A METHOD FOR TESTING AN OBJECT IN A TELECOMMUNICATIONS SYSTEM

Abstract: The present invention relates to a method and arrangement for testing an object in a telecommunications system, said object having an incoming side and an outgoing side. A plurality of test components is allocated in parallel for the incoming and the outgoing sides of the object. The testing routines are accomplished by the plurality of in parallel allocated test components for the incoming and the outgoing sides of the object. The operation of the in parallel allocated test components is equivalently controlled by a main test component connected to each of the parallely allocated test components, whereby a symmetric test structure is provided for testing the incoming and the outgoing sides of the object.

Description: A METHOD FOR TESTING AN OBJECT IN A TELECOMMUNICATIONS SYSTEM FIELD OF THE INVENTION The present invention relates to a method for testing objects in a telecommunications system. The invention relates further to an arrangement for performing testing operations in a telecommunications system. BACKGROUND OF THE INVENTION A telecommunications network includes various objects or implementations, such as exchanges or switches, that need to be tested. The purpose of the testing is to test e.g. the used protocol and functionality of the telecommunications network and the various part and components thereof. Two common testing procedures are conformance testing and function testing. From these the first is used to test the conformity with the used standard or protocol, and the latter is used to test that the system or object operates and functions in accordance with the standards and protocols. The "border line" between these is not, however, especially clear and tight, and thus these test may overlap. A test may be accomplished when taking a new system in use, after maintenance, preparations or upgrading of a system, or periodically, i.e. certain intervals, or occasionally, e.g. after a certain predetermined event has occurred, or even randomly. In a telecommunications system the test may concern only one of the plurality of objects, e.g. one exchange, or then the whole system may be tested entirely or partially, i.e. all or predefined components (objects) of the system are tested during one test cycle. An Abstract Test Method (ATM) and the testing configuration according to the ITU-T (International Telecommunication Union - Telecommunication Standardization Sector) and ETSI (European Telecommunications Standard Institute) are having a non-symmetric structure. The configuration of the testing arrangement is such that a Main Test Component (MTC) is arranged to serve the outgoing side of an apparatus to be tested and a Parallel Test Component (PTC) is arranged to serve the ingoing side of the apparatus to be tested (or vice versa) . However, a problem of this kind of testing arrangement is that the incoming and the outgoing sides of the objects cannot be equivalently controlled in the testing process. In addition, the results obtained from the different sides are not comparable to each others. This in turn causes difficulties when analyzing the obtained testing results. SUMMARY OF THE INVENTION It is an object of the present invention to overcome the disadvantages of the prior art testing solutions and to provide a new type of solution for implementing a testing process of objects in a telecommunications system. An object of the present invention is also to provide a method and arrangement by means of which it is possible to obtain comparable testing results from an incoming side and an outgoing side of an object, such as a telephone exchange. Other objects and advantages of the present invention will be brought out in the following part of the specification taken in conjunction with the accompanying drawings. The objects are obtained by a method for testing an object in a telecommunications system, said object having an incoming side and an outgoing side, wherein a plurality of test components is allocated in parallel for the incoming and the outgoing sides of the object, testing routines are accomplished by the plurality of in parallel allocated test components for the incoming and the outgoing sides of the object, the operation of the in parallel allocated test components is equivalently controlled by a main test component connected to each of the parallely allocated test components, whereby a symmetric test structure is provided for testing the incoming and the outgoing sides of the object. A preferred an arrangement for testing an object in a telecommunications system, said object having an incoming and an outgoing side, comprises a plurality of test components which are allocated in parallel for the incoming and the outgoing sides of the object under test, and a main test component arranged to equivalently control each of the in parallel allocated test components in the incoming and the outgoing sides of the object, whereby a symmetric test structure is provided for testing the object. Several advantages are obtained by means of the present invention. The solution provides a symmetric testing arrangement, in which all testing components can be equally controlled. The testing results obtained from two different sides of an object to be tested ar comparable to each other which makes the further analyzing of the results easier to accomplish, and gives more reliable results for the testing procedures. In the following the present invention and the other objects and advantages thereof will be described in an exemplifying manner with reference to the annexed drawings, in which similar reference characters throughout the various figures refer to similar features . BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic presentation of a prior art testing arrangement ; Figures 2a and 2b are schematic presentations of one embodiment of the present invention; Figures 3a and 3b are schematic presentations of another embodiment of the present invention; and Figure 4 discloses a still further embodiment . DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 is a schematical presentation of a prior art arrangement for testing an object in a telecommunications system. More precisely, the arrangement is an ISUP (ISDN User Part) test configuration for local exchanges. However, it is to be noted that other transit protocols than ISUP can also be tested by this solution. As illustrated, the prior art arrangement includes a Main Testing Component (MTC) 2 and a Parallel Testing Component (?TC) 3 for testing the object, i.e. an Implementation Under Test (IUT) 5. Test Coordination Procedures (TCP) 4 are implemented between the MTC 2 and the PTC 3 so as to provide a link between the two testers. The PTC 3 forms a slave process for the MTC 2, and is located in a separate test step. Thus, and as can be seen from figure 1, the structure is asymmetric (the MTC and the PTC are operating parallel, even though the operation and general structure thereof is different) , and thus the prior art configuration has the disadvantages already referred to in the above. Figures 2a and 2b disclose schematically one embodiment, and more precisely, a concept and configuration for testing intermediate exchanges (transit exchanges, gateway exchanges etc.) . The unit to be tested may be referred to as SUT (System Under Test) or an IUT (Implementation Under Test) . A SUT has an incoming and an outgoing side, which are to be considered during the test in order to test e.g. the protocol and functionality of a transit or a gateway exchange. An IUT (Implementation Under Test) 5 is provided on the interface between two network service providers 20 and 21. The IUT 5 is observed and controlled from two ISUP (ISDN User Part) links, i.e. LT (Lower Tester) ISUP links 6 and 7, with associated circuits, i.e. LT Circuits 8 and 9, respectively. A Test Coordination Procedures (TCP) link 14 can also be seen to be implemented beyond the LTs . Points of Control and Observation (PCOs) required for the testing are labelled as A_PCO and AC_PCO on the left hand side, and B_PCO and BC_PCO on the other or right hand side of the IUT 5, respectively. From these the A_PCO is intented for a signalling link between the IUT and the SPA (Signalling Point A) , B_PCO is intented for a signalling link between the IUT and the SPB (Signalling Point B) , AC_PCO for the circuits between the IUT and SPA, and BC_PCO for the circuits between the IUT and SPB. The A_PCO and B_PCO are used by the Lower Testers (LTs) for controlling the ISUP signalling links 6 and 7. The AC_PCO and the BC_PCO are used by the Lower Testers (LTs) for observing circuit related events, such as connectivity, echo control check, alerting tone etc. ISUP PDUs (Protocol Data Units) to be sent and observed on the B_PCO side allow for PDU constraints to be specified and coded down to bit level. The underlying network service provider 20, 21 can be e.g. a Message Transfer Part (MTP) protocol, which is specified in detail in ITU-T Recommendations Q.701-707, which are incorporated herein by reference. A possible configuration for the above testing arrangement for intermediate exchanges is disclosed by figure 2b. In this a Main Testing Component (MTC) 12 is implemented such that it is connected by means of TCPs 14 and 15 to two Parallel Testing Components (PTCs) 11 and 13. The arrangement is such that the MTC 12 is responsible for supervising the two Parallel Testing Components (PTCs) 11 and 13. From these the A_PTC is responsible for the A- IUT interface and the B_PTC is responsible for the IUT-B interface (the order of the abbreviations showing the signalling direction) . The Test Coordination Procedures (TCP) allow communication between the respective parallel testers 11 and 13. The test components may also be implicitly coordinated (asynchronously) , since the TCPs between the MTC and the respective PTCs are used only before checking the state of the ISUP signalling circuits and when it is necessary to obtain a verdict from the PTCs 11 and 13. Figure 2b discloses thus two PTCs or testing components which are parallelly allocated on both sides of the object to be tested. However, even though only two PTCs are disclosed, it is to be understood that the number of the parallely allocated test components can be even remarkably greater than two. The MTC 12 is controlling the PTCs 11 and 13 through the TCP links 14 and 15. Therefore it is possible to control the incoming and outgoing sides of the IUT 5 equivalently in the testing process. This, in turn, makes the arrangement symmetric and the test results for the incoming and outgoing sides comparable to each others . Figures 3a and 3b disclose a testing arrangement for local exchanges or originating/destination exchanges of a telecommunications network. A common problem in here has been that, when testing a local exchange, it has been difficult, and in many cases even impossible, to observe only the ISUP PDUs, if the functionality, such as connectivity, tones and announcements etc., associated with the protocol events is to be considered and used to assign the verdicts. The IUT 5 is now positioned on the interface between an access service provider 23 (access side) and a network service provider 20 (network side) . A PCO from an ISUP (IUT 5) to the access side is needed, e.g. for stimulating the local exchange to originate a call by sending an IAM (Initial Address Message) . Another PCO is needed to check the connectivity or tones generated by the local exchange . In most cases there is no exposed interface from the ISUP (which is now the IUT) towards the access side. For the practical testing purposes the access interface may be selected for this purpose. It is reasonable to make use of the access interface, e.g. the user access interface DSS1 (Digital Subscriber System 1 protocol) as a PCO and to use existing naming conventions for the Abstract Service Primitives (ASPs) to be used in this PCO. In the Abstract Testing Suite (ATS) there is a possibility to choose the used access protocol from the DSS1. A more general access-like speudo protocol may be used, or it is possible to just simply use manual operations to stimulate the ISUP (i.e. the IUT 5) . In the example of figures 3a and 3b disclosing a possible configuration for a multi party testing arrangement for local exchanges each of the testers has a single PCO. The PCO for the access uses the underlying access service provider (e.g. a LAPD in case of DSS1) for observing access events and stimulating the ISUP via the access. The ISUP implementation (i.e. 8 the IUT) cannot be tested without involving the User Network Interface (UNI 15) part to this process. The right hand side in figures 3a and b is considered as the network side, and the left hand side as the access side. Both sides are provided with two PCOs. In the network side the B_PCO is used by a LT controlling an ISUP signalling link, whereas the BC_PCO is used by another LT controlling traffic channels (e.g. for observing circuit related events, such as connectivity, alerting tone etc.). The ISUP PDUs to be sent and observed on the B_PCO side allow for PDU constraints to be specified and coded down to the bit-level. On the access side the ACCESS_PCO (or an Access signalling PCO (D-channel) ) is used to observe and control Call Handling events, whereas the ACCESS_C_PCO (or an Access physical circuit PCO (B-channel) ) is used to control and observe physical aspects (e.g. tones and announcements) . The access PDUs to be sent and observed on the ACCESS_PCO are chosen at an appropriate level of abstraction. DSSl-like primitive names can be used for the access ASPs (Abstract Service Primitives) . In the ATS the access PDU constraints are given for the DSS1 protocol, whereas the PDU constraints have not been coded to the bit-level for the pseudo access protocol. The access aspects cannot be left out for local exchanges. This widens in some extend the scope of the ISUP signalling. The exemplifying configuration for a local exchange is disclosed by figure 3b. A Master Testing Component (MTC) 12 is arranged to supervise two Parallel Testing Components (PTCs) 13 and 31. The B_ISUP_PTC is responsible for the ITU_B interface and the ACCESS_PTC is responsible for the UNI access interface. For simplifying reasons a maintenance PCO is integrated in the MTC. There are also such test cases for the local exchanges, especially when supplementary services are used, where it is appropriate to use a mixed testing configuration. Figure 4 discloses one example for such mixed testing configuration, showing and shortly explaining the respective Points of Control and Observation (PCOs) . In this configuration the Main Test Component (MTC) 12 supervises through a PCT link three Parallel Test Components (PTCs) 11,13 and 31: two ISUP PTCs and one access PTC. As can be seen the arrangement includes two network service providers 20, 21 (see figs 2a and b) and also an access service provider 23 (see figures 3a and b) . In this case the local exchange (IUT) is the exchange which serves that particular user who initially activated the supplementary service. Lets now consider the master-slave aspects of the above described configurations. Figs. 2b, 3b and 4 each show a logical test component of the adopted test configuration. Each of the arrangements includes a MTC supervising the plurality of parallelly allocated test components. In addition, there is always an ISUP PCT located on the right hand side of the IUT, whereas on the left hand side there are different kinds of Parallel Test Components (PCTs) : ISUP (figure 2b) , access (figure 3b) or both (figure 4) . The ATS for the arrangement can be written e.g. by a TTCN (Tree and Tabular Combined Notation) and so that an appropriate configuration is chosen in accordance with the role of the exchange to be tested. The right hand side PTC may be an international or national ISUP and configurable so that any two of these may be run. The selection is based on answers given to PIXIT (Protocol Implementation Extra Information for Testing) questions. The left hand side PCT may be of any kind. For instance, it may be an 10 international or national ISUP, and access signalling system or a non-ISUP user part. When executing a test only one of these configurations will be selected, the selection being made on the basis of information provided in the PICS (Protocol Information Conformats Statement) and PIXIT. For gateway exchanges it may be assumed by default that a call is set up from the left PTC to the right PTC. Thus a national network is located in this case on the left hand side of the IUT for the outgoing international exchange and the international network is then on the right hand side of the IUT. For incoming international exchanges the international network is located on the left hand side and the national network for handling the calls on the right hand side. The message flow in the tests can be designed such that the verdict is assigned on the basis of observing the behaviors synchronously in both sides. The behaviors (the behaviors being a form of the possible results) are thus comparable. According to one scenario an expected behaviour of the sides is required for assigning a positive verdict for the test, otherwise the test gives a negative verdict, i.e. the object failed in the test. Thus, the invention provides an apparatus and a method for testing by which a significant improvement can be achieved. The arrangement according to the present invention is easy and economical to realize by per se known components and reliable in use. It should be noted that the foregoing examples of the embodiments of the invention are not intended to restrict the scope of the invention to the specific forms presented above but the present invention is meant rather to cover all modifications, similarities and alternatives which are included in the spirit and scope of the present invention, as defined by the appended claims. All additional embodiments, modifications and applications obvious to those skilled in the art 11 are thus included within the spirit and scope of the invention as set forth by the claims appended hereto. Abbreviations in Figures Fig 1 IUT - Implementation Under Test MTC - Main Test Component PTC - Parallel Test Component TCP - Test Coordination Procedures LAB - PCO for the AB signalling link CAB - Circuit PCO for the AB interface ACH - Access call handling PCO (D-channel) APH - Access physical circuit PCO (B-channel) Fig 2a & 2b LT - Lower Tester PCO - Point of Control and Observation SP - Signalling Point B_PCO for signalling link between IUT and SPB BC_PCO for circuits between IUT and SPB A_PCO for signalling link between IUT and SPA AC_PCO for circuits between IUT and SPA Fig 3a & 3b TCP - Test Coordination Procedures UNI - User-network interface B_PCO - PCO for IUT-B signalling link BC_PCO - Circuit PCO on IUT-B interface Access_PCO - Access signalling PCO (D-channel) Access_C_PCO - Access physical circuit PCO (B-channel) MTC - Main Test TCP - Test Coordination B_PCO - PCO for the IUT-B signalling BC-PCO - Circuit PCO for the IUT-B Access_PCO - Access call handling PCO (D- Access_C_PCO - Access physical circuit PCO (B- Fig 4 TCP - Test Coordination Procedures B_PCO for the IUT-B signalling link BC_PCO Circuit PCO for the IUT-B interface A_PCO for the A-IUT signalling link AC_PCO Circuit PCO for the AC interface Access - Access call handling PCO (D-channel) Access_C_PCO - Access physical circuit PCO (B-channel) U - user call handling point

Claims: 12 Claims 1. A method for testing an object in a telecommunications system, said object having an incoming side and an outgoing side, wherein a plurality of test components is allocated in parallel for the incoming and the outgoing sides of the object, testing routines are accomplished by the plurality of in parallel allocated test components for the incoming and the outgoing sides of the object, the operation of the in parallel allocated test components is equivalently controlled by a main test component connected to each of the parallely allocated test components, whereby a symmetric test structure is provided for testing the incoming and the outgoing sides of the object. 2. A method according to claim 1, wherein the object to be tested is a telephone exchange, such as an intermediate exchange or an originating exchange or a destination exchange. 3. A method according to claim 1 or 2, wherein the testing is accomplished to observe the functionality of the object by means of comparable results obtained from the incoming and outgoing sides of the object. 4. An arrangement for testing an object in a telecommunications system, said object having an incoming and an outgoing side , comprising a plurality of test components which are allocated in parallel for the incoming and the outgoing sides of the object under test, a main test component arranged to equivalently control each of the in parallel allocated test components in the incoming and the outgoing sides of the object, whereby a symmetric test structure is provided for testing the object. 5. An arrangement according to claim 4, wherein the object to 13 be tested is an intermediate telephone exchange implemented between two network service providers in the telecommunications system. 6. An arrangement according to claim 4, wherein the object to be tested is an originating telephone exchange or a destination telephone exchange implemented on an interface between an access service provider and a network service provider. 7. An arrangement according to claim 4, wherein the object to be tested is a telephone exchange interfacing a plurality of network service providers and an access service provider. 8. An arrangement according to any of claims 4 to 7, wherein the test coordination procedures are arranged between the in parallel allocated test components and the main test component controlling each of the in parallel allocated test components.

Inventors: KAEMAERAEINEN MIKA, SWAHN TOM, KAEMAERAEINEN, MIKA, SWAHN, TOM
Applicants: ERICSSON TELEFON AB L M, KAEMAERAEINEN MIKA, SWAHN TOM, KAEMAERAEINEN, MIKA, SWAHN, TOM, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 1999
Main classification: H04M3
IPC codes: H04M3