The pair+N topology includes a pair of cluster nodes that are directly connected to the following:
An additional set of nodes that use the cluster interconnect to access shared storage (they have no direct connection themselves).
The following figure illustrates a pair+N topology where two of the four nodes (Host 3 and Host 4) use the cluster interconnect to access the storage. This configuration can be expanded to include additional nodes that do not have direct access to the shared storage.
Figure 2-6 Pair+N Topology