Clustering in general requires that all cluster nodes in the recovery domain of an application cluster resource group reside on the same LAN (use the same subnet addressing).
The underlying network protocol used to achieve the switching of the configured application takeover IP address from one node in the recovery domain to another is the Address Resolution Protocol (ARP). However, it is possible to extend the recovery domain to include cluster nodes that reside on other LANs separated by commercial routers.
This extension is possible through the use of Virtual IP address support and making use of the Routing Information Protocol (RIP) on the cluster nodes and the commercial routers in the network. See Enabling application switchover for more details.