RFC 926 (rfc926) - Page 1 of 101
Protocol for providing the connectionless mode network services
Alternative Format: Original Text Document
Network Working Group ISO
Request for Comments: 926 December 1984
Protocol for Providing the Connectionless-Mode Network Services
(Informally - ISO IP)
ISO DIS 8473
Status of this Memo:
This document is distributed as an RFC for information only. It does
not specify a standard for the ARPA-Internet. Distribution of this
memo is unlimited.
Note:
This document has been prepared by retyping the text of ISO DIS 8473 of
May 1984, which is currently undergoing voting within ISO as a Draft
International Standard (DIS). Although this RFC has been reviewed
after typing, and is believed to be substantially correct, it is
possible that typographic errors not present in the ISO document have
been overlooked.
Alex McKenzie
BBN
RFC 926 December 1984
RFC 926 December 1984
TABLE OF CONTENTS
1 SCOPE AND FIELD OF APPLICATION........................ 2
2 REFERENCES............................................ 3
3 DEFINITIONS........................................... 4
3.1 Reference Model Definitions......................... 4
3.2 Service Conventions Definitions..................... 4
3.3 Network Layer Architecture Definitions.............. 4
3.4 Network Layer Addressing Definitions................ 5
3.5 Additional Definitions.............................. 5
4 SYMBOLS AND ABBREVIATIONS............................. 7
4.1 Data Units.......................................... 7
4.2 Protocol Data Units................................. 7
4.3 Protocol Data Unit Fields........................... 7
4.4 Parameters.......................................... 8
4.5 Miscellaneous....................................... 8
5 OVERVIEW OF THE PROTOCOL.............................. 9
5.1 Internal Organization of the Network Layer.......... 9
5.2 Subsets of the Protocol............................. 9
5.3 Addressing......................................... 10
5.4 Service Provided by the Network Layer.............. 10
5.5 Service Assumed from the Subnetwork Service
Provider.............................................. 11
5.5.1 Subnetwork Addresses............................. 12
5.5.2 Subnetwork Quality of Service.................... 12
5.5.3 Subnetwork User Data............................. 13
5.5.4 Subnetwork Dependent Convergence Functions....... 13
5.6 Service Assumed from Local Evironment.............. 14
6 PROTOCOL FUNCTIONS................................... 16
6.1 PDU Composition Function........................... 16
6.2 PDU Decomposition Function......................... 17
6.3 Header Format Analysis Function.................... 17
6.4 PDU Lifetime Control Function...................... 18
6.5 Route PDU Function................................. 18
6.6 Forward PDU Function............................... 19
6.7 Segmentation Function.............................. 19
6.8 Reassembly Function................................ 20
6.9 Discard PDU Function............................... 21
ISO DIS 8473 (May 1984) [Page i]
RFC 926 December 1984
6.10 Error Reporting Function.......................... 22
6.10.1 Overview........................................ 22
6.10.2 Requirements.................................... 23
6.10.3 Processing of Error Reports..................... 24
6.11 PDU Header Error Detection........................ 25
6.12 Padding Function.................................. 26
6.13 Security.......................................... 26
6.14 Source Routing Function........................... 27
6.15 Record Route Function............................. 28
6.16 Quality of Service Maintenance Function........... 29
6.17 Classification of Functions....................... 29
7 STRUCTURE AND ENCODING OF PDUS....................... 32
7.1 Structure.......................................... 32
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............................................ 36
7.2.6.1 Segmentation Permitted and More Segments Flags. 36
7.2.6.2 Error Report Flag.............................. 37
7.2.7 Type Code........................................ 37
7.2.8 PDU Segment Length............................... 37
7.2.9 PDUChecksum...................................... 38
7.3 Address Part....................................... 38
7.3.1 General.......................................... 38
7.3.1.1 Destination and Source Address Information... 39
7.4 Segmentation Part.................................. 40
7.4.1 Data Unit Identifier............................. 41
7.4.2 Segment Offset................................... 41
7.4.3 PDU Total Length................................. 41
7.5 Options Part....................................... 41
7.5.1 General.......................................... 41
7.5.2 Padding.......................................... 43
7.5.3 Security......................................... 43
7.5.4 Source Routing................................... 44
7.5.5 Recording of Route............................... 45
7.5.6 Quality of Service Maintenance................... 46
7.6 Priority........................................... 47
ISO DIS 8473 (May 1984) [Page ii]
RFC 926 December 1984
7.7 Data Part.......................................... 47
7.8 Data (DT) PDU...................................... 49
7.8.1 Structure........................................ 49
7.8.1.1 Fixed Part..................................... 50
7.8.1.2 Addresses...................................... 50
7.8.1.3 Segmentation................................... 50
7.8.1.4 Options........................................ 50
7.8.1.5 Data........................................... 50
7.9 Inactive Network Layer Protocol.................... 51
7.9.1 Network Layer Protocol Id........................ 51
7.9.2 Data Field....................................... 51
7.10 Error Report PDU (ER)............................. 52
7.10.1 Structure....................................... 52
7.10.1.1 Fixed Part.................................... 53
7.10.1.2 Addresses..................................... 53
7.10.1.3 Segmentation.................................. 53
7.10.1.4 Options....................................... 54
7.10.1.5 Reason for Discard............................ 54
7.10.1.6 Error Report Data Field....................... 55
8 FORMAL DESCRIPTION................................... 56
8.1 Values of the State Variable....................... 57
8.2 Atomic Events...................................... 57
8.2.1 N.UNITDATA_request and N.UNITDATA_indication..... 57
8.2.2 SN.UNITDATA_request and SN.UNITDATA_indication... 58
8.2.3 TIMER Atomic Events.............................. 59
8.3 Operation of the Finite State Automation........... 59
8.3.1 Type and Constant Definitions.................... 61
8.3.2 Interface Definitions............................ 65
8.3.3 Formal Machine Definition........................ 67
9 CONFORMANCE.......................................... 84
9.1 Provision of Functions for Conformance............. 84
ISO DIS 8473 (May 1984) [Page iii]
RFC 926 December 1984
ISO DIS 8473 (May 1984) [Page iv]
RFC 926 December 1984
INTRODUCTION
This Protocol 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 Systems
Interconnection (ISO 7498). In particular, it is a protocol of the
Network Layer. The Protocol herein described is a Subnetwork
Independent Convergence Protocol combined with relay and routing
functions as described in the Internal Organization of the Network
Layer (ISO iiii). This Protocol provides the connectionless-mode
Network Service as defined in ISO 8348/DAD1, Addendum to the Network
Service Definition Covering Connectionless-mode Transmission, between
Network Service users and/or Network Layer relay systems.
The interrelationship of these standards is illustrated in Figure 0-1
below:
______________OSI Network Service Definition______________
| ^
|
| |
Protocol Reference to aims __________|
|
Specification | Reference to assumptions ___
|
| |
|
| |
|
| v
______________Subnetwork Service Definition(s) ___________
Figure 0-1. Interrelationship of Standards
ISO DIS 8473 (May 1984)
