CLUSTERS

Determining whether to create a private LAN for your cluster
To make a busy cluster more efficient, you can create a private network for your cluster. To do so, you install an additional network interface card in each cluster server and connect these network interface cards through a private hub or switch.

The main reason for creating a private LAN for your cluster is to separate the network traffic a cluster creates when it uses cluster replication and server probes. A private LAN can leave more bandwidth available on your primary LAN. If you anticipate a lot of cluster replication activity, you should create a private LAN.

You can also consider creating a private LAN for intra-cluster communication to ensure that cluster servers remain in communication with each other, even when certain network problems occur. By adding a private network, all servers in the cluster are connected by at least two distinct LAN segments. So if a network board or a cable on one LAN segment fails, there is still network connectivity between all servers in the cluster. This assures you that cluster servers remain in contact with each other and that cluster replication continues to keep databases synchronized.

If you create a private LAN for your cluster, all cluster members must be connected to both the private LAN, for intra-cluster communication, and the primary LAN, for client access.