TTMER18: Conformance testing of ATM switches

Measurement tasks

Mandatory measurement tasks:

Parts written in italic are the proposals of the author of the exercise.

We will execute the partial conformance test of an ATM switch at the measurement practice, according to the ISO 9646.

Details of the measurement tasks:

• 1. Studying the test arrangement, and its elements. Formulation of the examination task.
  Draft of the test arrangement is the following:

  

  • 1.1 Studying the ATM switch, as a SUT, with the help of its documentation abstract and data administrations program.

    At the end of studying answer to the following questions:

    • Is there any connectors on the switch, which is not in the abstract?
    • Is there any SVCs programmed into the switch?
    • Is there any point-to-multipoint connections programmed into the switch?

    List the virtual connection (VC) programmed into the switch with the help of the administration program of the switching data!
    Test excercise: examination of the first six connections in the above list.

    • Could you read out any parameters important for the test from this list? If yes, what kind of parameters are these?
    • Which are the ports of the switch we have to make a test between?
    • What does the value of QoS mean in the connection to be tested??

  • 1.2 Studying the ATM measuring equipment, configuration of measuring interfaces, cell processors on the basis of the handling guide of the ATM measuring equipment.
    • Switch the equipment on, log in.
    • Configurate cell processors and measuring interfaces under "Test Sessions" program!

• 2. Preparation of the execution of conformance test
  • 2.1 PICS, PIXIT, static conformance test

    Partial testing of ATM switch can be made with the help of the integrated test program (Test Manager) running on the testing tool. Time at our disposal is not able to provide filling in the whole PICS and PIXIT. Consequently we must set aside testing of the static conformance, too. We will fill in only menus Test Manager PICS and PIXIT, however, we will find only the amount of data necessary to the selection of testing cases, and parametering.

  • 2.2 Connection of ATM switch and tester

    We have to check, whether the switch and the tester are connected to each other properly, or not!

  • 2.3 ATS->ETS conversion
    • 2.3.1 Start the Test Manager program on the tester!
    • 2.3.2 Testing excercise can be executed with the UNI 3.1 ATM Layer Conformance for Intermediate Systems set of tests.
    • 2.3.3 In case of lack of full PICS leader of measurement will order the running of the following testing cases:
      • General/Ver_VP
      • General/Ver_VC
      • General/Ver_VC_Min
      • General/Ver_Cell_Seq_VC

      Study the functions of tests in documentations of TTCN formats of testing cases, and answer the following questions on the basis of the Ver_VP test case:

      • What is the value of VPI and VCI fields in the ATM cell sent by the tester?
      • What is the value of the first byte of the payload in the ATM cell sent by the tester?
      • What will happen, if an "unassigned cell" arrives to the B-port??
      • What kind of events will cause a "failed" result??

    • 2.3.4 Fill in the PICS, PIXIT and OTHERS menus of the Test Manager (parametering of testing cases).
      Usage of the following documents is necessary to the filling in:
      • Contracted technical data of the ATM switch
      • Data administration program of the ATM switch
      • Extraction of the related standard (ATM UNI 3.1 ATM layer)

      Suggestions to the filling in:

      • A part of these parameters asks only the characteristics of the tested tool. Theoretically we must know the answer to these questions from the documentation given to the tool, but these documentations are often deficient in practice. In this case we have to give tips for these parameters, and our tips will be justified, or confuted by results of tests.
      • A part of parameters with category of PIXIT (and Other) asks parameters of actual composition, e.g. VPI/VCI values of built-up VCs. We must be able to answer to a part of these questions after fulfilling the first task, and the help of the leader of measurement will be necessary to the other part.
      • Most often the default values can be accepted in case of data with characteristic of waiting time.
      • Among Other parameters there are ones, too, which can determine how detailed are the recordings made at the end of measurement. When you will got to there, do not forget it!

• 3. Running of the selected test cases

  Run test cases listed in 2.3.3:

  Running of test cases must be successful (PASS). If it is not successful, then search for the error, and correct it!
  An idea: We should pay attention not only to the fact, whether that kind of data element arrived, or not, what we expected, but also, whether it arrived on that PCO (A or B), where we expected it!

• 4. Preparation of testing reports

  Make testing reports (SCTR, PCTR)! Use Test Manager for this, and make a measurement record from the file generated by it, e.g. with the help of WinWord (on a PC). Define shortly the measured data in this record! Documentation must be so detailed, that the measurement could be reproducted from it any time!

  (Note: parameters of Other category can influence the size of the generated document...)

Facultative measurement task:

Go back to the Test Manager. Search for a test sequence, which gives a "Fail" result. Demonstrate with comparison of TTCN trace and ATS, why became the result of test "Fail". Try to guess the real cause of the error: does switch really not fulfil the recommendations, or only the measurement arrangement has a problem? Documentate your work!