ISO/IEC 8882-3:1995
(Main)Information technology — Telecommunications and information exchange between systems — X.25 DTE conformance testing — Part 3: Packet layer conformance test suite
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
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INTERNATIONAL ISO/IEC
STANDARD 8882-3
Second edition
1995-l 2-15
Information technology -
Telecommunications and information
exchange between systems - X.25 DTE
conformance testing -
Part 3:
Packet layer conformance test suite
Technologies de I’informa tion - T6kommunica tions et khange
d’information entre systkmes - Test de conformit X.25 DTE -
Partie 3: Suite d’essais de conformit pour la couche paquet
Reference number
ISO/lEC 8882-3:1995(E)
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ISO/IEC 8882=3:1995(E)
Contents
Page
1
1 Scope .
1
................................................
2 Normative references
2
......................................................
3 Definitions
2
3.1 Reference model definitions .
........................................ 2
3.2 Conformance testing definitions
.................................... 2
3.3 X.25DTE conformance testing definitions
2
...............................................
3.4 Additional definitions
................................................ 2
3.4.1 proper-packet
............................................... 2
3.4.2 improper packet
............................................. 2
3.4.3 inopportune packet
.................................................... 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
5
...............................................
6.3 DTE-initiated actions
................................................. 5
6.4 Timer definitions
........................................ 6
6.5 Causecodes anddiagnosticcodes
................................................ 6
6.6 Data transfer states
............................................... 7
6.7 Other user data fields
7
..................................................
6.8 Transient states
7
........................................
6.9 Relationship of PIGS to test suite
7
6.10 Relationship of PIXIT to test suite .
.............................................. . 7
6.11 Test case selection
. 7
.................................................
6.12 PIXIT proforma
19
......................................
6.13 Acceptable unexpected responses
.................................................. 20
6.14 Implicit send
.......................................... 20
6.15 Basic interconnection tests
............................................. 21
7 TTCN abstract test suite
............................................... 21
7.1 Test suite overview
23
.................................................
7.2 Test case index
42
.................................................
7.3 Test step index
46
.............................................
7.4 ASN.1 type definitions
0 lSO/IEC 1995
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.
lSO/lEC Copyright Office l Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
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ISO/IEC 8882=3:1995(E)
lSO/IEC 0
....................................... 61
7.5 Test suite parameter declarations
...................................
7.6 Test case selection expression definitions 71
........................................ 74
7.7 Test suite constant declarations
........................................ 74
7.8 Test suite variable declarations
........................................ 74
7.9 Test case variable declarations
................................................
7.10 PC0 declarations 75
...............................................
7.11 Timer declarations 75
.......................................... 76
7.12 ASN.1 ASP type definitions
.......................................... 77
7.13 ASN.l PDU type definitions
...................................... 83
7.14 ASN.1 type constraint declarations
7.15 ASN.1 ASP constraint declarations . 93
7.16 ASN.l PDU constraint declarations .
94
166
7.17 Verification of packet layer ready state Rl .
................................. 181
7.18 Verification of DTE restart request state R2
200
7.19 Verification of DXE restart indication state R3 .
232
7.20 Verification of packet ready state PI .
242
7.21 Verification of call request state P2 .
253
7.22 Verification of DXE incoming call state P3 .
264
7.23 Verification of data transfer state P4 .
271
7.24 Verification of call collision state P5 .
..................................... 282
7.25 Verification of clear request state P6
................................. 291
7.26 Verification of DXE clear indication state P7
.................................. 304
7.27 Verification of flow control ready state Dl
.................................. 314
7.28 Verification of DTE reset request state 02
................................. 320
7.29 Verification of DXE reset indication state 03
7.30 Verification of DTE interrupt ready state I1 . 329
7.31 Verification of DTE interrupt sent state I2 . 331
7.32 Verification of DXE interrupt ready state 31 . 333
.................................. 335
7.33 Verification of DXE interrupt sent state 32
.................................. 337
7.34 Verification of DXE receive ready state Fl
7.35 Verification of DXE receive not ready state Fl . 342
.................................. 347
7.36 Verification of DTE receive ready state Gl
7.37 Data transfer test cases . 353
7.38 Verification of DTE timers . 357
............................................. 365
7.39 Addressing test cases
7.40 Verification of DTE optional facilities . 367
7.41 Verification of the registration procedures . 380
......................................
7.42 Multiple assignment LCI test cases 387
7.43 Verification of DTE/DTE procedures . 389
................................................... 393
7.44 Preambles
................................................... 401
7.45 Postambles
7.46 Common sub-trees . 405
7.47 Local sub-trees . 426
. . . . . . . . . . . . . . . . . . . . . . . . . 446
Annex A (informative) - Conformance Testing Summary Matrix
. . .
III
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0 lSO/lEC
ISO/IEC 8882=3:1995(E)
Foreword
IS0 (the International Organization for Standardization) and IEC (the International Electrotechnical Commission)
form the specialized system for worldwide standardization. National bodies that are members of IS0 or IEC par-
ticipate in the development on International Standards through technical committees established by the respec-
Other international organizations, governmental
tive organization to deal with particular fields of mutual interest.
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 JTCl.
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.
International Standard ISO/IEC 8882-3 was prepared by Joint Technical Committee lSO/IEC JTCl, Information tech-
nology, Subcommittee SC 6, Telecommunications and information exchange between systems.
technically
This second edition cancels and replaces the first edition (ISO/lEC 8882-3:1991), which has
revised.
Te/ecommunications
ISO/ IEC 8882 consists of the followi ng parts II under the general title Information technology --
systems -- x.25 conformance testing:
and information exchange between DTE
- Part I : General principles
- Part 2 : Data link layer conformance test suite
- Part 3 : Packet layer conformance test suite
Annex A of this part of IOWIEC 8882 is for information only.
iv
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lSO/IEC 0
ISO/IEC 8882=3:1995(E)
Introduction
This part of ISO/IEC 8882 specifies a set of tests to evaluate Data Terminal Equipment (DTE) conformance to
International Standards ISO/IEC 7776 (X.25 LAPB) and/or lSO/lEC 8208 (X.25 Packet Layer). lSO/IEC 7776 and
ISOIIEC 8208 allow for a DTE to interface with a Data Circuit-Terminating Equipment (DCE) conforming to CCITT
Recommendation X.25 or to another DTE conforming to ISO/IEC 7776 and/or ISO/IEC 8208. ISO/IEC 8208 also
allows for connection to Local Area Networks.
CCITT Recommendation X.25 (1980) and X.25 (1984) 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 ISOAEC 8882 pertaining to X.25
(1980) and X.25 (1984) are based on the DTE operational characteristics implied by CCITT X.25.
This part of lSO/lEC 8882 presents the packet layer aspects for evaluating conformance to lSO/lEC 8208 and
guidelines defined in
follows the procedures and 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 lSO/IEC 8882 can be used to verify the implementation of the necessary protocol elements.
The test suite is presented in an abstr act form eans of the test case notation TTCN, as defined in ISO/IEC
bY t-n
-3. This is an abstract set of tests. Not ever ‘y test ies to every public network or every type of DTE.
9646
aPPl
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INTERNATIONAL STANDARD 0 lSO/IEC - ISO/IEC 8882-3:1995(E)
Information technology -
Telecommunications and
information exchange between systems
- X.25 DTE
conformance testing -
Part 3:
Packet layer conformance test suite
ISOllEC 7776: 1995, Information technology -- Teie-
1 Scope
communicaiions and information exchange systems --
High-level data link coniroi procedures -- Description
This part of ISO/IEC 8882 specifies a set of abstract
of the X.25 LAPB-compatib/e D7E data link proce-
tests for verifying that the implementation of X.25 pro-
dures.
tocols, for use by Data Terminal Equipment (DTE),
conform to the requirements of International Stand-
ISO/iEC 8208: 1990, lnformation technology -- Data
ards that specify those protocols.
communications -- X.25 Packet Layer Protocof for Data
Terminal Equipment.
This part of ISO/IEC 8882
a) specifies a PIXIT proforma;
lSO/IEC 8208/Amd. 1: 1990, Information technol’ogy --
Data communications -- X.25 Packet Layer Protocol for
b) describes the relationship of the PIGS to the test
Data Terminal Equipment -- Amendment I: Alternative
suite;
Logical Channel Identifier Assignment.
c) describes the relationship of the PIXIT to the test
suite;
ISO/IEC 8208/Amd. 3: 1991, Information technology --
Data communications -- X.25 Packet tayer Protocol for
d) specifies a set of abstract tests using TTCN
Data Terminal Equipment -- Amendment 3: Conform-
Graphical notation.
ance requirements.
This part of iSO/IEC 8882 defines the testing of a DTE
lSO/IEC 8824: 1990, Information technology -- Open
operating at the packet layer designed to access a
Systems fnterconnection -- Specification of Abstract
public or private packet-switched network conforming
Syntax Notation One (ASN.1) (See also CC177 Recom-
to CCITT Recommendation X.25 (1980, 1984) or
mendation X.680).
another DTE conforming to lSO/iEC 8208. The specifi-
cation of test cases in executable/machine
ISO/lEC 8882-l : 1993, Information technology =- Tele-
processable TTCN is outside the scope of this part of
communications and information exchange between
lSO/IEC 8882.
systems -- X.25-07E conformance testing -- Part I:
General principles.
lSO/IEC 8886: 1992, lnformation technology -- Tele-
communications and information exchange between
2 Normative references
systems -- Data link service definition for Open
Systems interconnection.
The following standards contain provisions which,
ISO/IEC 9646-l : 1994, Information technology -- Open
through reference in this text, constitute provisions of
Systems Interconnection -- Conformance testing meth-
this part of ISO/IEC 8882. At the time of publication,
odology and framework -- Part I: General concepts.
the editions indicated were valid. All standards are
(See also CC177 Recommendation X.290).
subject to revision, and parties to agreements based
on this part of lSO/lEC 8882 are encouraged to inves-
lSO/IEC 9646-2: 1994, Information fechnoiogy -- Open
tigate the possibility of applying the most recent edi-
Systems Interconnection -- Conformance testing meth-
tions of the standards listed below. Members of IEC
odology and framework -- Part 2: Abstract Test Suite
and IS0 maintain registers of currently valid Interna-
specification. (See also CCi77 Recommendation
tional Standards, and ITU-T maintains published edi-
X.291).
tions of its current Recommendations.
ISO/lEC 9646-3: 1992, Information technology -- Open
ISO/IEC 7498-l: 1994, Information technology -- Open
Systems Interconnection -- Conformance testing meth-
Systems Interconnection -- Basic Reference Model:
The Basic Model (See also CC177 Recommendation
X.200).
1
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ISO/IEC 8882-3 : 1995 (E) 0 lSO/IEC
Part 3: The Tree and h) Protocol Implementation Conformance Statement
0doIogy and framework --
Tabular Combined Notation (TTCN).
i) Protocol Implementation extra Information for
Testing
lSO/IEC 9646-4: 1994, Information technology -- Open
j) Test Group
Systems interconnection -- Conformance testing meth-
odology and framework -- Part 4: Test realization.
k) Test Step
(See also CC/T7 Recommendation X.293).
I) Test Suite
lSO/IEC 9646-5: 1994, Information technology -- Open
Systems interconnection -- Conformance testing meth-
3.3 X.25DTE conformance testing definitions
-- Part 5: Requirements on
odology and framework
test laboratories and clients for the conformance
This part of ISO/IEC 8882 makes use of the following
assessment process. (See also CUTT Recommenda-
terms defined in ISO/IEC 8882-l.
tion X.294).
a) Improper PDU
CCI7-T Recommendation X.25 (1980), Interface
b) Inopportune PDU
0etween Data Terminating Equipment (DTE) and Data
Circuit-Terminating Equipment (DCE) for Terminals
c) Proper PDU
Operating in the Packet Mode on the Public Data Net-
d) Test Subgroup
works.
Test Selection
CCITT Recommendation X.25 (1984), Interface
Tester
Between Data Terminating Equipment (DTE) and Data
Circuit-Terminating Equipment (DCE) for terminals
Transient States
operating in the Packet Mode on the Public Data Net-
works by Dedicated Circuit.
3.1 Additional definitions
Interface
CCITT Recommendation X.25 (1988),
r-
par the purposes of this part of ISO/IEC 8882, the fol-
0etween Data Terminal Equipment (DE} and Data
lowing definitions apply.
Circuit-Terminating Equipment (LICE) for terminals
operating in the Packet Mode and connected to Public
3.4.1 proper packet : A packet that is a proper PDU.
Data Networks by Dedicated Circuit, CC/T7 Blue Book.
3.4.2 improper packet : A packet that is an improper
PDU.
3.4.3 inopportune packet : A packet that is an
3 Definitions
inopportune PDU.
3.1 Reference model definitions
This part of ISO/IEC 8882 makes use of the following
term defined in lSO/lEC 7498-l.
4 Abbreviations
(N)-protocol-data-unit (N-PDU)
The following abbreviations are used in this part of
ISO/I EC 8882:
3.2 Conformance testing definitions
ADX Address
This part of lSO/IEC 8882 makes use of the following
ASP Abstract Service Primitive
terms defined in ISO/IEC 9646.
ATS Abstract Test Suite
a) Abstract Test Suite
ETS Executable Test Suite
b) Conforming System or Implementation
Facility
FAC
c) Conformance Test Suite
IUT Implementation Under Test
d) Conformance Testing
LCI Logical Channel Identifier
e) Executable Test Suite
LEN Length
f) Postamble
PCQ Point of Control and Observation
g) Preamble
PDU Protocol Data Unit
2
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0 lSO/IEC ISO/IEC 8882-3 : 1995 (E)
PIGS Protocol Implementation Conformance
5 Conformance
Statement
The test realizer shall comply with the requirements
PIXIT Protocol Implementation extra lnforma-
tion for Testing of ISO/IEC 9646-4. In particular, these concern the
realization of an ETS based on the ATS. Test labora-
PKT Packet
tories running conformance test services for this
abstract test suite shall comply with ISO/lEC 9646-5.
PLG Packet Layer Group
RX Receive
TST Tester
TX Transmit
6 Test suite information
UDF User Data Field
6.1 Packet layer test suite structure
The packet layer tests are grouped as shown in
Table 1.
Table 1. Packet layer test groups
Packet layer test groups Test group # Packet layer test groups
Test group #
rl - Packet Layer Ready State 15 i2 - DTE interrupt Sent State
1
r2 - DTE Restart Request State 16 jl - DXE Interrupt Ready State
2
j2 - DXE interrupt Sent State
3 r3 - DXE Restart indication State 17
pl - Ready State 18 fl - DXE Receive Ready State
4
p2 - DTE Call Request State 19 f2 - DXE Receive Not Ready State
5
20 gl - DTE Receive Ready State
6 p3 - DXE Incoming Call State
-
21 g2 - DTE Receive Not Ready (*)
7 p4 - Data Transfer State
-.
p5 - Call Collision State 22 Data Transfer
a
p6 - DTE Clear Request State 23 Timer Tests
9
10 p7 - DXE Clear Indication State 24 Address
25 Facility
11 dl - Flow Control Ready State
d2 - DTE Reset Request State 26 Registration
12
d3 - DXE Reset Indication State 27 Multiple Logical Channel Assign-
13
ment
14 il - DTE Interrupt Ready State 28 DTE/DTE Tests
NOTE - (“) This group has been
deleted but the number has been
retained for consistency.
these test cases are identified with a three
For each test group that tests a packet layer state
(PLGI through PLG28), the test cases specified are hundred series test case identifier xx 3xx.
-
categorized into the following three subgroups.
l Subgroup 1 contains test cases in which the
6.2 Packet layer initialization
Tester transmits a proper test packet, these test
cases are identified with a one hundred series
In accordance with ISO/IEC 8208 Section 3.10, the DTE
test case identifier xx-l xx.
must transmit a Restart Request whenever link layer
initialization has completed. However, DTEs devel-
l Subgroup 2 contains test cases in which the
oped in conformance with the 1980 and 1984 versions
Tester transmits an improper test packet, these
of Recommendation X.25 are not required to send a
test cases are identified with a two hundred
Restart Request at this time. To accommodate both
series test case identifier xx 2xx.
-
DTE implementations, the Tester initiates the restart
test cases in which the
l Subgroup 3 contains
procedure upon completion of link layer initialization.
Tester transmits an inopportune test packet,
3
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ISOIIEC 8882-3 : 1995 (E) 0 ISOllEC
The Tester will accept either a Restart Confirmation The following are examples of initialization of ISO/IEC
or a Restart Request as a valid response to its 8208 over ISO/IEC 7776 (L-APB). Any other examples
as shown below in example of initialization sequences using other underlying pro-
Restart Indication,
EG 001. Packet layer initialization always occurs tocols are not shown, but may be appropriate. For
-
example, normal state initialization steps in state rl
once at the start of a test session. State initialization,
(PLG 1) are as shown in Table 2.
on the other hand, is performed many times during a
test session as part of each test case. Packet layer
For those DTEs which disconnect the link upon receipt
initialization will also occur as part of state initializa-
of a Restart Indication (or transmittal of a Restart
tion when the previously executed test case results in
Request) the state initialization steps include link
a Fail or Inconclusive verdict, or the previously exe-
layer initialization as shown in Table 3.
cuted 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).
1 Table 2. Test Case Dynamic Behavior
I
Test Step Name : EG-001
: Example Test Step / Packet Layer Initialization
Group
Objective : An example test step illustrating Packet Layer Initialization
.
Default .
.
Comments .
Behavior Description Constraints Ref Verdict Comments
Nr Label
! Restart-Indication START TO STRT-DCE 1
1
2 ? Restart Confirmation CANCEL TO STRTC
? Restart-Request CANCEL TO STRT-DTEA
3
FAIL
4 ? TIMEOUT TO 4
5 ? OTHERWISE CANCEL TO FAIL
Detailed Comments:
1 The Restart indication is sent upon successful initialization of the Data Link Layer
4 TD expired
I
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lSO/lEC 8882-3 : 1995 (E)
0 ISOAEC
Table 3. Test Case Dynamic Behavior
Test Step Name : EG-002
Group : Example Test Step / Packet Layer Initialization / Link Layer Initialization
: An example test step illustrating Packet Layer Initialization that includes Data Link Layer Initializa-
Objective
tion
.
Default .
Comments : a) L is the PC0 at the Tester (Packet Layer) to Link Layer interface.
: b) D is the PC0 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.
Behavior Description Constraints Ref Verdict Comments
Nr Label
1 EG-002 [L, D]
L! Restart indication START TD STRT-DCE
2
STRTC
3 L? Restart Confirmation START TD
4
4 D? Disconnect CANCEL TD DISC-1
5 + LINK-INIT
6
L? TIMEOUT TD
6
L? Restart Request START TD STRT-DTEA
7
D? Disconnect CANCEL TD DISC-1
8
+ LINK-INIT
9
L? TIMEOUT TD FAIL
10
FAIL
11 L? TIMEOUT TD
L? OTHERWISE CANCEL TD FAIL
12
13 LINK-INIT
UA-DCE 14
14 D! UA
SABM-1 15
15 D? SABM
D! UA UA-DCE 14
16
L! Restart Indication START TD STRT-DCE
17
STRTC
L? Restart Confirmation CANCEL TD
18
STRT-DTEA
19 L? Restart-Request CANCEL 70
L? TIMEOUT TD FAIL
20
FAIL
L? OTHERWISE CANCEL TD
21
Detailed Comments:
4 Wait for DISC
TO expired
6
14 Send UA
15 Wait for SABM
TS the time required by the IUT to resume
6.3 DTE-initiated actions
testing after completion of the Reset
The duration is provided in
procedure.
DTE-initiated actions specified by the test suite are
PIXIT question 1 .18c and contained in
handled using the Implicit Send mechanism defined in
the test suite parameter TS-DELAY;
ISO/IEC 9646-3. The ability of the IUT to perform
these actions, and its ability to execute the tests con-
TD the time that the Tester waits before
taining the actions, is determined by the information
determining that the IUT will not
provided in the PIXIT and the PIGS.
For
respond to a Tester stimulus.
example, how long the Tester should
wait before assuming that the IUT has
6.4 Timer definitions
either discarded or failed to respond to
the stimulus. TO must be less than all
This part of lSO/IEC 8882 defines the following timers:
other timers specific to ISO/IEC 8208,
TR the time required by the IUT to resume
i.e. 7-20 through T28. The duration is
testing after completion of the Restart
calculated by the formula contained in
procedure. The duration is provided in
the PIXIT question 1.23 (TO = 2 *
PIXIT question 1 .18a and contained in
TO RESPONSE + MAX(T0 R3, TO P3,
the test suite parameter TR DELAY;
-
TdP7, TO 03, TO J2) and contained in
the- t&t kite parameter
the time required by the IUT to resume
TC
TO WAIT TIME;
-
testing after completion of the Clear
The duration is provided in
procedure.
PIXIT question 1.18b and contained in
the test suite parameter TC DELAY;
-
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0 ISO/IEC
ISO/IEC 8882-3 : 1995 (E)
TD RESP the maximum time that the tester Any one of several diagnostic codes may be gener-
ated by the IUT, on a per test case basis, especially
should wait for an immediate response
where multiple error conditions are present
from the IUT to a tester stimulus. The in the
same packet. In such instances any one of the pos-
duration is provided in PIXIT question
1.20 and contained in TD RESPONSE; sible diagnostic codes shall be accepted.
-
TDEL is a tolerance used in testing timers
The test cases allow for the use of multiple diagnostic
T20 - T28 of the base standard. The
codes by DTEs. In the case where the DTE imple-
duration is provided in PIXIT question
ments specific diagnostic codes it is recommended
1.21 and contained in the test suite
that these codes be in accordance with Tables 31-36
parameter TDELTA. The duration con-
in ISO/IEC 8208.
siders the round trip transit delay
between the Tester and IUT, and the
time necessary for an IUT to respond
6.6 Data transfer states
to a received packet or timer expiry;
A limited set of data transfer tests (PLG20 and PLG22)
is the minimum time that the IUT
TO R3
are included in this test suite to verify the IUT’s
remains in state R3. The duration is
ability to perform the following:
provided in PIXIT question 1.22 and
l
contained in TO DELAY R3 MIN;
- - - send and/or receive valid data packets;
l
TO P3 is the minimum time that the IUT
manage window rotation;
remains in state P3. The duration is
. detec t impr ‘oper data packets, and react accord-
provided in PIXIT question 1.22 and
ingly;
contained in TO-DELAY-P3-MIN;
observe the remote busy condition.
is the minimum time that the IUT
TO-P7
remains in state P7. The duration is
In order to facilitate the exchange of data packets
provided in PIXIT question 1.22 and
during these tests, the IUT provider shall specify the
contained in TO DELAY P7 MIN;
- - -
contents of the data packet user data field (UDF) for
is the minimum time that the IUT
TO-D3
the Tester. The UDF values are supplied by the IUT
remains in state D3. The duration is
provider in the PIXIT.
provided in PIXIT question 1.22 and
contained in TO DELAY 03 MIN;
- - - The following items should be considered when com-
pleting the PIXIT:
is the minimum time that the IUT
TO-J2
remains in state J2. The duration is
The UDF content in data packets received by the
4
provided in PIXIT question 1.22 and
Tester will not be verified. Consequently, the
contained in TO DELAY J2 MIN.
- - - information is not requested in the PIXIT.
Note: Receive-only IUTs are not expected to
6.5 Cause codes and diagnostic codes send data packets during data transfer tests.
The start of data transfer (i.e. Tester or IUT trans-
W
ISOllEC 8208 requires the cause code to be 0 or 128
mits first) is based on the response in the PIXIT.
and the diagnostic code to be present in the Restart,
Clear or Reset packet. Use of cause code 0 desig- Depending on the test being performed, the full
Cl
nates the use of standard diagnostic codes as speci- list of UDFs specified in the PIXIT may not be
fied in lSO/IEC 8208, figure 14-B. Use of cause code sent. Exchange of data packets containing UDFs
128 designates the use of DTE-specific diagnostic specified in the list may terminate at any point.
codes. Subsequent tests will start with the entry in the
UDF list that is specified in the PIXIT (i.e. first
CCITT X.25 (1984) requires the cause code in the entry or next entry).
Restart, Clear, or Reset Request packets to be either
If UDF contents are specified in the PIXIT, they
(4
0 or a value in the range of 128 through 255. The
will be sent (in sequence) whenever a data
diagnostic code field is not mandatory in the basic
packet must be sent, or in response to data
format of these request packets. However, when the
packets received from the IUT.
extended format is used, the diagnostic code field
shall be present. Note: Q-bit, D-bit and M-bit settings in these
data packets are based on information provided
CCllT X.25 (1980) requires the cause code field in the in the PIXIT. Receive Ready (RR) packets may
Restart, Clear, or Reset Request packet to be set to also be sent by the Tester and the IUT.
0. The diagnostic code field is not mandatory in the
It is also assumed that the IUT can send consec-
e)
request packets.
utive data packets as required for window rota-
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0 ISOAEC
ISOllEC 8882-3 : 1995 (E)
tion tests. The Tester will only send Receive
6.10 Relationship of PlXIT to test suite
Ready (RR) packets during these tests.
The PIXIT consists of a list of questions de
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Questions, Comments and Discussion
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