Repair of Communication system by working around failures

An application of functional reasoning to the repair of communication software is described. This type of repair, called a “work-around,” eliminates a failure, either permanently or temporarily, by reconfiguring the system. The reconfiguration replaces a faulty procedure with a functionally equivalent, working one. In contrast to classical fault-tolerance techniques, functional reasoning is employed to identify implicit functional redundancy. The motivation is the current and future reliability requirements of data and telecommunication networks and their components. The proposed functional model of communication procedures is based on information distributions and is formalized in modal logic. This functional model is appropriate for modeling safety properties of communication systems. The function of the alternating bit protocol (ABP) is described as an example. This example is used to outline the computation of work-arounds, where the functional equivalence is achieved by the correct parameterization o...