CAN/CSA-ISO/IEC 8208-02 (R2011)

Foreword
1 Scope
2 Normative references
   2.1 Identical Recommendations - International
        Standards
   2.2 Paired Recommendations - International
        Standards equivalent in technical content
   2.3 Additional references
3 General considerations
   3.1 Compatibility with versions of Recommendation
        X.25
   3.2 Environments
   3.3 Differences in DTE/DTE and DTE/DCE operation
   3.4 Operation over circuit-switched connections
   3.5 Provision of the OSI Network Service
   3.6 External Packet Layer interactions
   3.7 Logical channels
   3.8 Packet Layer entity
   3.9 Packet types
   3.10 Procedures for initialization
4 Procedures for restart
   4.1 Originating a restart request
   4.2 Receiving a restart indication
   4.3 Restart collision
   4.4 Restart confirmation
   4.5 Determining "DTE" or "DCE" characteristics
5 Procedures for Virtual Call setup and clearing
   5.1 Ready state
   5.2 Procedures for Virtual Call setup
   5.3 Rejecting a call
   5.4 Aborting a call request
   5.5 Procedures for Virtual Call clearing
6 Procedures for data and interrupt transfer
   6.1 States for data and interrupt transfer
   6.2 Maximum User Duo Field length of DATA packets
   6.3 Delivery Confirmation bit
   6.4 More Data mark
   6.5 Complete packet sequence
   6.6 Qualifier bit
   6.7 Fragmentation and reassembly of messages
   6.8 Procedures far interrupt
   6.9 Transit delay of DATA packets
7 Procedures for flow control
   7.1 Flow control
   7.2 Throughput characteristics and throughput
        classes
8 Procedures for reset
   8.1 Originating a reset request
   8.2 Receiving a reset indication
   8.3 Reset collision
   8.4 Reset confirmation
9 Effects of clear, reset, and restart procedures
   on the transfer of packets
10 Effects of Layers 1 and 2 on the Packet Layer
11 Error handling
   11.1 The DIAGNOSTIC packet
   11.2 Non-receipt of window-rotation information
   11.3 Receipt of erroneous DATA packets
12 Packet formats
   12.1 General
   12.2 Call setup and call clearing packets
   12.3 DATA and interrupt packets
   12.4 Flow control packets
   12.5 Reset packets
   12.6 Restart packets
   12.7 DIAGNOSTIC packet
   12.8 REJECT packet
   12.9 Registration packets
13 Procedures for optional user facilities
   13.1 On-line Facility Registration
   13.2 Extended and Super Extended Packet Sequence
        Numbering
   13.3 D-bit Modification
   13.4 Packet Retransmission
   13.5 Incoming Calls Barred
   13.6 Outgoing Calls Barred
   13.7 One-way Logical Channel Outgoing
   13.8 One-way Logical Channel Incoming
   13.9 Nonstandard Default Packet Sizes
   13.10 Nonstandard Default Window Sizes
   13.11 Default Throughput Classes Assignment
   13.12 Flow Control Parameter Negotiation
   13.13 Throughput Class Negotiation facilities
   13.14 Closed User Group related facilities
   13.15 Bilateral Closed User Group related facilities
   13.16 Fast Select
   13.17 Fast Select Acceptance
   13.18 Reverse Charging
   13.19 Reverse Charging Acceptance
   13.20 Local Charging Prevention
   13.21 Network User Identification (NUI) related
         facilities
   13.22 Charging Information
   13.23 RDA related facilities
   13.24 Hunt Group
   13.25 Call Redirection and Call Deflection related
         facilities
   13.26 Called Line Address Modified Notification
   13.27 Transit Delay Selection and Indication
   13.28 Alternative Addressing related facilities
   13.29 TOA/NPI address subscription
   13.30 Reference Number
14 Procedures for optional ITU-T specified DTE facilities
   14.1 Calling Address Extension
   14.2 Called Address Extension
   14.3 Minimum Throughput Class Negotiation
   14.4 End-to-End Transit Delay Negotiation
   14.5 Priority
   14.6 Protection
   14.7 Expedited Data Negotiation
15 Format for Facility Field in tail setup/clearing
   packets
   15.1 General
   15.2 Coding of the Facility Field for optional user
        facilities
   15.3 Coding of the Facility Field for ITU-T
        specified DTE facilities
16 Format for Registration Field in registration packets
   16.1 General
   16.2 Coding of the Registration Field for
        registration-facilities
17 Diagnostic codes
18 Timers and retransmission counts
19 State diagrams
20 State tables
21 Conformance
   21.1 Static conformance
   21.2 Protocol Implementation Conformance Statement
   21.3 Dynamic conformance
Annexes
A - Private networks
B - PICS Proforma
C - Differences between various editions of ISO/IEC 5208
D - Abbreviations

Scope This International Standard specifies the procedures, formats and facilities at the Packet Layer for Data Terminal Equipment (DTE) operating in conformance with ITU-T Recommendation X.25. Both Virtual Call and Permanent Virtual Circuit modes of operation are covered. The Packet Layer protocol specified herein can be used in both Open Systems Interconnection (OSI) and non-OSI environments. When used within the context of OSI, the Packet Layer protocol is encompassed in the Network Layer of the OSI Reference Model, ITU-T Rec. X.200 ISO/IEC 7498-1. This International Standard covers DTE operation at the Packet Layer when accessing a public or private packet-switched network conforming to ITU-T Recommendation X.25 by means of a dedicated path or a circuit-switched connection. It also covers the additional Packet Layer procedures necessary for two DTEs conforming to this International Standard to communicate directly (i.e., without an intervening packet-switched network) over a dedicated path, a circuit-switched connection, or a local area network (LAN). This International Standard also covers private networks that use ITU-T Recommendation X.25 to connect to packet-switched public data networks and that may also offer an X.25 interface to a DTE (see annex A). To evaluate conformance of a particular implementation, it is necessary to have a statement of which capabilities and options have been implemented. Such a statement is called a Protocol Implementation Conformance Statement (PICS), as defined in ITU-T Rec. X.290 ISO/IEC 9646-1. Annex B provides the PICS proforma in accordance with the relevant guidance given in ITUT Rec. X.296 ISO/IEC 9646-7. The first edition of this International Standard was based on the 1984 CCITT Red Book text of Recommendation X.25. It also contained the necessary provisions for compatibility with the earlier 1980 CCITT Yellow Book text of Recommendation X.25. The second edition was based on the 1988 CCITT Blue Book text of Recommendation X.25. The third edition is based upon the 1993 version of X.25. This fourth edition is based on the 1996 version of X.25. Retained within this fourth edition are the necessary provisions for compatibility with the 1993, 1988, 1984 and 1980 versions of X.25. The differences between various editions of this International Standard are summarized in annex C. It should be noted that this International Standard and ITU-T Recommendation X.25 as it applies to DTEs are different in scope. This International Standard contains the specifications that ITU-T Recommendation X.25 places on DTEs. In addition, this International Standard contains added specifications to facilitate interworking between DTEs and to cover direct DTE-to-DTE operation. This broader scope has to be recognized in the application of this International Standard.

Scope This International Standard specifies the procedures, formats and facilities at the Packet Layer for Data Terminal Equipment (DTE) operating in conformance with ITU-T Recommendation X.25. Both Virtual Call and Permanent Virtual Circuit modes of operation are covered. The Packet Layer protocol specified herein can be used in both Open Systems Interconnection (OSI) and non-OSI environments. When used within the context of OSI, the Packet Layer protocol is encompassed in the Network Layer of the OSI Reference Model, ITU-T Rec. X.200 ISO/IEC 7498-1. This International Standard covers DTE operation at the Packet Layer when accessing a public or private packet-switched network conforming to ITU-T Recommendation X.25 by means of a dedicated path or a circuit-switched connection. It also covers the additional Packet Layer procedures necessary for two DTEs conforming to this International Standard to communicate directly (i.e., without an intervening packet-switched network) over a dedicated path, a circuit-switched connection, or a local area network (LAN). This International Standard also covers private networks that use ITU-T Recommendation X.25 to connect to packet-switched public data networks and that may also offer an X.25 interface to a DTE (see annex A). To evaluate conformance of a particular implementation, it is necessary to have a statement of which capabilities and options have been implemented. Such a statement is called a Protocol Implementation Conformance Statement (PICS), as defined in ITU-T Rec. X.290 ISO/IEC 9646-1. Annex B provides the PICS proforma in accordance with the relevant guidance given in ITUT Rec. X.296 ISO/IEC 9646-7. The first edition of this International Standard was based on the 1984 CCITT Red Book text of Recommendation X.25. It also contained the necessary provisions for compatibility with the earlier 1980 CCITT Yellow Book text of Recommendation X.25. The second edition was based on the 1988 CCITT Blue Book text of Recommendation X.25. The third edition is based upon the 1993 version of X.25. This fourth edition is based on the 1996 version of X.25. Retained within this fourth edition are the necessary provisions for compatibility with the 1993, 1988, 1984 and 1980 versions of X.25. The differences between various editions of this International Standard are summarized in annex C. It should be noted that this International Standard and ITU-T Recommendation X.25 as it applies to DTEs are different in scope. This International Standard contains the specifications that ITU-T Recommendation X.25 places on DTEs. In addition, this International Standard contains added specifications to facilitate interworking between DTEs and to cover direct DTE-to-DTE operation. This broader scope has to be recognized in the application of this International Standard.