The two clusters and sites are connected by two separate networks that provide the replication transport.
The cluster peering network is an IP network that is used to replicate cluster configuration information between the sites. The shared storage fabric is an FC or IP connection that is used for storage and NVRAM synchronous replication between the two clubers. For MetroCluster IP, replication uses both iWARP for NVRAM and iSCSI for disk replication. All storage is visible to all controllers through the shared storage fabric.