• ITU-T Rec. X.224 (11/1988) – TRANSPORT PROTOCOL SPECIFICATION FOR OPEN SYSTEMS INTERCONNECTION FOR CCITT APPLICATIONS
  • CONTENTS
  • 0 Introduction
  • 1 Scope and field of application
  • 2 References
  • 3 Definitions
  • 4 Symbols and abbreviations
    • 4.1 Data units
    • 4.2 Types of transport protocol data unit
    • 4.3 TPDU fields
    • 4.4 Times and associated variables
    • 4.5 Miscellaneous
  • 5 Overview of the transport protocol
    • 5.1 Service provided by the transport layer
    • 5.2 Service assumed from the network layer
    • 5.3 Functions of the transport layer
    • 5.4 Classes and options
    • 5.5 Model of the transport layer
  • 6 Elements of procedure
    • 6.1 Assignment to network connection
    • 6.2 Transport protocol data unit (TPDU) transfer
    • 6.3 Segmenting and reassembling
    • 6.4 Concatenation and separation
    • 6.5 Connection establishment
    • 6.6 Connection refusal
    • 6.7 Normal release
    • 6.8 Error release
    • 6.9 Association of TPDUs with transport connections
    • 6.10 Data TPDU numbering
    • 6.11 Expedited data transfer
    • 6.12 Reassignment after failure
    • 6.13 Retention until acknowledgment of TPDUs
    • 6.14 Resynchronization
    • 6.15 Multiplexing and demultiplexing
    • 6.16 Explicit flow control
    • 6.17 Checksum
    • 6.18 Frozen references
    • 6.19 Retransmission on timeout
    • 6.20 Resequencing
    • 6.21 Inactivity control
    • 6.22 Treatment of protocol errors
    • 6.23 Splitting and recombining
  • 7 Protocol classes
  • 8 Specification for Class 0: simple class
    • 8.1 Functions of Class 0
    • 8.2 Procedures for Class 0
  • 9 Specification for Class 1: basic error recovery class
    • 9.1 Functions of Class 1
    • 9.2 Procedures for Class 1
  • 10 Specification for Class 2: multiplexing class
    • 10.1 Functions of Class 2
    • 10.2 Procedures for Class 2
  • 11 Specification for Class 3: error recovery and multiplexing class
    • 11.1 Functions of Class 3
    • 11.2 Procedures for Class 3
  • 12 Specification for Class 4: error detection and recovery class
    • 12.1 Functions of Class 4
    • 12.2 Procedures for Class 4
  • 13 Structure and encoding of TPDUs
    • 13.1 Validity
    • 13.2 Structure
    • 13.3 Connection request (CR) TPDU
    • 13.4 Connection confirm (CC) TPDU
    • 13.5 Disconnect request (DR) TPDU
    • 13.6 Disconnect confirm (DC) TPDU
    • 13.7 Data (DT) TPDU
    • 13.8 Expedited data (ED) TPDU
    • 13.9 Data acknowledgement (AK) TPDU
    • 13.10 Expedited data acknowledgment (EA)
    • 13.11 Reject (RJ) TPDU
    • 13.12 TPDU error (ER) TPDU
  • 14 Conformance
  • ANNEX A – State tables
  • A.1 Conventions
  • A.2 General
  • A.3 State tables for Classes 0 and 2
  • A.4 State tables for Classes 1 and 3
  • A.5 State tables for Class 4
  • ANNEX B – Transport protocol identification
  • B.1 Introduction
  • B.2 Conveyance of PI TPDU
  • B.3 Encoding of the PI TPDU
  • APPENDIX I – Checksum algorithms
  • I.1 Symbols
  • I.2 Arithmetic conventions
  • I.3 Algorithm for generating checksum parameters
  • I.4 Algorithm for checking checksum parameters
  • APPENDIX II – Differences between Recommendation X.224 and ISO 8073 (1986)
  • II.1 Defect reports
  • II.2 Conformance
  • II.3 Class negotiation
  • II.4 Precedence
  • II.5 Assignment to network connections
  • II.6 Transport protocol identification
  • II.7 Checksum algorithms