Clusters assumes a virtual server model. Connections to the database must be through the cluster alias and cluster IP address, which are different from a single node name and IP address.
Figure 22 shows the physical layout of a cluster where the cluster IP address is 192.168.0.01 (the virtual server IP address). For Clusters, clients connect to this IP address and not the address of one of the individual nodes. In essence, the clients really only know about the virtual server as the node to connect to. The following figure shows the clients connecting over the network to the virtual server with its IP address of 192.168.0.01. Within this cluster there might be several nodes with separate IP addresses, but the clients need not know about each node and must not connect to the individual nodes or Clusters will not work properly.
