To use virtual IP addresses, you set up an internal virtual IP network on each cluster node. The network consists of the following:
A virtual adapter is a software-based adapter. A virtual adapter behaves like a conventional loopback interface with external visibility. LAN routers can maintain accurate information on available routes to the virtual adapter destination. The last hop on a router path to cluster resources occurs inside the cluster node itself. A cluster resource’s IP address is bound to the virtual adapter instead of to a physical adapter.
Virtual adapters support configuring virtual IP addresses with a host mask. The mask treats each resource as a separate network segment. This allows each cluster resource to have its own entry in the routing table of the internal router on the cluster node where it resides.
An internal router is a software-based router that runs on the operating system in a cluster node. On Linux, the internal router is set up with the open source Quagga Routing Software Suite.
Quagga Routing Software Suite is an open source implementation of major routing protocols for IPv4 and IPv6, including OSPFv2, OSPFv3, RIPv1, RIPv2, RIPv3, and BGPv4. It is available under the GNU General Public License version 2.0. For information, see www.quagga.net.For information about Quagga, see the Quagga Routing Suite Web site.