You can connect up to 14 Exadata X11M racks together before external RDMA Network Fabric switches are required.
The diagram shows the RDMA Network Fabric architecture for two interconnected X11M racks. Each rack illustration shows two database servers (1 and n) and two storage servers (1 and m) representing all the database and storage servers in the rack.
Each rack has one spine switch and two leaf switches. The connections between the leaf switches are removed and replaced by connections between every spine switch and every leaf switch. As shown in the diagram, when connecting two racks, each spine switch has seven connections to each leaf switch. All database and storage servers connect to both leaf switches, the same as in a single rack.