1、CCITT RECMN*Qm92L BIS 93 W 48b259L 0580857 920 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DIGITAL SUBSCRIBER SIGNALLING SYSTEM No.1 Q .92 1 bis (03/93) ABSTRACT TEST SUITE FOR LAPD CONFORMANCE TESTING IT-T Recommendation Q.921 bis (Previously “CCIlT R
2、ecommendation”) - CCITT RECMN*Q.921 EIS 93 W 4862593 0580858 867 FOREWORD The IT Telecommunication Standardization Sector (ITLJ-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommen
3、dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
4、 IT-T Recommendation Q.921 bis was prepared by the IT-T Study Group XI (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCIIIT ceased to exist as of 28 February 1993. In its
5、 place, the ITU Telecommunication Standardization Sector (IT-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the JFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text
6、to references containing the acronyms ?CCITT, CCIR or IFRB? or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recognized operat
7、ing agency. In this Recommendation, the expression ?Administration? is used for conciseness to indicate both a O IT 1993 All rights reserved. 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
8、 permission in writing from the ITU. CCITT RECflN*Qm921 BIS 93 H 48b2591 0580859 7T3 CONTENTS 1 General 1.1 1.2 Definitions 2.1 Test groups and sub-groups . 2.2 Preamble . Scope and field of application . General aspects of testing . 2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 Test body Postamble . Timer def
9、initions Layer 2 information frame content PICSPIXIT relationship to abstract test suite Test implementation strategies Initialization procedures PIXIT proforma 3 Electronic format of the abstract test suite 3.1 Diskette interface and format 4 Abbreviations . References Page 1 2 2 3 3 4 4 4 4 5 5 5
10、5 6 9 9 10 10 Recommendation Q.921 bis (03/93) i Recommendation Q.921 bis ABSTRACT TEST SUITE FOR LAPD CONFORMANCE TESTING (Helsinki, 1993) 1 General This Recommendation presents the abstract test suite (ATS) for Link Access Procedures on the D-channel (LAPD) described in Tree and Tabular Combined N
11、otation (TICN), for an ISDN user side terminal equipment on ISDN basic access. This test suite aligns with the principles defined in OS1 Conformance Testing Methodology and Framework Recommendations X.290 to X.294, inclusive i. For basic rate, user-side testing, two equally valid but different Abstr
12、act Test Suites (ATS) have been submitted for CCITT consideration. Although these two ATS share a common subset of test purposes, they employ different test methods. This would make the comparability of the test results between the two ATS extremely difficult. In order to facilitate the comparabilit
13、y of the test results, which is fundamental to the achievement of the desirable goal of one-stop testing on a worldwide basis, it has been agreed that only one internationally standardized ATS is required for each protocol. Given the advanced stage of introduction of conformance testing within some
14、countries, it has further been agreed that a reasonable transition period is required before it is possible to move to a single standardized ATS. This Recommendation therefore contains two recommended ATS, one in the body of the text and the other in Annex A. During the transition period, organizati
15、ons wishing to foilow this Recommendation have the option of using either or both ATS, or a subset applicable to their environment. However, from 1 April 1994, the ATS for basic rate, user-side testing, contained in the body of this Recommendation will be the only recommended ATS. The ATS contained
16、in Annex A is recommended for use during the transition period ending 3 1 March 1994 only. Subclause 1.1 describes the scope and field of application which provides an objective basis for the applicability of the LAPD tests. Clause 2 contains general aspects of testing and the Protocol Implementatio
17、n Extra Information for Testing (PIXIT) proforma. Clause 4 contains abbreviations used in this Recommendation. The type of TTCN used in the development of the test suite for basic rate, user-side testing, pre-dates that to be found in Recommendation X.392 i. However, as reflected in X.292 i, Recomme
18、ndations produced during the 1989-1992 study period that use a version of TTCN that pre-dates X.292 i and which append to the Recommendation a copy of the specification of that version of TTCN used, will be regarded as compliant to Recommendation X.292. For that reason, Appendix III, OS1 Conformance
19、 Testing Methodology and Framework for Protocol Recommendations for CCITT Applications - Tree and Tabulax Combined Notation (TEN), contains full information on the version of ITCN used for the preparation of the test suite for basic rate, user-side testing. The General, General Aspects of Testing, A
20、bbreviations, and Reference clauses of this Recommendation are availablein printed form. All other clauses and subclauses, including the ATS, are available in electronic format he. diskette) only. Recommendation Q.921 bis (03/93) 1 CCIIT RECMN*Q-92L BIS 93 E 4862591 0580Abl 3-51 1.1 Scope and field
21、of application The LAPD abstract test suite for conformance testing is based on Recommendation Q.921 2. The Implementation Under Test (IUT) is the users side implementation of LAPD. The System Under Test (SUT) is functionally a Customer Premises Equipment (CPE), a Terminal Equipment of Type 1 (TE1)
22、or a Terminal Adapter (TA). The conformance testing for the complete LAPD protocol is covered in four abstract test suites, presented below. 1.1.1 Basic rate user-side The abstract test suite for conformance testing equipment for basic rate access on the user-side of the interface is specified in cl
23、ause 1. 1.1.2 Basic rate network-side For further study. 1.1.3 Primary rate user-side For further study. 1.1.4 Primary rate network-side For further study. The test metliodology is the “remote single layer embedded testing” as described in Recommendation X.291 i. It is possible that the entire test
24、suite is not applicable for all IUTs. A test selection procedure has to be performed to determine the applicability of a test to a particular IUT. Such selection shall be based on the Protocol Implementation Conformance Statement (PICS) and Protocol Implementation Extra Information for Testing (PIXI
25、T). In doing such a selection, interoperability among ISDN equipment shall be of prime importance. The abstract test cases contained in diis Recommendation are a comprehensive reflection of the base standards. This abstract test suite only tests a single TE1 link and assumes that the IUT only suppor
26、ts a single TE1 link. If more than one TE1 link is supported by the IUT, the test implementor must take actions to filter out messages generated by tlie TE1 links which are not under test. 1.2 Definitions This test suite uses valid, invalid, and inopportune frames to test the IUT behaviour. These te
27、rms are defined as follows: 1.2.1 belong to any of the categories listed under invalid frames. valid frames: A valid frame is an expected frame which arrives at the correct state or phase and does not 1.2.2 invalid frames: An invalid frame, as per Reference 1, is a frame which a) is not properly bou
28、nded by two flags; or b) has fewer than six octets between flags or frames that contain sequence numbers and fewer than five octets between flags of frames that do not contain sequence numbers; or c) does not consist of an integral number of octets prior to zero bit insertion or following zero bit e
29、xtraction; or d) contains a frame check sequence error; or e) contains a single octet address field; or I) contains a service access point identifier which is not supported by the receiver. 2 Recommendation 4.921 bis (03/93) - - CCITT RECIN*Q-921 BIS 93 B Y862591 0580862 298 Currently, test cases fo
30、r some of the above invalid frames are not included in this Recommendation. Additional test cases or the following type of frames have been written and included under tbis grouping. a) b) c) inopportune frames: An inopportune frame is a syntactically valid frame arriving at a time (IUTs state) super
31、visory and unnumbered frames (except XID frame) which are too long; undefined command and response frame (error in the control field); frames where the information field is not permitted. 1.23 when it should be considered irrelevant by the IUT. 2 General aspects of testing As per Recommendations X.2
32、90 and X.291 of testing i, “a complete and independent specification of the actions required to achieve a specific test purpose” is called an abstract test case. The abstract test cases for LAPD are defined at the level of abstraction of remote single layer embedded testing methodology. The test cas
33、es, along with the test body, include a preamble and a postamble, which are defined below, to ensure starting and ending in a stable state and involve one or more consecutive or concurrent connections. However, as per Recommendation X.291 i, it can be useful to use other stable states for starting a
34、nd ending abstract test cases, in order to concatenate test cases in a manner which permits efficient execution. 2.1 Test groups and sub-groups ISDN LAPD test cases have been grouped into three major groups: i) Management (MGMT); 2) Multiple Frame Operation (MFO); 3) System (SYSTEM). The fust group
35、(MGMT) consists of test cases covering the IUTs TE1 management procedures in States 1 through 3, and instances in States 4-8 in which an error recovery results in setting the MDL-ERROR primitive by the IUT. The test cases in the Management Group are referenced as LAPD/MGMT/DMx-Lij, where “x” denotes
36、 the IUTs State (1-8), followed by a letter “L”, which is set to “V”, “N, or “I”, denoting valid, invalid (not valid) or inopportune sub-groupings, respectively, as indicated below; and “if denoting the test case number. The second group (MFO) includes test cases for States 4 through 8. The bu - Sub
37、-group 2 involves those test cases where the tester transmits an invalid test frame; - Sub-group 3 involves those test cases where the tester transmits an inopportune test frame. The third group (SYSTEM) is designed to test frames defined in 1.2.2 for correctness of the IUTs system parameters, and w
38、indow rotation. The test cases in this group are referenced as LAPD/SYSTEM/DSx-Lij, where “x” denotes the IUTs state, and “L”, “ij” are defined as above. Recommendation Q.921 Vi (03/93) 3 2.2 Preamble The preamble of a test case consists of the steps required to bring the IUT to the appropriate init
39、ial state. There may be alternate sequences of test steps which can be performed to initialize the IUT. These test steps in the preamble for LAPD have been chosen carefully, considering the test methodology and the other test coordination procedures that are available. In general, it is preferred th
40、at these steps be built on an “idle state” which is stable and “most likely” under many testing situations. The bulk of the test suite is to test the IUTs behaviour in multiple frame operations. Choosing the TEI-Unassigned state (State 1) as the “idle state”, upon which a preamble is built, would re
41、sult in unnecessary and sometimes lengthy EI assignment procedures. Also, the IUT, depending upon the EI value it supports, may not present itself in the EI-unassigned state. In view of this, the preferred “idle stak for the entire test suite covering multiple frame operations is the EI-assigned sta
42、te (State 4). The alternative, whenever State 4 is not feasible, is multiple frame- established (MFE) state (State 7.0). Therefore, preambles may be different for different IUTs, depending upon the choice of idle state. The selection of “idle state” is determined by the PIXIT, and is applicable for
43、the entire test suite, except for States 1.0 and 2.0. 2.3 Test body The test body is the sequence of steps within a test case that is essential to achieve the test purpose, foilowed by the verification of the IUTs ending state. A verdict of Pass (P), Fail O, or Inconclusive (I) is assigned to the po
44、ssible outcomes of the test cases. It is important to test the observable behaviour of the IUT, which includes state transitions and Protocol Data Unit (PDU) responses. If one assumes that all states are implemented, it is not possible to obtain unique traces or signatures which would guarantee that
45、 the IUT is in the expected state. Also, many of the LAPD states are transitional and may not be implemented. The constraint references specify the frames which are sent and received by the IUT. The basic naming convention for these references is: FrameTypeP or F bit (O or 1) /- / User(v or Network(
46、N)/Command(C) or Response). For example, DM1-UC denotes a DM frame with a P/F bit = 1, sent by the User, and is a Command frame. 2.4 Postamble At the end of the execution of a test body, the IUT may not be in an “idle state”. A postamble is required to bring the IUT from the ending state to an “idle
47、 state”. For multiple frame operations, as mentioned previously, the “idle state” is either State 4 or 7.0. Therefore, postamble procedures may differ for various IUTs depending on the selected “idle state”. 2.5 Timer definitions The timer typ used by the tester are T200, T202, T203, as defined in R
48、ecommendation Q.921 2. There are additional timers defined that may be used during dynamic conformance testing: a) Td - Time delay to be ailowed before concluding that there is no frame response from the IUT; b) Topr - Time required for a test operator in initiating some test action. This is used in
49、 conjunction with an Implicit-send for test coordination; c) TI - Timer used to ensure timely response from the IUT when Layer 3 messages are expected. 4 Recommendation Q.921 bis (03/93) CCITT RECMN*Q.S21 BIS 93 U 4862591 0580864 Ob0 It should be noted that some timers, for example T200, are executed synchronously both in the IUT and in the tester. Any undue transmission or processing delay on either side because of the testing environment may have an adverse effect on the test cases which have verdicts based on timer expiry. Care should
