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AT&T 7500 series, 7100 series, 2500 series, 7200 series, 7400 series Figure D-1.OSI Reference Model

Models: 7400 series 2500 series 7200 series 7500 series 7300 series 7100 series

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D-4COMMUNICATIONS PROTOCOLS

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Figure D-1.OSI Reference Model

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AT&T 7500 series, 7100 series, 2500 series, 7200 series, 7400 series, 7300 series manual Figure D-1.OSI Reference Model

Contents

Definity Communications System Page Contents Multiplexing Outside the Switch Communication System Networking AN OverviewTandem TIE Trunk Networks Distributed Communications System DCS Data Connectivity AN OverviewSpecial Data Features Data Communications CapabilitiesData Communications Configurations Related Documents Synchronization of Digital FacilitiesTrunking Terms and Capabilities Communications Protocols GlossaryIndex List of Figures DSU MpdmFigure B-1 Options for Synchronization Figure B-11 External and Internal Reference Levels List of Tables BCCEIA RS-232C V.28 LEADS/DEFINITIONS EIA RS-232D V.28 LEADS/DEFINITIONSEIA RS-449 V.24 LEADS/DEFINITIONS EIA RS-366 LEADS/DEFINITIONSXvi Contents About this Document Prerequisite Skills and KnowledgeDocument Organization Part ∙ Glossary ∙ IndexHOW to Make Comments about this Document AT&TXx about this Document Introduction to Connectivity 2INTRODUCTION to Connectivity Transmission Types Analog TransmissionDigital Transmission Analog-to-Digital Conversion Analog VS. Digital 6TRANSMISSION Types Entering the Switch Transmission StatesVoice Transmission 8TRANSMISSION States Digital Switch Exiting the Switch ⎜ ModuleCircuit Packs Data Transmission Protocol Layers12TRANSMISSION States Originating Switch Destination Protocols Used Layer 1 ProtocolsLayer 2 Protocols Protocol States⎜DMI Mode Code Connectivity Rules16TRANSMISSION States Multiplexed Communication Types of MultiplexingFrequency-Division Multiplexing Time-Division MultiplexingStatistical Multiplexing Multiplexing Over DS1 FacilitiesLine Coding Alternating Mark InversionZero Code Suppression ZCS Line Coding B8ZS Line Coding Signal Inversion Restricted ⎜ Unrestricted⎜ DMI 7Data-Module Capabilities Part 2 D4 Framing FramingSignaling D4 FramingESF Framing Robbed-Bit Signaling 24th-Channel Signaling ⎜ Channels 24th Channel ⎜ 24th ChannelESF ⎜ Frame NoTrunk Types/Destinations ⎜ Signaling Types ⎜ DMI-BOS⎜ Isdn PRI Multiplexing Outside the Switch Multiplexing onto T1 TrunksCDM CEM Host Digital DMI PBX Compressing the Signal Getting the Signal Ready for the Central OfﬁceAltering Channel Assignments on T1 Trunks Multiplexing with Microwave Microwave System T1 Trunk CapacityDR23N DR18M DR18W DR23W Demultiplexing10.Possible Multiplexed Connections Statistical Multiplexing Trunking ApplicationLocal Exchange Trunks Tie Trunks Special-Access Trunks Auxiliary TrunksMiscellaneous Trunks Release Link Trunks RLTsRemote Access Trunks Host-Access TrunksAdvanced Private Line Termination Aplt Trunks ConnectivityAdministration Options System 85/G2 AdministrationSignaling Types Signaling Protocols Trunk TypeSystem 75/G1 Administration Comm TypeGroup Type DS1 OptionsInterface Circuit Trunk TablesTrunking 44TRUNKING 11.Generic 1 and Generic 2 Digital Trunks Voice BCC 46TRUNKING Trunking 48TRUNKING Trunking 50TRUNKING Trunking 52TRUNKING Communication System Networking AN Overview Types of Networks Network Evolution Software ⎜ Network Type S75/G1 S85/G2 Package PECDCS Software CapabilitiesSystem 75 and Generic 1 UDP Package DIMENSION, System 85, and Generic 2 Multipremises Package System 75 and Generic 1 PNA PackageDistributed Communications System Network Call ProcessingInternal Dial Plan Uniform NumberingRouting the Call DAC + EXT To ARS Auxiliary Call Information Automatic Alternate Routing Selecting a Routing Pattern∙ RNX ∙ Where the trunk group appears in the list of preferences Selecting a Trunk Group∙ The FRL of the call Modifying the DigitsAutomatic Route Selection Analyzing the Dialed NumberCommunication System Networking AN Overview To AAR Selecting the Routing Pattern Network Administration Networking Feature ParametersPrivate Network Trunks ⎜ Maap ⎜ Vmaap System Definity Feature PBX 20COMMUNICATION System Networking AN Overview Tandem TIE Trunk Networks Interactions with Other Networks2TANDEM TIE Trunk Networks Attendant Lines ⎜ Main Satellite ⎜ Trunks MS/T Configurations Main-Satellite ConﬁgurationMain-Tributary Conﬁguration MS/T Features Networking Package Multipremises with ETA Main Networking Package PNA, ETN Routing Incoming Calls Routing Outgoing CallsOther Routing Capabilities Engineering ConsiderationsInteractions Page ETN Configurations ETN Trunks Page Access and Bypass Access Tie Trunks Features Off-Net TrunksUniform Numbering Plan Attendant ETN Interactions with Other Networks Extension Number Portability Clusters Software-Deﬁned Network Call Routing SDN to ETN Call Routing ETN to SDN Release Link Trunk Networks CAS and ACD Centralized Attendant Service Automatic Call DistributionDistributed Communications System Clusters Main-Satellite/Tributary NetworksDistributed Communications System DCS Switch Node Capacity DCS ClustersDCS Links Signaling Links Switch Physical Links ⎜Logical Channels/LinkSignaling Link Speed Signaling Link ProtocolTransmission Media Direct Link DCS Connections Linkage Design Distributed Communications System DCS DCS Signaling Link Connections Equipment Distance LimitationMTDM/MPDM System 75 or Generic 1 G1 to System 75 or G1System 75/G1 Signaling Channel DCP Mtdm System 85 or Generic 2 G2 to System 85 or G2Modem System 75 or Generic 1 G1 to System 85 or Generic 2 G2 RS232C to RS449 Conversion Dciu Dimension Signaling Links Transparent FeaturesTransparent Attendant Features Attendant Call WaitingAttendant Control of Trunk Group Access ⎜ ACAAlphanumeric Display Automatic Circuit AssuranceClass-of-Service/Restriction Display Trunk Group Busy/Warning IndicatorsBusy Veriﬁcation of Terminal Lines Calling Number DisplayTransparent Voice Terminal Features Alerting-Distinctive RingingAutomatic Callback on Busy or No Answer Call Coverage Tone Call ForwardingCall Waiting Leave Word Calling LWC Without APAudio Information Exchange Audix Features Transparency Call Transfer/Conference20.AUDIX in a DCS Network Definity PBX ⎜ Feature 22DISTRIBUTED Communications System DCS Administration Considerations Distributed Communications System, Issue 3Dimension PBX Data Connectivity AN Overview Data Communications Variables Communications ProtocolsDigital PBX Public Switched Network Pooled Modem Analog vs. Digital Synchronous vs. Asynchronous∙ ∙ ∙ Simplex vs. Half-Duplex vs. Full-DuplexParallel vs. Serial Transmission SpeedCreating Switch Packet vs. Circuit Switches Type of Communications ChannelChannel Information Bearer vs. Signaling Channels Transmission Mode Changes and Modem PoolsChannel Assignment Dial-up vs. Dedicated Connections Special Data Features Terminal Dialing⎜Data Services Features Data Call Setup From a Voice TerminalComputer Dialing Data Hot LineData Protection Data PrivacyData Restriction Data Only Off-Premises ExtensionOff-Premises Data-Only Extension Conﬁgurations Data Communications Capabilities 2DATA Communications Capabilities DTE Connections DTE CompatibilityProtocol Converters Terminal Emulators PC/PBX or PC/ISDNDCE Possibilities Data ModulesVoice Terminal Adjunct Data Modules Data Module Characteristics Standalone Data ModulesADUs ModemsDTE Connections Dtdm ⎜ PC/PBX PC/PBXADM PC/ISDNModem Pooling Connections DCP TIP-RING 12DTE Connections Data Module Local Area Network Connections LAN TopologyLAN Protocol LAN Connectors LAN Transmission MediaAdvantages of a Communications System in a LAN Environment LAN Access to/from LANs That Use Other Operating Systems Type Operating Gateway PCLAN System SoftwareLocal Area Network Connections Remote PC ISN Communication Communication Between the LAN and Other NetworksX.25 Router Type Operating Communications System PackageSNA Gateway Communication System as a LAN Backup 12.LAN/SNA ConnectivityAccunet Packet Service APS AccessPublic and Private Data Network Connections Public Data NetworksCircuit-Switched Public Data Networks SDS and Sddn ApplicationsPublic and Private Data Network Connections MPDM/M1 Public and Private Data Network Connections DTE Mpdm Private Data Networks Terrestrial Private Data Network LinksPrivate Connections Through Accunet T1.5 and T45 MPDM/M1* AMI 28PUBLIC and Private Data Network Connections ⎜AMI Satellite Private Data Network Links Telemarketing Host Connections Isdn GatewayIntegrated Telemarketing Gateway 22.Telemarketing Gateway Conﬁguration For further details, see 34TELEMARKETING Host Connections Data Network Administration 36DATA Network Administration Data Communications Configurations DSC and PSC Connections DSC 4DATA Communications Configurations SNA Node Connections Connections Through Public or Private Data Networks File TransfersVideo Teleconferencing Image Processing FAX Transmittal8DATA Communications Configurations Related Documents GeneralOperation Reference2RELATED Documents Related Documents Dimension AdministrationSystem 75 and Generic 6RELATED Documents Service SalesSystem 85 and Generic 8RELATED Documents Sales 10RELATED Documents Synchronization of Digital Facilities Need for SynchronizationFigure B-1.Options for Synchronization Synchronization Hierarchy 4SYNCHRONIZATION of Digital Facilities Synchronization of Digital Facilities ∙ DDS Figure B-3.Stratum Levels for the Synchronization Hierarchy System 85 and Generic 2 Synchronization ArchitecturePage Primary Primary Secondary Reference Indicators ⎜ Reference ⎜ IndicatorsRED YEL Good LOS Misf ⎜ Blue REDSystem 75 and Generic 1 Synchronization Architecture Figure B-6.Tone-Clock Synchronizer Nonduplicated, Generic System 75 and Generic 1 Synchronization Software OperationCriteria for Switching to the Secondary Reference Criteria for Switching Back to the Primary ReferenceExternal Synchronization Clock CROSS-CONNECT B25A Cable Output Figure B-9.External-Clock Interface Selecting a Timing Source for the Switch Network Synchronization and EngineeringInternal Reference Selection Rules RuleExample for Rule Figure B-13.Proper Use of Backup Facilities Page Figure B-15.Optimal Diverse Routing Figure B-16.Less Than Optimal Diverse Routing Figure B-17.Excessive Cascading Figure B-19.Excessive Synchronization from One Node External-Reference Selection Rules Rules 2 ThroughAvailability of Synchronization Sources MisconceptionFact Line-Only Mode DS1/DMI-BOS ANN11 or TN767 Conclusions on SynchronizationUSE of Generic 2 AS a System Clock Reference ISDN-PRI Trunk FacilitiesLine+Trunk Mode DS1/DMI-BOS ANN35 or TN767 with TN555 DMI-MOS ANN35 or TN767 with TN555USE of Generic 1 AS a System Clock Reference Trunk-Mode ISDN-PRI TN767Line-Only Mode DS1/DMI-BOS TN767 Trunk-Mode Interface ISDN-PRI + Robbed Bit TN767Trunk-Mode DS1/DMI-MOS TN767 32SYNCHRONIZATION of Digital Facilities Wire Tie Trunk Address SignalingTrunking Terms and Capabilities Frequently Used TermsAlerting Signals APLT-Advanced Private Line TerminationAuto or Automatic-incoming Auto or Automatic-outgoingCcsa or Common Control Switching Arrangement CX Signaling or Composite SignalingCustomer Provided Access Cut-Through Mode of OperationDelay-Dial Delay-Dial IncomingDelay-Dial Outgoing Delay-Dial Start-Dial DdsdDerived E&M Lead Signaling Designed TrunksDial Repeating Tie Trunk Dial-PulseDirect Access Epscs or Enhanced Private Switched Communications ServiceLead Signaling or Ear & Mouth Signaling Standard or Type 1A and Type I compatible or Type 1BETN Trunking Facilities FX or Foreign ExchangeGlare Resolution GlareGlare Detection Ground Start High-Usage Trunk GroupImmediate Start Immediate Start IncomingInterdigit Time-out Intermediate High-Usage Trunk GroupIntermachine Trunk IMT Intertandem TrunkOut-of-Band Signaling Party Test SignalMain PBX Main-Satellite TrunksReverse Battery SF or Single Frequency signalingSenderized Mode of Operation Signal ConverterSignaling Type Special Access ConnectionsStop-Go Signaling Supervisory SignalingTouch-Tone Signaling Trunk Type or trunk group typeType of Dialing Type of OutpulsingWats Wide Area Telephone Service Trunk Wink-Start IncomingWink-Start Outgoing Suggestions and Helpful Hints Trunking Characteristics Table Signaling TypesSwitch a Supervision Signaling Tion GenericSystem 85, or Dimension PBX ⎜GROUP/CALL TypeSwitch B GROUP/CALL TypeDOD 23/FX-DOD OUTIN/DID GROUP/CALL Type Signaling 26/WATS 27/WATS OUT28/WATS-DOD OUT ⎜⎜ E&M 35/TIE ESS 5ESS ⎜OTHER ⎜ LS ⎜ RB ⎜ System 85, or ⎜DIMENSION PBX ⎜ ⎜57/CAS RLT-OUTGOING From Branch ⎜66/CAS RLT-INCOMING Main Satellite⎜DIAL-TONE with Digital Data ⎜DATA Module Side 103/HOST Access Line Side 104/HOST AccessAnalog Data Modem Side Trunk SideOther 32TRUNKING Terms and Capabilities Communications Protocols OSI Model Physical LayerData-Link Layer Network LayerPage Figure D-1.OSI Reference Model Session Layer Presentation LayerApplication Layer Standard ProtocolsTable D-1.Some Ccitt Digital Standards Table D-2.Some Ccitt Analog Standards Ccitt X.26 RS-423A FED-STDTable D-2.Some Ccitt Analog Standards Other Common Standards CCITT-ISOAT&T Protocols EIAData Mode Capabilities Digital Multiplexed InterfaceData Modes Applications DescriptionControl Data DCP DS1/DMI/BOS Channel 14COMMUNICATIONS Protocols Communications Protocols Flag Digital Communications Protocol Or multipoint BX.25 Communication Pathways and Endpoints Message, Packet, and Frame SldhLead Definitions SCF SCBSBA SBBRL/CG CH/CISDA STARDA RSADPR ACRCRQ PNDBBA BBBDDA DDB⎜ PIN 8LEAD Definitions Networking FEATURES--AVAILABILITY Matrix ⎜⎜ R1 Networking FEATURES--AVAILABILITY Matrix Contd ⎜ NA ⎜ Uniform Numbering ⎜ Plan Note 6NETWORKING FEATURES--AVAILABILITY Matrix Abbreviations CRC CSMCSU DACETA ETNFAX FEPMpdm MS/TMtdm NCPSDN SMTSNA TehoAB-6ABBREVIATIONS Glossary ACUADM AVDADS Also high-volume tandem Audix StandaloneAutomatic Alternate Routing AARService Bccos Bipolar signalBit-oriented signaling Message-oriented signalingBSC CcittCPU Ccis CORCOS CPESee network channel-terminating equipment See data communications equipmentDciu link DCP DCSDCS cluster DCS node See bit rateDDC DDDSee digital telephone DCS DMI-BOS DMI-MOSDMI/MOS DS1Error-free second ESS electronic switchingCommunications systems and switch Framing format Extended trunk accessBX.25 DCIU/PI Hdlc Keyboard dialing Kilo bits per second kbps LAN LapdSee basic rate interface See primary rate interface Listed directory number Local area network LANAlso wide area network Local exchange companyNcte NAUPAD PVC PDM921, and signaling system number Remote access trunkRobbed-bit signaling Protocol converter PCSdlc TDM UCD UNPService Wats trunk Telecommunications ServiceWats Wide Area TelecommunicationsIndex Bypass access trunk 1-37,4-7,4-8,5-1,5-4,C-2 IN-2 IndexARS 2-4,2-7,2-8,2-14plan Logical 6-3,D-19restricted 1-20unrestrictedDial access code 2-2,2-5,2-10,2-13,2-17,3-1,4-4 CRC 1-25CSMA/CD 8-13CSUChannel bank 1-9,1-10,1-29,1-30,B-20frame DAC 2-2,2-5,2-10,2-13,2-17,3-1,4-4,4-7,4-8,4-9,6-23Mode 1-15,1-16,1-42,2-13,9-1MOS 6digitizerDMI 1-14, D-11 DS1-ContdD4 1-24, 1-27 ESF 1-24, 1-27FRL 2-10, 2-13 Gateway 7-2Statistical 1-17,1-18,1-34 LOS B-9,B-13 LWC 6-18,6-21,6-24DCS 1-36,2-3,5-14 ETN 1-36,2-2,2-8,3-1,4-1,5-1,6-1PAD 7-2,8-21 PCM 1-5,1-7,1-14,1-18,B-1Analog 1-7,9-2trunk DS1 1-13,1-16,1-18RS-232C1-13,D-9 Physical layer 1-11,1-15,D-2,D-9PRI 1-13, D-11 RS-232C1-13,6-3RNX 2-10 Subnet trunking 2-11, 2-14, 4-91-39, C-3, C-5, C-6 Intelligent main 2-4, 4-4, 4-7Analog 1-3,7-2,7-4 Bypass access 1-37,4-7,4-8,5-1,5-4 T1 carrier 1-6,1-18,1-32TCM 2-11,6-23 ﬁnal 5-2,C-9Uniform dial plan 2-5, 2-8, 2-9 Analog 1-9Uniform numbering 2-8, 5-1, 5-5 Auxiliary 1-10, 1-35IN-12 Index