35 devices; and the 2704 MainStreet DTU connects to V.110 devices. 2606 MainStreet DTU The 2606 MainStreet DTU is a time division multiplexer that multiplexes eight synchronous and asynchronous RS-232/V.24 input channels onto one or two 64 kb/s output channels. 2610 MainStreet PAD The 2610 MainStreet PAD (Packet Assembler/Disassembler) provides two asynchronous RS-232/V.24 ports. It is used to connect other vendors’ equipment to a Newbridge network so the equipment can be managed by the MainStreetXpress 46020 Network Manager. 2902 MainStreet The 2902 MainStreet Multiservice Network Termination Multiservice NTU Unit provides high-speed data connections between public and private switched networks. It supports two E1 primary rate interfaces for data transmissions, which also allow voice calls to pass transparently through the node. The 2902 MainStreet NTU also provides two module positions for data interfaces, and offers super-rate functionality without the installation of a super-rate module. 2B+D two bearer channels plus data channel Each bearer channel provides 64 kb/s. The data channel provides 16 kb/s. 2B1Q two binary, one quaternary An ISDN line encoding technique that uses two bits to represent four variations in amplitude and polarity. 2W 2-wire 2WTO 2-wire transmission only 30B+D 30 bearer channels plus data channel For E1, each bearer channel provides 64 kb/s. The data channel provides 64 kb/s for out-of-band signalling. 3500 MainStreet TAP The 3500 MainStreet TAP (Transmission Access Platform) is a flexible, modular platform that provides cost-effective access to dedicated and switched bandwidth for applications such as videoconferencing and imaging. It offers advanced data traffic processing and control, inverse multiplexing through BONDING (Bandwidth ON Demand INteroperability Group), and encryption. 3600 MainStreet The 3600 MainStreet Bandwidth Manager is a Bandwidth Manager high-performance system for use in private and public networks. This platform can be used in a broad range of applications including voice compression, frame relay, subrate multiplexing, and subrate and super-rate data transmission. It supports channel units, frame relay switching cards, and T1 and E1 interfaces with signalling, companding and super-rate data conversion. 3601 MainStreet The 3601 MainStreet Frame Relay Network Adapter is a Frame Relay Network high-performance frame relay access device capable of Adapter adapting a wide range of data traffic to frame relay networks, including BOP (bit oriented protocol), SLIP (serial line Internet protocol), and PPP (point-to-point protocol) carrying IP (Internet protocol). The 3601 MainStreet unit contains an integrated 56 kb/s CSU/DSU to terminate the local DDS access loop. 3606 MainStreet The 3606 MainStreet Little Mux is available in voice Little Mux and data, or data-only versions for narrowband digital links. Both versions support one aggregate link of up to 256 kb/s and can be used in a narrowband network or as a narrowband multiplexer feeding into a broadband network. The 3606 MainStreet system supports subrate multiplexing and voice compression. A 3606 MainStreet iDSU data-only variant of the 3606 MainStreet node is also available. 3612 MainStreet The 3612 MainStreet Narrow-band Multiplexer is an Narrow-band integrated voice and data multiplexer for narrowband Multiplexer digital links and switched and leased ISDN. It supports up to four aggregate links with bandwidths of up to 512 kb/s each. It is often used as an end node in a narrowband network or as a narrowband multiplexer feeding into a broadband network. The 3612 MainStreet system supports subrate multiplexing, voice compression and super-rate data transmission. 36120 MainStreet The 36120 MainStreet PTX combines all the voice, data, PTX LAN and special application features of the 3600 and 3645 MainStreet products. In addition, it is a high-performance frame relay switch that delivers an aggregate switching performance of up to 100 000 frames per second. 3620 MainStreet The 3620 MainStreet Branch Access Controller Branch Access integrates voice, data and LAN interfaces into a Controller compact, flexible device for the branch office. As an intelligent T1 CSU/DSU, the 3620 MainStreet node can be used in point-to-point configurations or for access to public networks. 3624 MainStreet The 3624 MainStreet Intelligent T1 Channel Bank Intelligent T1 provides one T1 interface for connecting voice and Channel Bank data transmissions onto a T1 link. It is often used to provide customer access to public or private networks, or to provide point-to-point service. 3630 MainStreet The 3630 MainStreet Primary Rate Multiplexer is an Primary Rate integrated drop-and-insert voice and data multiplexer Multiplexer that provides one or two T1 interfaces, or one or two E1 interfaces. 3645 MainStreet The 3645 MainStreet High Capacity Bandwidth Manager High Capacity offers all the advanced functionality of the 3600 Bandwidth Manager MainStreet system, but at higher speeds and at eight times the capacity. It provides DS3, E3, T1 and E1 interfaces and supports T1 and E1 signalling, companding and super-rate data conversion. It is particularly well suited to networks that require larger nodes and more bandwidth between each node. 3664 MainStreet The 3664 MainStreet Fractional Access Multiplexer is a Fractional Access low-cost, high-performance system for feeder and Multiplexer backbone applications. It provides X.21 and V.35 aggregates, and a variety of voice, data and frame relay interfaces. The 3664 MainStreet system provides all the capabilities of the 3600 MainStreet system, except it only allows access to the first 12 DS0s on a T1 Card, and cross-connects to the first 15 timeslots on an E1 Card, and it has no FRE (Frame Relay Engine) support. 4601 MainStreet This PC-based management station provides node Network Manager management, centralized alarm reporting and database backup, verify and restore functions for networks containing 3600 MainStreet family backbone nodes and 3664, 3630, 3624, 3612 and 3606 MainStreet feeder nodes. 4601A MainStreet With the 4601A MainStreet network manager running on a Auxiliary Network laptop computer, network technicians can contact the Manager network nodes and the network manager from remote locations through the network links or through the PSTN (Public Switched Telephone Network). The 4601A MainStreet network manager provides node management, centralized alarm reporting, software downloading, and database backup, verify and restore functions. 4B/5B 4B/5B is the physical layer coding scheme for multimode transmission over FDDI. 4ESS four electronic switching system 4W 4-wire 4WDX 4-wire duplex 4WTO 4-wire transmission only 802.1 (d) transparent spanning tree This is the IEEE standard protocol for routing, loop detection and avoidance in a network of MAC bridges. IEEE 802.1 (d) is the MAC standard that defines architecture, addressing, internetworking and network management. It resolves the problems of connecting multiple LANs without eliminating redundant links. It is also known as STP (spanning tree protocol). 802.2 logical link control This is the IEEE standard for the data link layer of local area networks. Also ISO 8802/3. IEEE 802.2 defines the data link layer standard used with the IEEE 802.3, 802.4 and 802.5 standards. It is also defined as ISO 8802/2. 802.3 IEEE 802.3 defines the physical and data link layer standard specifying a LAN with CSMA/CD access on a bus topology. It is based on the Ethernet standard. IEEE 802.3 is also standardized as ISO 8802/3. 802.4 IEEE 802.4 defines the physical and data link layer standard specifying a LAN with a token passing access method on a bus topology. 802.5 IEEE 802.5 defines the physical and data link layer standard specifying a LAN with a token passing access method on a ring topology. It is known as Token Ring and standardized as ISO 8802/5. 802.6 IEEE 802.6 defines the physical and data link layer standard specifying a pseudo-LAN on high-speed telephone circuits. 8230 MainStreet The 8230 MainStreet Ethernet Little Bridge provides a Ethernet Little direct connection between IEEE 802.3 Ethernet LANs and Bridge backbone LANs or high-speed WAN circuits, or both. It supports up to two IEEE 802.3/Ethernet LAN interfaces and up to two WAN interfaces. 8B/10B 8B/10B is the physical layer coding scheme for single mode transmission over FDDI. A amperes A/D analog to digital AAL ATM adaptation layer A layer that sits above the ATM layer and adapts non-ATM bit streams into ATM cells. AAL1 ATM adaptation layer - type 1 A specific type of ATM adaptation intended for constant bit rate service applications. AAL5 ATM adaptation layer - type 5 AAR automatic alternate routing The algorithm by which the network manager automatically reroutes broken paths. The MainStreetXpress 46020 Network Manager has an AAR facility that automatically reroutes paths that are disrupted by problems in the network. For example, when a 3600, 3645, 3664 or 36120 MainStreet node detects a loss of synchronization on a primary rate link, it reports this event to the MainStreetXpress 46020 system. The MainStreetXpress 46020 Network Manager then reroutes all non-RAPID paths affected by the failure. AARP AppleTalk Address Resolution Protocol ABCD signalling The signalling bit used by voice channels in PRIs (E1/T1). ABR available bit rate ABR is an ATM Forum service category defined to support both connectionless and connection-oriented services. It is used for applications that have unpredictable bandwidth requirements. All ABR connections share resources fairly, and receive as much bandwidth as is available on an as-needed basis. ABR provides guaranteed low cell loss, but does not specify an upper limit on delay. ABR is primarily intended for LAN emulation services. ac alternating current AC15 a tone signalling protocol ACC a) Advanced Computer Communications ACC is a Newbridge affiliate and a leading manufacturer of wide area internetworking products. b) automate callback calling Access group An access group is a group of path and link endpoints in the MainStreetXpress 48020 MNSC. It is analogous to a MainStreetXpress 46020 Network Manager node. Access method Access method refers to the set of interface procedures for using an I/O resource. Some examples are TAM, VTAM and BTAM. ACK acknowledge This is an acknowledging signal that confirms the receipt of a data packet. ACO alarm cut off Allows the audible alarms to be extinguished without affecting the visual alarms. The audible alarms can be toggled as enabled or disabled. ACO/LT alarm cut off/lamp test ACR available cell rate ACR is the current rate in cells/s at which the ABR source is allowed to send data. ACSE association control service element ACSE is the OSI protocol for the application service element responsible for association establishment and release. ACT absolute congestion threshold ACT is a frame relay parameter related to the buffer capacity of a frame relay device. At the ACT, the frame relay device discards all newly arriving frames and raises a congestion alarm. See also MCT and SCT. Active Database An active Database NetworkStation is a NetworkStation NetworkStation with the active database. Other NetworkStations and other user interfaces (such as VT100s) access this database. Active Network An active Network Manager is the Network Manager with Manager the database that is being used. Other user interfaces, such as MainStreetXpress Connect Exec, access this database. See also Standby Network Manager. Activity indicator An activity indicator is a green circle found on the Control card. It represents the LED indicator on the panel of the physical card. Its presence indicates that the Control card is active. Add-on product An add-on product is one of the Newbridge or CrossKeys software packages that enhances network management capabilities. Add-on products include: Custom Node Manager, SNMP Manager, VBN Agent, VSN Agent, Statistics Reporter and KeyNotes. Address An address is a structured string of bits used to identify each device on a network. Address table Address tables are used by network devices to forward data packets to the destinations. ADI automatic or alternate digit inversion In CCITT voice channels, every second bit is inverted after encoding and before decoding using A-Law companding to ensure enough level transitions for clock extraction. ADM Add/Drop Multiplexer. Multiplexer equipment that provides interfaces between different signals in the network. For example, the 3600 + MainStreet node provides interfaces between SONET/SDH signals and narrowband signals. Administrator This term can be used in two ways: * The administrator is the person who administers the network and creates new accounts using the MainStreetXpress 46020 "admin" account. * In a partitioned network, "administrator" refers to a service provider’s mode of operation. An "admin" user in administrator mode can create partitions. All service providers in this mode can manage partitions. Administrator mode In a partitioned network, it refers to a service provider’s mode of operation. An "admin" user in administrator mode can create partitions. All service providers in administrator mode can manage partitions. ADPCM adaptive differential pulse code modulation ADPCM is a voice compression technique that reduces the bandwidth requirements of a voice path to 32 kb/s. The two types are delta ADPCM and transitional ADPCM. ADPCM bundle When two or more timeslots using ADPCM compression are grouped together to make three or more ADPCM voice connections, they are referred to collectively as an ADPCM bundle. ADPCM link An ADPCM link is a pairing of ADPCM transcoders, along with an associated set of communication channels. The transcoders join between two and six DS0 communication channels. AE (a) answering endpoint (b) application entity An application entity provides the service desired for communication. An application entity is named by an application entity title. AFI authority and format identifier The AFI is a two-digit field in the prefix of an ATM address. It defines the address format. Valid AFI formats include ICD, DCC and E.164. Aged This term refers to SVCs that have been inactive for a period of time set by the user. After the aging period, the SVC is dropped. Agent CME object The Agent CME object is how the UMS sees MainStreetXpress Connect Exec. It is an NM/Forum-compliant object that is managed through the CE driver process. It contains the MIB. Aggregate An aggregate uses multiplexing and demultiplexing techniques to transmit several connections along one channel. Newbridge uses the term "aggregate" when referring to V.35 or X.21 aggregate interfaces on the 3606 node or the E1 aggregate on the 3612 node. On the 3606 node, an aggregate supports a bandwidth of up to 256 kb/s and on a 3612 node up to 512 kb/s. Aggregate channel An aggregate channel is the channel on the merged side of an SRM. Several branch channels merge onto an aggregate channel. Aggregate interface Aggregate interfaces use multiplexing and demultiplexing techniques to transmit several connections along one V.35 or X.21 channel. Aggregate or Agg. Newbridge uses the term "aggregate" in two ways: * When referring to V.35 aggregate and X.21 aggregate interfaces on 3606 and 3612 MainStreet nodes. These interfaces use multiplexing and demultiplexing techniques to transmit several connections along one channel. * When referring to the aggregate component of the MainStreet Statistics Collector. The aggregate is software running the MainStreetXpress 46020 Network Manager or a separate workstation, that compiles statistical data from various collectors. AIA alarm indication area AIMM Advanced Inverse Multiplexing Module A device that combines multiple T1 or E1 communication facilities in a single broadband facility for the transmission of ATM cells. AIS alarm indication signal A code sent downstream in a digital network to indicate a traffic-related defect has been detected. ALAPB asynchronous link access protocol, balanced A Newbridge proprietary link layer intended for use over asynchronous data interfaces including modem connections. Alarm An alarm is a node-generated message created as a result of an event, such as a path status change. ALB analog loopback A method of testing modems and data terminals by disconnecting the device from the telephone line and looping a signal out through the device’s transmit side and in through its receive side. The test tells if the trouble is with the telephone line or with the modem. ALBO automatic line build out ALBO is a means of automatic cable equalization used in T1 span-line interface equipment. ALD active link detection A function that detects the presence of a network link. AM application module AMA automatic message accounting AMI alternate mark inversion The line-coding format in transmission systems whereby successive ones (marks) are alternately inverted (sent with polarity opposite that of the preceding mark). AMP Active Monitor Present Anchor point Anchor points are MainStreetXpress 46020 Network Manager map icons that are used with LAN segments to construct a LAN of any topology. They connect LAN nodes to the LAN via LAN links. Typically, anchor points represent T-connectors or AUI transceivers. ANI automatic number identification A series of digits, either in analog or digital form, which identify the incoming call. ANM advanced network management ANS automatic network synchronization ANS is a Newbridge proprietary algorithm which automatically selects a synchronization pattern for a network. It allows networks to be divided into sectors with independent timing. Each sector has a master synchronization node. ANS v2 automatic network synchronization, version 2 ANSI American National Standards Institute ANSI is a non-profit organization that develops and publishes standards and represents the U.S. in some international standards groups. AP action point APDU application protocol data unit The APDU is a PDU that operates at the application layer of the OSI reference model. API application programming interface A set of programming functions and routines that act as an interface to the network for application programs. APIs translate high-level program code into low-level computer instructions that run the network. Thus, application programs (for example, word processors) can communicate with low-level programs handling network data traffic. AppleTalk Apple Computer’s proprietary suite of protocols for linking Apple computers and peripherals. Application card Application cards on a 3600, 3645, 3664 or 36120 MainStreet node operate in conjunction with primary rate, voice, or data interface cards to perform specialized value-added functions. Application key The application key is a software security code used to activate authorized software features and products during startup. It also verifies network limitations with respect to the number of nodes and workstations. Application layer The application layer is the seventh and top-most layer of the OSI reference model. It defines protocols for user or application programs. Communications services such as electronic mail, file transfer, virtual terminal emulation, and remote database access are provided at this layer. AQA activity qualified access Architecture This is the manner in which hardware or software is structured, including how components fit together. It indicates the protocols and interfaces used for communication and co-operation among modules or components in the system. ARD automatic ring down A direct path signalling facility to a distant phone. Signalling happens automatically when the receiver is lifted on either phone. ARE all routes explorer A token ring frame transmitted by a source station to find all possible paths to a destination station. ARP address resolution protocol A protocol with the TCP/IP (transmission control protocol/internet protocol) suite that maps IP addresses to Ethernet MAC addresses. TCP/IP requires ARP for use with Ethernet. ARPA Advanced Research Project Agency ARPANET Advanced Research Projects Agency Network ARPANET was the first major packet-switched network, created by the U.S. DARPA. AS autonomous system AS is the IP term for a collection of routers that come under one administrative entity and co-operate by using a common IGP. AS is synonymous with the ISO term routing domain. Routing between autonomous systems is done with an inter-AS or interdomain protocol (EGP). AS/NZS Australian/New Zealand Standard ASC abnormal station code ASC circuit ATM Services card circuit ASCII American Standard Code for Information Interchange This standard defines codes for a character set in binary (on/off) bits. Out of a total of 128 characters, 96 are assigned to the alphabet, numbers, punctuation marks and other symbols. The remaining characters are assigned to control functions. ASIC application specific integrated circuit An IC which has been designed to address one particular application. ASN abstract syntax notation ASN.1 is used by MainStreetXpress Connect Exec to describe and define data types. Asynchronous This is the method of data transmission where each communication character is individually synchronized by having the transmitted character preceded by a start bit and followed by one or more stop bits. It is also known as start-stop transmission. AT&T American Telephone & Telegraph ATB address table builder ATD asynchronous time division ATM asynchronous transfer mode A multiplexing/switching technique in which information is organized into fixed-length cells, with each cell consisting of an identification header field and an information field. The transfer mode is asynchronous in the sense that the use of the cells depends on the required or instantaneous bit rate. ATM Forum The ATM Forum is an industry organization that defines standards for ATM networking protocols. ATM link An ATM link is a physical link carrying ATM traffic. ATM SC See ATM Services card. ATM Services card ATM Services cards allow the 3600 MainStreet family bandwidth managers to transmit circuit-switched voice, data, frame relay services and signalling from a T1, E1 or IMA interface into an ATM network. ATM Services cards have different external interfaces and ATM adaptation features. ATMF ATM Forum See ATM Forum. ATMnet asynchronous transfer mode network A Newbridge logo for the ATM product line. A very high-speed telecommunications transmission network that uses a high bandwidth and low delay. Atomic set Atomic set refers to a CMIP set command that changes the value of an unlocked groomed circuit’s bandwidth; it results in the groomed circuit being disconnected and then reconnected with its new bandwidth. Attribute This term refers to node and network parameters that can be configured by the MainStreetXpress 46020 Network Manager. AU3 Administrative Unit An SDH structure that contains either seven TUG2s or one bulk payload. AU4 Administrative Unit An SDH structure that contains three TUG3s. AUI attachment unit interface This is the point of demarcation between an 802.3 interface and the media access unit. AUI transceiver auxiliary unit interface transceiver An AUI transceiver is a LAN coupling device that acts as an interface between the LAN cabling and a LAN device, such as a PC or a printer. Auxiliary An auxiliary NetworkStation does not contain a NetworkStation database. It provides an interface to the network using the database residing in the active database NetworkStation. The Delegate NetworkStation and the Customer NetworkStation are both types of auxiliary NetworkStations. Auxiliary NetworkStations can be Sun workstations connected to the active database NetworkStation by way of IP links or X-terminals connected to an auxiliary server. Auxiliary server Auxiliary servers support concurrent user interface NetworkStation sessions through the use of X-terminals, which access the database residing in the active database NetworkStation. There are two types of auxiliary server NetworkStation: Delegate Server and Customer Service Management Server. AVoFR A-CELP voice over frame relay An application that applies the A-CELP (G.729A) voice compression algorithm to digital and analog voice circuits, which are then packetized for frame relay transport. Fax data is also packetized by this application, but no compression is applied to it. AWD average weighted distance AWG American wire gauge A standard measuring gauge for non-ferrous conductors. B channel bearer channel (64 kb/s) An ISDN user-network interface channel used for data transmission, operating at 64 kb/s. Equivalent to a DS0 channel. B-ICI Broadband Inter-Carrier Interface A cell relay link is a B-ICI if it spans two ATM switches belonging to different carriers. B-ISDN broadband integrated services digital network A set of public network services that are delivered over ATM. Included with ATM is data, voice and video. B-ISSI Broadband Inter-Switching System Interface A cell relay link is a B-ISSI if it spans two ATM switches belonging to one carrier. b/s bits per second B8ZS binary 8-zero suppression A technique used to accommodate the ones density requirement for digital T-carrier facilities in the public network, while allowing 64 kb/s clear data per channel. BABT British Approval Board for Telecommunication Bandwidth Bandwidth is transmission capacity measured in Hertz. The greater the bandwidth, the more information can be sent over a circuit or transmission medium in a given time. Baseband A baseband communication system handles one signal per communications line at a time. The entire bandwidth of the transmission medium is used to transmit an unmodulated signal. Baud Baud is a measurement of transmission speeds for a data transmission device. Baud is expressed in discrete conditions or signal events per second (bits per second). BBSY VMEbus Busy A hardware signal used to indicate bus ownership for the VME controller. Bc committed burst rate The Bc is the maximum number of bits of user data that the network commits to transfer over the committed rate measurement interval (Tc), under normal circumstances. BCD binary coded decimal A system of binary numbers where each digit of a number is represented by four bits. BCH Bose, Chaudhuri and Hocquenghem BCH is an error correction code, named after its three inventors. BD busy down Be excess burst rate The Be is the maximum number of bits of uncommitted user data in excess of Bc that the network will attempt to transfer over the committed rate measurement interval (Tc). BECN backward explicit congestion notification BECN bit backward explicit congestion notification bit The BECN bit is set in any frame switched from a DLC whose frame stream has entered a congested state. This informs the receiving device that any frame transmitted in reply on this DLC is likely to experience congestion. BER bit error rate The ratio of incorrect bits to total number of bits transmitted. BERT bit error rate tester A device used for testing the quality of a connection for communication. BES bursty errored seconds A second with more than one, but less than 320 CRC6EE. BGP border gateway protocol BGP is an IETF standard protocol used to propagate routing information between autonomous systems. It is an alternative to EGP. BHLI broadband high layer indication An information element defined in ATM Forum UNI v3.1 that conveys information related to higher layer protocols to check the compatibility of connection endpoints. BIP bit interleaved parity A parity technique where multiple parity bits are used in an interleaved fashion over the data. BIP-L bit interleaved parity in line overhead BIP-P bit interleaved parity in path overhead BIP-S bit interleaved parity in section overhead BITS building integrated timing source A clock that supplies DS1 or composite clock timing reference to all other clocks in a building. BLA business level agreement This agreement describes NM/Forum-optional information, agreed upon object identifiers, and other interoperation information. BLLI broadband low layer indication An information element defined in ATM Forum UNI v3.1 that conveys information related to lower layer protocols to check the compatibility of connection endpoints. Blocking Blocking describes the condition that occurs when calls cannot be completed due to congestion or full use of switching capacity. BME broadcast, multicast and exception BME is an encapsulation protocol used to exchange frames between the Route Server and the client within the VIVID system. BNC A bayonet-locking connector (Bayonet-Neill-Concelman) BONDING Bandwidth ON Demand INteroperability Group BOOTP bootstrap protocol BOOTP is a member of the IP family of protocols that allows a diskless client machine to discover, among other information, its own IP address. BOP bit oriented protocol An efficient transmission protocol that encodes communication control information in fields of bits rather than characters or bytes. BOTO Busy Out Test Object The BOTO is an object created to administer the busy-out test on full links and VPC links. The actions of this object include boLink and boRelease. BP backplane BPDU bridge protocol data unit The frame used by LAN bridges supporting the 802.1d Spanning Tree Protocol to communicate with each other. BPV bipolar violation Two consecutive T1 pulses of the same polarity. Branch channel A branch channel is a channel on the distributed side of an SRM. Several branch channels are merged onto an aggregate channel. BRG baud rate generator BRI basic rate interface BRI is one of two subscriber interfaces in ISDN. BRI provides a 2B+D channel. Bridge A bridge is a LAN/LAN or LAN/WAN interconnecting device that directs the flow of data. It either distributes data within its own network or forwards it to the destination network. Bridges make forwarding decisions based on MAC-layer addresses. Bridge/router A bridge/router is a device that provides both bridging and routing functions. Sometimes it is simply referred to as a router because most routers also perform bridging. Bridged protocol In a VIVID system, the bridged protocol domain defines domain the set of protocols allowed within bridged VNETs. Bridged VNET In a VIVID system, a bridged VNET contains port groups. There are two types of bridged VNET: * default bridged VNET * user-created bridged VNETs On initial startup, all Ridge Ethernet ports and VIVID NIC ATM ports detected by the system are placed in the default bridged VNET. In addition, when the system detects a new Ridge Ethernet port or NIC ATM port, it adds that port to the default bridged VNET. Each bridged VNET is firewalled from the rest of the system. Hosts attached to ports in the bridged VNET can communicate only with each other. Broadband A broadband communications system handles more than one signal per communications line at a time. Broadcast Broadcasting a message sends it to all devices or nodes on a network, rather than addressing it only to specific devices. It also refers to the address of all devices on a network. BSD Berkeley Software Distribution BSS business support system BT British Telecom BTAM basic tape access method BUD bring-up diagnostics Bus topology A bus topology is a one-cable LAN. All stations are connected to the cable. BW bandwidth C control A control signal for X.21. C/R command/response bit CA call accepted Cable Cable refers to the physical medium for transmitting communications data. CAC connection admission control Connection admission control is defined as the set of actions taken by the network during the call set- up phase (or during call re-negotiation phase) in order to determine whether a connection request can be accepted or should be rejected (or whether a request for re-allocation can be accommodated). CAD computer aided design Call A call is a stream of information that flows through the network on a path. Calls can be either voice or data, and are generated at the customer end of the network. Card A card is a modular unit comprised of electronic components mounted on a printed circuit board and attached to a faceplate. Specific card types provide data and primary rate interfaces. Carrier equipment Carrier equipment refers to resources, such as multiplexers and leased lines that belong to a transmission service provider. CAS channel associated signalling A type of E1 link where 4 bits of signalling per timeslot are multiplexed into timeslot 16. CBD courtesy busy down CBR constant bit rate An ATM service or traffic class that is used to carry traffic characterized by a service bit rate specified by a constant value and an evenly spaced cell stream. CBW central battery working CC a) call connected b) country code The portion of an international telephone number used to identify the country of the called party. The Country Code is one, two or three digits. CC3 control card 3 CCIP control card interconnect panel CCITT Comité Consultatif International de Télégraphie et Téléphonie (International Telegraphy and Telephony Consultative Committee). CCITT is now known as the ITU-T. CCM companding conversion module A CCM is a device that converts an A-law PCM stream to a Mu-law PCM and vice versa. CCS common channel signalling A type of E1 link where timeslot 16 is used for message-oriented signalling. CCT circuit The actual hardware interface on a DCM, DCC or module. CD called CDN call deflection notification CDT a) cell delay transfer b) channelized data transfer Channelized data transfer is an AAL1 convergence sublayer procedure where individual 8 kHz channels of the emulated circuit can be transferred on an ATM VC. No framing information is transferred through the ATM network in CDT VCCs. CDV cell delay variation CDVT cell delay variation tolerance The upper limit of allowable cell delay variation. When cells from two or more ATM connections are multiplexed, cells of an ATM connection may be delayed while cells of another ATM connection are inserted at the output of the multiplexer. Similarly, some cells may be delayed while physical layer overhead or OAM cells are inserted. CE a) called endpoint b) circuit emulation CE Agent Connect Exec Agent A UMS sees the MainStreetXpress 46020 Network Manager as an object known as the CE Agent; it is not an NM/Forum-compliant agent. CE_control process The CE_control process is the process within the gateway station that allows the operator to control MainStreetXpress Connect Exec. CE_driver process The CE_driver process is the process within the gateway station that manages the agent CME object, the MIB, and the information flow between MainStreetXpress Connect Exec and the UMS, and between MainStreetXpress Connect Exec and the Network Manager. It has options that allow it to be configured by the operator. Cell A cell is the basic unit of data in an ATM network. It is 53 bytes long, containing a 5-byte header and 48 bytes of user data. CELP code excited linear predictive An analog-to-digital voice coding scheme. CEPT Conférence des administrations Européennes des Postes et Télécommunications (European Conference of Postal and Telecommunications Administrations) CES circuit emulation service Service that supports emulation of existing TDM circuits over ATM networks via the use of the Constant Bit Rate (CBR) service category. CFM configuration management The function that manages the MACs and ports on an FDDI node. The CFM receives instructions from the PCM to connect or disconnect ports. CG calling CgPN calling party number An information element that identifies the number of the originating party to the person called. CGM circuit group manager The circuit group manager is a logical concept used to explain LAN connectivity. Where subrate multiplexers switch circuits, CGMs switch packets. Channel Channel refers to a physical or logical communications path that carries one call. Channel unit A channel unit is a single-circuit voice or data interface. CIC circuit identification code The part of a CCS signalling message used to identify the circuit being established between two signalling points. CIR committed information rate The CIR is the guaranteed minimum throughput between two end-user devices over the frame relay network, under normal operating circumstances. Circuit a) electronic An electronic circuit is one or more electronic components connected together to perform a specific function. b) telecommunications A circuit is a communications connection between two points. Circuit group The term circuit group refers to a LAN path endpoint that represents all devices on the LAN. When transmitting packets across the WAN, circuit groups may be composed of non-contiguous timeslots and may also span several ports. Circuit switching Circuit switching establishes an on-demand data transmission connection (path, channel or circuit) between two sending and receiving devices. The connection is maintained for their exclusive use until it is released. CLAMN called line address notification CLASS custom local area signalling service A Bellcore acronym. Class (object) An object class is the kind or type of object. There can be many instances of an object class. CLI calling line identity See ANI. CLINT command line interface The CLINT is the interface available from the Sun’s command tool or shell tool. Users enter commands at the prompt to execute operations. CLIP calling line identity presentation CLIR calling line identity restricted CLK Clock (card) CLLM consolidated link layer management message An explicit congestion notification message sent in the direction of the transmitting device. CLNP connectionless network protocol CLNP is the OSI-standard network layer protocol. It uses routing tables rather than dedicated connections to forward user information between end stations. CLP a) cell loss priority A one-bit field in the ATM cell header that corresponds to the loss priority of a cell. Lower priority (CSP=1) cells can be discarded under a congestion situation. b) cell loss probability The probability of losing a cell (typically in an ATM switch). Acceptable values are within the range 10-8 to 10-11. CLR cell loss ratio The ratio of discarded cells to cells that are successfully transmitted. CLR is defined in the ATM Forum’s "Traffic Management Specification - Version 4" as a method of using OAM cells for in-service measurement of cell loss. CLV cell loss variation CMA change management administration The CMA is used by the MainStreetXpress 46020 Network Manager to manage changes to the software-controlled attributes of certain types of network services, such as X.25. CME conformant management entity An open system which supports the NM/Forum defined inter-operable interface. CMI a) control module idle b) control mode idle c) code mark inversion CMIP common management information protocol An ITU-T standard for the message formats and procedures used to exchange management information in order to operate, administer, maintain and provision a network. CMIP services the CMIS. CMIS common management information services CMIS is the ISO-standard service-level definition for operation with CMIP. It layers the CMIP management exchange protocol on top of the TCP/IP stack. CMT connection management The component of SMT that manages the node ports and connections. CNM customer network management CNM is a set of features that allows service users to manage and optimize their subscribed network services. End-users monitor their network resources using a Customer NMS. CO central office A telephone company facility where subscribers’ lines are joined to switching equipment for connecting other subscribers to each other. CODEC coder/decoder CODEC equipment converts voice signals from analog to digital form, for use with digital PBXs and other digital transmission systems. The digital signals are then converted back to their original analog form. Collision A collision results when two or more stations try to transmit on a shared medium, such as an Ethernet network, at the same time. This ruins all transmissions. In most systems, a built-in random delay feature prevents the collision from occurring repeatedly. See CSMA/CD. Communication A communications server is a dedicated, standalone server system that manages communications activities for other computers. Companding A process in which compression is followed by expansion. Complex port A complex port is a port that has subordinate ports or timeslots. Examples are DS3, E3, T1 and E1. Composite input The term composite input describes the multiplexed paths that make up an SRM aggregate channel used as a branch (input) channel for a second SRM. Configuration This term is used in two ways: a) Configuration is the process of selecting parameters or assigning attributes to network objects. Configurable objects include a node, slot, card or module, port or resource, timeslot, account, partition, link or view. b) Configuration can also refer to the physical setup of a network. Congestion This term describes the relationship between the traffic load and buffer capacity of a device. Control card Control cards are used on all Newbridge nodes to provide all common control and node management facilities, including cross-connections, configuration databases, system clocks, node management sessions and system software operation. Control pair In networks managed by the MainStreetXpress 46020 system, the network is controlled by an active database NetworkStation. To protect against a failure, this NetworkStation can be paired with a second database NetworkStation, together forming the control pair. Controller A controller is a device that relays information between a host and terminals. CP control processor CPC call processing card A type of UCS card that performs ISDN-based call processing. CPE customer premises equipment CPN called party number CPSS control packet switching system A proprietary network protocol for communication between Newbridge equipment. Similar to X.25, CPSS is a packet-switched system used to transfer configuration and status information between nodes. CPSS v1 control packet switching system, version 1 The version of CPSS contained in nodes prior to NP-4. Only the DV router is provided in this version. CPSS v2 control packet switching system, version 2 The version of CPSS contained in NP-4 nodes. Both the DV router and the LS router are available in this version. CPU central processing unit The CPU is the part of a computer that performs the logic, computational and decision-making functions. The CPU is typically a single computer chip. CR call request CRC cyclic redundancy check A type of frame-check sequence. CRC-3 cyclic redundancy check - 3 bit CRC-32 cyclic redundancy check - 32 bit CRC-4 cyclic redundancy check - 4 bit CRC-5 cyclic redundancy check - 5 bit CRC-6 cyclic redundancy check - 6 bit CRM clear request message CRN call redirection notification Cross-connection A cross-connection is a connection of one circuit to another. In TDM networks, cross-connections are made between circuits or between timeslots on primary rate circuits. In ATM networks, cross-connections are logical connections between a VPI or VCI on one Workgroup Switch port and a VPI or VCI on another Workgroup Switch port. CS controlled slips Occurs when the replication or deletion of a DS1 frame is performed by the CI. CSA Canadian Standards Association CSM customer service management CSM allows service users to integrate network monitoring and control with a wide variety of management tools, accessed through an X-terminal Customer NetworkStation or from any SNMP network management system. CSM admin user The CSM admin user performs administrative functions on the CSM Agent by directly or remotely logging in to the CSM Agent workstation. The CSM admin user maintains the service user information, ensuring that access to CSM Agent data is granted only to authorized service user NMSs. CSM Agent The CSM Agent receives data from a network manager, stores it in a database and allows only authorized service users to access their portion of the data. The CSM Agent consists of Service Agent software running on a CSM Agent workstation on a service provider premises, and CSM Gateway software running on active and standby NetworkStations. CSM ConfigManager The CSM ConfigManager is the application used to configure CSM Agent attributes. CSM server customer service management server The CSM server is a Sun workstation located on the service provider’s premises that allows multiple service users to access Customer NetworkStation functions by way of X-terminals. CSMA/CD carrier sense multiple access with collision detection CSMA/CD is the method of accessing a LAN specified in IEEE 802.3. In this method, a device listens until no signals are detected (carrier sense), then transmits and checks to see if more than one signal is present (collision detection). If a signal is detected, each device backs off and waits briefly before attempting transmission again. CSMA/CD is used on 802.3 and Ethernet LANs. CSS controlled slip seconds A second with one or more CS. CSU channel service unit Provides the functionality for customer equipment to interface to a T1 line. CSU2 channel service unit 2 CTC common transmit clock CTL control CTLA control A CTLB control B CTS clear to send CTS/RTS clear to send/request to send CU channel unit CUG closed user group A group of X.25 NUAs with call access restrictions. CUGOA closed user group with outgoing access CVSD continuously variable slope with delta modulation A voice compression technique. CWC centre-weighted control D bit data bit D channel data channel (16 kb/s) An ISDN user-network interface channel operating at 16 kb/s. Used for signalling and low rate packet switched data. D/A digital to analog DACS digital access and cross-connect system The original name given to a DCS by AT&T. A digital switching device for routing and switching lines and portions of lines among multiple ports. A DACS perfoms like a normal switch, except that connections are typically set up in advance of the call, not together with the call, as in most normal low bandwidth communications such as voice-band voice and data. DARPA Defense Advanced Research Projects Agency DAS dual attached station An FDDI configuration for media redundancy. DASS digital access signalling system DASS2 digital access signalling system 2 Data card or Data interface cards or modules allow local and remote modules data devices to be connected to large and small multiplexers directly or through DTUs. Data link layer The data link layer is Layer 2 in the OSI model. This layer assembles messages and co-ordinates their flow. It defines the procedures for error-free transmission and reception. Datagram A datagram is a single, unacknowledged packet of information that is sent over a connectionless, packet-switched network without regard to previous or subsequent packets. It contains source and destination addresses, as well as data. A datagram is the basic unit of information passed across the Internet. dB decibel dBm A point of zero transmission level. DBA dynamic bandwidth allocation dc direct current DCC a) direct connect card DCCs provide direct connections between nodes and data devices. DCCs can have RS-232/V.24, X.21 and V.35 interfaces and RS-422. b) designated country code c) data communication channels DCD data carrier detect A V.24 control signal from the DCE to the connected DTE, indicating that the DCE is receiving a carrier signal from another DCE at the other end of the circuit. DCE a) data circuit-terminating equipment b) data communications equipment DCE refers to the gender of the interface on a data device, such as a modem or transceiver. The pinout wiring is such that pin 2 receives data and pin 3 transmits data. It must be connected to a DTE device. DCM direct connect module A module residing on a small multiplexer product. Either a low speed RS-232 variety, or a higher speed X.21, V.35 variety. DCP data communications processor The DCP card is an application card that supports 31 CPSS circuits and two serial ports. The DCP card provides transparent high-speed CPSS switching and removes most of the CPSS messaging burden from the Control card of the node. DCS a) digital cross-connect system b) digital cross-connect switch DDI direct dial in A service where calls made to a DDI number arrive direct, without assistance from an organization’s operator, to an extension or group of extensions. When an agent answers a call made to a DDI number, information is automatically displayed about the caller. DDN defense data network An X.25-based packet switching network operated by the U.S. Department of Defense. DDS Dataphone digital service DDS is an AT&T digital transmission service using DS0-A and DS0-B formats. The ITU-T version of DDS is Recommendation X.50 . DDS access DDS access is a form of DDS that is generally used at the edge of a network and in areas with low DDS traffic. It provides RTS lead propagation and HCM-to-DDS conversion. DDS core DDS core is a form of DDS that is generally used in the core nodes of a network, where all the traffic is already in DS0-A or DS0-B format. DDT dual DS1 transceivers DE or DE bit discard eligibility or discard eligibility bit The DE is a bit in the header of each frame relay frame that, when set, indicates that the frame should be discarded when network congestion has increased past an acceptable level. The frame should is discarded in preference to others that do not have the DE bit set. DE3 Dual E3 card DEC Digital Equipment Corporation DECnet Digital Equipment Corporation’s proprietary LAN protocol Delta ADPCM delta adaptive differential pulse code modulation Delta ADPCM is a type of ADPCM where signalling and compressed speech are carried in separate channels. DES data encryption standard DES is IBM’s recognized standard for data encryption. Destination address This is the part of a message that indicates the recipient. Device Typically, device refers to end-user equipment such as a PC, DTU or printer. DID direct inward dialling DIN Deutsches Institut fur Normung DIN is the German Institute for Standardization. DIN specifications are issued under the control of the German government. Some standards are used on a worldwide basis, for example, the dimensions of cable connectors are often described as DIN connectors. DIP dual in-line package An IC package with a row of pins on two opposite sides for electrical connection using through-hole mounting. DIP Switch dual in-line package switch A switch mechanically shaped to conform to the dual in-line package format. DISC disconnect DLC data link connection A DLC represents a segment of a PVC. The connection can be between an end-user device and a network device or between one network device and another. DLCI data link connection identifier A DLCI identifies a DLC. DLCIs need only be unique on a given frame stream; they need not be unique across the network. All frames that have the same DLCI and that are carried within the same frame stream are associated with the same logical connection. DLCMI data link connection management interface DLR direct link router DM degraded minutes DMA direct memory access A fast method of moving data between devices on a CPU data bus without CPU intervention. DMC digit modification command DMM a) DSP multi-module b) downloadable memory module DMS100 Digital Multiplex System 100 A digital central office switch from Northern Telecom. DN directory number DNIC a) Data Network Interface Circuit DNIC line cards and modules are supported on all 3600 MainStreet Family Bandwidth Managers. They support high modularity connections from a great variety of remote data devices to the nodes, via the 2600 MainStreet series DTUs. The 2B1Q line cards connect the nodes to data devices via the 2700 MainStreet series of DTUs. b) Digital Network Interface Chip A MITEL chip which provides 2B+D transmission over two wires using an echo cancellation scheme. DNIS dialled number identification service DNIS is a feature of 800 and 900 lines that provides the number the caller dialled to the telephony system. Using DNIS capabilities, one trunk group can be used to serve multiple applications. The DNIS number can be provided in a number of ways: inband or out-of-band, ISDN or through a separate data channel. Generally, a DNIS number identifies the caller’s application to the answering telephony system. Domain A domain is a management group into which ATM, TDM and management nodes are organized. This allows a large network to be divided into smaller subnetworks and reduces CPSS routing complexity. The result is improved network performance and reliability, particularly in large networks. Management nodes belong to domain 0 and can exchange CPSS messages with nodes in all other domains. Nodes in all other domains can exchange CPSS messages with only the nodes in their particular domain. Each domain can contain up to 1023 networking nodes. DOS disk operating system DOS is an operating system developed by Microsoft for IBM PCs. See OS. Double bandwidth Double bandwidth is a feature that allows the use of the full bandwidth of all ports and resources on dual T1 and E1 cards, DSP cards and DNIC cards. Without double bandwidth, the ports on these cards compete for the available bandwidth. Double bandwidth is provided on 3600 MainStreet nodes with a 16+ Expander card and on all 3645 MainStreet nodes. Download Downloading is the process of transferring software from one device or node to another device or mode by way of the network media. DP dial pulsing A method of signalling consisting of regular momentary interruptions of a direct or alternating current at the sending end. The number of interruptions corresponds to the value of the digit or character. Used in rotary dial phones. DPM a) DNIC processor module DNIC Processor modules (DPM or DPM2), which are configured on DNIC cards, provide two resources that can be configured for I.460, HCM, DDS or X.50 rate adaption. b) digital processor module DPM1 DNIC or digital processor module 1 DPM2 DNIC processor module 2 DPO dial pulse originating Refers to the dial pulse originating 2-wire channel unit signalling specification. DPT dial pulse termination Refers to the dial pulse termination in 2-wire channel signalling specification. DRAGA dual rate adaption gate array A Newbridge proprietary dual-port chip for adapting common data speed to the Mitel ST-BUS. One of the rate adaption schemes built into the chip is HCM for speeds up to 56 kb/s. DRAM dynamic random access memory DRAM is RAM that requires electronic refresh cycles every few milliseconds to preserve its data. Driver A driver is a software module that reformats or interprets communications between a computer and a peripheral device. DRM DSP Resource module DRX dual Rx (card) A card that terminates two independent 800 Mb/s intershelf links, converts them from serial to parallel data, and drives them along the backplane. DS0 digital service, level 0 DS0 is a worldwide standard for PCM digitized voice. It operates at 64 kb/s. DS0-A digital service, level 0A DS0-A is a DS0 signal with a single rate adapted channel. It uses 64 kb/s of bandwidth and is framed similarly to DS0-B, but data byte repetition, or stuffing, is used to fill the bandwidth. DS0-B digital service, level 0B DS0-B is a DS0 with multiple channels subrate multiplexed in DDS format. The 64 kb/s bandwidth is divided into subframes of 2.4, 4.8 or 9.6 kb/s. DS0-DP Digital Signal level 0 Data Port A channel unit that interfaces between the T1 line and central office 64kb/s cross-connect levels. It allows connection between existing data circuits being delivered from other manufacturers’ channel banks. In addition, it supports a 4-wire data interface to communicate between pieces of CO-based equipment. The DS0-DP is often used to interface between DS1 and DDS equipment in Hub and Intermediate Offices. DS1 digital service, level 1 DS1 refers to digital signal level 1, which is created by multiplexing 24 DS0 channels for a bandwidth of 1.544 Mb/s. It is also called T1. DS2 digital service, level 2 DS2 refers to digital signal level 2, which is created by multiplexing four DS1 channels for a bandwidth of 6.312 Mb/s. It is also called T2. DS3 digital service, level 3 DS3 refers to digital signal level 3, which is created by multiplexing 28 T1 channels for a bandwidth of 44.736 Mb/s. It is also called T3. DS3 card The DS3 card is a primary rate interface card that supports a 44.736 Mb/s transmission rate (28 times that of a T1). A DS3 is the equivalent of 28 DS1s or 7 DS2s. The card is housed in an HSPS on the 3645 MainStreet High Capacity Bandwidth Manager. Each DS3 card has its own CPSS address. DSA digital serving area DSAP destination service access point DSC dual switching card A card that filters cells off the switching backplane and sends them out through an intershelf link to an access shelf. Each DSC contains two intershelf link outputs. DSI digital speech interpolation DSL digital subscriber line DSLAC digital subscriber line audio processing circuit DSP digital signal processor A microprocessor which is optimized for signal processing applications. DSP card digital signal processor card The DSP card supports voice compression, rate adaption, G3/Fax, HCV-compressed voice and subrate switching. DSP1 digital signal processor 1 DSP2 digital signal processor 2 DSP3 digital signal processor 3 DSP4 digital signal processor 4 DSR data set ready A V.24 control signal. DSS 1 digital subscriber signalling system no. 1 This is a protocol which specifies the procedures for establishing, maintaining and clearing network connections at the N-ISDN user-network interface. DSS 2 digital subscriber signalling system no. 2 This is a protocol which specifies the procedures for establishing, maintaining and clearing network connections at the B-ISDN user-network interface. DSU data service unit or digital service unit A unit which provides the functionality of the CSU and in addition, provides timing recovery and interfaces to the DTE of the customer. DSX digital system cross-connect or digital signal cross-connect DSX-0 digital system cross-connect, level 0 An AT&T standard for the electrical and physical interface of a DS0 signal inside a building. DSX-1 digital signal cross-connect, level 1 An AT&T standard for the electrical and physical interface of a DS1 signal inside a building. DTE data termination equipment A communications interface such as a computer or terminal system. DTMF dual tone multiple frequency or dual tone multi-frequency A method of signalling using the voice transmission path. DTR data terminal ready A V-series control signal sent from the DTE to the DCE indicating that the DTE is powered and ready to communicate. DTR can also be used for hardware flow control. DTU data termination unit The 2600 and 2700 MainStreet series DTUs enable a range of asynchronous or synchronous data equipment to connect to the Newbridge 3600 MainStreet Family bandwidth managers. DUART dual universal asynchronous receiver DVR distance vector The DVR routing algorithm is used in CPSS version 1. DX digital cross-connect DXI data exchange interface E an E&M signal E bit error indication bit E&M ear and mouth E&M is colloquial for Receive and Transmit. It is an analog interface. In telephony, a trunking arrangement generally used for two way switch-to-switch or switch-to-network connections. E&M is also frequently used for computer telephony system to switch connections. E1 E1 refers to primary rate (or aggregate bandwidth) transmissions conforming to CCITT G.703 and G.732 at 2.048 Mb/s. This is the primary rate standard commonly used in Europe. E1D Dual E1 card Dual E1 cards can provide ISDN-compliant primary interface links on two 32-timeslot ports. The E1D can be configured on 3600, 3600+, 3664 and 3645 MainStreet nodes. E1D2 second generation dual E1 card Like the E1D card, the E1D2 can be configured on 3600, 3600+, 3664 and 3645 MainStreet nodes. E2 E2 refers to European digital signal level 2, which is created by multiplexing four E1s. E3 E3 refers to European digital signal level 3, which is created by multiplexing four E2s. E3 card The E3 card is a primary rate interface card that supports a 34.368 Mb/s transmission rate (16 times that of an E1). An E3 is the equivalent of 16 E1s or 4 E2s. The card is housed in an HSPS2 on the 3645 MainStreet node. Each E3 card has its own CPSS address. EA extended addressing In some bit-oriented protocols, extended addressing is a facility allowing larger addresses than normal to be used. EAI Electronic Industries Association EBIT European Broadcast Interconnection Trial EC a) earth calling b) error correction ECN explicit congestion notification Refers to both BECN and FECN bits. ED end delimiter EDCM enhanced direct connect module EDG energy dumping ground EDI error detected indicator EDX extended digital cross-connect EEPROM electronically erasable programmable read-only memory An EEPROM is a semiconductor memory device that can be electronically erased and reprogrammed. EFCI explicit forward congestion indication EGP exterior gateway protocol EGP is an IETF standard protocol used for exchanging routing information between autonomous systems. EGP is part of the TCP/IP protocol suite, and is used by a router or gateway in an autonomous system to advertise the Internet address of networks in that system to a gateway in another autonomous system. EIA Electronic Industries Association EIR excess information rate Electronic mail This is a service that enables users to send or receive electronic messages over a shared data communications medium, often a LAN. ELSU Ethernet LAN service unit An Ethernet-to-ATM adaptation device made by Newbridge. EMA enterprise management architecture EMA is a super manager designed to manage applications, databases, communications systems, and, potentially, any software or hardware that can be managed. It was developed by Digital Equipment Corporation. EMC electromagnetic compatibility EMI electromagnetic interference EMS element management system An EMS manages the components of a network. The MainStreetXpress 46020 Network Manager and the VIVID System Manager are EMSs. Emulation Emulation is the imitation of one device by another device. Terminal and printer emulation are the most common forms. EN European norm ENDEC encoder/decoder Endpoint SRM endpoint subrate merger A type of SRM that supports branch and aggregate channels as path endpoints. Endpoint SRMs can be configured on DSP cards programmed for HCVD. The individual branch channels can be named. For HCM endpoint SRMs, the transport bandwidth, HCM bandwidth and HCM frame position can be configured, and multidrop operation can be enabled. For I.460 endpoint SRMs, the transport bandwidth can be configured. ENET Ethernet Ensemble An ensemble is a set of equipment descriptors that are grouped together for packaging purposes. EOC embedded operation channel at the carrier system level The system of transport/support of the ISDN U-interface eoc within Transport Network Elements. The exact means of communication will vary with the carrier system concerned. eoc embedded operation channel at the DSL level An assigned portion of the ISDN U-interface M-channel. The eoc is framed into 12-bit messages, and is used to communicate maintenance and monitoring comands and associated data between the U-interface units. The eoc messaging is expected to be supported by the line termination (LT), the network termination (NT), and supported/transported across any intermediate elements (repeaters or carrier systems). EPD early packet discard A congestion control mechanism for ATM paths that attempts to prevent delivery of partial packets through the network. EPM encryption processor module Used to encrypt and decrypt data in the 3500 MainStreet node. EPROM erasable programmable read-only memory An EPROM is a read-only semiconductor memory device that can be erased with ultraviolet light and electronically reprogrammed. ERL echo return loss Error detection Error detection refers to the method of finding errors in received data. ES errored seconds A second with one or more error events other than failed seconds. ESD electrostatic discharge ESF extended superframe format A framing format for T1 links which provides a 24-frame multi-frame with 24 64 kb/s channels per frame, a 4 kb/s FDL and CRC-6 frame-check sequence over each multi-frame. ESI PRI external sync indication primary rate interface ET exchange termination ETH See Ethernet. Ethernet Ethernet is a data link layer protocol for interconnecting computer equipment into LANs, jointly developed by Xerox, Digital Equipment Corporation, and Intel. This standard forms the basis for IEEE 802.3. The Ethernet protocol specifies how data is placed on and retrieved from a common transmission medium. It is used as the underlying transport vehicle by several upper-level protocols, including TCP/IP and UDP/IP. ETL Eddison Test Laboratories ETS European Telecommunications Standard ETSI European Telecommunications Standards Institute EXP expander card F bit framing bit F-AIS framed alarm indication signal F-AIS is an all ones condition on the E1 link that represents the loss of data while the link is not down. FAD frame assembler/disassembler FAP fuse and alarm panel FAS frame alignment signal On E1s, this is a seven bit sequence sent once per two frames of data for alignment. FAST frame relay adaptive switching and transport FAST is a family of Newbridge frame relay products. FAST queuing FAST queuing works with congestion thresholds to determine those packets that must get through during times of high congestion. It forces heavy usage applications, such as bulk file transfers, to share link capacity. FASTbus The FASTbus is a high-speed packet switching bus for frame relay links that provides 100 Mb/s of bandwidth. Counter-rotating dual token ring architecture provides redundancy. The 36120 MainStreet PTX adds a FIP to 3600 MainStreet and 3645 MainStreet nodes, enabling up to 64 FRE cards to be connected. In addition to the circuit switched network created by the 3600 MainStreet and 3645 MainStreet nodes, the interconnected FRE cards form a network of high-speed (80 Mb/s) FASTbus links. The MainStreetXpress 46020 Network Manager uses the 36120 MainStreet node icon to represent the FASTbus connectivity. FAX/Fax/fax facsimile The analog signal transmission of a text or graphic image. FC see Flow control FC-PC fibre connector - physical connector FCC Federal Communications Commission The FCC is a regulatory body responsible for network connection approvals and managing the radio spectrum in the United States. FCP failure condition propagation FCS frame check sequence A cyclic redundancy check used to determine errors in data packet transmissions. FDB forwarding database FDDI fibre distributed data interface A 100 Mb/s fibre optic LAN standardized in ANSI X3T9.5. FDL facilities data link A 4000 b/s communications path between the two ends of a T1 ESF link that uses a message protocol to send information in 12 of the 24 framing bits in a superframe. FDM frequency division multiplexing FE far end FEBE far-end block error The number of blocks containing errors detected at the far end of a connection. FEC forward error correction FECN forward explicit congestion notification FECN bit forward explicit congestion notification bit FECN bits are used for congestion management in frame relay networks. The FECN bit is set in any frame switched onto a DLC whose frame stream has entered a congested state. This informs the receiving device that the frame is experiencing congestion. FEP front end processor A front end processor is a communications computer under the control of a larger host computer. FERF far-end receive failure A FERF indicates a failure at a far-end network node. FFR frame relay FGND frame ground Fibre optic This is a data transmission medium made from glass fibres. Light sources such as lasers and LEDs send light through the fibre to a detector, which then converts the light back to electrical signals. FIC a) fibre interface card A DS3/E3 Fibre Interface card. b) facility interface code FIFO first in first out Filter In bridges and routers, a filter blocks the transfer of packets from one LAN to another. Filters may be set to block all packets originating from a specific destination (source address filtering), or all packets heading for a particular destination (destination address filtering). Filters may also be set to exclude the packets of a particular protocol. FIP FASTbus interconnect panel FLASH memory This is a memory device (usually an IC chip) that contains program or data information. FLASH memory can be reprogrammed through software. Flow control Flow control is the procedure that shuts down transmission when a receiving workstation is unable to store the data it is receiving. Force error The force error diagnostic allows you to insert errors into the outgoing signals on SONET OC3, SDH STM1, TU12 Mapper or VT1.5 Mapper circuits to test if the network behaves correctly when certain errors occur at various signal levels. Forwarding Forwarding is the process by which a bridge transfers data packets from one LAN to another. The bridge copies the packet and passes it to the remote LAN. FP frame pulse FPGA field programmable gate array fps frames per second FR frame relay FR-SSCS card Frame Relay Service Specific Convergence Sublayer Fractional link A fractional link is a subdivision of a full link. It uses part of the full link’s bandwidth. FRAD a) frame relay access device b) frame relay assembler/disassembler Frame When referring to a window on a workstation, the frame refers to the border that outlines the window. When referring to network communications, a frame is a unit of data. At the primary rate network level, a frame is the basic unit into which primary rate streams are divided. A T1 frame contains 193 bits and an E1 frame contains 256 bits. A primary rate stream can be thought of as an endless sequence of frames. In packet switched networks, a frame is the data payload and its encapsulating address information, protocol identifiers, error checking and correction, and so on. These frames are used by X.25, frame relay, Ethernet and other packet-based protocols. An ATM frame is called a cell. Frame relay Frame relay is a packet switching protocol similar to X.25 that requires much less processing and is designed to operate at much higher speeds. Numerous remote LAN terminals can use frame relay packet switching to share the bandwidth of a single DS0 on a T1 link. Frame relay offers a low-cost way of handling high-volume, bursty data transmissions. FRATM frame relay to ATM interworking unit FRC frame stream circuit A circuit on an FRS or FRE card that switches frame relay traffic. The endpoint of a frame stream. FRE frame relay engine Frame relay engine is a frame switching card that resides within the 3600, 3645 and 36120 MainStreet nodes’ environment. The FRE switches frames between 3600, 3645 and 36120 MainStreet nodes, WAN interfaces and the FASTbus. FRE card frame relay engine card The FRE card provides high-speed frame relay packet switching between devices. It can also provides a FASTbus resource for connection to the FASTbus. Frequency Frequency is the rate at which a signal changes. It is measured in oscillations per second (Hertz [Hz]). One Hz equals one oscillation per second. FRL frame relay link A frame relay link is a pairing of frame relay resources on the MainStreetXpress 46020 Network Manager. It is a logical link that has path-like qualities that can be connected, disconnected, and protected by AAR and RAPID. Frame relay links carry MainStreetXpress 46020 Network Manager frame relay paths through the network. FRM frame relay module FRMR frame reject FRP frame relay path A frame relay path is a MainStreetXpress 46020 Network Manager communications channel that carries frame relay transmissions between two ports or timeslots in the network. FRQoS frame relay quality of service FRQoS provides an end-to-end multiservice solution that allows the user to better utilize network resources for frame relay traffic. FRQoS extends the frame relay service capabilities to provide ATM-like QoS connections with network-wide committed Frame Loss Ratio and Frame Transfer Delay. FRS frame relay switch A frame relay switch is a frame switching card that resides within the 3600, 3645 and 36120 MainStreet nodes’ environment. The FRS switches frames between 3600, 3645 and 36120 MainStreet node WAN interfaces. FRS card frame relay switch card The FRS card provides high-speed frame relay packet switching between devices. FS frame stream FSC frame stream circuit FSR full status report FT1 fractional T1 FTA fax T.30 analysis FTP file transfer protocol FTP is the Internet standard protocol for transferring files from one computer to another. Full link A full link is a link on the MainStreetXpress 46020 Network Manager that uses all the bandwidth available to both its endpoints. A full link is also known as a physical link. FXO foreign exchange office FXO refers to the foreign exchange 2-wire channel unit, office-end signalling specification. FXS foreign exchange subscriber The foreign exchange 2-wire channel unit, station-end signalling specification. G.703 G.703 is the ITU-T recommendation pertaining to several digital telecommunication interfaces. It relates to the physical and electrical levels only. One example is E1 (2.048 Mb/s). G3 group 3 G3 Fax G3 Fax is the Group 3 analog facsimile standard at data rates up to 9.6 kb/s. GAT global address table Gateway A gateway is a dedicated computer that attaches to two or more dissimilar networks and provides protocol translation between them. Gateway node The gateway node connects the MainStreetXpress 46020 Network Manager to the network. Gateway station The gateway station is the Sun workstation that runs MainStreetXpress Connect Exec. Connections are either Ethernet or X.25. GDI generating-system to data-collector interface Gen/Gen generator/generator Gen/gen is a method of interworking between two phone handsets directly connected over a copper wire. GFC a) general facilities card A 3600 MainStreet node card with a dedicated position that provides maintenance facilities and test access points. b) generic flow control GFC is a field in the ATM header which can be used to provide local functions such as flow control. It has local significance only if the value encoded in the field is not carried end-to-end. GFC bits general flow control bits GFC bits are the part of the ATM header that controls the flow of cells across an ATM UNI. GFC2 general facilities card 2 GFI general format identifier GFR generic frame router GFR trunk A GFR trunk is a communication channel that carries X.25 encapsulated in frame relay frames between TCs (trunk circuits) forming the X.25 backbone. GIO graphics input/output GIO is a proprietary bus type used in Silicon Graphics workstations. GMT Greenwich Mean Time GND ground GOSIP Government Open Systems Interconnection Profile standard GOSIP is the functional applications profile that outlines the U.S. government policy and strategy for converting to a communications system based on OSI. Group In the MainStreetXpress 46020 Network Manager, a group is a collection of nodes, or nodes and groups combined. Generally, nodes are configured in a group because they have something in common, such as function, location or supervision by one user. GS ground start A way of signalling on subscriber trunks in which one side of the 2-wire trunk, typically the ring conductor of the tip and ring, is momentarily grounded to get dialtone. GS EM ground start E&M GS_DNIS ground start and DNIS GUI graphical user interface A GUI is a computer user interface that incorporates graphics to make software easier to use. h hours H bit high-speed bit H0 H zero (ISDN 384 kb/s channel) HCM high capacity multiplexing HCM is a Newbridge proprietary rate adaption and SRM scheme that provides bandwidth granularity of 800 b/s, allowing 98% bandwidth utilization on aggregate links. HCS header check sequence The header check sequence is an 8-bit CRC-8 used to verify the integrity of an ATM header. The HCS is used in some modes to perform single bit error correction for the ATM header. HCV high capacity voice HCV is a Newbridge proprietary voice compression technique that reduces a voice path ‘s bandwidth requirement from 64 kb/s to either 8 kb/s or 16 kb/s. HCVD high capacity voice and data HDB3 high density bipolar 3 Method of preserving one’s density of an electrical signal by encoding strings of more than three zeroes with bipolar violations. HDLC high-level data link control An ISO standard for serial data communication. A family of bit-oriented protocols providing frames of information with address, control and frame check sequence fields. It is considered a superset of several other protocols such as SDLC, LAP, LAPB, LAPD. HDSL high bit-rate digital subscriber line An alternate technology to repeatered T1 lines. Supports repeaterless DS1 rate access over non-conditioned copper loops that conform to CSA guidelines. HDTV high definition television HEC header error check A field in an ATM cell used to detect and correct single bit errors in an ATM header. HG see Hunt group HO-DSP higher order - domain specific portion The HO-DSP is the part of the ATM address that is specified by the authority identified in the IDI field. It contains the DFI, the AA, the Res field, the RD and the Area. Hop The number of hops indicates the number of full or fractional links a path or connection uses to get from source to destination. Host A host is a computer attached to a network primarily for providing services such as computation, database access, special programs, or programming languages. HP OpenView HP OpenView is a Hewlett-Packard network management platform. It is used primarily for managing SNMP nodes. HP-UX HP-UX is an operating system used by Hewlett-Packard workstations. HS HCM high speed high capacity multiplexing HSA high speed aggregate HSA cards fit into HSA slots. HSA slots support up to 155 Mb/s of broadband bandwidth and up to 64 Mb/s of narrowband bandwidth. HSA cards include the SONET OC3, SDH STM1 and Mapper cards. HSM high speed modem HSPS high speed peripheral shelf The HSPS is the physical organizer for DS3 cards on the 3645 MainStreet system, and provides a power supply and backplane. HSPS2 high speed peripheral shelf 2 The HSPS2 is the physical organizer for E3 cards on the 3645 MainStreet system, and provides the power supply and backplane. HSPU high speed peripheral unit HSSI high speed serial interface A serial interface with transmission rates up to 52Mb/s. The HSSI is often used to connect one or more LAN routers and network devices to a T3 line, which provides 44.736 Mb/s. A T3 multiplexer using HSSI can divide the T3 bandwidth into the appropriate speeds of the various devices. Hub 10BaseT hub module A central connecting device in a network that joins communication lines, such as 10BaseT, together in a star configuration. Hub hardware can be either active or passive. Hunt group A set of X.25 NUAs that can be signalled using one or more addresses configured for the group. I a)indicator An X.21 control signal. b) information I frame information frame I/F interface I/O input/output I.460 I.460 is a transparent data protocol using (n x 8) kb/s divisions, where n can be 1 to 8. IA5 international alphabet five IAB Internet activities board IBM International Business Machines IBR intermediate bit rate IC a) integrated circuit b) incoming call ICB a) intelligent channel bank b) incoming call barrier ICD international code designator This identifies an international organization. The registration authority for the International Code Designator is maintained by the British Standards Institute. The length of the field is two octets. ICMP Internet control message protocol ICMP is a protocol that sends and receives the control and error messages used to manage the behaviour of the TCP/IP protocol stack. ICMP is defined in RFC 792 and RFC 950. Icon An icon is a graphical symbol that represents an object or a function. ICP IMA control protocol ICRD internetwork call redirection and deflection ID identifier or identification IDI international domain identifier The IDI is part of the network prefix in the ATM address. It contains the ICD and the AFI. IDP Internet datagram protocol IDP is the network layer protocol for the Xerox Network Systems suite of protocols. iDSU integrated digital switching unit IE information element IEC International Electrotechnical Committee IEEE Institute of Electrical and Electronic Engineers The IEEE is the organization responsible for defining many of the standards used in the electrical and electronics industries. IEEE 802.2 Logical Link Control This is the IEEE standard for the data link layer of local area networks. IEEE 802.2 defines the data link layer standard used with the IEEE 802.3, 802.4 and 802.5 standards. It is also defined as ISO 8802/2. IEEE 802.3 IEEE 802.3 defines the physical and data link layer standard specifying a LAN with CSMA/CD access on a bus topology. It is based on the Ethernet standard. IEEE 802.3 is also standardized as ISO 8802/3. IETF Internet Engineering Task Force The standards-making group for the Internet. IFM ISDN framing module IGMP Internet group membership protocol IGMP is a host-to-router protocol used to communicate group membership for IP multicast services. IGP interior gateway protocol IHTU integrated HDSL terminal unit ILMI integrated local management interface ILMI is a protocol developed by the ATM Forum to verify the operation of, and communicate addressing and connectivity across, the UNI. ILMT insertion loss measurement test IMA inverse multiplexing over ATM An algorithm which provides modular bandwidth for user access to ATM networks over multiple links. IMC inverse multiplexer card IMM inverse multiplexer module Imported access An imported access group is a group that maps directly group to one VSN of a MainStreetXpress 46020 Network Manager. InATMARP inverse ATM address resolution protocol InATMARP is a form of ARP that allows an ATM station to request a protocol address corresponding to a given hardware address. InATMARP is a variation of InARP, which was defined in RFC 1293 for Frame Relay networks. The VIVID system uses InATMARP to obtain IP addresses from hardware addresses; VIVID NICs then use the IP addresses when transmitting over PVCs. Informix Informix is a relational database used by a number of Newbridge software products. INS-net fixed Japanese ISDN Instance An instance is an individual occurrence of an object in a class. For example, a network of twenty nodes could have a power supply in each node; each of these power supplies would be an instance of the equipment managed object class. Interconnect (noun) An interconnect is a circuit administration point, other than a cross-connect or an information outlet, that provides routing and rerouting capabilities for circuits. Interconnect (verb) To interconnect means to connect with each other. Interface An interface is a common boundary between two devices where electrical signals, connectors and handshaking meet. An interface enables devices to pass information to and from one another. Interface protocol An interface protocol is a set of physical and logical rules that define communication between two adjacent entities. The physical interface corresponds to the physical wires that connect the entities. The logical interface corresponds to the logical messages sent between adjacent layers or sublayers. Intermediate An intermediate termination point is any DS0 pathpoint termination point that has physical links associated with it on the MainStreetXpress 46020 Network Manager user interface. Internal link An internal link is a logical link between two access groups on the MainStreetXpress 48020 MNSC. Internal links are used to influence the Bandwidth allocator (BWA); they do not represent physical links. Internet The Internet is a network of networks, connecting tens of thousands of government, university and private computers worldwide. It uses the TCP/IP protocol stack as a basis of communication. internet An internet (with a lowercase i) refers to a collection of interconnected networks that function as a single, virtual network. Internetwork link An internetwork link is a physical link between two access groups on the MainStreetXpress 48020 MNSC. Internetwork links carry bandwidth between MainStreetXpress 46020 Network Management networks. Internetworking Internetworking is communication between two networks or two types of networks or end equipment. Interoperability Interoperability is the ability to operate software and exchange information in a large network that is made up of several LANs. INTL_1 International 1 IOTU integrated optical termination unit IP Internet protocol A network layer protocol which provides an unreliable, connectionless, packet delivery service to its users (transport layer: TCP or UDP). IP address The IP address is the address used for routing packets in an IP network. The MainStreetXpress 46020 Network Manager supports two kinds of IP addresses: internal and external. The internal IP address is assigned to Workgroup Switches and is derived from the switch ATM address. The external IP address is the more general IP address assigned for routing on the Internet. Each external IP address must be unique. IPSO IP security option IPX Internet packet exchange IPX is the native LAN communications protocol for Novell NetWare. It is used to move data between server and workstation programs running on different nodes. IPX packets are encapsulated and carried by packets used in Ethernet and similar frames used in Token Ring networks. IR a) intermediate reach An optical fibre specification for single mode fibre transmission systems suitable for distances of up to 15 km. b) intermediate range IRIX IRIX is the Silicon Graphics Inc. UNIX-based operating system. IRQ information request IS2DN integrated special services digital network ISDN integrated services digital network ISDN is a technology offered by telephone carriers whereby voice connections and digital data network services are carried over the same line. The standards are specified by the ITU-T (formerly the CCITT). ISL inter-shelf link ISO International Standards Organization The ISO is the official international recognized organization responsible for establishing standards, including network management standards. ISSU intelligent system synchronization unit ISUP ISDN supplementary user part ITB Integral Token Ring Bridge A high performance Token Ring Bridge integrated within a 3600 or 3645 MainStreet Bandwidth Manager. ITC independent transmit clock ITU-T International Telecommunications Union - Telecommunications The ITU-T is the telecommunications standardization sector of the ITU. An advisory committee established under the United Nations to recommend international telecommunications standards. JB7 jam bit 7 Data transmission mode which guarantees ones density on a T1 carrier while, in general, reducing effective transport bandwidth to 56 kb/s. JJ20.11 Transceiver This loopback occurs in the transceiver component of a Loopback TTC2M card and allows faults in the Line Interface Card to be identified. This loopback provides local loopback of the entire line and can be used to test up to the transceiver, but not the line interface. Looped-back data and signalling sent internally to the TTC2M card from the Control card are received by the backplane. Join The Join function is used to create a MainStreetXpress 48020 MNSC path based on selected path segments. The Join All function makes as many MainStreetXpress 48020 MNSC paths as possible using all segments in the list. JPEG Joint Photographic Experts Group JPEG is the ISO standard for compression of still images. kb kilobits kb/s kilobits (thousands of bits) per second LAM local ATM management The LAM application on VIVID NICs provides a command line interface for configuring NIC parameters. LAN local area network A LAN is a network that operates within a limited geographical area, such as within a building. It connects a variety of data devices, such as PCs, servers and printers. Communication between devices is at a very high rate, between 1 and 100 Mb/s. LAN link On the MainStreetXpress 46020 Network Manager, a LAN link is the link that connects a LAN node to a LAN anchor point. LAN node On the MainStreetXpress 46020 Network Manager, a LAN node is a device that connects to a LAN. LAN nodes include bridges, routers, PCs, servers and printers. LAN path A LAN path indicates an exchange of data packets between two LAN nodes or between a LAN node and an anchor point. A LAN path is a logical connection and is not administered by the MainStreetXpress 46020 Network Manager bandwidth allocator. LAN paths are seen in LAN views. LAN path-end A LAN path-end is the end-point of a LAN path. It has an SNMP interface number and an IP address associated with it. LAN segment A LAN segment is a link that connects two anchor points. A limited number of LAN segments can terminate on the same anchor point. LAN-control VPC A LAN-control VPC link is a VPC link that carries LAN link control information, such as routing table updates. LAN-data VPC link A LAN-data VPC link is a VPC that carries SVC traffic over the VIVID system. It handles all the bandwidth that has not been assigned to the LAN-control VPC link or any manually configured PVCs. LANE LAN emulation LANE is an ATM Forum standard for bridging over an ATM switching fabric. LANE is a precursor of MPOA. Using LANE, external routers are required for communication between subnetworks. LAPB link access procedure balanced LAPB is the most common data link control protocol used to interface X.25 DTEs. It is a full-duplex, point-to-point bit-synchronous protocol used in packet-switched networks. LAPD link access protocol for D channel A link access procedure for the D channel. Similar to LAPB, the main difference is the addition of more addressing information. LAT a) local address table b) local area transport LAT is a Digital Equipment Corporation proprietary protocol for terminal- and printer-to-host connections over a LAN optimized for low-delay, high-bandwidth paths. LATA local access and transport area LATM local asynchronous transfer mode LATM card local asynchronous transfer mode card A LATM card provides low-cost, single-mode and multimode fibre interfaces at 100 Mb/s and 140 Mb/s for use in ATM applications. LAVC local area VAX cluster LBC laser bias current LBO line build out Variable attenuation provided in the CSU transmitter. LBTO Loop Back Test Object The LBTO is an object created to administer the loopback test on ports on the MainStreetXpress 36150 Access Switch and MainStreetXpress 36170 Multiservices Switch. The actions of this object include lbEquipment, lbLine and lbRelease. LC a) logical channel b) link connection A connection reserved for CPSS. LCA logical cell array LCD a) liquid crystal display b) loss of cell delineation; see LOD LCDC loop calling disconnect clear LCN logical channel number LCT link confidence test Learning Learning is a LAN bridge term that describes how a bridge analyzes its traffic to learn about the topology of the network on which it resides. The bridge uses this knowledge to decide if and where to forward packets. Leaf node A PE node that routes traffic directly to another node. A leaf node will not be a transit node for routing. LED light emitting diode An LED is a semiconductor diode that emits light when a current passes through it. LER link error rate The error rate on a connection, in errors/s. Level Level is another term for layer in the OSI model. LF a) largest frame b) link factor LGE loop start/ground start exchange Exchange-end voice interface which supports loop start and ground start signalling. LGE card loop start/ground start-exchange card The LGE card is functionally equivalent to the FXO circuit. Each circuit on the card provides ring and tip supervision, origin detection and ring ground capability. The ports on this card can be configured for loop start, ground start, private line automatic ringdown (PLAR) circuit, loop start to E&M and ground start to E&M. Other programmable parameters include transmission level points, input impedance and line balancing (short or long loop). LGE EC LGE earth calling LGE GS LGE ground start LGE LS LGE loop start LGE RE LGE remote extension LGS loop start/ground start subscriber Subscriber-end voice interface which supports loop start and ground start signalling. LGS card loop start/ground start - subscriber The LGS card is functionally equivalent to the FXS, DPO and MFO circuits. The ports on this card can be programmed to function as a private line automatic ringdown (PLAR) circuit. Each card takes 12 two-wire analog circuits from the customer premises. Programmable parameters include signalling, transmission level points, and short or long loop line balance. LGS EC LGS earth calling LGS GS LGS ground start LGS LS LGS loop start LGS MRD LGS manual ringdown LGS PLAR LGS private line extension LGS PLAR_D3 LGS private line automatic ringdown_D3 LGS RE LGS remote extension LIF loss of IMA frame LIM line interface module A network terminator for CEPT and T1. It can be installed on a Control card or in the NTI module positions on the E1/T1 card. Link A link represents the physical medium (or the equivalent, such as a satellite link) that carries paths through the network. Links connect ports to ports, timeslots to timeslots or ports to timeslots. A single link may contain a single path, such as an asynchronous data link, or many paths, such as an E1 link from a PBX. Link group A link group is a group of one or more links. Link groups show physical connectivity. On MainStreetXpress 46020 Network Manager and VIVID System Manager maps, each link group is represented by a line connecting nodes or node groups. The links in a link group are not necessarily of the same medium. LIS loss of incoming signal LIV link integrity verification LL local loopback LLC logical link control LLC is the upper sublayer of the ISO model data link layer. LLC governs packet transmission as specified by IEEE 802.2. LLI link-layer interface LMI local management interface A frame relay link management protocol defined by: Digital Equipment Corporation, Northern Telecom, Cisco and Stratacom. LN load number Local access group A local access group is a group created by a MainStreetXpress 48020 MNSC user to logically group some of the endpoints of an imported access group, for example, by location or technology. LOD loss of cell delineation An indication that ATM cell boundaries cannot be determined. LODS line out of delay synchronization LOF loss of frame An indication that framing of the transmission or ATM layer has been lost. LOFC loss of frame count Accumulation of the number of times a LOF is declared. Logical Logical connectivity refers to non-physical connectivity communication lines, such as paths or overlay network links, between nodes. Logical link A logical link is a conceptual MainStreetXpress 46020 Network Manager link. It represents part, or parts, of a full (physical) link that cannot be physically removed from the link, but have the attributes of a link. Examples of logical links are ADPCM links and subrate links. LOIS loss of optical incoming signal Loopback A loopback is a diagnostic test where a signal is transmitted from, and returned to, a sending device. Usually, the signal is sent across a data communications link or network. A technician compares the transmitted signal with the returned signal to see if the circuit is operating correctly. LOOS local out of service second A second during which a local fault, such as LIS, LOF or LOMF, has been declared. LOP loss of pointer An indication that the boundaries of the path payload cannot be determined. LOS a) loss of signal An indication that no valid signal can be detected at the transmission interface. b) loss of synchronization LQ1 link quality bit 1 LQ2 link quality bit 2 LR a) line reversal b) long reach An optical fibre specification for single mode fibre transmission systems suitable for distances from 15 km to 40 km. c) long range LRB loop reverse battery LRU least recently used LS a) link state b) loop start A way of signalling on subscriber trunks by bridging through a resistance on the tip and ring (both wires) of a telephone line, forming a dc loop. LS EM loop start E&M LS router link state router LS router is the routing algorithm used in CPSS v2, and takes into account the link state (for example, up, down, congested), the number of hops and the link cost. LS_DNIS loop start and DNIS LSB least significant bit LSU LAN service unit An LSU is a LAN interface device connected to the MainStreetXpress 36170 ATM switch through OC3. LT line termination The ISDN equipment that terminates the access line at the network end of the interface. LULT line unit, line termination LUNT line unit, network termination M an E&M signal M13 multiplexer between 28 T1s and a DS3 M24 multiplexer between 24 DS0s and a T1 MAC media access control A sublayer of the data link layer (defined in IEEE 802.2 specifications) that is responsible for accessing the LAN medium. MAC layer media access control layer The MAC layer is a sublayer of the data link layer in the OSI communications stack. The MAC layer is defined in IEEE 802.2. Every computer and network node has a MAC address that is hardware encoded. MainStreetXpress The MainStreetXpress 36150 Access Switch is a 36150 Access Switch high-capacity broadband switch that uses advanced cell switching technology based on B-ISDN ATM standards. The MainStreetXpress 36150 system provides a range of ATM and non-ATM interfaces. MainStreetXpress The MainStreetXpress 36170 Multiservices Switch is a 36170 Multiservices broadband switch that is ideal for high-capacity Switch backbones supporting multiple services such as cell relay, circuit emulation, LAN interconnectivity and frame relay. The MainStreetXpress 36170 system provides a range of ATM interfaces. MainStreetXpress The MainStreetXpress 36190 Core Services Switch is a 36190 Core Services very high-speed ATM platform. Its modular architecture Switch is designed to support broadband service applications and offers throughput of up to 1 terabit per second (1000 Gb/s) in an ATM core network. MainStreetXpress 36190 service applications include ATM cell relay, circuit emulation, n *64 kb/s trunk switching and broadband supplementary services. MainStreetXpress The MainStreetXpress 45020 Element Manager extends the 45020 Element SNMP management capabilities of HP OpenView to provide Manager a graphical user interface for managing SNMP nodes. The MainStreetXpress 45020 Element Manager and HP OpenView can also be integrated with the MainStreetXpress 46020 Network Manager through an optional OpenSNMP module. This module provides MainStreetXpress 46020 Network Manager users with a consistent graphical user interface for managing both Newbridge and SNMP nodes. MainStreetXpress The MainStreetXpress 46020 Network Manager provides 46020 Network advanced management of large, complex LAN/WAN Manager networks, including hybrid circuit switched, ATM frame relay networks and X.25 networks. The graphical user interface operates on a Sun Workstation. It can be used to configure databases, monitor network operation in real-time, set up and manage paths, and perform diagnostics to isolate and manage problems on the network. With the addition of optional software modules, the MainStreetXpress 46020 Network Manager can perform advanced management functions such as managing multivendor equipment, interfacing with UMS, and partitioning networks. MainStreetXpress The MainStreetXpress 48020 MultiNetwork Service 48020 MultiNetwork Controller is a service management software product Service Controller that is a component of the MainStreetXpress 48020 Service Director family of products. The MainStreetXpress 48020 MNSC presents partitions of multiple MainStreetXpress 46020 Network Manager networks as one end-to-end service network. MainStreetXpress MainStreetXpress Connect Exec is a Newbridge software Connect Exec program that acts as a translator for a UMS and a Newbridge network. It allows Newbridge equipment to be managed by a UMS. Maintained path A maintained path is a path with one or more maintenance connections. It is also referred to as a target path. Maintenance circuit A maintenance circuit is one of two circuits connected to a pathpoint to create a maintenance connection. Maintenance A maintenance connection allows access to a target connection connection so it can be tested for integrity. Each maintenance connection requires a target connection and two maintenance circuits. MAN metropolitan area network Managed device A managed device is any electronic device that uses SNMP agent software to store and retrieve data from the device’s MIB. Managed object This is a MainStreetXpress Connect Exec term for an object that is a view of one or more network components. These components may exist independently or they may support the management of other components. A managed object may also represent a relationship between components. Map In the MainStreetXpress 46020 Network Manager, a map is that part of the network map window where the MainStreetXpress 46020 displays a view of the network. MAP manufacturing automation protocol MAP is a computer processing protocol based on the OSI model. It is designed for factory environments. Map group A map group consists of a logical (rather than physical) arrangement of access groups or NetworkStations. Mate A mate is one of a redundant pair of database NetworkStations. MAU media attachment unit A transceiver device used in LANs between the AUI and the physical cabling. Mb/s megabits (millions of bits) per second MBM motherboard module MBS maximum burst size A traffic parameter that specifies the maximum number of cells (in a burst) that can be transmitted at the peak rate (PCR). In the signalling message, the burst toleramce (BT) is conveyed through the MBS, which is coded as a number of cells. The BT, together with the SCR and the GCRA, determine the MBS that a node can transmit at the peak rate and still conform with the GCRA. MCR minimum cell rate MCS multicast server MCT mild congestion threshold MCT is a frame relay parameter related to the buffer capacity of a frame relay device. At the MCT, the frame relay device sets the FECN and BECN bits for those frames queued for transmission. No frames are discarded. See also ACT and SCT. MDDB multidrop data bridge MDNS multiple domain networking software Medium The medium is the material over which data is transmitted, such as coaxial, twisted pair or fibre optic cable. For satellite transmissions, the medium is the atmosphere. MFAS multi-frame alignment signals MFO multi-frequency originate MHz megaHertz A unit of frequency denoting one million Hertz. MIB management information base The MIB is a database that stores objects representing the components of the network. It is managed by the MainStreetXpress Connect Exec through CMIP commands. MIB Walker The MIB Walker is a MainStreetXpress 46020 Network Manager software tool used for reading and writing a LAN node’s MIB using SNMP. Min minutes min minutes MIR minimum information rate The minimum data transfer rate for a frame relay, VPC or VCC path. Mixed link A mixed link is a MainStreetXpress 46020 Network Manager link between ports of different types, for example, T1 to E1. MJU multijunction unit An MJU is a type of SRM that functions as a multidrop data bridge. Its inputs and output are formatted for DS0-A. MLHG multi-line hunt group MLID Multiple Link Interface Driver MLID is a Novell LAN Driver written to the ODI specification. MLM multilongitudinal mode MM2 memory module 2 MMF multi-mode fibre An optical fibre capable of supporting the propagation of multiple bound modes through the fibre. The dispersion effects caused by the multiple bound modes limits the useful length of this type of fibre to less than 2 km. MMI management and maintenance interface Mode The term mode refers to the three modes of operation available for MainStreetXpress 46020 Network Manager service provider accounts: administrator mode, operator mode and service level manager mode. Modem modulator-demodulator A modem is a device that converts digital signals to analog signals and vice versa. Modems are installed in pairs, one at each end of an analog communications line. Module A module is a printed circuit board that is installed on a larger circuit board. Each module provides specialized functionality. Module position Interface modules are installed in module positions on small multiplexers like the 3606, 3612, 3620, 3624, 3630 and 3638 MainStreet nodes. Mon monitor Monitor maintenance A monitor maintenance connection is a non-intrusive connection maintenance action. You can route the target circuits of the monitored connection to a maintenance circuit on which you can perform tests without affecting service. MOP maintenance operation protocol MOS a) mean option score b) multiplexer out-of-sync MP multi-path MPA multiport aggregate (card) MPEG Motion Picture Experts Group MPEG is an image compression scheme for full motion video. MPM master processor module MPOA multiprotocol over ATM MPOA is an evolving ATM Forum standard for routing over an ATM network. MPOA is modelled on the VIVID network architecture, and eliminates the need for external routers to route between subnetworks. MRD manual ring down Manual ring down is a method of connecting a DS0 to a telephone that has a permanent audio connection, a ringing generator and a recall button. ms milliseconds A millisecond is one thousandth of a second. MSB most significant bit MSI management systems interfaces MSN multiple subscriber numbering MSR mean slip rate MTA maintenance and test access MTAU metallic test access unit MTSM The Multiservice Traffic Shaping Module enhances traffic management functionality on UCS-2 cards within MainStreetXpress 36170 nodes, Release 3.1 or later. The MTSM provides traffic shaping in both ingress and egress directions on a per port basis for each service category of VPC and VCC paths, and dynamic shaping for ABR connections using VSVD. MTU maximum transmission unit The MTU is the largest unit of data that can be transmitted over a particular interface type in one packet. Multicast Multicast refers to messages sent from one device to a specific set of devices, rather than to all devices, on a LAN. Multidrop data In a multidrop data bridge, several data devices share bridge the same bandwidth to communicate with one main device. For example, several terminals (slaves) take turns communicating with a host computer (master). Each terminal, in sequence, uses the same bit positions within the frame. The master device polls the slaves one at a time. MultiNetwork Service Controller See MNSC Multiprotocol A multiprotocol device supports more than one protocol. MUX multiplexer MVNM multivendor network management MX mate interface n/a not applicable NA North America NATB Newbridge advanced technical bulletin NATM Newbridge asynchronous transfer mode The NATM is the driver on VIVID ATM NICs that supports ATM connections. It provides services to the NEE and NIP layers for bridged and routed connections, respectively. nc no connection NCI network control interface NCI is a Newbridge protocol that enables Newbridge network managers (such as MainStreetXpress 46020 Network Manager and the VIVID System Manager) to communicate with and control the network nodes. It uses CPSS for inter-node messages. NDC national destination code NE near end NEE Newbridge emulated Ethernet NEE is the layer of the protocol stack on a VIVID NIC that supports emulated Ethernet MAC layer bridging. NEE encapsulates Ethernet MAC frames according to the format described in RFC 1483, section 4.2, for bridged PDUs. Network A network is an entire communications web of nodes and the links that interconnect them. Networks controlled by a MainStreetXpress 46020 Network Manager are digital backbone networks. They employ digital signal processing and are the backbone or foundation of a business communications system. See also VBN and VSN. Network layer This is the third layer in the OSI model. This layer routes and delivers datagrams, relaying them through intermediary systems. It also provides error checking and correction. Network management Network management is the process of maintaining a network by installing and configuring software, controlling operations, monitoring performance, troubleshooting problems, and keeping statistics. Under a network management program, much maintenance and control can be accomplished remotely from a personal computer or workstation on the network. Network Manager The Network Manager is the 4602 MainStreet Intelligent NetworkStation software or the MainStreetXpress 46020 Network Manager software. It manages a Newbridge network and runs on a NetworkStation. The Network Manager can be an active Network Manager or a standby Network Manager. Network Performance A statistics collector, running on the Monitor MainStreetXpress 46020 Network Manager that allows you to collect real-time statistics from primary rate, aggregate, frame relay, X.25 and ATM objects. Network prefix The network prefix is the first part of an ATM address. It is composed of the AFI, the ICD and the HO-DSP field. NetworkStation A NetworkStation is a Sun workstation running or communicating with the MainStreetXpress 46020 Network Manager software. There are several types of NetworkStations: active, standby, Delegate NetworkStation, VBN Director, and VSN Manager. NF node factor NFAS non-frame alignment signal NI-1 national ISDN 1 NIC a) network interface card An NIC is an adapter board that can be added to a workstation or PC to provide a connection to a LAN or an ATM network. b) network interface controller or card An NIC is an adapter board that provides physical connection between a computer and the network medium. c) Network Information Centre The NIC maintains and distributes information about TCP/IP and internetworking. NIP Newbridge IP NIP is the layer of the VIVID NIC protocol stack that supports IP routing. The NIP layer encapsulates outgoing PDUs from a routed IP interface in the format specified in RFC-1483, section 4.1. NIS network information service NIS is used to administer UNIX databases that provide network reachability and host alias information. NIST National Institute of Standards and Technology NLM NetWare Loadable Module An NLM is a software module that is dynamically linked to the NetWare operating system, v3.x and above, at run time. NLPID network layer protocol identifier NM a) network management b) node management NM/Forum Network Management Forum The NM/Forum is an industry consortium producing and collating network management standards. MainStreetXpress Connect Exec conforms to OMNIpoint 0. NMS network management system NMS refers to the equipment used to monitor, control and manage a data communications network. NMT node management terminal NMTI node management terminal interface The local user interface for a Newbridge network product. NNI network-to-node interface An NNI is the interface between two network nodes that operate under different administrative domains, such as a Newbridge ATM Switch and a non-Newbridge ATM switch. NNP Newbridge Network practice NOC network operations centre Node Nodes are the basic building blocks of a network. They serve as a termination point for communications links and forward data to other nodes and elements of a network. Nodes have a unique CPSS or IP address on the network. Examples of nodes include network management stations and transmission nodes (WAN, LAN and ATM). Node icon Nodes are represented on the MainStreetXpress 46020 Network Manager map by icons. Node management A node management session is a general term that session refers to a communication or control session between a node manager and a node. Node manager VT100 or PC with VT100 emulation software connected to a node and used for node configuration and management functions. Non-blocking The term non-blocking refers to a system that has enough capacity to connect all calls simultaneously. NP4 network product 4 NP5 network product 5 NPI numbering plan identification or indicator NPID network level protocol identifier NRT-VBR non real-time variable bit rate The NRT-VBR is an ATM service category that guarantees low cell loss and low delay for applications such as video and frame relay, that are characterized by an on/off source with known, predictable transmission patterns. During the on period, cells are transmitted at the peak information rate. No cells are transmitted during the off period. NRT-VBR is a variant of the VBR service category that is only available for VPC and VCC paths. RT-VBR is the other variant of VBR available for these paths. The 3600 MainStreet Family Bandwidth Managers Technical Practices treats NRT-VBR and RT-VBR identically for routing and rerouting purposes, and uses both to calculate the total VBR bandwidth utilization. NRTL nationally recognized testing laboratories NRZ non-return to zero NSAP network service access point NSF non-standard facilities NSN national significant number NT network termination Network termination represents the termination point of a virtual channel, virtual path or virtual path/virtual channel at the UNI. NT1 or NT-1 network termination type 1 (ISDN) NT2 or NT-2 network termination type 2 (ISDN) NTI network termination interface NTN national terminal number NTP network time protocol The NTP standardizes time among Internet hosts around the world, with a maximum difference of about 1 second. NTSC National Television Standards Committee of the Electronic Industries Association (EIA) NTT Nippon Telephone and Telegraph NTU network termination unit Any of a number of terminators for primary rate links. NU national use NUA network user address In an X.25 network, the NUA specifies the address of an XAC and its call subscription options. NUI network user identifier A unique alphanumeric number provided to dial-up users to identify them to packet-switched networks around the world. The number is used for accessing the network and for billing purposes. NVM non-volatile memory NVM is memory which maintains its contents during power loss conditions. NVRAM non-volatile random access memory OAM operations, administration and maintenance Network maintenance features such as connectivity verification, alarm surveillance, continuity checking and performance monitoring. OAM cell operations, administration and maintenance cell OAM cells provide ATM network maintenance features such as connectivity verification, alarm surveillance, continuity checking and performance monitoring. A different header distinguishes an OAM cell from a user data ATM cell. OAM&P protocol operations, administration, maintenance and provisioning protocol. OAMTO OAM Cell Test Object The OAMTO is an object created to administer the OAM cell loop-back test on VPC links, VPC paths and VCCs. The action of this object is OAM-cell. Object a) In general, the term object refers to anything that can be selected from any window on a graphical user interface, including physical or logical entities. Nodes, links, cards, paths, accounts, partitions and views are examples of objects. b) For the MainStreetXpress Connect Exec, objects are MIB representations of the components in a MainStreetXpress 46020 Network Manager, such as nodes, cards and ports. Objects are represented by MainStreetXpress Connect Exec in accordance with OSI and NM/Forum standards for managed objects. There are classes and instances of objects. c) For SNMP devices, an object is a piece of information in the MIB. OC optical carrier OC is the optical equivalent of an STS-1 signal. It specifies a line rate for transmission of optical signals. See OC1. OC1 optical carrier, 1 An optical SONET signal at 51.84 Mb/s. OC3 optical carrier, 3 An optical SONET signal at 155.52 Mb/s. OCB outgoing call barring OCD out-of-cell delineation OCU office channel unit An OCU is a device that provides an interface between a local loop and the DDS network. Its function is to convert data into DS0-A format. OCU-DP office channel unit - data port ODI open data-link interface ODI is a Novell specification that consists of a set of interface and software modules used to decouple device drivers from protocol stacks and to enable multiple protocol stacks to share network hardware and media transparently. OMNIpoint 0 OMNIpoint 0 is the first level of network management standards produced and collated by the NM/Forum. OOF out-of-frame An OOF event occurs when the terminal loses frame synchronization. OOS out-of-service The status of a primary rate link when it is out of service. OpenSNMP module Open Simple Network Management Protocol module The OpenSNMP module is a Newbridge package that allows you to create custom SNMP nodes and enhance the 3600 MainStreet Family Bandwidth Managers network capabilities by providing integrated access to HP OpenView NNM. Operating system An operating system is a collection of programs that govern the operation of a computer. The operating system manages system resources, such as memory and input and output devices (including hard disk storage), and manages the execution of applications. Examples include SunOS and DOS. Operator This term can be used in a number of ways. In general: * An operator is a person who manages a network using the network management software. Operators are also referred to as users, where a user is the owner of a network management software account. * In a partitioned network, operator refers to a mode of operation for the service provider. In operator mode, a service provider can manage network resources that have not been allocated to a partition. * Operator can also refer to a type of network manager account. A MainStreetXpress Connect Exec operator is a person at the gateway station. The MainStreetXpress Connect Exec operator can: * start up MainStreetXpress Connect Exec * manage the MainStreetXpress Connect Exec MIB * monitor system and communication messages for the gateway station A UMS operator is a person at the UMS workstation. Through MainStreetXpress Connect Exec, the UMS operator can: * configure network objects * manage events * maintain an inventory of network equipment Operator access This term refers to the division of network control partitioning among several operators. It is useful when managing a network by geographical regions. OPS off-premise station OPT optical power transmitted OPX off-premises extensions OS operating system An OS is a collection of programs that govern the operation of a computer. The operating system manages system resources, such as memory and input and output devices (including hard disk storage), and manages the execution of applications. Examples include Solaris and DOS. OSHA Occupational Safety and Health Association OSI open systems interconnection or interface A framework of ISO standards for communication between different systems. Areas covered include systems management, and directory and transaction processing. OSI model open systems interconnection model The OSI model organizes network processing functions into a seven-layer hierarchy. Each layer performs a specific function that helps move information from sender to receiver. The standards for the OSI model were published in 1978 by the ISO. OSPF open shortest path first OSPF is an IETF standard link-state routing protocol used for route determination in IP networks. OSS operations support system Methods and procedures that directly support the daily operation of the telecommunications infrastructure. OUI organizationally unique identifier Outage time Outage time is the amount of time that a system, device, network, link, etc. is unavailable for use. Overlay link An overlay link segment is a MainStreetXpress 46020 segment Network Manager overlay network link that is part of a MainStreetXpress 48020 MNSC overlay network link. Overlay network For the MainStreetXpress 46020 Network Manager, overlay networks are carried on existing physical and fractional links using specialized resources, such as subrate mergers, ADPCM resources or frame stream circuits. An overlay network provides subrate multiplexing, voice compression or frame relay switching for paths routed over the network. For the VIVID system, an overlay network is a network of VPC links that carry SVC or PVC connections. Overlay networks are carried on ATM links. Overlay network An overlay network link is a logical link that carries link subrate, ADPCM or frame relay paths over a full (physical) or fractional link. P2MP point-to-multipoint A connection that originates at a single endpoint and terminates on multiple endpoints. P2P point-to-point A connection that originates at a single endpoint and terminates at a single endpoint. PABX private automatic branch exchange A PABX is an internal corporate telephone network with an internal dialling system used for switching telephone calls within a business or to outside lines. Also used for low-speed data transmission. Packet A packet is a group of binary digits formatted to include the message, address, data and call control signals. The format is determined by the transmission protocol. Packet switching Packet switching is WAN technology that transmits messages as a sequence of packets (typically of 128 bytes). Packets are passed along pre-established paths known as virtual circuits. Virtual circuits can be permanently established or set up as needed by user devices. PAD packet assembler/disassembler A PAD is a protocol conversion device that converts asynchronous bit streams (from a start-stop mode device) to packets for transmission over a packet-switching network. PAL phase alternating line A format for colour TV signals. Partition a) In general, a partition is a portion of a network having exclusive control of its assigned resources. There are two types of partitions: VBNs and VSNs. b) To the MainStreetXpress Connect Exec, a partition is a portion of a network having exclusive control of its assigned network equipment and channels. Path A path is an association between two network access points (path-ends). It can be in one of two states: connected, where it can carry information, or disconnected, where it cannot. A backup path can be set up to protect another path, such as in the case of the MainStreetXpress 46020 Network Manager alternate routing feature known as RAPID. Path and overlay A path and overlay link group is a collection of paths link group and overlay links that have been logically configured as a group usually because they have something in common, such as function, or management by one operator. Path and overlay link groups are created by users to simplify operations such as connecting or disconnecting all of the paths and overlay links in a configuration. Path group Path groups are the interconnecting lines seen in views showing path connectivity. Path groups can be zoomed to reveal one or more paths. Path recovery Path recovery is the ability of the MainStreetXpress 46020 Network Manager to search for a new path and reroute calls if a link goes down. Path segment A path segment is a MainStreetXpress 46020 Network Manager path that can be part of a MainStreetXpress 48020 MNSC path. Path status change Path status changes are changes in the status of a path. Path status log A path status log is a text file that contains information about paths in the network. Every time the status of a path or path segment changes, a record is added to the file. Path-end Path-ends terminate paths. They connect Newbridge network equipment with customer equipment. A path-end can be a physical entity (such as a port on an LGS card that is connected to a subscriber loop), or a logical entity (such as a timeslot within a T1 link that is connected to a PBX). Pathpoint A pathpoint is any point along a path, such as a port, timeslot or SRM. It is not a path-end. PBX private branch exchange A PBX is a private branch exchange within a company. PC a) personal computer b) printed circuit PCB printed circuit board A specially manufactured board on which electronic components are mounted. PCM a) pulse code modulation b) physical connection management The function that manages the physical connection with the network. PCR peak cell rate PDN public data network A PDN is a WAN operated by a common carrier. PDU protocol data unit The unit of data in the OSI Reference Model. It contains both protocol-control information and user data from the layer above, and allows the two processes to co-ordinate interactions. PE packet engine X.25 switching UCS card which resides on a 3600 MainStreet family bandwidth manager node. PE card packet engine card Peer-to-Peer This term refers to communications between devices with equal access to a network. PEP packet exchange protocol PHY Physical Layer Medium independent The component of the FDDI standard that deals with the physical layer, but is not media-dependent. Physical layer This is the first (or lowest) layer of the OSI model. This layer provides an interface to the medium, detecting and generating signals on the medium, and converting and processing signals received from both the medium and the data link layer. The physical layer is the only layer involved in the physical transfer (via electrical and mechanical connections) of information between network nodes. Physical link A physical link is a medium (such as a coaxial or fibre cable or the equivalent, such as a satellite link) through which paths carrying customer information travel through the network and over which overlay network links are routed. Links connect ports or timeslots. A single link may contain a single path, such as an asynchronous data link, or many paths, such as a T1 link from a PBX. Physical network The physical network manager is one of the two viewing manager applications used to view and manage the VIVID system on the VIVID System Manager (the other is the Virtual Network Manager). Through the physical network manager, you perform component management, connection management, troubleshooting and diagnostics. PIR peak information rate The peak data transfer rate for a frame relay, VPC or VCC path. PISO parallel input serial output PLAR private line automatic ringdown A point-to-point LS/GS telephone line where lifting the handset off-hook at one end automatically rings the phone at the other end. When both telephones are off-hook, a voice path exists between them. PLAR FXO private line automatic ringdown foreign exchange office PLCP physical layer convergence protocol The format used to map a structure of data from the physical layer of networking processing functions, to the data link layer. PLD programmable logical device PLL phase locked loop A circuit used to regenerate the far-end clock from the incoming data stream. PLR pulse link repeater PMX parallel MX interface chip PN part number PNNI private network node interface A protocol for use between private ATM switches. PNNI includes a protocol for distributing topology information between switches and clusters of switches, used to compute paths through the network, and a signalling protocol used to establish point-to-point or point-to-multipoint connections across the ATM network. The signalling protocol is based on ATM Forum UNI signalling, with extensions to support PNNI functions. PNNI Link A PNNI link is a path that carries network topology and ATM address reachability information between MainStreetXpress 36170 nodes. Polling Polling is the method used by a primary station for soliciting input or acknowledgment from one or more secondary stations. POP point-of-presence Port a) logical port In bridge/routers, a logical port is the internal connection between a bridging or routing module and an interface (and possibly a sub-interface, such as a logical channel). Examples of logical ports are bridge ports, DECnet circuits, AppleTalk logical ports, IPX logical ports and IDP logical ports. For an ATM Services card, the IMA group is considered to be a logical port. b) physical port A physical port is the physical access point on a bridge/router that makes a connection to LAN or WAN interfaces. c) For a 3600 MainStreet Bandwidth Manager, ports are points of connection for links between network equipment. There are primary rate ports, aggregate ports, voice ports and data ports. d) For a VIVID system, ports are points of connection for links between network equipment. The Workgroup Switch provides up to twelve OC3c ATM ports. Port group On the VIVID Virtual Network Manager, port groups are used to organize ports for assignment to virtual networks. A port group can contain either Ethernet or ATM ports. Two port groups are created automatically: the default Ethernet port group and the default ATM port group. Port groups are assigned to virtual networks to define bridged VNET membership and to restrict access to IP routed VNETs. POS point-of-sale Position Position refers to the physical location where a module is installed on 3606, 3612, 3624, 3630 and 3638 MainStreet nodes. The 3600 MainStreet Family Bandwidth Managers graphical interface shows module positions in the same way that it shows slots on the 3600 MainStreet and 3645 MainStreet nodes. POTS plain old telephone service PPDU presentation protocol data unit The PPDU is a PDU that operates at the presentation layer of the OSI protocol. ppm parts per million PPP point-to-point protocol PPP is a protocol that allows a computer to use TCP/IP with a standard telephone line and a high-speed modem to establish a link between two (and only two) terminal installations. Preferred mate A preferred mate is one of a redundant pair of database NetworkStations. If the two NetworkStations come up at the same time, for example, after a power failure, then the one identified as the preferred mate becomes the active database NetworkStation. Presentation layer This is the sixth layer of the OSI model. This layer controls screen and file formats. Control codes, special graphics and character sets work in this layer. Presentation The presentation protocol is a protocol used by the protocol presentation layer of the OSI seven-layer reference model for protocols and interfaces. PRI primary rate interface PRI is one of two subscriber interfaces for ISDN. (The other is BRI.) It is similar to a T1 circuit, providing 23B+D (in North America) or 30B+D (in Europe). Primary rate Primary rate refers to the digital transmission standards used by public telephone companies for channelized links. North American primary rate is the T1 interface (1.544 Mb/s). European primary rate is the E1 interface (2.048 Mb/s). Primary rate Primary rate interface cards terminate the channelized interface card network links that interconnect one 3600, 3645, 3664 or 36120 MainStreet node to another across the network. Process A process is a software application that produces a specific result. MainStreetXpress Connect Exec has a number of processes, two of which are CE_control and CE_driver. Some MainStreetXpress Connect Exec processes run on the gateway station and some run on the NetworkStation. PROM programmable read-only memory A programmable semiconductor memory device in which the contents cannot be modified. Protocol Protocol is the set of rules that specify how computers communicate. These rules govern format, timing, sequencing and error control of data exchanged between two communicating processes. Protocol converter This is a device that translates the communications protocols of one network or device to the protocols of another device or network. Protocol converters enable different types of networks or devices to communicate with one another. Protocol domain On the Virtual Network Manager, protocol domains provide the means of viewing and configuring virtual networks. There are two protocol domains: the bridged domain and the routed domain. Protocol priority This is the capability of a bridge to set transmission (or precedence) priority depending on the protocols of the packets they carry. Protocol priority can also be used to prevent selected protocols from being transmitted. PS a) packet size b) packet system c) personal system PS1 power supply 1 PS2 power supply 2 PSDN packet switched data network PSN public switched network PSPDN packet switched public data network PSTN public switched telephone network PSTN is the worldwide voice telephone system. PT payload type A field in the ATM cell header that indicates the type of cell. PTI packet type identifier PTT postal, telephone and telegraph PTX packet transfer exchange PTZ pan/tilt/zoom PU peripheral unit A 3645 MainStreet Peripheral Unit. PUB publication PVC a) permanent virtual channel (ATM) b) permanent virtual connection (ATM) A PVC is an end-to-end logical ATM path that is established through network provisioning procedures. In the VIVID system, PVCs are typically established by an operator at the VIVID System Manager. A PVC can be a VPC path or a VCC path. VPC paths are connections for which the VIVID system is only aware of the VPIs; the VCIs are assigned by external equipment. These connections are typically established between two non-VIVID ATM switches. VCC paths are typically connections between two ATM hosts on the VIVID system. They can be routed over PVC-support VPC links, or they can be individually routed. Because of their long-term nature and because they must be operator-provisioned and operator-disconnected, PVCs are permanent. c) permanent virtual circuit (frame relay) A PVC is a frame relay end-to-end logical connection that extends between two user or network interfaces. A single PVC may pass through several frame relay switching modes. PVC-support VPC A PVC-support VPC link is a VPC link that carries VCC link paths created by an operator at the VIVID System Manager. PVPC permanent virtual path connection A PVPC is a long-term VPC that is set up and taken down by a network operator. Because of these factors, a PVPC is considered permanent. It is identified by its VPI. Q.922 An ITU-T ISDN Data Link Layer Specification for Frame Mode Bearer Services. The specification consists of Annex A, usually called DL-CORE and the remainder of the specification, usually called DL-CONTROL. Q93B Q93B is a signalling protocol standard used for call setup in ATM networks. It is specified by the ITU-T and endorsed with modifications by the ATM Forum in its implementation agreement on the ATM UNI. QoS quality of service For ATM, the quality of service of a connection is defined by its traffic characteristics such as cell loss probability, cell delay variation and cell delay. Qs Qs is a proprietary interface used by products and applications at the element, network and service management layers to communicate objects and their status. QUICC quad integrated communications controller R a) ISDN reference point Non-ISDN (TE2) terminal equipment connects to ISDN at the R-reference point through a terminal adapter. b) ring R2D signalling R2 digital signalling RAI remote alarm indication A code sent upstream in a network as a notification that a failure condition has been declared downstream. Also known as AIS or Yellow Alarm. RAM random access memory The primary memory in a computer, RAM can be repeatedly read and overwritten. RAPID reserved alternate path with immediate diversion RAPID is a function that reserves an alternate path for a high priority path. If the primary path becomes unavailable due to a network problem, the network nodes automatically switch to the reserved path. RARP reverse address resolution protocol RBS a) robbed bit signalling A signalling technique used in T1 which steals the least significant bit of a channel every few frames to use as a signalling bit. b) reverse battery signalling A type of loop signalling in which batteries and ground are reversed on the tip and ring of the loop to give an off-hook signal when the called party answers. Some systems use this type of signalling to indicate a toll call. RDF Rate Decrease Factor An ABR service factor by which a source should decrease its transmission rate if there is congestion. RDI remote defect indication A signal returned to the transmitting equipment upon detection of certain defects on the incoming signal. RDL remote digital loopback RE remote extension Redundancy In general, this term means that all or part of a system is duplicated so that the redundant part can take over should the active part of the system fail. For example, you can configure an active and a standby database NetworkStation. Redundancy allows notification and recovery from Ethernet failures, from MainStreetXpress 46020 Network Manager failures and from divided networks resulting from node or link failures. At any point, the standby can become active through a manual activity switch or an automatic switch performed by the MainStreetXpress 46020 Network Manager. REJ reject REM EXT remote extension Remote maintenance A remote maintenance circuit terminates a path that circuit extends the maintenance connection from one node to another node in the network during off-node testing. REN ringer equivalence number The REN determines the number of devices that can be connected to a telephone line and still ring properly. Repeater This is a device that amplifies or regenerates a signal so that the physical length of the network cable can be increased or the number of devices attached can be increased. Resources a) In general, resources are processing circuits found on cards and modules. Resources can be used for voice compression, subrate multiplexing, subrate switching, G3/FAX processing and FASTbus connectivity. b) For the MainStreetXpress 46020 Network Manager or MainStreetXpress Connect Exec, resources can refer to the following: * processing circuit (as above), such as a voice compression circuit * network hardware, such as a node, card or power supply * transmission bandwidth or channels, such as a link, path, timeslot or channel RFC request for comment This acronym is the prefix for all published IETF documents. These documents typically define IP, TCP and related application layer protocols. RI ring indicator or ring identification RIF (a) routing information field (b) rate increase factor An ABR service factor by which a source can increase its transmission rate if the (returning) RM cell indicates no congestion. It can result in an Additive Cell Rate (ACR). Ring topology This is a LAN topology where each node is connected to at least two other nodes so that they form a loop (or ring). Data moves around the ring from node to node in one direction. RIP routing information protocol A Bellman-Ford routing protocol based on distance vector algorithms that measure the shortest path between two points on a network in terms of the number of hops between those points. Various forms of RIP are used to distribute routing information in IP, XNS, IPX and VINES networks. RL remote loopback RLS release RMS root mean square RNR receive not ready ROM read only memory A semiconductor memory device that cannot be overwritten. ROOS remote out of service second A second during which a remote fault, such as SAI, has been declared. Routed protocol In a VIVID system, the routed protocol domain contains domain all routed VNETs. Routed VNET VIVID supports IP routed VNETs. Each routed VNET forms a separate broadcast domain. Cells are forwarded within a routed VNET directly. Cells are forwarded between routed VNETs using the VIVID Route Server. An IP routed VNET can be defined to include ATM port groups or Ethernet port groups, but not both. An Ethernet port group can be assigned to multiple IP routed VNETs. For a host to be a member of an IP routed VNET, the host subnet address must match the configured subnet address of the virtual network, so different hosts on the same Ethernet segment can belong to different IP routed VNETs. Router A router is an interface device between two networks. It selects the most cost-effective route for moving data between source and destination devices. A router is a LAN/LAN or LAN/WAN interconnecting device. It selects the most cost-effective route for data flow between multiprotocol LANs, making sure that only one route exists between source and destination devices. Routers make forwarding decisions based on network-layer addresses. Routing SRM routing subrate merger A type of SRM that can either merge branch channels into one aggregate channel or distribute one aggregate channel into many branch channels. On the 3600 MainStreet Family Bandwidth Managers, routing SRMs, unlike endpoint SRMs, do not support branch channels as path endpoints. Routing SRMs are supported on DNIC cards and on DSP cards. RPOA recognized private operating agency RR a) receive ready b) ring return c) ring 1 RS-232 RS-232 is an EIA electrical interface standard specifying mechanical and electrical characteristics of the DTE-DCE interface. It applies to synchronous and asynchronous serial and binary data transmissions, and unbalanced transmission at relatively slow speeds. Physical connection is through 8, 9 and 25-pin connectors. RS-422 RS-422 is an EIA electrical interface standard operating in conjunction with RS-449 and specifying the electrical characteristics for balanced circuits. Signal pairs (signal and return) are balanced lines rather than referenced to ground, and the cable typically uses twisted pairs. Also see V.24. RS-449 RS-449 is an EIA electrical interface standard for high-speed transmission. An RS-449 connector uses 37 pins, where each pin has its own return line instead of a common ground return. RSA Rivest, Shamir, Adleman RT-VBR real-time variable bit rate An RT-VBR is an ATM service category that guarantees very low cell loss and very low delay for time-sensitive applications such as voice and video, which are characterized by unpredictable, bursty transmission patterns. RT-VBR is a variant of the VBR service category that is only available for VPC and VCC paths. NRT-VBR is the other variant of VBR available for these paths. The 3600 MainStreet Family Bandwidth Managers Technical Practices treats RT-VBR and NRT-VBR identically for routing and rerouting purposes, and uses both to calculate the total VBR bandwidth utilization. RTP reliable transfer protocol RTS request to send A V.24 control signal on a standard RS-232-C connector. RTS places the modem in the originate mode so it can begin to send. RTU router termination unit RUT router upgrade tool Rx receive RxD receive data S a) ISDN reference point b) signalling element timing (an X.21 signal) s microsecond (millionths of a second) S bit signalling bit S interface interface between TA and NT-2 (ISDN) S/T BRI ISDN S type/T type basic rate interface An interface that connects at either S or T reference points of the ISDN reference model. The basic rate interface consists of two 64 kb/s data channels and one 16 kb/s control channel. SAAL signalling ATM adaptation layer An adaptation layer that adapts signalling to the ATM layer. There is a SAAL defined for the UNI, and a SAAL defined for the NNI. The protocol used in the SAAL is SSCOP. SABM set asynchronous balanced mode SABMR set asynchronous balanced mode retry SAM super-rate adapter module A SAM is used to equalize delay when switching super-rate data circuits between an E1 link (2.048 Mb/s) and a T1 link (1.544 Mb/s), or between two T1 links. SAP a) service access point SAP is a point of communication exchange between an application and the LLC or between layers of software. b) service advertisement protocol SAP is a member of the Novell NetWare family of protocols used to advertise the presence of servers in a NetWare network. SAR PDU segmentation and reassembly protocol data unit The SAR aspect refers to the segmentation and reassembly of Token Ring frames into ATM cells and the reassembly of ATM cells into Token Ring frames. The PDU is information that is delivered as a unit between peer entities of a LAN that contains control and address data, and may contain user data. Together, SAR PDU is the process of segmenting PDUs into ATM cells and reassembling the cells back into single PDUs. SAS single attachment station A configuration used in non-redundant FDDI networks. SB signal battery SBP stay in boot PROM SBus The SBus is a workstation expansion bus introduced by Sun Microsystems and standardized in IEEE 1496. SC a) switching card The 3645 MainStreet matrix card in the switching shelf. b) secondary channel (Digital Dataphone Service) c) snap connection A snap connection is a type of plastic connector for fibre optic cable that snaps into place when pushed into the port. SCA systems communications architecture SCC3 system control card 3 SCCS source code control system A set of UNIX utility programs for source code control. SCR a) signal carrier ready A V.24/RS-232 signal. b) silicon controlled rectifier c) sustained cell rate SCSI small computer system interface A bus and interface standard; it is a way for magnetic hard disks, optical disk drives, tape drives, CD-ROM drives, printers, and scanners to communicate with the main processor of a computer. SCT a) severe congestion threshold SCT is a frame relay parameter related to the buffer capacity of a frame relay device. At the SCT, the frame relay device sets the FECN and BECN bits for those frames queued for transmission. It discards frames identified with a DE bit. b) signal carrier transmit A V.24/RS-232 signal. SD a) starting delimiter An 8-bit binary sequence that marks the beginning of a data packet. b) service data SDH synchronous digital hierarchy SDH is an ITU-T standard for optical interfacing that is technically consistent with SONET. SDLC synchronous data link control SDLC is a bit-oriented synchronous communications protocol developed by IBM. It typically operates in half-duplex mode and carries SNA traffic. SDM synchronous data module SDU service data unit An SDU is a data unit that is passed from one layer of a protocol stack to the next lower layer for transmission. The higher layer uses the services of the lower layer. SE3 single E3 A card with one E3 interface. SEEP serial electrically erasable PROM SEEP is the memory used to store and report product identity and other long-lasting information about hardware assembly. Selected object For the MainStreetXpress 46020 Network Manager, an object becomes the selected object when you click it. Information about the selected object appears in the selected object panel. If the object is a graphic object, such as a node icon, link or timeslot, its colour dims. When the object is text, such as a path or partition name, the text is highlighted in reverse video. Selected object This is the top panel of the MainStreetXpress 46020 panel Network Manager map. It lists important information about the selected object. SELV safety extra low voltage Serial interface This is where the parallel arrangement of data within a computer is changed to the serial stream of bits used on transmission lines, and vice versa. Server A server is the processor that provides shared resources and services to a network. Resources and services could include files, printers, modems or gateways to other systems. Service Agent Service Agent software receives network data from a 4602 MainStreet or MainStreetXpress 46020 Network Management station and stores it in accordance with a standard management protocol. Service card A service card is a card on MainStreetXpress 36170 nodes that performs applications for the Control card. You can configure the service card to perform call control, data spooling or P-NNI routing. Service category The service category determines the priority an ATM connection receives when using connection bandwidth. The possible service categories, from highest to lowest priority, are CBR, VBR, ABR, and UBR. Service level In a partitioned network, service level manager refers manager to a mode of operation available to a service provider. In service-level manager mode, a service provider can view and operate on the network resources assigned to a particular partition. Service-level manager mode is typically used in help desk applications. Service manager The service manager is a VSN partition with access to all data in the service agent database. It stores the IP addresses for all partitions configured with the MainStreetXpress CSM Agent. Service provider In a partitioned network, the service provider is the organization running the backbone-transmission network. A service provider creates partitions and allocates network resources to them, monitors the status of all network equipment and handles maintenance procedures for failed components. Service user In a partitioned network, a service user is an outside group that controls a partition within the service-provider network. The service user manages the partition from a Customer NetworkStation located on their premises, and can view and control only those network resources allocated to the partition by the service provider. SES severely errored seconds A second (other than a failed second) in which the bit error rate exceeds 10 -3 or in which any loss of frame alignment has occurred. Session A session is an active communication connection between devices or nodes on the network or between applications. Session layer The session layer is the fifth layer of the OSI model. This layer sets up the conditions whereby individual nodes on the network can communicate or send data to each other. The session layer manages, maintains and controls the dialogue between the users of the service. Session protocol Session protocol is a protocol used by the session layer of the OSI reference model. SF superframe format A framing format for T1 links which provide a 12 frame multi-frame with 24 kb/s channels per frame. Also known as D4. SG signal ground SGND signal ground Shelf A shelf is a division of the 3600, 3645, 3664 or 36120 MainStreet node. Each node can contain one or two shelves, labelled A and B. Each shelf contains a number of slots into which cards are inserted. SHUB Switching Hub Card Located in the peripheral shelf, this card provides switching services for the UCSs as part of the MainStreetXpress 36170 standalone system. SI switching interface SI Alm switching interface alarm SI card switching interface card Sieve A sieve is an attribute of some MainStreetXpress Connect Exec managed objects that allows an operator to determine which items are selected for further action by the object. SIG 24 timeslot 24 signalling Signalling link An end-to-end logical connection that can be established between two ATM nodes, in order to exchange information related to SPVCs and SVCs which are passing between the node. In the MainStreetXpress 46020 network management system, signalling links are a type of VCC path. Signalling link A signalling link profile is a set of preconfigured profile attributes that can be sent to all MainStreetXpress ATM nodes in the network to define the operation of their associated signalling links. SIMM single in-line memory module Simple port A simple port is a port that does not have subordinate ports or timeslots. Examples are LGS and LGE. SIPO serial input parallel output SIR a) sustained information rate The long-term average data transfer rate for a frame relay, VPC or VCC path. b) sole internal route SLC subscriber line carrier SLIC subscriber line interface circuit SLIP serial line internet protocol A simple protocol that allows one machine to communicate with another using IP over an asynchronous serial line. It is being superseded by PPP, but is still in common use. SLM single-longitudinal mode SLMF signal label match failure Slot Slots are the openings in a shelf of a Newbridge node where interface, application or control cards are installed. SMAC state monitoring array controller A mechanism used for rapid detection of hardware state changes. SMDR station message detail recording The SMDR refers to the RS-232-C port or plug located on most PBXs and some larger key systems. SMDS switched multimegabit data service A high-speed, connectionless, public, packet switching service that provides for the exchange of variable-length data up to a maximum of 9188 octets. SMF single mode fibre An optical fibre capable of supporting the propagation of only the lowest order bound mode through the fibre. SMI structure of management information Common definitions for the structure and identification of management information for TCP/IP-based internets. SMP symmetric multiprocessing SMP is the ability of an OS to distribute tasks to all available CPUs in a hardware platform and to execute these tasks in parallel. SMT station management The facilities that manage the MAC, PHY and PMD layers of an FDDI station. SMTP simple mail transfer protocol The IETF standard for transferring electronic mail messages from one computer to another. SMUX SNMP client SNMP multiplexer SMUX is the software used to facilitate communication between an SNMP agent and an NMS. See SNMP manager. SMVI small multiplexer voice interface SN subscriber number SNA systems network architecture SNA is IBM’s proprietary network architecture. It also refers to a class of networking protocols defined by IBM. SNAP a) subnetwork access protocol A version of the IEEE local area network logical link control frame. Similar to the more traditional data link level transmission frames, this frame uses non-standard higher-level protocols. b) subnetwork attachment point SNI Subscriber-Network Interface The point at which customer premise equipment interfaces to a network supporting SMDS. SNMP simple network management protocol The IETF standard management protocol used for equipment in a TCP/IP LAN. SNMP provides access to a device MIB. SNMP agent An SNMP agent is the software process that runs in a managed device. The agent stores management data in the device’s MIB and responds to requests from the SNMP manager. SNMP client An SNMP client is software that runs on a network management station. The client queries SNMP agents for data stored in the agent’s MIB. SNMP community An SNMP community is a pairing of an SNMP agent with one or more SNMP managers. The managers are given either read-only or read/write access. SNMP manager An SNMP manager is software that runs on a network management station. The manager queries SNMP agents for data stored in the agent’s MIB. SNMP node simple network management protocol node An SNMP node is a data device that can be managed using the 5638 MainStreet SNMP Manager software. Examples include bridges, routers, IP hosts, repeaters, PCs and printers. SNMP nodes communicate with the MainStreetXpress 46020 Network Manager by way of IP links. Software module See Add-on product. SOFV fixed German ISDN Solaris Solaris is the operating environment on a Sun workstation, including the operating system, utilities, tools and windowing system. SONET synchronous optical network An ANSI standard for fibre optic transmission of high-speed digital traffic. It uses synchronous high-speed signals and provides easy access to low-speed signals by mapping them into VTs. Source address This is the part of a message that indicates who sent the message. Source-route Source route bridging is an IBM method of bridging, bridging popular in token ring networks. It is used by a bridge for moving data between two networks. The bridge relies on information in the packet to route the data between the two networks. Since the routing information is supplied by the computer that sends the packet, that computer must know on which network the destination computer is located. For source routing to work, every computer and every bridge on all networks must support this protocol. If some computers do not use this protocol, they do not receive packets from bridges that use source routing. See Transparent bridging. SP serial port SP1 serial port 1 SP2 serial port 2 SPC single path call SPDU session protocol data unit The SPDU is a PDU that operates at the session layer of the OSI model. SPI serial port interchange A 3600 MainStreet card that is placed in an unused GFC card position of a redundant node to provide automatic switching of a maintenance terminal to the active control. SPID service profile identifier/identification Split-back A split-back maintenance connection is an intrusive maintenance maintenance action that splits a target connection, connection then routes each end of the connection to its respective maintenance circuit. Split-through A split-through maintenance connection is an intrusive maintenance maintenance action that inserts maintenance circuits connection between the pathpoints on data and signalling paths. SPP sequenced packet protocol SPVC soft permanent virtual connection An SPVC is a path that is created by the 3600 MainStreet Family Bandwidth Managers, but is routed by the MainStreetXpress 36170 nodes it traverses. SQE signal quality error A signal from a MAU that signifies a detected collision, a successfully completed SQE test sequence, or an active jabber circuit. SQL structured query language SQL is a standard query language used to manipulate information in relational databases. SR short reach SRAM static random access memory SRAM is RAM that does not require a refresh cycle, therefore it can be accessed more than twice as quickly as RAM requiring a refresh cycle. SRAM requires power to maintain data. SRF specifically routed frame SRIM subrate interface module SRL subrate link A subrate link is a pairing of subrate resources. It is a logical link that has path-like qualities; for example, it can be connected, disconnected and protected by AAR and RAPID. Subrate links are restrictive in their rate adaption type and as a consequence, are restrictive in their path usage. Subrate links may be X.50, DS0-B or HCM/I.460. Subrate links travel along subrate paths. SRM a) subrate multiplexer A device which allows data and compressed voice to be multiplexed together and put on a single DS0. b) subrate merger SRMs are used to transmit bit streams from one or more subrate circuits, voice or data, over a single 64 kb/s channel. SRMs perform rate adaption and can either merge branch channels into one aggregate channel or distribute one aggregate channel into many branch channels. There are two types of SRMs: routing SRMs and endpoint SRMs. SRMs are available in four types of rate adaption: I.460, DS0-B, HCM and X.50. SRS subrate switch A subrate switch is a logical device that is used to switch subrate paths. SRT source routing transparent An IEEE standard protocol for combining source-routed bridging capabilities with transparent bridging. SS subaddress SSCOP service specific connection-oriented protocol A standard protocol used to provide assured delivery of signalling messages. Defined in ITU-T Recommendation Q.2110. SSCS service specific convergence sublayer SSP system signalling protocol SSR single shelf redundancy SSU system synchronization unit The circuit which generates the system clocks (C4M, FP, C3M) from whatever master-clock source is selected. ST HCV super tandem high capacity voice Standby (database) A standby (database) NetworkStation is a NetworkStation or NetworkStation containing the standby database. It Network Manager provides a user interface to the network and regularly copies the active NetworkStation database so that the standby database is up to date. If the active NetworkStation fails, network control switches to the standby NetworkStation, thus making it the active NetworkStation. Star topology A network topology where all nodes are wired directly to a central node that establishes, maintains and breaks connections between the nodes. Status indicator A status indicator is a coloured symbol found on most MainStreetXpress 46020 Network Manager objects. It can take the shape of a circle, square, oval or rectangle. Its colour changes to reflect status changes. STE spanning tree explorer A token ring frame transmitted by a source station and forwarded in order to accumulate the source-route information. STM synchronous transfer mode A transport and switching method that depends on information occurring in regular and fixed patterns with respect to a reference such as a frame pattern. STM1 Synchronous Transport Module - Level 1 An SDH construct that carries data at the rate of 155.52 Mb/s. Equivalent to OC3. STP a) shielded twisted pair This is a form of wiring where two insulated wires are twisted together and covered with a sleeve of wire strands that help reduce electrical interference. b) spanning tree protocol STP is a technique based on an IEEE 802.1 standard that detects and eliminates logical loops in a bridged network. When multiple paths exist, STP lets a bridge use only the most efficient one. If that path fails, STP automatically reconfigures the network to make another path become active. This protocol is used mostly by local bridges. STS synchronous transport signal This is an electrical variant of the SONET OC signal. The basic rate is 51.84 Mb/s; higher rates are direct multiples of the base rate. STS-3c Synchronous Transport Signal level 3 - concatenated STS-3c is an electrical signal that is converted to or from a SONET optically based signal. It is equivalent to the OC3 signal operating at 155.52 Mb/s. STS1 Synchronous Transport Signal - Level 1 A SONET construct that carries data at the rate of 51.84 Mb/s. SU switching unit A 3645 MainStreet Switching Unit. Subframe A subframe is a component of a frame; several subframes make up one frame. Bits are arranged in subframes because they have some sort of commonality, such as originating from a single source or belonging to a multiplexing scheme. Channels and timeslots are both examples of subframes. Subnet A subnet is a collection of OSI end-systems and intermediate systems under the control of a single administrative domain. It uses a single network access protocol. Subnet mask A subnet mask provides both an Internet address and a subset of addresses to use within an organization. The mask is used to distinguish between the network and local parts of an IP address. Each station and router in the organization has a defined mask. Subrate Subrate speeds are data rates that are less than 64 kb/s. Subrate path A subrate path is an association between two path-ends defined as subrate resources. SunOS SunOS is the UNIX operating system on a Sun workstation. SunOS release 4 is based on BSD UNIX. SunOS release 5 is based on AT&T/Bell Labs System V UNIX, and is more commonly known as Solaris. Super-rate Super-rate speeds are data rates that are greater than 64 kb/s. Supervisory channel The supervisory channel is a reserved channel that can carry CPSS, signalling and framing data, and voice and data calls. It corresponds to timeslot 0 on V.35 and X.21 primary rate interfaces. Supply network In a partitioned network, the supply network is the pool of network resources that have not been allocated to partitions. SVC switched virtual connection (ATM and frame relay) A connection that is set up on demand via a signalling protocol. SVCs tend to be of shorter duration than PVCs and are not automatically re-established after they are torn down. SVCC switched virtual channel connection (ATM) An SVCC is a VCC set up by a dynamic switching protocol in response to a call setup. It is normally set up for minutes or hours. Synchronous This is a mode of data transmission where information communication transmission and reception are synchronized to a clock signal that is not part of the character stream. System cards System cards perform fundamental system-wide functions for the 3600, 3645, 3664 and 36120 MainStreet nodes, and MainStreetXpress 36150 and 36170 nodes. System-created path A system-created path is a path with a special "system" designation, indicating it is created internally by the MainStreetXpress 46020 Network Manager. System-created paths can be configured, connected and disconnected as normal paths, although configuration is restricted to ensure off-node test integrity. T a) ISDN reference point b) tip T/R tip/ring T::DAX transparent digital access and cross-connection system The T::DAX is a high-capacity DCS that can switch up to 1792 DS1s in its three-bay configuration and 3584 DS1s in its six-bay configuration. T1 transmission signal level 1 T1 is the first level of the digital transmission hierarchy commonly used in North America and Japan. T1 operates at a link speed of 1.544 Mb/s. T1 LIM T1 line interface module T1D Dual T1 T3 transmission signal level 3 T3 is the third level of the digital transmission hierarchy commonly used in North America. T3 operates at a link speed of 44.736 Mb/s. TA terminal adapter A terminal adapter allows existing non-ISDN terminals to operate on ISDN lines. It provides conversion between a non-ISDN terminal device and the ISDN user/network interface. TABS telemetry asynchronous block serial protocol TAM telecommunications access method Tandem nodes Three or more nodes connected in series. TAP a) transmission access processor b) transmission access platform The 3500 MainStreet. TAP is a multi-purpose access processor with a universal modular platform, providing inverse multiplexing , bandwidth on demand and dynamic bandwidth allocation for the transmission of high-speed data over non-contiguous channels. TAXI terminal access transmission interface An AMD-proprietary 100 Mb/s electrical interface most widely known for its use carrying ATM. TBD to be determined TC a) transmission convergence The Tc sublayer is the upper half of B-ISDN Layer 3. b) termination card (VIVID) Tc committed rate measurement interval The Tc is the time interval over which the user may transfer Bc bits of committed data, or Bc + Be bits of uncommitted data. It is calculated as Tc= Bc/CIR. TCP transmission control protocol An Internet transport layer protocol, TCP is a window-based reliable transport protocol used for all sorts of stream-related operations. The transport layer (roughly) protocol for the TCP/IP protocol suite. Often referred to in conjunction with the network layer protocol IP as TCP/IP. TCP/IP transmission control protocol/Internet protocol This is a set of protocols developed by the U.S. Department of Defense to link dissimilar computers across many kinds of networks. TCP/IP is commonly used over subnetworks, including Ethernet, ATM, frame relay and leased line. TCP corresponds to layers three and four of the OSI model. TCP/IP is a multivendor, non-proprietary standard. TDM time division multiplexing A process of sharing a communication channel among several users by allowing each to use the channel for a given period of time in a defined, repeated sequence. TDM card time division multiplexing card A TDM card provides a direct-to-copper interface for a T1 trunk for transport over ATM. TE terminal equipment Terminal equipment represents the endpoints of one or more ATM connections and the termination of the various protocols within the connections. It is typically a PBX or a computer. TE1 ISDN-compatible terminal equipment TE2 non ISDN-compatible terminal equipment. TEI terminal end point identifier Field in link layer frames used for the point-to-point data link connections associated with the addressed SAPI. Telco telephone operating company Telnet Telnet is the Internet-standard TCP/IP protocol for remote terminal connection service. Temporal order A property of a network (or of parts of a network) which indicates that timeslots sent from some point in a specific order will arrive at their destination in that same order. Super-rate paths must use network equipment and links that guarantee temporal order. TEP-1(E) telecommunications equipment practices - 1(E) A British Post Office standard for displaying alarms on telecommunications equipment. TEST TEST frames are used by many HDLC-like protocols to verify connectivity. TFTP trivial file transfer protocol A simple file-transfer protocol standardized by the IETF which operates over unreliable datagrams with a simple retransmission scheme. TG trunk group A group of trunks with similar electrical characteristics running between two geographical points. Typically, trunks in a trunk group are all accessed the same way. A trunk group carries more traffic than a single trunk, Throughput This term refers to the amount of information that is transmitted or processed on a communications link. Timeslot A timeslot is a division of time within a primary rate frame. A T1 frame is divided into 24 timeslots of equal duration, and an E1 frame is divided into 32. TLP transmission level point Defined as the analog audio level with respect to a 0 dBm0 level at the digital demarcation. TM test mode TNV telecommunications network voltage TO transmission only TOA type of address A method of addressing used in an X.25 network. Token bus Token bus is a network with a bus topology that uses the token-passing procedure. Token passing Token passing is a network access method where each device on the network receives and passes the token. The token gives the device exclusive access to the network for message transmission. Token ring Token ring is a network with a ring topology that uses the token-passing procedure. See IEEE 802.5 and Ring topology. TON type of number TOP task oriented procedure Topology The arrangement of network components and their interconnection. It can be centralized or distributed. Typical topologies are bus, ring, star, tree and mesh. TP2 transport protocol class 2 TP2 is an ISO standard communications protocol that allows multiple transport connections over a single network connection, with flow control for each transport connection. TP4 transport protocol class 4 TP4 is a communications protocol designed for connectionless network service; it also works over a connection-mode network service. TP4 achieves reliability through retransmission. TR a) tip return b) tip 1 Traffic shaping Traffic shaping is a mechanism that changes the traffic characteristics of a stream of cells on a connection to achieve better network efficiency while meeting the QoS objectives. Shaping guarantees the cells adhere to traffic descriptors. Transceiver A transceiver is a device for receiving and transmitting data. In a baseband network, it takes digital signals from a computer or terminal and imposes them on the baseband medium. Transceiver cable The cable that connects an Internet AUI to the network interface controller. Transitional ADPCM A method for exchanging compressed voice where signalling is in-band with the compressed speech, and compression is ADPCM. Transmission A transmission service provider is a telephone service provider company, carrier, PTT or other bandwidth reseller acting as a service provider. Transparent Transparent bridging is so called because the bridging intelligence necessary to make relaying decisions exists in the bridge itself and is thus transparent to the communicating workstations. It involves frame forwarding, learning workstation addresses and ensuring no topology loops exist. Transport layer The transport layer is layer four of the OSI model. It specifies message transfer protocol between end users. Transport link An overlay link that allows routing of narrowband data across SONET/SDH networks. Transport path A SONET/SDH data path. Trap A trap is an unsolicited message sent by an SNMP agent to an SNMP manager. The manager is then responsible for querying the agent to find out why the trap was sent. Tree topology This is a network topology where there is only one route between any two nodes on the network. The pattern of connections resembles a tree. Trouble ticket Trouble tickets are generated by the MainStreetXpress 46020 Network Manager in order to keep track of node-generated event failures and operator responses to those failures. TS 16 timeslot 16 TS0 timeslot 0 The first timeslot in a CEPT frame. Timeslot zero can be used to carry CPSS messages. TSAP transport service access point Combined with the network address, the TSAP uniquely defines a connection endpoint for an OSI application entity. TSM timeslot 24 signalling module A module for the dual T1 card, that moves all the signalling to timeslot 24. TTC2M Telecommunication Technology Committee 2.048 Mbps UCS card The TTC2M card provides a digital CMI voice interface between 3600, 3600+, 3664 and 3645 MainStreet nodes, and a PBX that conforms to the TTC Vol.4 JJ-20.11 standard. TTI tributary T1 TTRT target token rotation time The time required for the token to move around the ring. TU tributary unit An information structure within an SDH frame consisting of a VC payload and a TU pointer. Equivalent to a VT in a SONET frame. TVX valid transmission timer An alarm timer that monitors operation of the FDDI ring. Twisted pair This is a form of wiring where two insulated wires are twisted together. It is commonly used to connect telephones, terminals and computers. Tx transmit TxD transmit data TxD/RxD transmit data/receive data U a) ISDN interface between CO and CP b) unacknowledged UA unnumbered acknowledgment UART universal asynchronous receiver transmitter A UART is an integrated circuit designed to perform character assembly/disassembly, and the conversion of parallel data into serial data for transmission over an asynchronous data channel. UAS unavailable seconds A count of one-second intervals during which the CI is in UST. UBR unspecified bit rate UBR is an ATM service category which does not specify traffic-related service guarantees. Specifically, UBR does not include the notion of a per-connection negotiated bandwidth. No numerical commitments are made with respect to the cell loss ratio experienced by a UBR connection, or as to the cell transfer delay experienced by cells on the connection. UCS universal card slot A system slot into which one of many different peripheral cards may be inserted, as distinguished from the dedicated slots for the Control, Alarm or Power Supply cards. UDP a) user datagram protocol A connectionless datagram protocol that forms the basis for Internet communications. UDP resides in the transport layer of the OSI model, beside the TCP protocol. Defined in RFC 768. b) universal distribution panel UDP/IP user datagram protocol/Internet protocol UDT unchannelized data transfer An unchannelized data transfer is an AAL1 convergence sublayer procedure where all payload and framing bits of an emulated circuit are carried on an ATM VC. UI a) see User interface b) unnumbered information UK United Kingdom UL Underwriter’s Laboratories UMC unassigned multiplexer channel A DDS control code carried in unused sub-channels of a DS0-B signal. UMS umbrella management system UMS is a high-level network management system that interfaces with EMSs and other network management systems. MainStreetXpress Connect Exec provides the interface between a UMS and a Newbridge Network Manager. UNI user-network interface An interface point between ATM end users and a private ATM switch, or between a private ATM switch and the public carrier ATM network; defined by physical and protocol specifications per ATM Forum UNI documents. The standard adopted by the ATM Forum to define connections between users or end stations and a local switch. UNIX UNIX is a computer operating system first developed by Bell Labs and now used on mainframes, workstations and personal computers. UNIX is the basis of Solaris, the operating system used by Sun workstations. UPC usage parameter control Parameter control is defined as the set of actions taken by the network to monitor and control traffic, in terms of traffic offered and validity of the ATM connection, at the end-system access. Its main purpose is to protect the network resources from malicious as well as unintentional misbehaviour, which can affect the QoS of other already established connections, by detecting violations of negotiated parameters and taking appropriate actions. UPS uninterruptible power supply UPSR unidirectional path-switched ring A protection scheme using a ring topology for SONET/SDH ADMs. US United States (of America) User interface The user interface (UI) is what the user sees on a computer or terminal screen. It changes in response to inputs from the keyboard and mouse. The UI is sometimes also referred to as the man-machine interface (MMI), human-machine interface (HMI) or the graphical user interface (GUI). USOC universal service order code UTP unshielded twisted pair A cable medium with one or more pairs of twisted insulated copper conductors bound in a single plastic sheath. V rms volts (root mean square) V.35 ITU-T Recommendation V.35 A standard for high-speed synchronous data communication interface. The physical interface uses a 34-pin connector with assignment as described by ISO 2593. V.35 PRI V.35 primary rate interface V.35 is a primary rate interface delivered over a V.35 physical layer. It can support aggregate links of n x 64 kb/s, where n ranges from 1 to 30 (that is, up to 1920 kb/s), including supervisory channel bandwidth. VAN value added network VAP value added products VAS VMEbus address strobe Indicates when the VMEbus has been asserted. Vbat voltage battery VBN virtual backbone network A VBN is a partition that has apparent exclusive control of its allocated bandwidth and path-end resources, such as port and timeslots. It is used for setting up connections on demand through a WAN. VBN Director A VBN Director is an auxiliary NetworkStation located on the service user’s premises. It provides the capabilities of the MainStreetXpress 46020 Network Manager for viewing and controlling the VBN equipment and bandwidth. VBR variable bit rate VBR is an ATM service category that provides guaranteed low cell loss and low delay for applications such as video and frame relay, that are characterized by an on/off source with known, predictable transmission patterns. During the on period, cells are transmitted at the peak information rate. No cells are transmitted during the off period. VC a) virtual channel (ATM) A VC is a logical channel that is available across a physical ATM interface. This communications channel provides for the sequential, unidirectional transport of ATM cells. b) virtual circuit (frame relay) A virtual circuit is a communications link that behaves like a dedicated point-to-point circuit, even though it is not. Data packets are delivered to the user in guaranteed sequential order, as if they were sent over a true point-to-point circuit. c) virtual container An information structure within an SDH frame that contains a tributary payload. Equivalent to a VT-SPE in a SONET frame. VCB voice conference bridge VCC virtual channel connection A VCC is the series of cross-connections used to traverse an ATM network end to end. VCC endpoint VCC endpoints are the points where ATM cells are passed to or received from the end users. VCC path virtual channel connection path For the MainStreetXpress 46020 Network Manager, a VCC path is a MainStreetXpress 46020 Network Manager-controlled path that can be connected across full and fractional links or across VPC links to carry voice, video, image and data between two MainStreetXpress 36150 nodes. For the VIVID System Manager, a VCC path is a VCC that is created and controlled from the VIVID System Manager. It is a permanent connection that can only be removed by the operator at the System Manager. VCI virtual channel identifier A unique numerical tag as defined by a 16-bit field in the ATM cell header that identifies a virtual channel, over which the cell is to travel. VCID voice card identification VCM voice compression module A VCM is an optional module which may be installed on either a dual E1 or dual T1 card to provide five ADPCM voice compression resources. VCM2 voice compression module 2 VCM3 voice compression module 3 VCon virtual connection VCPM virtual circuit policy manager A device responsible for all control messages transferred by the VIVID ATM NIC. VCPM handles VC connection and disconnection indicators, ILMI up/down indicators, and conceals the NIC implementation from the Route Server code. VCU voice compression unit VCXO voltage controlled crystal oscillator VDU video display unit VF voice frequency View A view is a graphic representation of the network on the MainStreetXpress 46020 Network Manager map. You can configure a view to show almost any aspect of the network, including the main (or physical) view, LAN views, connection views or views of network partitions. VINES virtual network system Virtual Backbone Network see VBN Virtual circuit see VC Virtual Network The Virtual Network Manager is one of the two viewing Manager applications used to manage the VIVID system (the other is the Physical Network Manager). Virtual Switched Network see VSN VIVID video, voice, image, data This acronym refers to the broad range of traffic types carried on the VIVID system. VIVID Ridge A VIVID Ridge is a multiport network access device that provides ATM connectivity for legacy LANs. VIVID system The VIVID system is an enterprise networking solution that uses a network of ATM switches to provide high-speed forwarding between hosts attached through legacy LAN/WAN and ATM connections. It uses ATM technology to provide integrated access, switching and control for video, voice, image and data communications. VIVID System The VIVID System Manager provides advanced management Manager for large and complex extended LANs composed of VIVID system components, Ethernet hosts and ATM hosts. Users interact with the network through the System Manager graphical user interface, which displays nodes and other equipment on a network navigation map. VIVID Workgroup The VIVID Workgroup Switch is a twelve OC3 port, 1.6 Switch Gb/s ATM switch for use in customer premises applications. It is used primarily as the backbone within the VIVID system. VIVID Yellow Ridge The VIVID Yellow Ridge provides connectivity between Ethernet LANs and ATM in a VIVID network. It provides 12 10Base-T Ethernet interfaces operating at 10 Mb/s and one ATM OC3 interface operating at 155 Mb/s. VLES VIVID LAN emulation server VLES is the VIVID system implementation of the LAN emulation server. It resides in the route server. VME VersaModule-Europe A 1- through 21-slot mechanical and electrical bus standard; the VME backplane runs at 80 Mb/s. VMS video management system VNET virtual network See Routed VNET and Bridged VNET. VNET ID virtual network ID The VIVID system supports up to 2000 VNET IDs. One VNET ID is required for each protocol carried by a bridged VNET, and one VNET ID is required for each routed VNET. Voice cards or Voice interface cards or modules allow telephones, modules PBXs and key systems to be directly connected to a large or small multiplexer. VP virtual path A unidirectional logical association or bundle of VCs. VPC virtual path connection A VPC is a virtual path connection that has end-to-end significance. It is a concatenation of VP links that extends between the points where the ATM service users access the ATM layer. A long-term VPC is known as a PVPC. VPC endpoint VPC endpoints are the points where ATM cells are passed to or received from the end users. VPC link For the MainStreetXpress 46020 Network Manager, VPC links are logical links used to create VPC overlay networks. VPC links are connected across full and fractional ATM links and carry VCC paths between MainStreetXpress 36150 nodes. VPI virtual path identifier An 8-bit field in the ATM cell header which indicates the virtual path over which the cell should be routed. VPL see VPC link VQ vector quantization Quantizing in higher dimensions. Takes advantage of linear and non-linear dependence among adjacent samples, the source probability density function, and the quantizer cell shape. VQC vector quantization coding A Newbridge proprietary speech compression technique that operates at either 16 or 32 kb/s. VSN virtual switched network A virtual switched network (VSN) is a partition that contains pathend equipment only. Bandwidth is drawn from the parent partition, which must be a VBN or the supply network. A VSN has apparent exclusive control of its allocated terminating points. The service user sees a physical view of pathend network equipment and a logical view of connected paths. VSN Manager A VSN Manager is an auxiliary NetworkStation located on the service premises of the user. It provides the capabilities of the MainStreetXpress 46020 Network Manager for viewing and controlling VSN network connections. VSVD virtual source virtual destination VSVD divides ABR connections into two or more distinct ABR loops. Each ABR loop, except the first, is sourced by a virtual source that implements the behaviour of an ABR source endpoint. Backwards RM cells received by a virtual source are removed from the connection. Each ABR loop, except the last, is terminated by a virtual destination that assumes the behaviour of an ABR destination endpoint. Forward RM cells are turned around and not forwarded to the next segment of the connection. VSVD provides earlier feedback. VT100 video terminal 100 The VT100 is a terminal that provides a de facto standard for cursor-control sequences for computer terminals. The VT100 is obsolete but the cursor control sequences are used universally for terminal emulation. VTAM virtual telecom access method VTAM is the IBM software package that handles some of the communications processing tasks for an application program. It performs addressing and path control functions in an SNA network, and also provides resource sharing. VTU video termination unit VU vertical unit A VU is the unit used to measure height for rack-mounted equipment equivalent to 1.75 in. or 45 mm. WAN wide area network A WAN is a network of digital transmission equipment that provides data communications over large geographical areas. WAN ID0 wide area network identification 0 WAN ID1 wide area network identification 1 WAN ID2 wide area network identification 2 WATS wide area telephone service A discounted toll service provided by all long distance and local phone companies. There are two types of WATS services: in and out WATS. WII Where is I Window A window is a visual element in a graphical user interface, which can contain such items as an equipment drawing, a configuration form, or user information. Windows commonly allow a user to input data and initiate functions but some windows simply display information. Workstation A workstation is a high-speed personal computer, such as a Sun workstation, which is used for high-powered processing tasks. WTR wait to restore The timer used in revertive ring or 1+1 protected interfaces that must elapse before connections revert to the working card following failure and recovery of the working card. X-terminal An X-terminal is a terminal, workstation or microcomputer configured with X-server software and Ethernet and TCP/IP communications that enable it to run software remotely. An X-terminal can offer all the functionality of a delegate or customer NetworkStation. X.21 CCITT Recommendation X.21 A standard for high-speed synchronous data interface with balanced transmission of all signals. X.21 PRI X.21 primary rate interface The X.21 PRI is a primary rate interface for links that can be rented from European PTTs. In frame type 2, it can support aggregate links of n x 64 kb/s, where n ranges from 1 to 30 (that is, up to 1920 kb/s), including supervisory channel bandwidth. X.25 X.25 is the ITU-T-recommended standard that defines the standard protocol for communication between packet-switched public data networks and user devices in the packet-switched mode. X.28 Standard describing an interface between an X.3 OAD, and a piece of equipment that communicates using asynchronous character-based protocols (that is, a simple VT100, or a PC running a terminal emulation package). X.29 X.29 is the ITU-T-recommended standard for control information and user data exchanged between a remote packet-mode DTE and a PAD. X.400 series The X.400 series of ITU-T standards apply to a store-and-forward message handling system in a multivendor environment. X.50 X.50 is the ITU-T standard comparable to DDS. It uses 20 subframes, each with a 2.4 kb/s data rate; transmission rates faster than this occupy consecutive subframes. XAC X.25 access circuit The logical element on an X.25 switch that handles the physically connected X.25 device. XCLK external clock XFR X.25 to frame relay service internetworking An XAC configured for the XFR service type can be a path-end for an XFR access path. XFR access path An X.25 access path configured for X.25 to frame relay service internetworking. It transports frame relay frames to and from the X.25 switch, where the frame relay frames are converted to X.25. XID exchange identification A frame used for identification and negotiation by many HDLC-like protocols. Xmodem Xmodem is a de facto standard file transfer protocol for transferring files over a serial line. XNS Xerox Network Services XNS is a multilayer protocol system developed by Xerox. It is a distributed-file-system protocol that allows network stations to use the files and peripherals of other computers as if they were local. XNS functions at the third and fourth layer of the OSI model. YCP yellow condition propagation ZCO zero crossing origin Zoom Zooming an object on a network map refers to the process of opening the object to see more detail about its next level in the network hierarchy.