Distributed fault detection in communication protocols using extended finite state machines

Run-time fault detection in communication protocols is essential because of faults that occur in the form of coding defects, memory problems, and external disturbances. Finite State Machine models have been used in the past to detect and diagnose protocol faults. However, the fault coverage of these models is limited to vocabulary faults and sequencing faults. We present an Extended Finite State Machine Model (EFSM) to augment the fault coverage of the FSM model. We extend the parallel decomposition method to EFSMs in order to reduce the size of the observer used to detect faults. The decomposition of the EFSM into several independent EFSMs results in multiple observers. The distributed fault detection mechanism increases the reliability of the fault detection and the EFSM model improves the fault coverage.