1 General
1.1 Introduction
1.2 References
1.3 Definitions
1.4 Abbreviations and acronyms used in this Recommendation
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
2.8.1 Numbering convention
2.8.2 Order of bit transmission
2.8.3 Field mapping 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
3.3.1 Address field extension bit (EA)
3.3.2 Command/response field bit (C/R)
3.3.3 Service Access Point Identifier (SAPI)
3.3.4 Terminal Endpoint Identifier (TEI)
3.4 Control field formats
3.4.1 Information transfer (I) format
3.4.2 Supervisory (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
3.5.3 Unacknowledged operation – variables and
parameters
3.6 Frame types
3.6.1 Commands and responses
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 Unnumbered information (UI) command
3.6.6 Receive ready (RR) command/response
3.6.7
Reject (REJ) command/response
3.6.8 Receive not ready (RNR) command/response
3.6.9 Unnumbered acknowledgement (UA) response
3.6.10 Disconnected mode (DM) response
3.6.11 Frame
reject (FRMR) response
3.6.12 Exchange identification (XID)
command/response
4
Elements for layer-to-layer communication
4.1 General
4.1.1 Generic names
4.1.2 Primitive
types
4.1.3 Parameter definition
4.2 Primitive procedures
4.2.1 General
4.2.2 Layer 3 – Data link layer interactions
4.3 Block interaction diagram of the data link layer
5
Definition of the peer-to-peer procedures of the data link layer
5.1 Procedure for the use of the P/F bit
5.1.1 Unacknowledged information transfer
5.1.2 Acknowledged multiple frame information
transfer
5.2 Procedures for unacknowledged information transfer
5.2.1 General
5.2.2 Transmission of unacknowledged
information
5.2.3 Receipt of unacknowledged information
5.3 Terminal Endpoint Identifier (TEI) management procedures
5.3.1 General
5.3.2 TEI assignment procedure
5.3.3 TEI check procedure
5.3.4 TEI removal procedure
5.3.5 TEI identity verify procedure
5.3.6 Formats and codes
5.4 Initialization of data link layer parameters
5.4.1 General
5.4.2 Parameter initialization
5.5 Procedures for establishment and release of multiple frame
operation
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
5.5.5 Collision of unnumbered commands and
responses
5.5.6 Unsolicited DM response and SABME or DISC
command
5.6 Procedures for information transfer in multiple frame
operation
5.6.1 Transmitting I frames
5.6.2 Receiving I frames
5.6.3 Sending and receiving acknowledgements
5.6.4 Receiving REJ frames
5.6.5 Receiving RNR frames
5.6.6 Data link layer own receiver busy
condition
5.6.7 Waiting acknowledgement
5.7 Re-establishment of multiple frame operation
5.7.1
Criteria for re-establishment
5.7.2 Procedures
5.8 Exception condition reporting and recovery
5.8.1 N(S) sequence error
5.8.2 N(R) sequence error
5.8.3 Timer
recovery condition
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 TEI value
5.9 List of system parameters
5.9.1 Timer T200
5.9.2 Maximum number of retransmissions (N200)
5.9.3 Maximum number of octets in an information field (N201)
5.9.4 Maximum number of transmissions of the
TEI Identity request message (N202)
5.9.5 Maximum number of outstanding I frames
(k)
5.9.6 Timer T201
5.9.7 Timer T202
5.9.8 Timer T203
5.10 Data link layer monitor function
5.10.1 General
5.10.2 Data link layer supervision in the
multiple-frame-established state
5.10.3 Connection verification procedures
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.2 Key to the state transition table
D.2.1 Definition of a cell of the state
transition table
D.2.2 Key to the contents of a cell
Annex E – Provision of Multi-Selective Reject Option
E.1 General
E.2 Frame structure for peer-to-peer communication
E.3 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 parameters and associated
state variables
E.3.6 Frame types
E.4 Elements for layer-to-layer communication
E.5 Definition of the peer-to-peer procedures of the data link
layer
E.5.1 Procedure for the use of the P/F bit
E.5.2 Procedures for unacknowledged information
transfer
E.5.3 Terminal Endpoint Identifier (TEI)
management procedures
E.5.4 Initialization of data link layer
parameters
E.5.5 Procedures for establishment and release
of multiple frame operation
E.5.6 Procedures for information transfer in
multiple frame operation
E.5.7 Re-establishment of multiple frame
operation
E.5.8 Exception condition reporting and
recovery
E.5.9 List of System parameters
E.5.10 Data link layer monitor function
E.6 SDL for point-to-point 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
E.7 State transition Tables
E.7.1 General
E.7.2 Key to the state transition Table
E.7.3 State Transition Table
E.8 Examples of the use of multi-selective reject option
Annex F – Protocol Implementation Conformance Statement (PICS) to Recommendation Q.921 for Basic Rate
(User-side)
F.1 General
F.2 Abbreviations and special symbols
F.3 Instructions for completing for PICS Proforma
F.4 Global statement of conformance
F.5 Protocol Capabilities (PC)
F.6 Frames – Protocol Data Units (FR)
F.7 System Parameters (SP)
Annex G – Protocol Implementation Conformance Statement (PICS) to
Recommendation Q.921 for Basic Rate (Network-side)
G.1 General
G.2 Abbreviations and
special symbols
G.3 Instructions for completing for PICS Proforma
G.4 Global statement of conformance
G.5 Protocol Capabilities (PC)
G.6 Frames – Protocol Data Units (FR)
G.7 System Parameters (SP)
Annex H – Protocol Implementation Conformance Statement (PICS) to
Recommendation Q.921 for Primary Rate (User-side)
H.1 General
H.2 Abbreviations and special symbols
H.3 Instructions for completing for PICS Proforma
H.4 Global statement of conformance
H.5 Protocol Capabilities (PC)
H.6 Frames – Protocol Data Units (FR)
H.7 System Parameters (SP)
Annex I – Protocol Implementation Conformance Statement (PICS) to
Recommendation Q.921 for Primary Rate (Network-side)
I.1 General
I.2 Abbreviations and special symbols
I.3 Instructions for completing for PICS Proforma
I.4 Global statement of conformance
I.5 Protocol
Capabilities (PC)
I.6 Frames – Protocol Data Units (FR)
I.7 System Parameters (SP)
Appendix I – Retransmission of REJ response frames
I.1 Introduction
I.2 Procedure
I.2.1 Recovery state variable V(M)
I.2.2 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
II.2 Layout of Table II.1
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 indication
III.4 Deactivation procedure without MPH-DEACTIVATE indication
Appendix IV – Automatic negotiation of data link layer parameters
IV.1 General
IV.2 Automatic negotiation
of data link layer parameter values