Interactive consistency with multiple failure modes

The authors address the problem of reaching Byzantine agreement in a distributed system in the presence of different types of faults and show that significant improvements in reliability and performance are possible if faults can be partitioned into disjoint classes. They show that, in a distributed system, to guarantee Byzantine agreement requires N>2a+2s+b+r where N is the total number of processors, a is the number of malicious asymmetric faults (a⩽r), s the number of malicious symmetric faults, b the number of nonmalicious or intercepted faults, and r an algorithm-dependent term. The practical value of this unified model in designing ultrareliable systems is demonstrated by examples