40 The Byzantine Agreement problem The upper bound on number of faulty processors: –It is impossible to reach a consensus (in a fully connected network) if the number of faulty processors m exceeds  ( n - 1) / 3  (from Pease et al) –Lamport et al were the first to provide a protocol to reach Byzantine agreement which requires m + 1 rounds of message exchanges –Fischer et al showed that m + 1 rounds is the lower bound to reach agreement in a fully connected network where only processors are faulty –Thus, in a three processor system with one faulty processor, agreement cannot be reached
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