Information technology — Telecommunications and information exchange between systems — X.25 DTE conformance testing — Part 3: Packet layer conformance test suite

This part of ISO/IEC 8882 specifies a set of abstract tests for verifying that the implementation of X.25 protocols for use by Data Terminal Equipment (DTE), conforms to the requirements of International Standards that specify those protocols. Testing of a DCE is not subject of this test suite. Testing of a DTE in DCE mode is covered in test group 28 of this test suite a) specifies a PIXIT proforma; b) describes the relationship of the PICS to the test suite, c) describes the relationship of the PIXIT to the test suite, d) specifies a set of abstract tests using TTCN Graphical notation. This part of ISO/IEC 8882 defines the testing of a DTE operating at the packet layer designed to access a public or private packet-switched network conforming to CCITT respectively ITU-T Recommendation X.25 (1980, 1984, 1988, 1993) or another DTE conforming to ISO 8208. The specification of test cases in executable/machine processable TTCN is outside the scope of this part of ISO/IEC 8882.

Technologies de l'information — Télécommunications et échange d'information entre systèmes — Test de conformité X.25 DTE — Partie 3: Suite d'essais de conformité pour la couche paquet

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
Ref Project

RELATIONS

Buy Standard

Standard
ISO/IEC 8882-3:2000 - Information technology -- Telecommunications and information exchange between systems -- X.25 DTE conformance testing
English language
779 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

INTERNATIONAL ISO/IEC
STANDARD 8882-3
Third edition
2000-04-15
Information technology —
Telecommunications and information
exchange between systems — X.25 DTE
conformance testing —
Part 3:
Packet layer conformance test suite
Technologies de l'information — Télécommunications et échange
d'information entre systèmes — Test de conformité X.25 DTE —
Partie 3: Suite d'essais de conformité pour la couche paquet
Reference number
ISO/IEC 8882-3:2000(E)
ISO/IEC 2000
---------------------- Page: 1 ----------------------
ISO/IEC 8882-3:2000(E)
PDF disclaimer

This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not

be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this

file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this

area.
Adobe is a trademark of Adobe Systems Incorporated.

Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters

were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event

that a problem relating to it is found, please inform the Central Secretariat at the address given below.

© ISO/IEC 2000

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 either ISO at the address below or ISO's member body

in the country of the requester.
ISO copyright office
Case postale 56 � CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 734 10 79
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO/IEC 2000 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC 8882-3:2000(E)
Contents Page

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

2. NORMATIVE REFERENCES..................................................................................................................................1

3. DEFINITIONS ..........................................................................................................................................................2

4. ABBREVIATIONS ...................................................................................................................................................3

5. CONFORMANCE ....................................................................................................................................................3

6. TEST SUITE INFORMATION..................................................................................................................................3

6.1 PACKET LAYER TEST SUITE STRUCTURE .................................................................................................3

6.2 PACKET LAYER INITIALIZATION...................................................................................................................4

6.3 DTE-INITIATED ACTIONS...............................................................................................................................6

6.4 TIMER DEFINITIONS.......................................................................................................................................6

6.5 CAUSE CODES AND DIAGNOSTIC CODES..................................................................................................6

6.6 FACILITY FIELDS ............................................................................................................................................7

6.7 DATA TRANSFER STATES.............................................................................................................................7

6.8 OTHER USER DATA FIELDS..........................................................................................................................7

6.9 TRANSIENT STATES ......................................................................................................................................7

6.10 RELATIONSHIP OF PICS TO TEST SUITE..................................................................................................7

6.11 RELATIONSHIP OF PIXIT TO TEST SUITE .................................................................................................8

6.12 TEST CASE SELECTION ..............................................................................................................................8

6.13 PIXIT PROFORMA.........................................................................................................................................8

6.14 ACCEPTABLE UNEXPECTED RESPONSES.............................................................................................18

6.15 IMPLICIT SEND............................................................................................................................................18

6.16 ENCODING AND ORDER OF BIT TRANSMISSION ..................................................................................18

6.17 BASIC INTERCONNECTION TESTS ..........................................................................................................18

ANNEX A ABSTRACT TEST SUITE (ATS) .............................................................................................................19

A.1 THE TTCN GRAPHICAL FORM (TTCN.GR) ................................................................................................19

A.2 THE TTCN MACHINE PROCESSABLE FORM (TTCN.MP).........................................................................19

© ISO/IEC 2000 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/IEC 8882-3:2000(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 8882-3 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 8882-3 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 8882-3:1995), 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
---------------------- Page: 4 ----------------------
ISO/IEC 8882-3:2000(E)
Introduction

This part of ISO/IEC 8882 specifies a set of tests to evaluate Data Terminal Equipment (DTE) conformance to

International Standards ISO 7776:1986, ISO 7776:1995 (X.25 LAPB) and/or ISO 8208:1987, ISO 8208:1990,

ISO 8208:1995 (X.25 Packet Layer). ISO 7776 (1986,1995) and ISO 8208 (1987,1990, 1995) allow for a DTE to

interface with a Data Circuit-Terminating Equipment (DCE) conforming to CCITT respectively ITU-T

Recommendation X.25 or to another DTE conforming to ISO 7776 (1986,1995) and/or ISO 8208 (1987,1990, 1995)

also allows for connection to Local Area Networks.

CCITT respectively ITU-T Recommendation 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 explicitly specify the DTE operation. However, recommended operation

of DTEs is included by implication because of the need to communicate with X.25 DCEs. Tests within this part of

ISO/IEC 8882 pertaining to X.25 1980, X.25 1984, X.25 1988 and X.25 1993 are based on the DTE operational

characteristics implied by CCITT X.25 respectively ITU-T X.25.

This part of ISO/IEC 8882 presents the packet layer aspects for evaluating conformance to ISO 8208 (1987, 1990,

1995) and follows the procedures and guidelines defined in ISO/IEC 9646.

Where it is claimed that X.25 is used to provide the OSI Network Layer Service, the conformance tests as defined

in this part of ISO/IEC 8882 can be used to verify the implementation of the necessary protocol elements.

The test suite is presented in an abstract form by means of the test case notation TTCN, as defined in

ISO/IEC 9646-3. This is an abstract set of tests. Not every test applies to every public network or every type of

DTE.
© ISO/IEC 2000 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO/IEC 8882-3:2000(E)
Information technology — Telecommunications and information
exchange between systems — X.25 DTE conformance testing —
Part 3:
Packet layer conformance test suite
1 Scope

This part of ISO/IEC 8882 specifies a set of abstract tests for verifying that the implementation of X.25 protocols for use by Data

Terminal Equipment (DTE), conforms to the requirements of International Standards that specify those protocols.

Testing of a DCE is not subject of this test suite. Testing of a DTE in DCE mode is covered in test group 28 of this test suite

a) specifies a PIXIT proforma;
b) describes the relationship of the PICS to the test suite,
c) describes the relationship of the PIXIT to the test suite,
d) specifies a set of abstract tests using TTCN Graphical notation.

This part of ISO/IEC 8882 defines the testing of a DTE operating at the packet layer designed to access a public or private

packet-switched network conforming to CCITT respectively ITU-T Recommendation X.25 (1980, 1984, 1988, 1993) or another

DTE conforming to ISO 8208. The specification of test cases in executable/machine processable TTCN is outside the scope of

this part of ISO/IEC 8882.
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 8208:1987, Information processing systems — Data communication — X.25 Packet Layer Protocol for Data Terminal

Equipment.

ISO/IEC 8208:1990, Information technology — Data communication — X.25 Packet Layer Protocol for Data Terminal

Equipment.

ISO/IEC 8208:1995, Information technology — Data communication — X.25 Packet Layer Protocol for Data Terminal

Equipment.

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 8886:1992, Information technology — Telecommunications and information exchange between systems — Data link

service definition for Open Systems Interconnection.

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 2000 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/IEC 8882-3:2000(E)

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)

CCITT Recommendation X.25 (1980), X.25 (1984), and X.25 (1988), Interface between Data Terminating Equipment (DTE) and

Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode on the public data networks.

ITU-T Recommendation 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 and definitions
3.1 Reference model terms
This part of ISO/IEC 8882 makes use of the following term defined in ISO 7498.
a) (N)-protocol-data-unit (N-PDU)
3.2 Conformance testing terms

This part of ISO/IEC 8882 makes use of the following terms defined in ISO/IEC 9646

a) Abstract Test Suite
b) Conforming System or Implementation
c) Conformance Test Suite
d) Conformance Testing
e) Executable Test Suite
f) Postamble
g) Preamble
h) Protocol Implementation Conformance Statement
i) Protocol Implementation eXtra Information for Testing
j) Test Group
k) Test Step
l) Test Suite
3.3 X.25 DTE conformance testing terms

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

a) Improper PDU
b) Inopportune PDU
c) Proper PDU
d) Test Subgroup
e) Test Selection
f) Tester
g) Transient States
2 © ISO/IEC 2000 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/IEC 8882-3:2000(E)
3.4 Additional terms and definitions

For the purposes of this part of ISO/IEC 8882, the following terms and definitions apply.

3.4.1
proper packet
packet that is a proper PDU
3.4.2
improper packet
packet that is an improper PDU
3.4.3
inopportune packet
packet that is an inopportune PDU
4 Abbreviations
The following abbreviations are used in this part of ISO/IEC 8882.
ADX Address
ASP Abstract Service Primitive
ATS Abstract Test Suite
ETS Executable Test Suite
FAC Facility
IUT Implementation Under Test
LCI Logical Channel Identifier
LEN Length
PCO Point of Control and Observation
PDU Protocol Data Unit
PICS Protocol Implementation Conformance
PIXIT Protocol Implementation eXtra Information for Testing
PKT Packet
PLG Packet Layer Group
RX Receive
TST Tester
TX Transmit
UDF User Data Field
5 Conformance

The test realizer shall comply with the requirements of ISO/IEC 9646-4. In particular, these concern the realization of an ETS

based on the ATS. Test laboratories running conformance test services for this abstract test suite shall comply with

ISO/IEC 9646-5.
6 Test suite information
6.1 Packet layer test suite structure
The packet layer tests are grouped as shown in Table 1.
© ISO/IEC 2000 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO/IEC 8882-3:2000(E)
Table 1 — Packet layer test groups
Test Group # Packet layer test Test group # Packet layer test groups
groups
1 R1 - Packet Layer 15 I2 - DTE Interrupt Sent
Ready
2R2-DTERestart 16 J1 - DXE Interrupt Ready
Request
3 R3 - DXE Restart Ind 17 J2 - DXE Interrupt Sent
4 P1 - Ready 18 F1 - DXE Receive Ready
5 P2 - DTE Call Request 19 F2 - DXE Receive Not Ready
6 P3- DXE IncomingCall 20 G1- Receive Ready
7 P4 - Data Transfer 21
G2 - DTE Receive Not Ready
8 P5 - Call Collision 22 Data Transfer
9 P6 - DTE Clear Request 23 Timer Tests
10 P7 - DXE Clear 24 Address
Indication
11 D1 - Flow Control 25 Facility
Ready
12 D2 - DTE Reset 26 Registration
Request
13 D3 - DXE Reset Ind 27 Multiple Logical Channel Asg
14 I1 - Interrupt Ready 28 DTE/DTE Tests
This group has been deleted, but the number has been retained for consistency.

For each test group that tests a packet layer state (PLG1 through PLG28) the test cases specified are categorized into the

following three subgroups.

• Subgroup 1 contains test cases in which the Tester transmits a proper test packet, these test cases are identified with a one

hundred series test case identifier xx_1xx.

• Subgroup 2 contains test cases in which the Tester transmits an improper test packet, these test cases are identified with a

two hundred series test case identifier xx_2xx.

• Subgroup 3 contains test cases in which the Tester transmits an inopportune test packet, these test cases are identified with

a three hundred series test case identifier xx_3xx.
6.2 Packet layer initialization

In accordance with ISO 8208 (1987, 1990, 1995) the DTE must transmit a Restart Request whenever link layer initialization has

completed. However, DTEs developed in conformance with the 1980, 1984, 1988, and 1993 versions of Recommendation X.25

are not required to send a Restart Request at this time. To accommodate both DTE implementations, the Tester initiates the

restart procedure upon completion of link layer initialization.

The Tester will accept either a Restart Confirmation or a Restart Request as a valid response to its Restart Indication as shown

below in example EG_001. Packet layer initialization always occurs once at the start of a test session. State initialization, on the

other hand, is performed many times during a test session as part of each test case. Packet layer initialization will also occur as

part of state initialization when the previously executed test case results in a Fail or Inconclusive verdict, or the previously

executed test case is part of PLG 1, 2, 3, 26 or in test groups in which the Restart procedure is executed as part of state

initialization (PLG 1, 2, 3 and 26).

The following are examples of initialization of ISO 8208 over ISO 7776 (LAPB). Any other examples of initialization sequences

using other underlying protocols are not shown, but may be appropriate. For example, normal state initialization steps in state r1

(PLG 1) are as shown in Table 2.

For those DTEs which disconnect the link upon receipt of a Restart Indication (or transmittal of a Restart Request) the state

initialization steps include link layer initialization as shown in Table 3.
4 © ISO/IEC 2000 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/IEC 8882-3:2000(E)
Table 2 — Test Case Dynamic Behavior
Test Case Name: EG_001
Group: Example Test Step / Packet Layer Initialization
Purpose: An example test step illustrating Packet Layer Initialization
Default:
Comments:
Nr Label Dynamic Behavior Constraint Ref Verdict Comments
1 ! Restart_Indication START TD STRT_DCE 1
2 ? Restart_Confirmation CANCEL TD STRTC
3 ? Restart_Request CANCEL TD STRT_DTEA
4?TIMEOUTTD FAIL4
5?OTHERWISE FAIL

Detailed Comments: 1. The Restart Indication is sent upon successful initialization of the Data Link

Layer.
4. TD expired.
Table 3 — Test Step Dynamic Behavior
: EG_002
Test Case Name
: Example Test Step / Packet Layer Initialization / Link Layer Initialization
Group

: An example test step Illustrating Packet Layer Initialization that includes Data Link

Objective
Layer Initialization
Default
: a) L is the PCO at the Tester Packet Layer to Link Layer interface.
Comments
: b) D is the PCO at the Link Layer to Physical Interface.

: c) This example uses the Multi-Layer testing method, the Packet Layer Test Suite

only uses the Remote Single-layer test method.
Nr Label Dynamic Behavior Constraint Ref Verdict Comments
1 EG_002 [L,D]
2 L! Restart Indication START TD STRT_DCE
3 L? Restart Confirmation START TD STRTC
4 D? Dlsconnect CANCEL TD DISC_1 4
5 + LINK_INIT
6L?TIMEOUTTD 6
7 L? Restart_Request START TS STRT_DTEA
8 D? Disconnect CANCEL TD DISC_1
9 + LINK_INIT
10 L? TIMEOUT TD FAIL
11 L? TIMEOUT TD FAIL
12 L? OTHERWISE FAIL
13 LINK_INIT
14 D! UA UA_DCE 14
15 D? SABM SABM1 15
16 D! UA UA_DCE 14
17 L! Restart_Indication START TD STRT_DCE
18 L? Restart_Confirmation CANCEL TD STRTC
19 L? Restart_Request CANCEL TD STRT_DTEA
20 L? TIMEOUT TD FAIL
21 L? OTHERWISE CANCEL TD FAIL
Detailed Comments: 4Wait for DISC
6TDexpired
14 Send UA
15 Wait for SABM
© ISO/IEC 2000 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/IEC 8882-3:2000(E)
6.3 DTE-initiated actions

DTE-initiated actions specified by the test suite are handled using the Implicit Send mechanism defined in ISO/IEC 9646-3. The

ability of the IUT to perform these actions, and its ability to execute the tests containing the actions is determined by the

information provided in the PIXIT and the PICS.
6.4 Timer definitions
This part of ISO/IEC 8882 defines the following timers:

TR the time required by the IUT to resume testing after completion of the Restart procedure. The duration is provided in

PIXIT question 1.18a and contained in the test suite parameter TR_DELAY;

TC the time required by the IUT to testing after completion of the Clear procedure. The duration is provided in PIXIT question

1.18b and contained in the test suite parameter TC_DELAY;

TS the time required by the IUT to resume testing after completion of the Reset procedure The duration is provided in PIXIT

question 1.18c and contained in the test suite parameter TS_DELAY;

TD the time the Tester waits before determining that the IUT will not respond to a Tester stimulus. For example, how long

the Tester should wait before assuming that the IUT has either discarded or failed to respond to the stimulus. TD must be less

than all other timers specific to ISO 8208, i.e. T20 through T28. The duration is calculated by the formula contained in the PIXIT

question 1.23 (TD = 2 * TD_RESPONSE + MAX(TO_R3, TO_P3, TO_P7, TO_D3, TO_J2) and contained in the test suite

parameter TD_WAIT_TIME;

TD_RESP the maximum time that the tester should wait for an immediate response from the IUT to a tester stimulus. The

duration is provided in PIXIT question 1.20 and contained in TD RESPONSE;

TDEL is a tolerance used in testing timers T20 - T28 of the base standard. The duration is provided in PIXIT question 1.21 and

contained in the test suite parameter TDELTA. The duration considers the round trip transit delay between the Tester and I UT,

and the time necessary for an IUT to respond to a received packet or timer expiry;

TO_R3 is the minimum time that the IUT remains in state R3. The duration is provided in PIXIT question 1.22 and contained

in TO_DELAY_R3_ MIN;

TO_P3 is the minimum time that the IUT remains in state P3. The duration is provided in PIXIT question 1.22 and contained

in TO_DELAY_P3_ MIN;

TO_P7 is the minimum time that the IUT remains in state P7. The duration is provided in PIXIT question 1.22 and contained

in TO_DELAY_P7 MIN;

TO_D3 is the minimum time that the IUT remains in state D3. The duration is provided in PIXIT question 1.22 and contained

in TO_DELAY_D3_ MIN;

TO_J2is the minimum time that the IUT remains in state J2. The duration is provided in PIXIT question 1.22 and retained in

TO_DELAY_ J2_ MIN.
6.5 Cause codes and diagnostic codes

ISO 8208 (1987) requires the cause code to be 0 or 128 and the diagnostic code to be present in the Restart, Clear or Reset

packet. Use of cause code 0 designates the use of standard diagnostic codes as specified in ISO 8208 (1987), Figure 14-B.

Use of cause code 128 designates the use of DTE-specific diagnostic codes.

CCITT X.25 (1984) requires the cause code in the Restart, Clear, or Reset Request packets to be either 0 or a value in the

range of 128 through 255. The diagnostic code field is not mandatory in the basic format of these request packets. However,

when the extended format is used, the diagnostic code field shall be present.

CCITT X.25 (1980) requires the cause code field in the Restart, Clear, or Reset Request packet to be set to 0. The diagnostic

code field is not mandatory in the request packets.

Any one of several diagnostic codes may be generated by the IUT, on a per test case basis, especially where multiple error

conditions are present in the same packet. In such instances any one of the possible diagnostic codes shall be accepted.

The test cases allow for the use of multiple diagnostic codes by DTEs. In the case where the DTE implements specific

diagnostic codes it is recommended that these codes be in accordance with Tables 31-36 in ISO/IEC 8208 (1987).

6 © ISO/IEC 2000 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/IEC 8882-3:2000(E)

Although, as noted above, cause and diagnostic code fields are optional in some circumstances, the test suite requires these

fields to be present. In practice, the great majority of implementations of the X.25 Packet Layer Protocol do not omit cause and

diagnostic code fields, so the usefulness of the test suite is not significantly impaired by this limitation.

6.6 Facility fields

The definition of the field ”facility” in Facility_Field as a SET does not permit repetitions of facilities within a facility field. In

practice, implementations of the X.25 Packet Layer Protocol very rarely repeat facilities, and are unlikely to do so in a testing

environment. The definition’s limitation therefore does not significantly impair the usefulness of the test suite.

6.7 Data transfer states

A limited set of data transfer tests (PLG20 and PLG22) are included in this test suite to verify the IUT’s ability to perform the

following:
• send and/or receive valid data packets;
• manage window rotation;
• detect improper data packets and react accordingly;
• observe the remote busy condition.

In order to facilitate the exchange of data packets during these tests, the IUT provider shall specify the contents of the data

packet user data field (UDF) for the Tester. The UDF values are supplied by the IUT provider in the PIXIT.

The following items should be considered when completing the PIXIT:

a) The UDF content in data packets received by the Tester will not be verified. Consequently, the information is not requested

in the PIXIT.

NOTE Receive-only lUTs are not expected to send data packets during data transfer tests.

b) The start of data transfer (i.e. Tester or IUT transmits first) is based on the response in the PIXIT.

c) Depending on the test being performed the full list of UDFs specified in the PIXIT may not be sent. Exchange of data

packets containing UDFs specified in the list may terminate at any point. Subsequent tests will start with the entry in the

UDF list that is specified in the PIXIT (i.e. first entry or next entry).

d) If UDF contents are specified in the PIXIT, they will be sent (in sequence) whenever a data packet must be sent, or in

response to data packets received from the IUT.

NOTE Q-bit, D-bit and M-bit settings in these data packets are based on information provided in the PIXIT. Receive

Ready (RR) packets may also be sent by the Tester and the IUT.

e) It is also assumed that the IUT can send consecutive data packets as required for window rotation tests. The Tester will

only send Receive Ready (RR) packets during these tests.
6.8 Other user data fields

When necessary, the content of user data fields in the Call setup, Clearing and Interrupt packets shall be provided to the Tester

by the IUT provider in order to successfully execute the Packet Layer Test Suite. In this case the IUT requires the Tester to

transmit user data fields in accordance with higher layer protocols which are operating above the packet layer.

6.9 Transient States

It is recognized that for those DTEs that process packets sequentially certain states are not observable. Specifically, the testing

of the DTE during the DXE defined states (for example r3 - RESTART INDICATION, p3 - INCOMING CALL, p7 - CLEAR

INDICATION and d3 - RESET INDICATION) may end up in the testing of some other states P1 - Packet Layer Ready, d4 - Data

Transfer, d1 - Flow Control Ready). For example, to test the response to an error (r3) state the Tester would send a RESTART

INDICATION immediately followed by the error packet. The Tester is expecting the DTE to discard the error packet, then send a

RESTART REQUEST in response. However, the DTE generally responds immediately to the RESTART INDICATION with a

RESTART CONFIRMATION and processes the next packet from the packet layer state r1. This test suite contains tests for

these transient
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.