ISO/IEC 8878:1992
(Main)Information technology — Telecommunications and information exchange between systems — Use of X.25 to provide the OSI Connection-mode Network Service
Information technology — Telecommunications and information exchange between systems — Use of X.25 to provide the OSI Connection-mode Network Service
For a protocol to support the CONS, there must be a mapping between the abstract primitives and parameters of the CONS and the real elements of the protocol. For the X.25 Packet Layer Protocol (PLP), the main body of this standard provides such a mapping for the X.25/PLP-1984 using Virtual Calls. Also provides a mapping of the CONS primitives and parameters to the X.25/PLP-1980 plus an SNDCP. These mappings apply to the X.25 VC service. Specifies two sets of procedures from which three classes of implementation are described.
Technologies de l'information — Télécommunications et échange d'informations entre systèmes — Utilisation du protocole X.25 pour fournir le service de réseau OSI en mode connexion
General Information
Relations
Standards Content (Sample)
INTERNATIONAL lSO/IEC
STANDARD
Second edition
1992-I 2-l 5
Information technology -
Telecommunications and information
exchange between systems - Use of X.25
to provide the OSI Connection-mode
Network Service
- T6lkommunications et khange
Technologies de I’informa tion
en tre s ys t&mes - Utilisation du protocole X.25 pour
d ‘in formations
fournir le service de r&eau OSI en mode connexion
Reference number
lSO/IEC 88783 992(E)
SO/l EC 8878: 1992(E) 0 ISO/IEC
CONTENTS Paae
WA
Foreword. . . . . . . n l . l l . l l l l . . . . . . . . . . . . . . . iv
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
1. Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Normative references . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Identical Recommendations 1 International Standaids. . . . . .
2.2 Paired Recommendations 1 International Standards equi.valent.in &hni’ca~content . . . . . .
2.3 Additional references . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . .
3. Definitions . . . . . . . . .
3.1 Referendehnodelbe;inition’s . . . . . . . . . . . . . . . . . . . . . . .
3.2 Service Conventions definitions . . . . . . . . . . . . . . . . . . . . . .
3.3 Network Service definitions l . . . . . . . . . l . . l l . l l . . . . . .
3.4 X.25 definitions . . . . . . . . . . . . . l l l l l . . . l . l . . . .
3.5 X.96 definitions l l l . l l . . l l l l . . l l . . l . l l . . . l . .
4. Abbreviations l l l l . . . . . l m . l l . l l l l l .
. . 3
4.1 Network Semwide abbeviatibns . l . l . . . . l . . . . l . . l . . . . . .
4.2 X.25 abbreviations . l l l . l . l l l l . l l l l l l . l l l l . l . .
5. Overview. . l . l l l l l l l l l l . . l l l l l l l l l l l l . . . .
5.1 Elements Of the X.25/PLP-I984 USed tO SUppOe the OSI CONS . . . . . l l l . . . .
5.2 General operation of the X.25/PLP-1984 for supporting the OSI CONS . . . . . l . . . .
6. Network connection establishment phase . . . . . . . . . l . . . . . l . l l . .
6.1 Primitive/Parameter and packet/field relationships . . . . . . . . . l l . . . . l
6.2 Procedures l l l l l l l l l l . l l l l . l l l l l . l . . . . . l
7. Networkconnection release phase . l . l . . l . . . l . . l . . l . l . . . .
7.1 Primitive/Parameter and packet/field relationships . . . . . . . . . . . . . . . l
7.2 Procedures l l l l l l l l l l . l l . . . l l l l l l l l . l l . .
8. Data transfer phase- Data transfer service . . . . l . . l . . . . l l . l . l . l 17
8.1 Primitive/Parameter and packet/field relationships . . . l . . . . l . l . . . . . 17
8.2 Procedures . . l l l . m l l l l . . . . l l l l l l l l l l l . . . 17
9. Data transfer phase - Receiptconfirmationsewice . . . . . . . . . . . l . l . l l 18
9.1 Primitive and packet/field relationships l l . . . . . . . . . . . l l . l l l . 18
9.2 Procedures . . l . . . . . l . . . . . l l l l l . . . l l . . l . . 18
10. Data transfer phase - Expediteddatatransferservice . . . . l . . . . . . . l l . l . 19
10.1 Primitive/Parameter and packet/field relationships . . . l . . . . l l l . . l . . 19
10.2 Procedures l l . l l l m l l . . l . . l l . l l . . l m l l l l . . 19
11. Data transfer phase - Reset service l l l l . . 8 . . l . l . l l l
11 .I Primitive/Parameter and packet/field relatibnships . . l l l . . . . . . . l . l . l
Il.2 Procedures . . m l l l l l l l . l . . l l l l . . l l l l l l l . l
0 ISO/lEC 1992
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
ISO/lEC Copyright Office l Case postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
o ISO/IEC
lSO/IEC 8878:1992(E)
12. Response to protocol violations . . . . . . . . . . . l . . . . l .
. . . . . . 21
13. Conformance
. . l l . . .
. . . . l l .
13.1 Conformance &&em% . l l . . . . . . . . . . . 1 1 1 1 l l . . l . 22
l l . . . .
.
13.2 Optional features . . . . . . . . . l . l
. . . .
. . . . l l l l
. . . 22
Annex A: X.25 (1980) Subnetwork Dependent Convergence Protocol . . . . . . . l l . . . . 23
A.1 Introduction . . . . . . . . . l . . . .
A.2 Scope . . . . . . . . . . . . l l . . l . l . . l . . . l . . l l . 23
. .
. . . . . . . . . .
. . .
A.3 Abbreviations
. . . . . . . l . .
A.4 Overview of the pro&l . . . . . . l l . . : . . . . . . . . . . . . . . 24
A.5 Protocol mechanisms . . . . . . . . . . . . : . . . . . . . . . . . . . 26
. . . . . . . . . . . .
.
A.6 Protocol description
. l l l l l l .
. . . . . 0 . . . . . . .
. 38
A.7 Protocol encoding in X.25 packeis . . . . l . . . . . . . . . . . . . . . . . 48
Annex B: Classification . . . . . . . . . l . l .
l
B.1 Classification of systems . . . . l . l l . . : : : . l . l l l l . . l l l 54
B.2 Functionality of classes . . . . . . l l l l . .
. . . l l . . l . . . . l . . . . 54
. . . . . 0 . .
B.3 Scenarios . . . . . . . l .
. l l l l . . .
8.4 Procedures for selecting class of operation . l l . . . . . : : : l . l . . . . . 55
l l . . . . . .
B.5 lntenworking by relay system . . l . . . . . l . . .
. . .
. . . . . . 0 . 55
Annex C: Subnetwork Convergence Protocol for Use With X.25 Permanent Virtual Circuits
. l . . . .
C.l Introduction and scope . . . . . . . . l . . . l
. . . . l l
. . . . . . 58
C.2 OveMew . . . . . . l . . . .
C.3 Abbreviations . . . . . . . l . . : : : . . . . . l l l . . . . D . 58
. . . . l l . . . .
. . . .
C.4 Protocol mechanisms
. . . . . . l l . .
C.5 Protocol encoding for NC establishment and .rel&e . . . . . . . . . . : : : : : : 60
Annex 0: Protocol Implementation Conformance Statement Proforma
. . . . . . . . . .
. . . 62
D.1 Introduction . . . . . . . . . l . . . .
. . l l l l . . . .
. . . 62
0.2 Scope . . . . . . . . . l . . . l
l . . . l . . l l l . . .
. . . . 62
0.3 Normative references . . l l l l l . . l l I
. . . . . l . . l
. . . . . . 62
0.4 Definitions . . . . . . l l . l .
l l . . . . l l l l . .
. . . . . 62
D.5 Abbreviations .
. . . l l l l
. . . . . . 63
D.6 Protocol Implementation Ccnforr&ce.State&t Proforma.
l . . l l l l
. . . . . . 64
0.7 Modified PICS requirements for ISO/IEC 8208 . . . . .
l . . l l l l
l l . . . . 76
Annex E: Additional Considerations of CONS Primitives . . . . . . . . l . . . . .
.
. . . 83
E.l Introduction . . . . . . l l l l l l
. . . .
E.2 Environment for X.25/PLP operation . l . . . l . l l : : : : l . l l . . l l 83
. . . . .
l l .
Annex F: Use of X.25/PLP NPAI l l . l . l l l . l . . . . l l . l . . . . . . . 85
F.l Introduction . . . . l l . . . . . l . .
F.2 Obtaining an SNPA address . . l . . . l . . : : : : : : l l . l . . . . . 85
F.3 Examples of Network Address encoding . . . . l l l l . l . : I : : : . . . l 85
. . . l
Annex G: Transit Delay Calculations . . . . . l l . m l l . . . . .
l .
. . . . . l 87
Annex HZ Example of Priority Negotiation . . l . . l . l . . l l l l . .
.
. . . . . . 89
Annex I: Differences between Recommendation X.223 and ISO/IEC 8878 . . . . . . . l . . . . 81
0 ISOAEC
ISOAEC 8878:1992( E)
Foreword
IS0 (the International Organization for Standardization) and IEC (the Inter-
national Electrotechnical Commission) form the specialized system for
worldwide standardization. National bodies that are members of IS0 or
IEC participate in the development of International Standards through
technical committees established by the respective organization to deal
with particular fields of technical activity. IS0 and IEC technical commit-
tees collaborate in fields of mutual interest. Other international organiz-
ations, governmental and non-governmental, in liaison with IS0 and IEC,
also take part in the work.
In the field of information technology, IS0 and IEC have established a joint
technical committee, lSO/IEC JTC 1. Draft International Standards adopted
by the joint technical committee are circulated to national bodies for vot-
ing. Publication as an International Standard requires approval by at least
75 % of the national bodies casting a vote.
International Standard lSO/IEC 8878 was prepared by Joint Technical
’ Committee lSO/IEC JTC 1, Information technology.
This second edition cancels and replaces the first edition
which has been technically revised. It consolidates
(IS0 8878:1987),
Technical Corrigenda 1, 2 and 3, Addenda 1 and 2 and Amendment 1 as
well as Technical Corrigendum 1 to Addendum 2.
NOTE - lSO/lEC DIS 8878-2 as well as defect reports 8878-012, 013,
014 and 015 have also been included in this second edition.
Annexes A, B, C and D form an integral part of this International Standard.
Annexes E, F, G, H and I are for information only.
0 ISO/IEC ISOAEC 8878:1992( E)
Introduction
This International Standard defines methods for providing the OSI Connection-Mode Network Service (CONS)
through the use of the virtual circuit services of the X.25 Packet Layer Protocol (X.25 PLP). The method presented
in the main body of this International Standard specifies a mapping between elements of the 1984 or later versions
of the X.25/PLP (referred to as X.25/PLP-1984) using X.25 Virtual Call (VC) services and elements of the OSI
CONS. Features associated with versions of X.25 later than 1984 are identified as to which version they relate.
This International Standard is similar to CCITT Recommendation X.223; however, the two are currently published
as separate documents.
Clause 13 contains the requirements for systems claiming conformance to this International Standard.
Other methods using other virtual circuit services and/or other versions of X.25 are also defined. In particular, a
second method for VCs, which is presented in Annex A, defines a Subnetwork Dependent Convergence Protocol
(SNDCP) that shall be used to provide the OSI CONS over subnetworks or with equipment using the 1980 or
earlier versions of the X.25/PLP (referred to as X.25/PLP-1980). This SNDCP should only be used if the elements
of the X.Z5/PLP-1984, as defined in 5.1 herein, are not available to support the OSI CONS. Annex B contains a
classification of systems according to whether they implement the procedures defined in the main body of this
International Standard, the procedures defined in Annex A, or both. In addition, it describes the possibilities and
the rules for interworking between the classes of equipment identified.
Annexes A and B are integral parts of this International Standard. They are intended to provide a migration
strategy towards the use of the 1984 version of X.25 in both subnetworks and DTEs. Because of the evolution of
technology, the status of Annexes A and B will be reviewed in the future.
Annex C defines another method for providing the OSI CONS, in this case in conjunction with the PVC sewice of
X.25.
Annex D provides the Protocol Implementation Conformance Statement (PICS) Proforma for this International
Standard.
Annexes C and D are integral parts of this International Standard.
Annex E provides additional considerations on the relationship between the X.25 protocol procedures and the
CONS primitives.
Annex F illustrates the use of X.25 Network Protocol Address Information (NPAI), i.e., the Address Field and the
Address Extension Facilities.
Annex G illustrates the use of the X.25 transit delay facilities.
Annex H illustrates the use of the X.25 Priority Facility.
Annex I lists the differences between CCITT Rec. X.223 and lSO/IEC 8878.
Annexes E through I are not integral parts of this International Standard.
The relationship between the X.25/PLP-1984 and the OSI CONS is shown in Figure 1. This relationship is
described only in terms of the Network Layer entities that provide the CONS. No discussion is given here to
describe the actions of a Network Layer entity that only provides a relay function for a given network connection.
The OSI Network Service is defined in terms of
a) the primitive actions and events of the Service;
b) the parameters associated with each primitive action and event, and the form which they take;
c) the interrelationship between, and the valid sequences of, these actions and events.
ISOAEC 8878:1992(E) 0 ISOAEC
TRANSPORT
TRANSPORT -------USESSERVICE--------:
c
PROTOCOL
I
LAYER
I
I
V
NETWORK SERVICE
A
X.25 PACKET I
NETWORK
LAYER
LAYER
-------
PROVIDES SERVICE - - - - - 1
PROTOCOL
Figure 1 - Relationship of the X.25 Packet Layer Protocol to the OSI Connection-Mode Network Service
The OSI Network Service does not specify individual implementations or products nor does it constrain the
implementation of entities and interfaces within a computer system.
The X.25/PLP-1984 is defined in terms of
a) procedures for Virtual Calls and Permanent Virtual Circuits;
b) formats of packets associated with these procedures;
c) procedures and formats for optional user facilities and CCIlTSpecified DTE facilities.
The use of the word “Network” to name the “Network” Layer of the OSI Reference Model should be distinguished
from the use of the word “network” to denote a communications network as conventionally understood. To
facilitate this distinction, the term “subnetwork” is used for a collection of physical equipment, commonly called a
“network” (reference CCITT Rec. X.200 1 IS0 7498). Subnetworks may be either public or private networks. In
the case of public networks, their properties may be determined by separate CCITT Recommendations such as
CCllT Rec. X.21 for a circuit-switched network or CCIlT Rec. X.25 for a packet-switched network.
Throughout the set of OSI-related Recommendations 1 International Standards, the term “Service” refers to the
abstract capability provided by one layer of the OSI Reference Model to the layer above it. Thus, the Network
Service is a conceptual architectural Service, independent of administrative divisions.
It is important to distinguish the specialized use of the term “Service” within the set of OSI-related
NOTE -
Recommendations 1 international Standards from its use elsewhere to describe the provision of a service by an organization
(such as the provision of a service, as defined in CCllT Recommendations, by an Administration).
vi
INTERNATIONAL STANDARD 0 ‘sunEC
ISOIIEC 8878:1992(E)
Information technology -
Telecommunications and
information exchange between sys
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.