Red Hat CLUSTER SUITE - CONFIGURING AND MANAGING A CLUSTER 2006 Manual page 108

92 Chapter 7. Linux Virtual Server Overview
7.4.1. NAT Routing
Figure 7-3, illustrates an LVS cluster utilizing NAT routing to move requests between the
Internet and a private network.
Figure 7-3. An LVS Cluster Implemented with NAT Routing
In the example, there are two NICs in the active LVS router. The NIC for the Internet has
a real IP address on eth0 and has a floating IP address aliased to eth0:1. The NIC for the
private network interface has a real IP address on eth1 and has a floating IP address aliased
to eth1:1. In the event of failover, the virtual interface facing the Internet and the private
facing virtual interface are taken-over by the backup LVS router simultaneously. All of the
cluster's real servers located on the private network use the floating IP for the NAT router
as their default route to communicate with the active LVS router so that their abilities to
respond to requests from the Internet is not impaired.