A protocol standard can be implemented by different manufacturers. Therefore, conformance testing of protocol implementations to standards is important to achieve the main purpose of the open systems interconnection. In this paper, after briefly introducing the session layer protocol and the conformance testing methodology we depict important errors found in the session layer implementations and the shortcomings of the test system.

A technique is proposed for generating a synchronizable test sequence to ensure protocol implementation conformity to protocol specification. This duplex technique converts the transition graph of a protocol into a duplex graph in order to generate a synchronizable test sequence for the protocol. By introducing the Chinese postman tour, this technique can be applied to the transition-tour method for generating the optimally synchronizable test sequence.>