Rec. CCITT Q.921 (11/1988) – ISDN USER-NETWORK INTERFACE – DATA LINK LAYER SPECIFICATION
1 General
2 Frame structure for peer-to-peer communication
2.1 General
2.2 Flag sequence
2.3 Address field
2.4 Control field
2.5 Information field
2.6 Transparency
2.7 Frame check sequence (FCS) field
2.8 Format convention
2.9 Invalid frames
2.10 Frame abort
3 Elements of procedures and formats of fields for data link layer peer-to-peer communication
3.1 General
3.2 Address field format
3.3 Address field variables
3.4 Control field formats
3.5 Control field parameters and associated state variables
3.6 Frame types
4 Elements for layer-to-layer communication
4.1 General
4.2 Primitive procedures
5 Definition of the peer-to-peer procedures of the data link layer
5.1 Procedure for the use of the P/F bit
5.2 Procedures for unacknowledged information transfer
5.3 Terminal endpoint identifier (TEI) management procedures
5.4 Automatic negotiation of data link layer parameters
5.5 Procedures for establishment and release of multiple frame operation
5.6 Procedures for information transfer in multiple frame operation
5.7 Re-establishment of multiple frame operation
5.8 Exception condition reporting and recovery
5.9 List of system parameters
5.10 Data link layer monitor function
ANNEX A – Provision of point-to-point signalling connections
ANNEX B – SDL for point-to-point procedures
B.1 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 broadcast procedures
ANNEX D – State transition table of the point-to-point procedures of the data link layer
D.1
D.2 Key to the state transition table
APPENDIX I – Retransmission of REJ response frames
I.1 Introduction
I.2 Procedure
APPENDIX II – Occurrence of MDL-ERROR-INDICATION within the basic states and actions to be taken by the management entity
II.1 Introduction
II.2 Layout of Table II-1/Q.921
II.3 Preferred management actions
APPENDIX III – Optional basic access deactivation procedures
III.1 Introduction
III.2 Description of the Conceptual Model
III.3 Deactivation procedure with MPH-DEACTIVATE-IND
III.4 Deactivation procedure without MPH-DEACTIVATE-IND
APPENDIX IV – Automatic negotiation of data link layer parameters
IV.1 General
IV.2 Parameter initialization
IV.3 Internal parameter initialization
IV.4 Automatic notification of data link layer parameter values
ABBREVIATIONS AND ACRONYMS USED IN RECOMMENDATION Q.921
References