# Byzantine Agreement: Why does OM need f+1 rounds in a synchronous setting?

To get Byzantine Fault Tolerance in a synchronous model you can use an Oral Message Algorithm. For n > 3f+1 it gets an Byzantine agreement in f+1 rounds. Why f+1?

I will use $$m$$, not $$f$$ according the original paper. It gets an Byzantine agreement in $$m+1$$ rounds.
Since it is a recursive algorithm, from $$OM(0)$$ to $$OM(m)$$, so it is $$m+1$$ rounds.