1、INTERNATIONAL TELECOMMUNICAT STD-ITU-T RECMN Q.921-ENGL 1997 W 48b2591 Ob47b95 5bT ON ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU ON UN Q.921 SERIES Q: SWITCHING AND SIGNALLING Digital subscriber Signalling System No. 1 - Data link layer (09197) ISDN user-network interface - Data link laye
2、r specification ITU-T Recommendation Q.921 (Previously CCIlT Recommendation) ITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE Q.1-Q.3 INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN CLAU
3、SES APPLICABLE TO ITU-T STANDARD SYSTEMS SPECIFICATIONS OF SIGNALLING SYSTEMS No. 4 AND No. 5 Q.4-Q.59 Q.60-Q.99 Q.lOO-Q.119 Q.120-Q.249 SPECIFICATIONS OF SIGNALLING SYSTEM No. 6 Q.250-Q.309 SPECIFICATIONS OF SIGNALLING SYSTEM RI Q.310-Q.399 SPECIFICATIONS OF SIGNALLING SYSTEM R2 Q.400-Q.499 DIGITAL
4、 EXCHANGES Q.500-Q.599 INTERWORKING OF SIGNALLING SYSTEMS Q.600-Q.699 SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 Q.700-(2.849 DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 Q.850-(2.999 General Q. 850-Q. 9 1 9 Network layer Q.930-Q.939 User-network management Stage 3 description for supplementary service
5、s using DSS 1 PUBLIC LAND MOBILE NETWORK INTERWORKING WITH SATELLITE MOBILE SYSTEMS INTELLIGENT NETWORK BROADBAND ISDN Q.940-Q. 949 Q.950-Q.999 Q.? 0004. I O99 Q. 1 I 004.1 1 99 Q.1200-Q.1999 Q.2000-(2.2999 For further details, please refer to ITU-T List of Recommendations. STDmITU-T RECMN Q.92L-ENG
6、L 1997 W 48b259L 0647b97 332 ITU-T RECOMMENDATION Q.921 ISDN USER-NETWORK INTERFACE - DATA LINK LAYER SPECIFICATION Summary This Recommendation specifies the Link Access Procedures on the D-channel (LAPD) of an ISDN customer access. Implementations of this Recommendation are in use in existing netwo
7、rks. This Recommendation has been revised for the sake of clarity, to cover new functionality, and to reflect the requirements of Q.92 1 in Protocol Implementation Conformance Statement (PICS) proformas. Clarifications are: o Definition of terms used in 4.921 (new subclause 1.3); Amendment to 5.2.1
8、for clarification on signalling arrangement and circumstances under Amendment to 5.3.4 for clarification on TE1 procedures; Amendment to Annex A of 4.921 for clarification on signalling arrangement and o which TE1 management and U1 fiame need not be supported; o o circumstances under which TE1 manag
9、ement need not be supported. New functions were specified as follows: o New SAP1 value 12 for teleaction communication (revised Table 2/Q.92 1); New Annex E “Provision of Multi-Selective Reject option“. Protocol Implementation Conformance Statement (PICS) proformas were amended, or generated, as app
10、ropriate, as follows: o Amendment to Annex F (former Annex E) of Q.921 “PICS Basic Rate User-side“ in order New Annex G to 4.921 “PICS Basic Rate Network-side“; New Annex H to Q.921 “PICS Rate User-side“; New Annex I to Q.92 1 “PICS Primary Rate Network-side“. to reflect modifications to 4.92 1, as
11、indicated above; o o o Source ITU-T Recommendation 4.921 was revised by ITU-T Study Group 11 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 12th of September 1997. STD.ITU-T RECMN Q=LIZL-ENGL 1997 m 4862573 Ob47678 279 m FOREWORD ITU (International Telecommunication Un
12、ion) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view
13、to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendat
14、ions by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of infomation technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Admin
15、istration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual P
16、roperty Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU hadhad not rece
17、ived notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 1998 All rights reserv
18、ed. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the IT. Recommendation 4.921 (09/97) 11 STD-ITU-T RECMN Q.92L-ENGL 1997 m 48b259L Ob47b99 LO5 m CONTENTS Page
19、1 General . 1.1 Introduction 1.2 References ; . 1.3 Definitions 1.4 Abbreviations and acronyms used in this Recommendation 2 2.1 General . Frame structure for peer-to-peer communication . 2.2 Flag sequence . 2.3 Address field . 2.4 Control field 2.5 Information field . 2.6 Transparency 2.7 Frame Che
20、ck Sequence (FCS) field . 2.8 Format convention 2.8.1 Numbering convention 2.8.2 Order of bit transmission . 2.8.3 Field mapping convention . 2.9 Invalid frames . 2.10 Frame ab0 rt . 3 Elements of procedures and formats of fields for data link layer peer-to-peer communication . 3.1 General . 3.2 Add
21、ress field format . 3.3 Address field variables . Address field extension bit (EA) . 3.3.1 3.3.2 3.3.3 3.3.4 Commandresponse field bit (CR) . Service Access Point Identifier (SAPI) . Terminal Endpoint Identifier (TEI) . 3.4 Control field formats Information transfer (I) format 3.4.1 3.4.2 Supervisor
22、y (S) format 3.4.3 Unnumbered (U) format 3.5 Control field parameters and associated state variables . 3.5.1 Poll/Final (P/F) bit . 3.5.2 Multiple frame operation - variables and sequence numbers . Recommendation 4.921 (09197) 6 6 6 6 7 7 7 8 8 8 8 8 9 10 10 10 10 10 10 10 11 11 12 12 13 13 13 13 13
23、 . 111 STD=ITU-T RECMN Q.92L-ENGL 1997 48b259L Ob47700 757 3.6 4 4.1 4.2 4.3 5 5.1 5.3 iv 3.5.3 Unacknowledged operation - variables and parameters . Frame types 3.6.2 Information (I) command 3.6.3 Set Asynchronous Balanced Mode Extended (SABME) command . 3.6.4 Disconnect (DISC) command . 3.6.5 Unnu
24、mbered information (UI) command 3.6.6 Receive ready (RR) commandresponse . 3.6.7 Reject (REJ) commandresponse 3.6.8 Receive not ready (RNR) commandresponse 3.6.9 Unnumbered acknowledgement (UA) response 3.6.1 O 3.6.11 3.6.12 Exchange identification (XID) commandresponse 3.6.1 Commands and responses
25、. Disconnected mode (DM) response Frame reject (FRMR) response . Elements for layer-to-layer communication . General . 4.1 . 1 Generic names . 4.1.2 Primitive types 4 .i . 3 Parameter definition Pnmitive procedures . 4.2.1 General 4.2.2 Layer 3 - Data link layer interactions . Block interaction diag
26、ram of the data link layer . Definition of the peer-to-peer procedures of the data link layer Procedure for the use of the PF bit 5.1.1 Unacknowledged information transfer 5.1.2 Acknowledged multiple frame information transfer . 5.2 Procedures for unacknowledged information transfer 5.2.1 General 5.
27、2.2 5.2.3 Transmission of unacknowledged information . Receipt of unacknowledged information Terminal Endpoint Identifier (TEI) management procedures 5.3.1 General 5.3.2 TE1 assignment procedure . 5.3.3 TE1 check procedure . 5.3.4 TE1 removal procedure 5.3.5 TE1 identity verify procedure Recommendat
28、ion 4.921 (09/97) Page 14 14 14 15 15 15 16 16 16 16 16 17 17 18 19 19 19 22 22 23 23 23 24 27 27 27 27 27 27 28 28 25 25 30 32 33 35 STDoITU-T RECMN Q.923-ENGh 3797 m 4Bb2593 Ob47703 693 m 5.4 5.5 5.6 5.7 5.8 5.9 5.3.6 Formats and codes . Initialization of data link layer parameters . 5.4.1 General
29、 Procedures for establishment and release of multiple frame operation 5.4.2 Parameter initialization . 5.5.1 Establishment of multiple frame operation . 5.5.2 Information transfer . 5.5.3 Termination of multiple frame operation 5.5.4 TEI-assigned state . 5 S.5 Collision of unnumbered commands and re
30、sponses . 5.5.6 Unsolicited DM response and SABME or DISC command . Procedures for information transfer in multiple frame operation . 5.6.2 5.6.3 5.6.1 Transmitting I frames Receiving I frames . 5.6.4 Receiving REJ frames . Data link layer own receiver busy condition . Sending and receiving acknowle
31、dgements 5.6.5 Receiving RNR frames 5.6.6 5.6.7 Waiting acknowledgement Re-establishment of multiple frame operation . 5.7.1 Criteria for re-establishment 5.7.2 Procedures . Exception condition reporting and recovery 5.8.1 N(S) sequence error . 5.8.2 N(R) sequence error 5.8.3 Timer recovery conditio
32、n 5.8.4 Invalid frame condition . 5.8.5 Frame rejection condition 5.8.6 Receipt of an FRMR response frame 5.8.7 Unsolicited response frames 5.8.8 Duplicate assignment of a TE1 value List of system parameters . 5.9.1 Timer T200 5.9.2 Maximum number of retransmissions (N200) 5.9.3 Maximum number of oc
33、tets in an information field (N20 i) . 5.9.4 Maximum number of transmissions of the TE1 Identity request message 5.9.5 (N202) . Maximum number of outstanding I frames (k) . Recommendation 4.921 (09/97) Page 36 38 38 38 39 39 40 40 41 41 42 42 42 42 43 43 44 46 46 47 47 47 48 48 48 49 49 49 49 49 50
34、50 50 51 51 51 51 V STD.1TI.J-T RECMN Q-923-ENGL 3797 W 4862593 0647702 52T 5.9.6 Timer T201 5.9.7 Timer T202 5.9.8 Timer T203 Data link layer monitor function 5.10.1 General 5.10.2 5.1 O Data link layer supervision in the multiple-frame-established state . 5.10.3 Connection verification procedures
35、. Annex A - Provision of point-to-point signalling connections . Annex B - SDL for point-to-point procedures B.l General . B.2 An overview of the states of the point-to-point data link layer entity B.3 Cover notes . B.4 The use of queues . B.5 SDL representation . Annex C - SDL representation of the
36、 broadcast procedures . Annex D - State transition table of the point-to-point procedures of the data link layer Key to the state transition table Key to the contents of a cell Annex E - Provision of Multi-Selective Reject Option D.2 D.2.1 D.2.2 Definition of a cell of the state transition table . E
37、 . 1 E.2 E.3 E.4 ES vi General . Frame structure for peer-to-peer communication . Elements of procedures and formats of fields for data link layer peer-to-peer communication . E.3.1 General E.3.2 Address field format E.3.3 Address field variables E.3.4 Control field formats . E.3.5 Control field par
38、ameters and associated state variables E.3.6 Frame types . Elements for layer-to-layer communication . Definition of the peer-to-peer procedures of the data link layer Procedure for the use of the PE bit . Procedures for unacknowledged information transfer Terminal Endpoint Identifier (TEI) manageme
39、nt procedures . ES . 1 ES . 2 ES . 3 Recommendation 4.921 (09/97) Page 51 51 51 52 52 52 54 55 55 55 56 58 59 60 93 93 94 94 94 136 136 136 136 136 136 136 136 136 137 142 142 143 143 143 E.6 E.7 E . 8 E.5.4 E.5.5 ES . 6 ES . 7 ES . 8 E.5.9 E.5.1 O Initialization of data link layer parameters Proced
40、ures for establishment and release of multiple fiame operation . Procedures for information transfer in multiple frame operation Re-establishment of multiple fiame operation Exception condition reporting and recovery . List of System parameters . Data link layer monitor function . SDL for point-to-p
41、oint procedures . E.6.1 General E.6.2 An overview of the states of the point-to-point data link layer entity . E.6.3 Cover notes E.6.4 The use of queues E.6.5 SDL representation State transition Tables i . E.7.1 General E.7.2 E.7.3 State Transition Table . Examples of the use of multi-selective reje
42、ct option Key to the state transition Table Annex F . Protocol Implementation Conformance Statement (PICS) to Recommendation 4.92 1 for Basic Rate (User-side) . F . 1 General . F.2 F.3 F.4 Abbreviations and special symbols Instructions for completing for PICS Proforma . Global statement of conforman
43、ce . F.5 Protocol Capabilities (PC) F.6 Frames - Protocol bata Units (FR) F.7 System Parameters (SP) . Annex G - Protocol Implementation Conformance Statement (PICS) to Recommendation Q.921 for Basic Rate (Network-side) . G.l General . G.2 G.3 G.4 Abbreviations and special symbols Instructions for c
44、ompleting for PICS Proforma . Global statement of conformance . G.5 Protocol Capabilities (PC) Frames - Protocol Data Units (FR) G.6 G.7 System Parameters (SP) . Recommendation 4.921 (09197) Page 143 144 144 152 152 154 154 154 154 154 154 154 154 158 158 158 158 160 209 209 209 210 210 211 216 217
45、218 218 219 219 220 220 226 227 vii STD-ITU-T RECMN Q-921-ENGL 1997 4862591 Ob47704 3T2 Annex H . Protocol Implementation Conformance Statement (PICS) to Recommendation 4.921 for Primary Rate (User-side) . H.l General . H.2 . Abbreviations and special symbols H.3 H.4 Global statement of conformance
46、. H.5 Protocol Capabilities (PC) H.6 Frames - Protocol Data Units (FR) H.7 System Parameters (SP) . Instructions for completing for PICS Proforma . Annex I . Protocol Implementation Conformance Statement (PICS) to Recommendation Q.921 for Primary Rate (Neork-side) . I . 1 General . 1.2 Abbreviations
47、 and special symbols . 1.3 Instructions for completing for PICS Proforma . 1.4 Global statement of conformance . 1.5 Protocol Capabilities (PC) 1.6 Frames - Protocol Data Units (FR) 1.7 System Parameters (SP) . Appendix I . Retransmission of REJ response frames I . 1 Introduction 1.2 Procedure 1.2.1
48、 1.2.2 Recovery state variable V(M) . N(S) sequence error supplementary procedure . Appendix II . Occurrence of MDL-ERROR indication within the basic states and actions to be taken by the management entity II . 1 Introduction 11.2 Layout of Table 11.1 11.3 Preferred management actions Appendix III .
49、 Optional basic access deactivation procedures . III . 1 Introduction 111.2 Description of the Conceptual Model . 111.3 111.4 Deactivation procedure with MPH-DEACTIVATE indication . Deactivation procedure without MPH-DEACTIVATE indication Page 228 228 228 229 229 230 236 237 238 238 238 239 239 240 246 247 248 248 248 248 248 249 249 249 249 251 251 251 252 254 . v111 Recommendation 4.921 (09/97) STD-ITU-T RECMN Q.92I-ENGL I997 M 48b259L Obi17705 239 D Page Appendix IV - Automatic negotiation of data link lay
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