Nortel Networks Circuit Card

Page 906 of 906 Appendix A: LAPB Data Link Control protocol

553-3001-211 Standard 3.00 August 2005

Contents

Main Circuit Card Description and Installation Page Revision history Page Contents Acceptance tests . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Option settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 NT4N39AA CP Pentium IV Card . . . . . . . . . . . . . . . 183 NT5D60/80 CLASS Modem card (XCMC) . . . . . . . 313 NT5D97 Dual-port DTI2/PRI2 card . . . . . . . . . . . . . 319 NT5K02 Flexible Analog Line card . . . . . . . . . . . . 367 NT5K21 XMFC/MFE card . . . . . . . . . . . . . . . . . . . . . 369 NT6D70 SILC Line card . . . . . . . . . . . . . . . . . . . . . . 379 NT6D71 UILC Line card . . . . . . . . . . . . . . . . . . . . . . 385 NT6D80 MSDL card . . . . . . . . . . . . . . . . . . . . . . . . 389 NT7D16 Data Access card . . . . . . . . . . . . . . . . . . . 427 NT8D02 and NTDK16 Digital Line cards . . . . . . . . 527 NT8D03 Analog Line card . . . . . . . . . . . . . . . . . . . . 545 NT8D14 Universal Trunk card . . . . . . . . . . . . . . . . 565 NT8D15 E&M Trunk card . . . . . . . . . . . . . . . . . . . . 627 Page Page NTDK20 Small System Controller card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811 NTRB21 DTI/PRI/DCH TMDI card . . . . . . . . . . . . . . 825 NTVQ01xx Media Card . . . . . . . . . . . . . . . . . . . . . . 839 NTVQ55AA ITG Pentium card . . . . . . . . . . . . . . . . 845 QPC841 Quad Serial Data Interface card . . . . . . . 869 Page Page LIst of procedures Page About this document Subject Applicable systems Intended audience Conventions Related information Page Overview Line cards Table 2 Line card characteristics Page Page Operation Page Page Figure 2 Typical IPE analog line card architecture Analog or digital telephone linesAnalog or digital telephone lines Page Page Analog line interface units Figure 4 Typical analog line interface unit block diagram Page Digital line interface units Page Analog line call operation Overview Page 43 of 906 Figure 6 Call connection sequence near-end station receiving call Signal/directionState Remarks Figure 7 Call connection sequence near-end originating call Signal/directionState Remarks Page Digital line call operation Lineside T1 call operation Overview Page 47 of 906 Figure 8 Battery reversal answer and disconnect supervision sequence Note 1: Remarks Signal/directionState Figure 9 Hook flash disconnect supervision sequence Signal/directionState Note 2: Note 1: Remarks Page Page Page Page Page Page Page Page Voice frequency audio level Off-premise line protection Line protectors Line protection grounding Line and telephone components Trunk cards Page Page Page Host interface bus Figure 11 Typical IPE trunk card architecture Page Page Page Page Trunk interface unit Page Page Serial Data Interface (SDI) cards Uses Features Specifications Page Maintenance Page Page Circuit card installation Card slots Large System Page 80 of 906 Circuit card installation Circuit card installation Table 12 Large System card slots (Part1 of 4) Page Page 82 of 906 Circuit card installation Table 12 Large System card slots (Part3 of 4) Circuit card installation Page 83 of 906 Table 12 Large System card slots (Part4 of 4) Precautions Page Installing a circuit card Page Page Acceptance tests Conference cards Page Digitone receiver cards Line cards Multifrequency sender cards Multifrequency signaling cards Network cards Trunk cards Use the following procedures to test a trunk card. Tone and digit switch cards Page Page Page Option settings Circuit card grid Option settings Page 103 of 906 Figure 17 Circuit card grid NT1R20 Off-Premise Station card Table 14 lists option settings for the NT1R20 Off-Premise Station analog Page Page NT5D12AA Dual DTI/PRI (DDP) card General purpose switches Trunk interface switches Page Ring ground switches A set of four DIP switches selects which Ring lines are connected to ground (see Table 19). DCH mode and address select switches Illustrations of switch locations and settings Figure 18 on page 112 displays functional areas for switches on the NT5D12AA DDP card. Page Option settings Page 113 of 906 Figure 19 displays default settings for switches on the NT5D12AA DDP Figure 19 Switch default settings J5 J6 NT6D42 Ringing Generator DC Tables 22 through 27 list option settings for the NT6D42 Ringing Generator. Page Page NT5D2101/NT9D1102 Core/Network module backplane NT6D68 Core module backplane NT6D80 Multi-purpose Serial Data Link card NT8D14 Universal Trunk card Tables 31 through 35 list option settings for the NT8D14 Universal Trunk Page Page Page Page NT8D15 E&M Trunk card NT8D17 Conference/TDS card NT8D21 Ringing Generator AC Page Page Page Page Page NT8D41BA Quad Serial Data Interface Paddle Board Page NT8D72 Primary Rate Interface card Page QPC43 Peripheral Signaling card QPC71 E&M/DX Signaling and Paging Trunk cards QPC414 Network card QPC441 3-Port Extender cards For CS 1000M SG and Multi Group systems, QPC441 vintage F or later must be used in all modules. Page Page QPC559, QPC560 Loop Signaling Trunk cards Table 48 and Table 49 on page 142 list option settings for loop signaling trunk cards. Page QPC528 CO/FX/WATS Trunk cards Table 50 lists switch and jumper settings for options available. QPC471 Clock Controller card Table 51 lists option settings for the QPC471 Clock Controller card. QPC525, QPC526, QPC527, QPC777 CO Trunk card QPC550 Direct Inward Dial Trunk card Tables 52 through 56 give the option settings for the QPC550 DID Trunk card. Page Page QPC551 Radio Paging Trunk card QPC595 Digitone Receiver cards QPC577, QPC596 Digitone Receiver daughterboards QPC720 Primary Rate Interface card Page QPC775 Clock Controller card Tables 58 and 59 give option settings for the QPC775 Clock Controller QPC841 4-Port Serial Data Interface card Tables 60 through 62 list option settings for the QPC841 4-Port SDI card. Page Page Page NT1R20 Off-Premise Station Analog Line card Self Test Page Page 160 of 906 NT1R20 Off-Premise Station Analog Line card Figure 22 OPS analog line card block diagram 553-6193 Page Page Page See Software Input/Output: Administration (553-3001-311) for LD 10 service change instructions. Circuit power Analog line interface Table 64 lists the electrical characteristics of NT1R20 OPS analog line card line interface units. Ringer limitations Page Incoming calls Outgoing calls Page Page Page Configuring the OPS analog line card Jumper strap settings Application Off-premise station application Page Page Page Other applications Transmission considerations Page Page Page NT4N39AA CP Pentium IV Card Page Page Media Memory Front panel connector pin assignments COM1 and COM2 ports Page USB port 10/100/1000 Mbps Ethernet ports Front panel LED indicators ITP connector (25 PIN, Debug Only) Post 80 Debug LEDs (Optional) Page NT5D11 and NT5D14 Lineside T1 Interface cards Card connections Faceplate Page Page Page Page 198 of 906 NT5D11 and NT5D14 Lineside T1 Interface cards Figure 30 Lineside T1 card block diagram Page T1 interface circuit Signaling and control Page T1 channel specifications Page Installation and configuration Dip switch settings Page Page Page Page Page Page Page Cabling the lineside T1 card Page 214 of 906 NT5D11 and NT5D14 Lineside T1 Interface cards Figure 32 Lineside T1 card connection using the NT5D13AA lineside T1 cable NT8D37 IPE Module Slot 0 Module I/O panel System A NT8D81 Tip & Ring Cable Line Side T-1 Card NT5D13 Maintenance Interface Cable Page Page Table 86 shows the pin assignments when using the NT5D13AA lineside T1 I/O cable. Page Page Page Page Terminal configuration Software configuration cross-referenced to the corresponding card unit number. This mapping is shown in Table 87. Page Man-Machine T1 maintenance interface software Description Page Login and password Basic commands Page Page Sets the alarm self-clearing function to either enable or disable. Configuring parameters Page Page Page Alarm operation and reporting Page Page Performance counters and reporting Page Testing Page Page Page Page Page Page Page NT5D33 and NT5D34 Lineside E1 Interface cards Page Card connections Faceplate Page Page Page Page Page Overview E1 interface circuit Signaling and control Page ELEI additional functionality E1 channel specifications Page Installation and Configuration Dip switch settings Page Page Page 266 of 906 NT5D33 and NT5D34 Lineside E1 Interface cards Figure 44 LEI card E1 protocol dip switch locations ON OFF 18 18 S1 S2 dip switches Page Page Page Page Page Page Page Cabling the LEI card Page Page Page Page Page Terminal configuration Software Configuration Page Page Man-Machine E1 maintenance interface software Description Page Login and Password Basic commands Page Page Configuring parameters Page Page Page Page Page 1) 2) Page Page 298 of 906 NT5D33 and NT5D34 Lineside E1 Interface cards Figure 51 Set Mode (S M): Table screen Page Page Alarm operation and reporting Page Page Performance counters and reporting Page Page Testing Page Page Page Page Page NT5D60/80 CLASS Modem card (XCMC) Page Page Page Data transmission specifications Page NT5D97 Dual-port DTI2/PRI2 card External D-Channel Interface DCH or MSDL NT5D97 faceplate Page Page Page Page Port definitions System capacity and performance Cable requirements Page Page Table 118 which follows lists the pin attributes for the NT8D7217 cable. P1 P2 I/O Panel Trunk D-type 9 pin, female Multiplexer Trunk D-type 9 pin, male Page Page Page P1 P2 Page Cable diagrams LED's Switch DCH Trunk LED's Switch DCH Trunk NT5D97 circuit card locations NT5D97AA/AB DIP switch settings Page Page Trunk interface switches for NT5D97AA/AB Page DCH Address select switch for NTBK51AA daughter board for NT5D97AA/AB Page NT5D97AD DIP switch settings Page 348 of 906 NT5D97 Dual-port DTI2/PRI2 card Figure 76 Dip switches locations for NT5D97AD Page Page Page MSDL external card Use Table 138 to set the card address. Clock operation Reference clock errors Secondary Automatic clock recovery Automatic clock switching Clock configurations Page Page Secondary Page NT8D72BA Port 0 DDP2 Port 1 Page CAUTION Configuring the NT5D97 Testability and diagnostics NT5K02 Flexible Analog Line card Page NT5K21 XMFC/MFE card MFC signaling Signaling levels Forward and backward signals Page MFE signaling Sender and receiver mode XMFC sender and receiver specifications XMFE sender and receiver specifications Physical specifications Table 147 outlines the physical specifications of the NT5K21 XMFC/MFE circuit card. Page Page NT6D70 SILC Line card ISDN BRI Page Micro Controller Unit (MCU) IPE interface logic S/T interface logic Page Page NT6D71 UILC Line card Micro Controller Unit (MCU) IPE interface logic U interface logic Page NT6D80 MSDL card Page Page CPU bus interface NT6D80 MSDL card Page 393 of 906 Figure 83 MSDL block diagram Micro Processing Unit (MPU) Memory Serial interface MSDL operations Page Data flow Engineering guidelines Available network card slots Card mix Address decoding Port specifications Page Page Page supported circuit type. It also indicates whether the signal originates at the DTE or DCE device. Implementation guidelines Environmental and power requirements Device number MSDL interfaces Page Page 406 of 906 NT6D80 MSDL card Figure 85 MSDL switch setting example Installing the MSDL card Cable requirements Page Cable installation Page MSDL planning form Maintenance MSDL states Page Page Maintaining the MSDL System controlled maintenance Manually controlled maintenance Page Manually isolating and correcting faults Page Replacing MSDL cards Symptoms and actions System disabled actions Page Page Page NT7D16 Data Access card Content list Features Controls and indicators Card status Electronic Industries Association signal monitors CONNECT Dialing operations NT7D16 Data Access card Page 431 of 906 Figure 88 NT7D16 Data Access card faceplate Call Set-up abort Make Port Busy on loss of DTR Inactivity timeout Wire test mode Page Independent storage of dialing parameters Operating modes Page Page Page Page Selecting the proper mode for Modem connectivity Page Mode 0 Page Page Page Mode 1 Mode 2 Mode 3 Selecting the proper mode for Gateway connectivity Page Mode 4 Page Mode 5 Mode 6 Mode 7 Selecting the proper mode for Host connectivity Mode 8 Mode 9 Mode 10 Mode 11 Selecting the proper mode for Terminal connectivity Mode 12 Page Mode 13 Mode 14 Mode 15 Mode selection baud rates Page Page Page Page Page Page Page Page Page Page Page Keyboard dialing Initiating conditions Echo Prompts Call abort Autobaud Auto parity Dialing operation Primary commands Page Page Page Page Ring Again Page Page Not in service No response from the system Hayes dialing Initiating conditions Input requirements Echo Result codes and messages Baud rate detection Parity detection Dialing operation S registers Page Page Reset Hayes parameters Page Outbound calls Inbound calls Off Line mode Specifications QPC430 and QPC723 interfaces Download parameters System parameters Operating parameters Page Upload parameters System database requirements NT7D16 Data Access card Page 501 of 906 Figure 95 Operating mode selectionRS422 Page 502 of 906 NT7D16 Data Access card Figure 96 Operating mode selectionRS-232-C Page Power supply EIA signals supported Environmental Reliability Installing the Data Access card Cabinet system Large System System compatibility Port configuration Page Cabling Page 510 of 906 NT7D16 Data Access card Figure 98 Cabling to the data equipment Page Page Page Backplane pinout and signaling Page Page Configuring the Data Access card DAC administration (LD 11) Page LD 11 Configure Data Access card. (Part2 of 3) LD 11 Configure Data Access card. (Part3 of 3) Printing the card parameters (LD 20) Connecting Apple Macintosh to the DAC Upgrading systems NT7D16 Data Access card Page 523 of 906 Figure 102 Macintosh to DAC connection9-pin subminiature D Figure 103 Macintosh to DAC connectionmini-8 DIN Large System and CS 1000M HG upgrade Page Page NT8D02 and NTDK16 Digital Line cards NT8D02 Digital Line card NTDK16 Digital Line card Page NT8D02 Digital Line card NT8D02 and NTDK16 Digital Line cards Page 531 of 906 Figure 105 Digital line card block diagram NTDK16 Digital Line card Digital line interfaces Page Page Page Circuit power Digital line interface specifications Table 173 provides a technical summary of the digital line cards. Page Page Page Jumper and switch settings Page Page Page NT8D03 Analog Line card Overview Page NT8D09 Analog Message Waiting Line card Page Page Page Page Page 552 of 906 NT8D09 Analog Message Waiting Line card Figure 110 Analog message waiting line card block diagram 553-6168 Line interface units Page Analog line interface Table 179 provides a technical summary of the analog message waiting line Table 180 provides the power requirements for the NT8D09 Analog Message Waiting Line card. Overload level Installation and Configuration (553-3021-210) for cable pinout information at the I/O panel. Page Jumper and switch settings Page Page Page NT8D14 Universal Trunk card Page Page Page Page Figure 114 NT8D14 Universal trunk card block diagram Page Page Loop start operation Page NT8D14 Universal Trunk card Page 575 of 906 Figure 116 Loop start call connection sequence incoming call from CO/FX/WATS RemarksSignal/direction A B State Page NT8D14 Universal Trunk card Page 577 of 906 Figure 118 Ground start call connection sequence incoming call from CO/FX/WATS A B Ground start operation Page Page Page Page NT8D14 Universal Trunk card Page 583 of 906 Figure 122 Ground start call connection sequence outgoing call to CO/FX/WATS Near end System Far end CO Direct inward dial operation Two-way, loop dial repeating, TIE trunk operation CO (far) end Page Page Figure 126 Two-way, loop DR, TIE trunk call connection sequence incoming call from far-end PBX A B Page Page NT8D14 Universal Trunk card Page 591 of 906 Figure 128 Two-way, loop DR, TIE trunk call connection sequence outgoing call to far-end PBX A B Page NT8D14 Universal Trunk card Page 593 of 906 Figure 130 Two-way, loop DR, TIE trunk call connection sequence outgoing call to far-end PBX A B Senderized operation for DID and two-way loop DR trunks Note 3 Note 4: Note 3 Note 4: Outgoing automatic, incoming dial operation Note 1 Note 2: Note 3: Page Page Far end A B Recorded announcement trunk operation Figure 138 Connecting RAN equipment to the NT8D14 Universal Trunk card (typical) Note 1: Note 2: Page Figure 139 RAN control signals (Control GRD = IDLE) Page Page NT8D14 Universal Trunk card Page 609 of 906 Table 185 gives the electrical characteristics of the NT8D14 Universal Trunk Power to the NT8D14 Universal Trunk card is provided by the module power supply (ac or dc). Release control PAD switching Page The insertion loss from IPE ports to IPE ports is as follows: Page Page Page Page Jumper strap settings Service change entries Figure 140 Universal trunk card jumper locations (for NT8D14BA, NT8D14BB Release 9 and below) Unit 3 Unit 4 Unit 1 Unit 2 Unit 0 Unit 6 Unit 5 Unit 7 Page Page Page Paging trunk operation Music operation NT8D14 Universal Trunk card Page 625 of 906 Figure 141 Connecting paging equipment to the NT8D14 Universal Trunk card (typical) Page NT8D15 E& M Trunk card Page Page Page Common features Software control of A/-Law mode. Software control of digit collection. Figure 143 E&M trunk card block diagram 553-6201 Facility services interfaces (2-W E&M, 4-W E&M, and Paging) Signaling interface Page Trunk circuit features Page Note: NT8D15 E&M Trunk card Page 637 of 906 Figure 146 4-wire DX signaling Note 5: Note 4: Note 3: Unit 0 Unit 1 Unit 3 NT8D37 IPE Module MDF Page Page Maintenance features Signaling and call control Page NT8D15 E&M Trunk card Page 643 of 906 Figure 149 E&M Type I signaling patterns originating party release Outgoing calls from near end Incoming calls to near end Figure 150 E&M Type I signaling patterns originating party release on a tandem connection Outgoing calls from near end Incoming calls to near end IMM = Immediate start DDL = Delayed dial WNK = Wink start Page Page NT8D15 E&M Trunk card Page 647 of 906 Figure 151 E&M Type II signaling patterns originating party release Outgoing calls from system (near end) Incoming calls to system (near end) Figure 152 E&M Type II signaling patterns originating party release on a tandem connection Outgoing calls from system (near end) Incoming calls to system (near end) IMM = Immediate start DDL = Delayed dial WNK = Wink start Page Page Page Table 202 lists the electrical characteristics of the trunk interface on the E&M trunk card. Page Page Page Page NT8D15 E&M Trunk card Page 657 of 906 Figure 153 E&M trunk card typical cross connection example NT8D37 IPE Module NT8D15 E&M Trunk Card Unit 0 Unit 1 Jumper settings Page Page Software service entries Page Page PAD switching Table 210 shows the insertion loss from IPE port to IPE port. Paging trunk operation Page NT8D41AA Serial Data Interface Paddle Board Page Page System considerations Page Configuring the SDI paddle board Option switch settings Page Page Page Page Page Page Page NT8D41BA Quad Serial Data Interface Paddle Board Page NT8D41BA Quad Serial Data Interface Paddle Board Page 683 of 906 Figure 161 NT8D41BA QSDI paddle board Enable Disable LED Note: DCE-DTE mode selection for each port applies to both switch sets shown. System considerations Figure 162 NT8D41BA QSDI paddle board block diagram Page Page Configuring the QSDI paddle board Option switch settings Page SW15 and SW16 must not be configured identically. Figure 161 on page 683 displays SW15 and SW16. Page Page Page Page Page NTAG26 XMFR card MF signaling Signaling levels Table 219 lists the frequency values used for received signals. XMFR receiver specifications Table 220 provides the operating requirements for the NTAG26 circuit card. Page Page Physical specifications NTAK02 SDI/DCH card NTAK02 SDI/DCH card Page Page Connecting to the ports Page Page Page Characteristics of the low speed port Characteristics of the high speed port NTAK09 1.5 Mb DTI/PRI card Page Page NTAK09 DTI/PRI power on self-test NTAK20 power on self-test NTAK93 self-test DTI/PRI local self-test Page Interconnection Digital pad D-channel interface DS-1 Carrier interface Page Clock rate converter Page NTAK10 2.0 Mb DTI card Page Page Page Page Page Page Page Page Page Page Page Switch settings Page NTAK20 Clock Controller daughterboard Page Clocking modes Faceplate LEDs Phase difference detector circuit Digital phase lock loops Page Digital to analog converter CPU-MUX bus interface Signal conditioning Sanity timer External timing interface Hardware integrity and regulatory environment Page NTAK79 2.0 Mb PRI card Page Page NTAK79 switches Page Page Page Page Page Page Carrier grounding CEPT transceiver Slip control D-channel support interface Page Card-LAN interface Page Page Page Page NTAK93 D-channel Handler Interface daughterboard Page Faceplate LEDs Microprocessors Page D-Port SDTI/PRI interface Page NTBK22 MISP card Micro Processing Unit (MPU) High-Level Data Link Controller (HDLC) CPU to MISP bus interface MISP network bus interface Page NTBK50 2.0 Mb PRI card Page NTBK50 2.0 Mb PRI card Page 775 of 906 Figure 166 NTBK50 2.0 Mb PRI card with daughterboards The LEDs are described in Table 249. Page Page Page Page Carrier grounding Page CEPT transceiver Slip control D-channel support interface Card-LAN interface NTBK51 Downloadable D-channel Handler daughterboard Page Microprocessors Page Sanity timer Bus timer Download operation System initialization Card enabling or application enabling Card reset Background audit NTCK16 Generic Central Office Trunk cards Page Switch settings Self-test Common features Loop start operation Page Page Pad switching Cross connections Page 798 of 906 NTCK16 Generic Central Office Trunk cards Figure 167 NTCK16 Central Office trunk connections for NT8D37 I/O panel connectors A, E, K, R NTCK16 Generic Central Office Trunk cards Page 799 of 906 Figure 168 NTCK16 Central Office trunk connections for NT8D37 I/O panel connectors B, F, L, S Page 800 of 906 NTCK16 Generic Central Office Trunk cards Figure 169 NTCK16 Central Office trunk connections for NT8D37 I/O panel connectors C, G, M, T NTCK16AX Central Office trunk card Route Data Block Respond to the prompts in LD 16 as shown. LD 16 Route Data Block for NTCK16AX. Page Page NTCK16BX Central Office trunk card Route Data Block Respond to the prompts in LD 16 as shown: LD 16 Route Data Block for NTCK16BX. Page Page Periodic Pulse Metering Busy tone detect Loss switching Page Trunk to Trunk connection Call disconnect NTDK20 Small System Controller card Page Page Memory NTTK25 daughterboard 100BaseT IP daughterboards Page Page PC card interface Call Server connection to Media Gateway 1000S LAN Security device SDI ports Conferencing MG 1000S/Expansion card slot assignment Page Page Page NTRB21 DTI/PRI/DCH TMDI card Page Page Page Page Page Software description Hardware description NTRB21 TMDI card Interconnection Page 832 of 906 NTRB21 DTI/PRI/DCH TMDI card Figure 178 NTRB21 TMDI card faceplate TMDI Digital pad D-channel interface DS-1 Carrier interface Page NTAK20 Clock Controller (CC) daughterboard Page NTVQ01xx Media Card Page Hardware architecture Faceplate connectors and indicators Page Survivability Page NTVQ55AA ITG Pentium card Faceplate components Page Backplane interfaces Assembly description Page QPC513 Enhanced Serial Data Interface card Page Page Page 854 of 906 QPC513 Enhanced Serial Data Interface card Figure 183 ESDI card block diagram Synchronous communication Clock timing option Test and maintenance features Connection characteristics Page Page Page Page Configuring the ESDI card Address switch settings DTE/DCE mode jumper settings Page Page Page Page Page 868 of 906 QPC513 Enhanced Serial Data Interface card Figure 186 QPC513 ESDI card cabling Note 2: Note 1: QPC841 Quad Serial Data Interface card Page Page Page QPC841 Quad Serial Data Interface card Page 873 of 906 Figure 188 QPC841 QSDI card block diagram Page Page Configuring the QSDI card Page Baud rate switch settings Table 276 lists the switch settings necessary to set the baud rate. Page Page 880 of 906 QPC841 Quad Serial Data Interface card Figure 189 QSDI card option switch locations J2 SW1 DS1 J1 Port 1 Page Page Page Page The TDS/DTR card Features Tones and cadences The following tables give the tones and cadences provided by the NTAK03 TDS/DTR card. Page Page Page Page Page Page Page Page Page Page Page Page Page Appendix A: LAPB Data Link Control protocol Frame structure LAPB balanced class of procedure Commands and responses Description of procedure Page Page Nortel Communication Server 1000 Circuit Card Description and Installation