1 DTE/DCE interface characteristics
(physical layer)
1.1 X.21 interface
1.2 X.21 bis interface
1.3 V-Series interface
1.4 X.31 interface
2
Link access procedures across the DTE/DCE interface
2.1 Scope and field of applications
2.2 Framing aspects
2.3 LAPB elements of procedures
2.4 Description of the LAPB procedure
2.5 MultiLink Procedure (MLP) (Subscription-time selectable
option)
3
Description of the packet layer DTE/DCE interface
3.1 Logical channels
3.2 Basic structure of packets
3.3 Procedure for restart
3.4 Error handling
4
Procedures for virtual circuit services
4.1 Procedures for
virtual call service
4.2 Procedures for permanent virtual circuit service
4.3 Procedures for data and interrupt transfer
4.4 Procedures for flow control
4.5 Effects of clear, reset and restart procedures on the transfer
of packets
4.6 Effects of the physical layer and the data link layer on the
packet layer
5
Packet formats
5.1 General
5.2 Call set-up and clearing packets
5.3 Data and interrupt packets
5.4 Flow control and reset packets
5.5 Restart packets
5.6 Diagnostic packet
5.7 Packets required for optional user facilities
6
Procedures for optional user facilities (packet layer)
6.1 TOA/NPI address subscription
6.2 Extended and super extended packet sequence numbering
facilities
6.3 D-bit modification
6.4 Packet retransmission
6.5 Incoming calls barred
6.6 Outgoing calls barred
6.7 One-way logical channel outgoing
6.8 One-way logical channel incoming
6.9 Non-standard default packet sizes
6.10 Non-standard default window sizes
6.11 Default throughput classes assignment
6.12 Flow control parameter negotiation
6.13 Throughput class negotiation facilities
6.14 Closed user group related facilities
6.15 Bilateral closed user group related facilities
6.16 Fast select
6.17 Fast select acceptance
6.18 Reverse charging
6.19 Reverse charging acceptance
6.20 Local charging prevention
6.21 Network user identification (NUI) related facilities
6.22 Charging information
6.23 ROA related facilities
6.24 Hunt group
6.25 Call redirection and call deflection related facilities
6.26 Called line address modified notification
6.27 Transit delay selection and indication
6.28 Alternative addressing related facilities
7
Formats for facility fields
7.1 General
7.2 Coding of the facility code fields
7.3 Coding of the facility parameter fields
Annex A – Range of logical channels used for virtual calls and
permanent virtual circuits
Annex B – Packet layer DTE/DCE interface state diagrams
B.1 Symbol definition of the state diagrams
B.2 Order definition of the state diagrams
Annex C – Actions taken by the DCE on receipt of packets
in a given state of the packet layer DTE/DCE interface as perceived by the DCE
Annex D – Packet layer DCE time-outs and DTE time-limits
D.1 DCE time-outs
D.2 DTE time-limits
Annex E – Coding of X.25 network generated diagnostic
fields in clear, reset and restart indication, and diagnostic packets
Annex F – Subscription-time optional user facilities that
may be associated with a network user identifier in conjunction with the NUI
override facility
Annex G – ITU-T specified DTE facilities to support the
OSI Network service and other purposes
G.1 Introduction
G.2 Coding of the facility code fields
G.3 Coding of the facility parameter field
Appendix I – Examples of data link layer transmitted bit
patterns by the DCE and the DTE
Appendix II – An explanation of how the values for N1 in
2.4.9.5 are derived
II.1 DTE N1
II.2 DCE N1
II.3 General DCE N1 calculations
Appendix III – Examples of multilink resetting procedures
III.1 Introduction
III.2 MLP reset initiated by either the DCE or the DTE
III.3 MLP reset initiated by both the DCE and the DTE simultaneously
Appendix IV – Information on addresses in call set-up and
clearing packets
IV.1 Main address and complementary address
IV.2 Addresses in call request packet
IV.3 Addresses in incoming call packets
IV.4 Addresses in call accepted packets
IV.5 Addresses in
call connected packets
IV.6 Addresses in clear request packets
IV.7 Addresses in clear indication packets
IV.8 Addresses in clear confirmation packets
IV.9 Addresses in call redirection and call deflection related
facilities
Appendix V – Guidelines for transmission over channels
with long round trip delay and/or transmission rates higher than 64 000
bit/s.
V.1 Preamble
V.2 Common guidelines
V.3 Guidelines for channels with long round trip delays operating
at 64 000 bit/s
V.4 Guidelines for circuits with long round trip delays operating
at 1920 kbit/s
Appendix VI – Format for NUI parameter field
Appendix VII – Examples of the use of multi-selective
reject option