NDB Cluster Replication: Bidrectional and Circular Replication Figure 23.36 NDB Cluster Circular Replication with All Sources As Replicas In this scenario, SQL node A in Cluster 1 replicates to SQL node C in Cluster 2; SQL node C replicates to SQL node E in Cluster 3; SQL node E replicates to SQL node A. In other words, the replication line (indicated by the curved arrows in the diagram) directly connects all SQL nodes used as replication sources and replicas. It is also possible to set up circular replication in such a way that not all source SQL nodes are also replicas, as shown here: 4638