Both - Timers - off Both - Timers - on Top - Update Timer - on Top - Update Req - Timer

An optimization method is introduced for generating minimum-length test sequences taking into account timing constraints for FSM models of communication protocols. Due to active timers in many of today's protocols, the number of consecutive self-loops that can be traversed in a given state before a timeout occurs is limited. A test sequence that does not consider timing constraints will likely be unrealizable in a test laboratory, thereby potentially resulting in the incorrect failing of valid implementations (or, vice versa). The solution uses a series of augmentations for a protocol's directed graph representation. The resulting test sequence is proven to be of minimum-length while not exceeding the tolerable limit of consecutive self-loops at each state. Although UIO sequences are used for state veri cation method, the results also are applicable to test generation that uses distinguishing or characterizing sequences.