Chapter 16. SS7 Testing

When a new implementation of C7 is introduced into a network, it must be conformance tested against the appropriate standard to ensure that it functions correctly. This is known as validation testing. Validation testing is performed before the implementation is put into a live network.

After validation testing has been successfully completed, the implementation can be deployed into the live network, where more testing will be performed. Testing at this stage is known as compatibility testing. Compatibility testing ensures that the implementation can interwork properly with the other signaling points that are already in the network; it might also be referred to as interoperability testing. The validation phase is performed against an offline implementation and is used for protocol verification, whereas compatibility testing is performed against an online implementation and is used to verify the proper interworking of two or more protocol implementations.

The ITU-T has produced framework test specifications covering both validation and compatibility for MTP2, MTP3, TUP, ISUP, ISUP Supplementary Services, SCCP, and TCAP. The test specifications are contained in Recommendations Q.781 to Q.787, respectively. While all tests are validation tests, a subset is also marked as compatibility tests:

• Q.781 [87] covers MTP2 [50]

• Q.782 [88] covers MTP3 [51]

• Q.783 [89] covers TUP [64]

• Q.784.1 [90] covers ISUP [75–78, 80–81]

• Q.785 [91] covers ISUP Supplementary Services [69]

• Q.786 [92] covers SCCP [58–63]

• Q.787 [93] covers TCAP [82–86]

Test Specifications for SIGTRAN (see Chapter 14, "SS7 in the Converged World") are just becoming available at the time of this writing. The following are available as drafts from the IETF:

• MTP2— User Peer-to-Peer Adaptation Layer (M2PA) Test Specification

• MTP2— User Adaptation Layer (M2UA) Test Specification

• MTP3— User Adaptation Layer (M3UA) Test Specification

A prerequisite for testing a given protocol layer is that the underlying layers have been implemented correctly; that is, they have already passed validation and compatibility testing. The tests intend to test the given protocol's key functionality under normal and abnormal conditions; testing all work under all abnormal conditions is impossible and impractical because of the nearly endless number of tests that would be required.

The tests do not have to be performed sequentially; however, on the whole it is generally more convenient to follow the test list in order. For some parts of the test specification it might be easier to order by pre-test conditions because the end of a test might be the pre-test condition of another test.

The chapter begins with an overview of the types of equipment that are available for SS7 testing and discusses how to use the appropriate ITU-T test specification to produce the required test specification. The rest of the chapter provides examples with full explanations for common tests (as specified by the ITU-T) for validation and compatibility of MTP2 to show the breadth of testing against a particular layer. Finally, a few examples for MTP3, ISUP, Supplementary Services, and TCAP are shown.