rfc994.txt

RFC 相关的技术文档

Network Working Group                                   ANSI X3S3.3 86-80
Request for Comments: 994                             ISO TC97/SC6/N 3998
                                                               March 1986





                                 I S O
             INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
              ORGANISATION INTERNATIONALE DE NORMALISATION

     ______________________________________________________________________
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    |                            ISO/TC 97/SC 6                           |
    |                TELECOMMUNICATIONS AND INFORMATION                   |
    |                     EXCHANGE BETWEEN SYSTEMS                        |
    |                       Secretariat: USA (ANSI)                       |
    |                                                                     |
    |                                                                     |
    |_____________________________________________________________________|




Title:  Final Text of DIS 8473, Protocol for Providing the Connectionless-
        mode Network Service

Source:  DIS 8473 Editor

























ISO 8473                                                        [Page 1]

RFC 994                                                    December 1986


Contents

1   Scope and Field of Application                                         6

2   References                                                             7


SECTION ONE. GENERAL                                                       9

3   Definitions                                                            9
    3.1   Reference Model Definitions  . . . . . . . . . . . . . . . . .   9
    3.2   Service Conventions Definitions  . . . . . . . . . . . . . . .   9
    3.3   Network Layer Architecture Definitions . . . . . . . . . . . .   9
    3.4   Network Layer Addressing Definitions . . . . . . . . . . . . .  10
    3.5   Additional Definitions . . . . . . . . . . . . . . . . . . . .  10

4   Symbols and Abbreviations                                             11
    4.1   Data Units   . . . . . . . . . . . . . . . . . . . . . . . . .  11
    4.2   Protocol Data Units  . . . . . . . . . . . . . . . . . . . . .  11
    4.3   Protocol Data Unit Fields  . . . . . . . . . . . . . . . . . .  11
    4.4   Parameters . . . . . . . . . . . . . . . . . . . . . . . . . .  11
    4.5   Miscellaneous  . . . . . . . . . . . . . . . . . . . . . . . .  11

5   Overview of the Protocol                                              12
    5.1   Internal Organization of the Network Layer . . . . . . . . . .  12
    5.2   Subsets of the Protocol  . . . . . . . . . . . . . . . . . . .  12
    5.3   Addresses and Titles . . . . . . . . . . . . . . . . . . . . .  13
          5.3.1   Addresses  . . . . . . . . . . . . . . . . . . . . . .  13
          5.3.2   Network-entity Titles  . . . . . . . . . . . . . . . .  13
    5.4   Service Provided by the Network Layer  . . . . . . . . . . . .  14
    5.5   Underlying Service Assumed by the Protocol . . . . . . . . . .  14
          5.5.1   Subnetwork Points of Attachment  . . . . . . . . . . .  15
          5.5.2   Subnetwork Quality of Service  . . . . . . . . . . . .  15
          5.5.3   Subnetwork User Data   . . . . . . . . . . . . . . . .  16
          5.5.4   Subnetwork Dependent Convergence Functions . . . . . .  16
    5.6   Service Assumed from Local Environment . . . . . . . . . . . .  16


SECTION  TWO.  SPECIFICATION  OF  THE  PROTOCOL                           18

6   Protocol Functions                                                    18
    6.1   PDU Composition Function . . . . . . . . . . . . . . . . . . .  18
    6.2   PDU Decomposition Function . . . . . . . . . . . . . . . . . .  19
    6.3   Header Format Analysis Function  . . . . . . . . . . . . . . .  19










ISO 8473                                                        [Page 2]

RFC 994                                                    December 1986


    6.4   PDU Lifetime Control Function  . . . . . . . . . . . . . . . .  20
    6.5   Route PDU Function . . . . . . . . . . . . . . . . . . . . . .  20
    6.6   Forward PDU Function . . . . . . . . . . . . . . . . . . . . .  21
    6.7   Segmentation Function  . . . . . . . . . . . . . . . . . . . .  21
    6.8   Reassembly Function  . . . . . . . . . . . . . . . . . . . . .  22
    6.9   Discard PDU Function . . . . . . . . . . . . . . . . . . . . .  23
    6.10  Error Reporting Function . . . . . . . . . . . . . . . . . . .  24
          6.10.1  Overview . . . . . . . . . . . . . . . . . . . . . . .  24
          6.10.2  Requirements . . . . . . . . . . . . . . . . . . . . .  25
          6.10.3  Processing of Error Reports  . . . . . . . . . . . . .  25
          6.10.4  Relationship of Data PDU Options to Error Reports  . .  26
    6.11  PDU Header Error Detection . . . . . . . . . . . . . . . . . .  27
    6.12  Padding Function . . . . . . . . . . . . . . . . . . . . . . .  28
    6.13  Security . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
    6.14  Source Routing Function  . . . . . . . . . . . . . . . . . . .  28
    6.15  Record Route Function  . . . . . . . . . . . . . . . . . . . .  29
    6.16  Quality of Service Maintenance Function  . . . . . . . . . . .  30
    6.17  Priority Function  . . . . . . . . . . . . . . . . . . . . . .  31
    6.18  Congestion Notification Function . . . . . . . . . . . . . . .  31
    6.19  Classification of Functions  . . . . . . . . . . . . . . . . .  31

7   Structure and Encoding of PDUs                                        33
    7.1   Structure  . . . . . . . . . . . . . . . . . . . . . . . . . .  33
    7.2   Fixed Part . . . . . . . . . . . . . . . . . . . . . . . . . .  34
          7.2.1   General  . . . . . . . . . . . . . . . . . . . . . . .  34
          7.2.2   Network Layer Protocol Identifier  . . . . . . . . . .  34
          7.2.3   Length Indicator   . . . . . . . . . . . . . . . . . .  35
          7.2.4   Version/Protocol Identifier Extension  . . . . . . . .  35
          7.2.5   PDU Lifetime   . . . . . . . . . . . . . . . . . . . .  35
          7.2.6   Flags  . . . . . . . . . . . . . . . . . . . . . . . .  35
                  7.2.6.1   Segmentation Permitted . . . . . . . . . . .  35
                  7.2.6.2   More Segments  . . . . . . . . . . . . . . .  35
                  7.2.6.3   Error Report   . . . . . . . . . . . . . . .  36
          7.2.7   Type Code  . . . . . . . . . . . . . . . . . . . . . .  36
          7.2.8   PDU Segment Length   . . . . . . . . . . . . . . . . .  36
          7.2.9   PDU Checksum   . . . . . . . . . . . . . . . . . . . .  36
    7.3   Address Part   . . . . . . . . . . . . . . . . . . . . . . . .  37
          7.3.1   General  . . . . . . . . . . . . . . . . . . . . . . .  37
                  7.3.1.1   Destination and Source Addresses . . . . . .  37
    7.4   Segmentation Part  . . . . . . . . . . . . . . . . . . . . . .  38
          7.4.1   Data Unit Identifier . . . . . . . . . . . . . . . . .  38
          7.4.2   Segment Offset . . . . . . . . . . . . . . . . . . . .  38
          7.4.3   PDU Total Length . . . . . . . . . . . . . . . . . . .  39
    7.5   Options Part   . . . . . . . . . . . . . . . . . . . . . . . .  39
          7.5.1   General  . . . . . . . . . . . . . . . . . . . . . . .  39
          7.5.2   Padding  . . . . . . . . . . . . . . . . . . . . . . .  40
          7.5.3   Security . . . . . . . . . . . . . . . . . . . . . . .  40
                  7.5.3.1   Source Address Specific  . . . . . . . . . .  41
                  7.5.3.2   Destination Address Specific . . . . . . . .  41
                  7.5.3.3   Globally Unique Security . . . . . . . . . .  41
          7.5.4   Source Routing   . . . . . . . . . . . . . . . . . . .  41



ISO 8473                                                        [Page 3]

RFC 994                                                    December 1986


          7.5.5   Recording of Route . . . . . . . . . . . . . . . . . .  42
          7.5.6   Quality of Service Maintenance . . . . . . . . . . . .  43
                  7.5.6.1   Source Address Specific  . . . . . . . . . .  43
                  7.5.6.2   Destination Address Specific . . . . . . . .  43
                  7.5.6.3   Globally Unique QoS  . . . . . . . . . . . .  43
          7.5.7   Priority   . . . . . . . . . . . . . . . . . . . . . .  44
    7.6   Data Part  . . . . . . . . . . . . . . . . . . . . . . . . . .  45
    7.7   Data (DT) PDU  . . . . . . . . . . . . . . . . . . . . . . . .  46
          7.7.1   Structure  . . . . . . . . . . . . . . . . . . . . . .  46
          7.7.1.1   Fixed Part . . . . . . . . . . . . . . . . . . . . .  47
          7.7.1.2   Addresses  . . . . . . . . . . . . . . . . . . . . .  47
          7.7.1.3   Segmentation . . . . . . . . . . . . . . . . . . . .  47
          7.7.1.4   Options  . . . . . . . . . . . . . . . . . . . . . .  47
          7.7.1.5   Data   . . . . . . . . . . . . . . . . . . . . . . .  47
    7.8   Inactive Network Layer Protocol  . . . . . . . . . . . . . . .  47
          7.8.1   Network Layer Protocol Id  . . . . . . . . . . . . . .  47
          7.8.2   Data Field   . . . . . . . . . . . . . . . . . . . . .  47
    7.9   Error Report PDU (ER)  . . . . . . . . . . . . . . . . . . . .  48
          7.9.1   Structure  . . . . . . . . . . . . . . . . . . . . . .  48
                  7.9.1.1   Fixed Part . . . . . . . . . . . . . . . . .  49
                  7.9.1.2   Addresses  . . . . . . . . . . . . . . . . .  49
                  7.9.1.3   Options  . . . . . . . . . . . . . . . . . .  49
                  7.9.1.4   Reason for Discard . . . . . . . . . . . . .  50
                  7.9.1.5   Error Report Data Field  . . . . . . . . . .  51

8   Conformance                                                           51
    8.1   Provision of Functions for Conformance . . . . . . . . . . . .  51


List of Tables

1     Service Primitives for Underlying Service  . . . . . . . . . . . .  14
2     Service Primitives for Underlying Service  . . . . . . . . . . . .  14
3     Timer Primitives   . . . . . . . . . . . . . . . . . . . . . . . .  14
4     Categorization of Protocol Functions . . . . . . . . . . . . . . .  32
5     Valid PDU Types  . . . . . . . . . . . . . . . . . . . . . . . . .  36
6     Encoding of Option Parameters  . . . . . . . . . . . . . . . . . .  39
7     Reason for Discard . . . . . . . . . . . . . . . . . . . . . . . .  50
8     Categorization of Functions  . . . . . . . . . . . . . . . . . . .  52


List of Figures

1     Interrelationship of Standards   . . . . . . . . . . . . . . . . .   6
2     PDU Structure  . . . . . . . . . . . . . . . . . . . . . . . . . .  34
3     PDU Header -- Fixed Part . . . . . . . . . . . . . . . . . . . . .  34
4     PDU Header -- Address Part   . . . . . . . . . . . . . . . . . . .  37
5     Address Parameters . . . . . . . . . . . . . . . . . . . . . . . .  38
6     PDU Header -- Segmentation Part  . . . . . . . . . . . . . . . . .  38
7     PDU Header -- Options Part . . . . . . . . . . . . . . . . . . . .  39
8     PDU Header -- Data Field   . . . . . . . . . . . . . . . . . . . .  45



ISO 8473                                                        [Page 4]

RFC 994                                                    December 1986


9     DT PDU   . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
10    Inactive Network Layer Protocol  . . . . . . . . . . . . . . . . .  47
11    Error Report PDU . . . . . . . . . . . . . . . . . . . . . . . . .  48



















































ISO 8473                                                        [Page 5]

RFC 994                                                    December 1986


0     Introduction

   This Protocol Standard is one of a set of International Standards
   produced to facilitate the interconnection of open systems. The set
   of standards covers the services and protocols required to achieve
   such interconnection.

   This Protocol Standard is positioned with respect to other related
   standards by the layers defined in the Reference Model for Open Sys-
   tems Interconnection (ISO 7498).  In particular, it is a protocol of
   the Network Layer. This Protocol may be used between network-entities
   in end systems or in Network Layer relay systems (or both).  It pro-
   vides the Connectionless-mode Network Service as defined in Addendum
   1 to the Network Service Definition Covering Connectionless-mode
   Transmission (ISO 8348/AD1).

   The interrelationship of these standards is illustrated in Figure 1
   below:


   --------------------+--- ISO NETWORK SERVICE PROVIDER -----^-----------------
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           PROTOCOL    |  REFERENCE TO AIMS  -----------------+
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