1、INTERNATIONAL STANDARD ISO/IEC 8882- 1 Second edition 1996-09-I 5 Information technology - Telecommunications and information exchange between systems - X.25 DTE conformance testing - Part 1: General principles Technologies de Iinformation - T - test suite designers or implementors (for determining
2、what tests are required and what results can and should he anticipated by the test device): and users implementing ISOiIEC 7776 or ISO/IEC X208 or DTEs interfacing to DCEs that implement CCITT X.2.5 (19X0, 19X4 or 19Xx) (for determining the functionality required of their implementations to he consi
3、dered in con- formance). INTERNATIONAL STANDARD OISO/IEC ISWIEC 8882-l : 19!%(E) Information technology - Telecommunications and information exchange between systems - X.25DTE conformance testing - Part 1: General principles 1 Scope ISO/IEC 8882 defines the testing of a DTE operating at the Data Lin
4、k Layer and at the Packet Layer when accessing, by means of a dedicated path connection, switched or permanent, a public or private packet-switched network conforming to CCITT Recommendation X.25 or another DTE conforming to ISO/IEC 7776 and ISO/IEC X208. The tests will test the conformance of an im
5、plementation by ohserving its external hehaviour. The conformance tests will not test the DTE performance characteristics, the diagnostic and maintenance functions. the correctness of the protocol itself, or DTE internal implementation, or the full capabilities as stated in the PICS. This part of IS
6、O/IEC X882 provides a general introduction; refers to those applicable International Standards; defines terms applicable to X.25-DTE conformance testing: states the test case derivation and description: and - states the test methodology. ISWIEC X882-1 contains no statement of conformance. Specific s
7、tatements of conformance are given in ISO/IEC 8882-2 and ISO/IEC 8882-m3. 2 Normative references ISOAEC 96463 : 1992, Iforrrration technology - Open S:stenI.s Interconnection - Con,ji)nnance testin,? rnethodoloy antlfrarnc- work - Part .1: The Tree and T(lbular Con,bined Notation (TTC.N). The follow
8、ing standards contain provisions which, through refer- ence in this text, constitute provisions of this part of ISO/IEC X882. 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 encoura
9、ged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. CCIIT Recommendation X.2.5 ( 1980). Interfarc benieen Data Tcr- rninal Equipment (DTE) and Data Circuit-Term
10、inating Equipnrcnt (DCE) for Terrnina/.r Operating in the Packet Mode on Public Data Networks. ISOlIEC 7498-1 : 1994, Information technology - Open Systems Interconnection - Basic Reference Model : The Basic Model. CCIlT Recommendation X.25 (1984). Interfare be&cen Data Trr- rninal Equipment (DTE) a
11、nd Data Cirruit-Terminating Equipment (DCE) for Terminals Operating in the Packet Mode and Connc,cttzd to Public Data Nehvorks I)!, Dedirated Circuit. ISOAEC 7776 : 199.5. Information technology - Telerommuni- CCIIT Recommendation X.25 (19X8). Intelfare between Data T(ar- cations and information exc
12、hange between systems - High-lerlel rninal Equipment (DTE) and Data Circuit-Terminating Equipment data link contrnl procedures - Description of the X.25 LAPB- (DCE)for Terminals Operating in the Pac,ket Mode and Connec-tcrl compatible DTE data link procedures, to Public Data Networks ig Dedirated Ci
13、rruir. ISO/IEC 8208 : 1995, Information technology - Data communi- cations - X.25 Packet Luyer Protocol for Data Terminal Equipment. NOTE - ISO/IEC 8208 : 1995 supersedes ISO/IEC 8208 : 1990. How- ever, when this part of ISO/IEC 8882 was under development, the previous edition was valid and this par
14、t of ISO/IEC 8882 is therefore based on that edition, which is listed below. ISOflEC 8208 : 1990, Information technology - Data communi- cations - X.25 Packet Layer Protocol for Data Terminal Equipment. ISOfiEC 8882-2 : 199.5. lforrrration technology - T&rorrurr4- nications and information c.rcllan,
15、yc bctwecn .ssterrrs - X. 25 DTE conformance testin,q - Part 2: Data /ink IaTer ronfornmncr tt.Tt .suite. ISO/IEC 8882-3 : 199.5. Information terlrnolog - Telerornrnlc- nications and information exchange benL,een .sIstems - X. 25 DTE confomiance testing - Part 3: Packet laker ronfornfancc test .rtci
16、tf. ISOlIEC 9646- 1 : 1994, Ifonrration technology - Open S,sten/.s Interconnection - Conji)nnanre testin ,g rnethodo/o,qy and jlarncp- work - Part I: General concepts. (See al.o CCITT Recorrrmcn- dation X.290 (I 992). ISOAEC 9646-2 : 1994, Information technoloqy - Open S1stern.c Interconnection - C
17、onformance te.rtin,q nrethodolo,qy and jianu- work -Part 2: Abstract Test Suite .sper$ration. (See also CCITI Recommendation X.291 (1992). ISO/IEC 8882-l : 1996(E) O1S0/IEC 3 Definitions 3.1 Reference model definitions This part of ISO/IEC XXX2 makes use of the following term detined in ISO/IEC 7498
18、-l : (N)-protocol-data-unit (N)-PDU 3.2 Conformance testing definitions This part of ISOAEC XXX2 makes use of the following terms defined in ISO/IEC 9646-I : a) b) C) d) e) f) S) h) i) j) k) I) m) 3.3 Abstract Test Case Conformance Test Suite Conformance Testing Implementation Under Test Inopportune
19、 PDU Lower Tester Protocol Implementation Conformance Statement Protocol Implementation extra Information for Testing Remote Single Layer Test Method System IJnder Test Test Group Test Step Test Suite X.25 DTE conformance testing definitions For the purposes of this part of ISO/IEC 8882. the followi
20、ng definitions apply. 3.3.1 improper PDU: The (N)-PDU whose syntax does not conform to the format ,pecifications of ISO/IEC 7776 or ISO/IEC 8208 or CCIIT X.25. 3.3.2 proper PDU: The (N)-PDU whose syntax conforms to the format specification of CCITIX.25, ISO/IEC 7776 or ISO/IEC 8208 and is acceptable
21、 to the state or phase of the interface. 3.3.3 tester: Refer to Lower Tester. 3.3.4 test case: Refer to Abstract Test Case 3.3.6 test subgroup: A set of test cases that share a common characteristic, such as testing for proper, improper, or inopportune PDlJs. A test subgroup is the smallest testable
22、 set of test cases that can he selected. 3.3.7 sub-function: A subset of the PDlJs and functional capabilities of the protocol level above the IIJT that are needed to allow data transfer testing to be accomplished. 4 Abbreviations The following abbreviations are used in this part of ISOAEC 8882: DCE
23、 Data Circuit-Terminating Equipment DTE Data Terminal Equipment DXE DTE or DCE IUT Implementation 1Jnder Test PDIJ Protocol Data ITnit PICS Protocol Implementation Conformance Statement PIXIT Protocol Implementation extra Information for Test- ing RS Remote Single Layer SUT System LJnder Test TPDU T
24、ransport Protocol Data 1Jnit TTCN Tree and Tabular Combined Notation 5 Test notation The test notation used in ISO/IEC XxX2-2 and ISWIEC XxX2-3 is ITCN as defined in ISOflEC 9646-3. 6 Test suite structure The test suite structure used in ISWIEC XxX2-2 and ISO/IEC 88X2-3 is defined in ISO/IEC 9646-2
25、and is illustrated below. Test Suite Structure Test Group Test Subgroup 1 (Proper PDl Js) Test Case No. 101 Test Case No.102 Test Case No. Inn 3.3.5 test selection: Test selection is the process of choosing test cases according to the specific criteria based on the IIJTs PICS and PIXIT in order to c
26、onstitute a conformance test suite for the IUT. 2 OISO/IEC ISO/lEC 8882-l : 1996(E) Test Subgroup 2 (Improper PDUs) Test Case No.201 Test Case No.202 Test Case No.2nn Test Subgroup 3 (Inopportune PDUs) Test Case No.301 Test Case No.302 Test Case No.31111 7 Testing methodology The testing methodology
27、 is based on the OS1 Conformance Testing Methodology and Framework. The test method used is the Remote Single layer (RS) method. To employ the RS method effectively, the concept of using sub-functions of higher layer protocols is introduced. Sub-functions are a subset of the PDUs and functional capa
28、bilities of the protocol layer above the IUT that are needed to allow data transfer testing to be accomplished. The required properties of the sub-functions used are: a) That the numher and sequence of data-PDlJs received from the IlJT after receiving a data-PDU from the tester is pre- dictahle. and
29、 that the numher received from the IUT is greater than zero. h) That the reactions of the IUT upon receipt of these data- PDlJs are hwwn. C) That the suh-function allows either the tester or IlJT to initiate transmission of the data-PDUs. d) That the sub-function allows for the exchange of data-PDUs
30、 hy the layer under test with minimal interference from other functions of the protocol layer(s) above the IUT (e.g PDIJ retransmission. error recovery. etc.). Examples of data transfer confgurations are shown for the Data Link Layer and the Packet Layer in tigures I and 2 respectively. 7.1 Test pri
31、nciples The testing of the Data Link and the Packet Layer protocols is done separately. The data link layer is normally tested tirst since the packet layer requires the correct operation of the data link layer. The RS method is the selected test method since it cannot be assumed that a tester will h
32、e ahle to test completely each level as a separate entity. The KS method requires that the tester shall recognize and respond to a PDU received from the higher level protocols. The specific PDlJs which shall he accepted are defned in ISO/IEC 8X82-2 and ISO/IEC 8Xx2-3. 7.2 Data transfer The sub-funct
33、ion chosen hy the IlJT provider should create a11 alternating exchange of data-PDIJs between the IIJT and the tester. This exchange will he repeated until the sequence numhers of the layer under test have heen rotated. The sub-function chosen shall be defined in the PIXIT of the II JT. and shall inc
34、lude the sequence and contents of the user data tields required for the test. Two examples of the use of a sub-function to accomplish data transfci testing are shown in tigures 3 and 4. A more detailed explanation of data transfer testing is provided in ISO/IEC X882-2 and ISO/IEC XxX2-3. These expla
35、nations also address the data transfer testing of send-only and receivc- only IIJTs. It is recognized that an 11 JT provider may not he ahle to accomplish data transfer testing by this means. In such instances the data transfer tests are not selected. 7.3 Other user data fields When necessary. the c
36、ontent of user data fields in other than data- PDlJs shall he provided to the tester hy the owner of the 1117 in order to execute successfully the conformance test suite. In this Data Link Layer (layer under test) Figure 1 - Data Link Layer Data Transfer Configuration Sub-function of OS1 Protocol(s)
37、 Sub-function of non-OS1 Protocol(s) Packet Layer (layer under test) Data LAN Other Protocol(s) Link Protocol(s) Layer Note Note Note Figure 2 - Packet Layer Data Transfer Configuration 3 ISO/IEC 8882-I : 1996(E) OISO/IEC case. the IIJT requires the tester to transmit user data fields in accordance
38、with higher level protocols which are operating above the IUT. For example, user data fields of call set-up. clearing. and interrupt packets of the Packet Layer may be affected. environment 7.5 Operational consideration The content of such user data fields shall be provided by the IIJT owner in the
39、PIXIT. 7.4 Testing configuration The SIJT is connected to the tester. point-to-point, when partici- pating in active testing. The points of observation and control for each test sequence are within the tester. ISO/IEC X882Z2 and ISO/IEC 8882-j include PIXIT proformas which. when completed. describe
40、the dynamic conformance test Testing is done in a controlled environment. It is not the intent of this document to define the operational characteristics of test devices used to achieve DTE Conformance Testing. However. it is highly desirable that the device be capable of segregating IIJT test activ
41、ity from normal operation of underlying layers. At a minimum, the tester should be capable of distinguishing between I-frame retransmission at the data link layer (due tcl Tl expiration) and a packet layer retransmission. Some recommended functions of the tester include: a) Detection of failures of
42、the physical layel Tester PDU sent by IUT Packet Layer CLEAR INDICATION Data Link Layer Data Link Layer I - frame -b I - frame Packet Layer Figure 3 - Example of the use of a Packet Layer Sub-function Tester PDU sent by IUT CLEAR CONFIRMATION Transport Layer Packet Layer Packet Layer Transport Layer Erroneous Connect request TPDU (CR TPDU) Data packet Disconnect request TPDU (DR TDPU) Figure 4 - Example of the use of a Transport Layer Sub-function directly over ISWIEC 8208 (i.e. OS1 Network Layer) 4
