Architecture and design of a portable protocol tester

The architecture and design of a new generation portable protocol tester that includes most of the capabilities of dedicated protocol test systems and all of the capabilities of commercial portable testers are discussed. The general tester environment and model of the system under test as viewed by the protocol tester are presented. A conceptual model of a protocol tester that captures its main functional requirements is proposed, and the basic performance requirement is presented. The design and structure of a protocol tester that provides the functional and performance capabilities described are outlined. The implementation utilizes custom VLSI multiprocessors and a special-purpose multiprocessing operating system to allow active and passive testing of more than one system simultaneously. The testing software on each processor is organized as a single process consisting of protocol and test entities with event occurrences being implemented as procedure calls aided by hardware subprocessors. All testing methodologies defined by the ISO, including the ferry method, can be implemented and standardized conformance test suites supported. Suggestions for future extensions to the design are offered