Modeling robust asynchronous communication protocols with finite-state machines

A.V. Aho et al. (Comput. Math. Applic., vol.8, p.205-14, 1982) used communicating finite-state machines to model synchronous protocols for reliable communication across unreliable channels. Their ideas are extended to modeling asynchronous protocols for communication across unreliable channels using finite-state machines communicating via an unreliable shared memory. Lower bounds on the size of machines and the number of symbols in the transmission alphabet required to achieve reliable communication are established. Two types of finite-state machines and two fault models for the shared memory are considered. In each case it is shown that there are robust protocols for deletion and insertion errors. It is also shown that there are no robust protocols for mutation errors. In contrast, in the synchronous case, robust protocols exist for all of these types of errors.< >