One-to-one and ring synchronization
The one-to-one and ring (or round-robin) patterns are simple patterns
that are most suitable for small numbers of replicas. As the number of replicas
increases, so does the amount of time for changes originating at one replica
to be received at a replica at the other side of the ring.
Figure 1. One-to-one synchronization
pattern 

Figure 2. Ring synchronization
pattern 
