Modellgestützte Untersuchung konkurrierender Zugriffe bei leitungsvermittelnden Kommunikationssystemen (English shop)

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Communication systems must have very high availability. Faults in the software of these systems can lead to the failure of the entire telecommunications network. For this reason, a high level of quality is required when testing such systems.

The starting point of this work were fault reports of failures that occurred in the fault class “concurrent accesses” during the testing of a newly developed 40 Gbit transmission system in industry. It is investigated how the frequency of occurrence of such failures can be increased by means of load tests. The novel investigation presented here is based on a stochastic simulation model. The results obtained from it are compared with the frequencies of occurrence determined analytically in a probability model. One of the central questions here is the dependence of the frequency of occurrence on various parameters, such as the number of connections switched.

Further new insights into the frequency of occurrence as a function of operating system properties are gained. Potential possibilities for variation in the execution of load tests to increase the frequency of occurrence, and their relevance, are determined.

This work provides, for the first time, a description of a systematic approach to conducting load tests on communication systems in industry. This makes an improved analysis of this type of software fault possible. A higher availability of communication systems in operation at the customer’s site is thereby achieved.