Information technology — Telecommunications and information exchange between systems — X.25 DTE conformance testing — Part 2: Data link layer conformance test suite

This part of ISO/IEC 8882 defines an abstract test suite for testing the conformance of the Data Link Layer of an IUT with respect to ISO/IEC 7776 (1986, 1995) or the ITU-T Recommendation X.25 (1980, 1984, 1988, 1993). Conformance of a Data Terminal Equipment (DTE) to the above ISO International Standard or ITU-T Recommendations is tested using a dedicated circuit between the tester and the DTE. It is noted that ITU-T Recommendations X.25 (1980), X.25 (1984), X.25 (1988) and X.25 (1993) are written from the perspective of a DCE and therefore do not always explicitly specify the DTE's operation. In such cases it is assumed that recommended operation of a DTE is included by implication because of the need to communicate with X.25 DCE's. This part of ISO/IEC 8882 excludes the testing of the LAP procedures given in the ITU-T Recommendations. NOTE Test cases for extended mode operation (Modulo 128), multilink procedure and DTE-DTE operation as per ISO/IEC 7776 are for further study. The tests in this part of ISO/IEC 8882 are designed for six possible interworking situations, shown in Figure 1. This part specifies tests for all six cases shown in Figure 1, but recognizes that not every test may apply to a particular DTE. A test selection procedure has to be performed to determine the applicability of a test to a particular DTE. Such selection will be based on the PICS and the PIXIT. Figure 1 — Testing X.25-DTE/DCE and X.25-DTE/DTE Interworking In the rest of this part of ISO/IEC 8882, the term "X.25 standards" means all four of ITU-T Recommendations X.25 (1980), X.25 (1984), X.25 (1988), X.25 (1993), and International Standards ISO/IEC 7776 (1995) and ISO/IEC 7776 (1986), unless stated otherwise.

Technologies de l'information — Télécommunications et échange d'information entre systèmes — Test de conformité X.25 DTE — Partie 2: Suite d'essais de conformité pour la couche liaison de données

General Information

Status
Published
Publication Date
31-May-2000
Current Stage
9093 - International Standard confirmed
Start Date
15-Sep-2005
Completion Date
15-Sep-2005
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INTERNATIONAL ISO/IEC
STANDARD 8882-2
Third edition
2000-04-15
Information technology —
Telecommunications and information
exchange between systems — X.25 DTE
conformance testing —
Part 2:
Data link layer conformance test suite
Technologies de l'information — Télécommunications et échange
d'information entre systèmes — Test de conformité X.25 DTE —
Partie 2: Suite d'essais de conformité pour la couche liaison de
données
Reference number
ISO/IEC 8882-2:2000(E)
ISO/IEC 2000
---------------------- Page: 1 ----------------------
ISO/IEC 8882-2:2000(E)
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ii © ISO/IEC 2000 – All rights reserved
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ISO/IEC 8882-2:2000(E)
Contents Page

1. SCOPE ....................................................................................................................................................................1

2. NORMATIVE REFERENCES..................................................................................................................................2

3. DEFINITIONS AND ABBREVIATIONS ..................................................................................................................2

3.1 REFERENCE MODEL DEFINITIONS..............................................................................................................3

3.2 CONFORMANCE TESTING TERMS...............................................................................................................3

3.3 X.25-DTE CONFORMANCE TESTING TERMS..............................................................................................4

3.4 ADDITIONAL DEFINITIONS ............................................................................................................................4

3.5 ABBREVIATIONS.............................................................................................................................................4

4. TEST SUITE INFORMATION..................................................................................................................................4

4.1 TEST SUITE STRUCTURE..............................................................................................................................4

4.2 DATA LINK LAYER TEST GROUPS AND SUBGROUPS...............................................................................5

4.3. METHOD FOR CONFORMANCE TESTING ..................................................................................................5

4.4 TEST CASE NOTATION ..................................................................................................................................5

4.5 PREAMBLE ......................................................................................................................................................6

4.6 VERIFICATION SEQUENCE ...........................................................................................................................6

4.7 IUT INITIATED ACTIONS ................................................................................................................................7

4.8 ACCEPTABLE UNEXPECTED IUT FRAMES .................................................................................................7

4.9 TRANSIENT STATES ......................................................................................................................................7

4.10 UNREACHABLE STATES..............................................................................................................................7

4.11 DECLARATIONS............................................................................................................................................7

4.12 ENCODING AND ORDER OF BIT TRANSMISSION ....................................................................................7

4.13 PIXIT PROFORMA.........................................................................................................................................8

4.14 CLASSIFICATION OF IUT .............................................................................................................................9

ANNEX A ABSTRACT TEST SUITE (ATS) .............................................................................................................10

A.1 THE TTCN GRAPHICAL FORM (TTCN.GR) ................................................................................................10

A.2 THE TTCN MACHINE PROCESSABLE FORM (TTCN.MP).........................................................................10

© ISO/IEC 2000 – All rights reserved iii
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ISO/IEC 8882-2:2000(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission)

form the specialized system for worldwide standardization. National bodies that are members of ISO 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. ISO and IEC technical committees

collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in

liaison with ISO and IEC, also take part in the work.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.

In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.

Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting.

Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this part of ISO/IEC 8882-2 may be the subject of

patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.

International Standard ISO/IEC 8882-2 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information

technology, Subcommittee SC 6, Telecommunications and information exchange between systems.

This third edition cancels and replaces the second edition (ISO/IEC 8882-2:1995), which has been technically

revised.

ISO/IEC 8882 consists of the following parts, under the general title Information technology — Telecommunications

and information exchange between systems — X.25 DTE conformance testing:
� Part 1: General principles
� Part 2: Data link layer conformance test suite
� Part 3: Packet layer conformance test suite
Annex A forms a normative part of this part of ISO/IEC 8882.
iv © ISO/IEC 2000 – All rights reserved
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ISO/IEC 8882-2:2000(E)
Introduction

This part of ISO/IEC 8882 presents the X.25-DTE Conformance Test Suite for Data Link Layer, described in Tree and Tabular

Combined Notation (TTCN).
ISO/IEC 8882-1 explains the objectives and usage of this part of ISO/IEC 8882.

Clause 1 of this part of ISO/IEC 8882-2 is the scope which provides an objective basis for the applicability of the tests within this

part of ISO/IEC 8882. Clauses 2 and 3 give the references, definitions and abbreviations used in this part of ISO/IEC 8882.

Clause 4 contains information relating to procedures performed in conformance testing. The test suite structure is defined in

terms of test groups and subgroups in Table 1. This clause also gives an overview of the test suite. Annex A provides

information on the Abstract Test Suite for the X.25-DTE LAPB Data Link Layer protocol both in TTCN GR and TTCN MP format.

© ISO/IEC 2000 – All rights reserved v
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INTERNATIONAL STANDARD ISO/IEC 8882-2:2000(E)
Information technology — Telecommunications and information
exchange between systems — X.25 DTE conformance testing —
Part 2:
Data link layer conformance test suite
1 Scope

This part of ISO/IEC 8882 defines an abstract test suite for testing the conformance of the Data Link Layer of an IUT with

respect to ISO/IEC 7776 (1986, 1995) or the ITU-T Recommendation X.25 (1980, 1984, 1988, 1993).

Conformance of a Data Terminal Equipment (DTE) to the above ISO International Standard or ITU-T Recommendations is

tested using a dedicated circuit between the tester and the DTE. It is noted that ITU-T Recommendations X.25 (1980), X.25

(1984), X.25 (1988) and X.25 (1993) are written from the perspective of a DCE and therefore do not always explicitly specify the

DTE's operation. In such cases it is assumed that recommended operation of a DTE is included by implication because of the

need to communicate with X.25 DCE’s. This part of ISO/IEC 8882 excludes the testing of the LAP procedures given in the ITU-T

Recommendations.

NOTE Test cases for extended mode operation (Modulo 128), multilink procedure and DTE-DTE operation as per ISO/IEC 7776 are for

further study.

The tests in this part of ISO/IEC 8882 are designed for six possible interworking situations, shown in Figure 1. This part

specifies tests for all six cases shown in Figure 1, but recognizes that not every test may apply to a particular DTE. A test

selection procedure has to be performed to determine the applicability of a test to a particular DTE. Such selection will be based

on the PICS and the PIXIT.
Local Station Remote Station
DTE DCE (X.25 LAPB 84)
(based on ISO/IEC 7776:1995) DTE (ISO/IEC 7776:1995)
DTE DCE (X.25 LAPB 84)
(based on ISO/IEC 7776:1986) DTE (ISO/IEC 7776:1986)
DTE DCE
(based on X.25 LAPB 93) (X.25 LAPB 93)
DTE DCE
(based on X.25 LAPB 88) (X.25 LAPB 88)
DTE DCE
(based on X.25 LAPB 84) (X.25 LAPB 84)
DTE DCE
(based on X.25 LAPB 80) (X.25 LAPB 80)
Figure 1 — Testing X.25-DTE/DCE and X.25-DTE/DTE Interworking
© ISO/IEC 2000 – All rights reserved 1
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ISO/IEC 8882-2:2000(E)

In the rest of this part of ISO/IEC 8882, the term "X.25 standards" means all four of ITU-T Recommendations X.25 (1980), X.25

(1984), X.25 (1988), X.25 (1993), and International Standards ISO/IEC 7776 (1995) and ISO/IEC 7776 (1986), unless stated

otherwise.
2 Normative references

The following standards contain provisions which, through reference in this text, constitute provisions of this part of

ISO/IEC 8882. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to

agreements based on this part of ISO/IEC 8882 are encouraged to investigate the possibility of applying the most recent

editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.

ISO/IEC 7498-1:1994, Information technology — Open Systems Interconnection — Basic Reference Model: The Basic Model.

(See also ITU-T Recommendation X.200)

ISO/IEC 7776:1995, Information technology — Telecommunications and information exchange between systems — High-level

data link control procedures — Description of the X.25 LAPB-compatible DTE data link procedures.

ISO/IEC 8824:1990, Information technology — Open Systems Interconnection — Specification of Abstract Syntax Notation One

(ASN.1).

ISO/IEC 8882-1:1996, Information technology — Telecommunications and information exchange between systems — X.25-DTE

conformance testing — Part 1: General principles.

ISO/IEC 9646-1:1994, Information technology — Open Systems Interconnection — Conformance testing methodology and

framework — Part 1: General concepts. (See also ITU-T Recommendation X.290)

ISO/IEC 9646-2:1994, Information technology — Open Systems Interconnection — Conformance testing methodology and

framework — Part 2: Abstract Test Suite specification. (See also ITU-T Recommendation X.291)

ISO/IEC 9646-3:1998, Information technology — Open Systems Interconnection — Conformance testing methodology and

framework — Part 3: The Tree and Tabular Combined Notation (TTCN).

ISO/IEC 9646-4:1994, Information technology — Open Systems Interconnection — Conformance testing methodology and

framework — Part 4: Test realization. (See also ITU-T Recommendation X.293)

ISO/IEC 9646-5:1994, Information technology — Open Systems Interconnection — Conformance testing methodology and

framework — Part 5: Requirements on test laboratories and clients for the conformance assessment process.(Seealso ITU-T

Recommendation X.294)

ITU-T Recommendations X.25 (1980), X.25 (1984), X.25 (1988), X.25 (1993), Interface between Data Terminating Equipment

(DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to the public

data networks by dedicated circuit.
3 Terms, definitions and abbreviations

For the purposes of this part of ISO/IEC 8882, the terms and definitions given in 3.4 and in the following International Standards

apply:
a) ISO/IEC 7498-1;
b) ISO/IEC 9646;
c) ISO/IEC 8882-1.
2 © ISO/IEC 2000 – All rights reserved
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ISO/IEC 8882-2:2000(E)
3.1 Reference model terms
The following terms defined in ISO/IEC 7498-1 are used:

a) (N)-protocol data unit (N-PDU). In the context of this part of ISO/IEC 8882-2. (N) is layer 2 and so N-PDU is abbreviated to

PDU. A PDU in the Data Link Layer is also referred to as a "frame".
b) Data Link Layer
3.2 Conformance testing terms

The following terms are used from the Conformance Testing Methodology and Framework, International Standard

ISO/IEC 9646:
a) Conformance Testing
b) Conformance Test Suite
c) Implementation Under Test (IUT)
d) Protocol Implementation Conformance Statement (PICS)
e) Protocol Implementation Extra Information for Testing (PIXIT)
f) Static Conformance Requirements (SCR)
g) Behavior Testing
h) Test Purpose
i) Tree and Tabular Combined Notation (TTCN)
j) Preamble
k) Test Body
l) Test Step
m) Test Event
n) Abstract Service Primitive (ASP)
o) Test Group
p) Abstract Test Suite (ATS)
q) Executable Test Suite (ETS)
r) Test Verdicts
s) Lower Tester
t) Upper Tester
u) Test Methods
v) Remote Single (layer) Test Method (RS method)
w) Valid Test Event
x) Invalid Test Event
y) Inopportune Test Event
z) Point of Control and Observation (PCO)
© ISO/IEC 2000 – All rights reserved 3
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ISO/IEC 8882-2:2000(E)
3.3 X.25-DTE conformance testing terms

This part of ISO/IEC 8882-2 makes use of the following terms defined in ISO/IEC 8882-1:

a) Improper PDU
b) Proper PDU
c) Test Case
d) Test Subgroup
e) Tester
3.4 Additional terms and definitions

This test suite uses test subgroups for proper, improper and inopportune frames to test the IUT behavior. These terms are

defined below.
3.4.1
improper frame
frame that satisfies one or more of the following conditions:
a) it is not properly bounded by two flags;
b) it contains fewer than 32 bits between flags;
c) it contains a Frame Check Sequence (FCS) error;
d) it contains an invalid address field encoding;

e) it contains a command or response control field encoding that is undefined or not implemented in X.25-DTE LAPB Data

Link Layer protocol as specified in ISO/IEC 7776;
f) it is an I frame exceeding the maximum established frame length;

g) it is an unnumbered or supervisory frame with an information field which is not permitted;

h) it is a frame with an invalid N(R)
3.4.2
inopportune frame

syntactically valid frame arriving at a time (DTE's state) when it should be considered irrelevant by the DTE. Syntactically v

...

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