IP address takeover via IP aliases

You can configure IP address takeover on certain types of networks using the IP aliasing network capabilities of the AIX® operating system.

Defining IP aliases to network interfaces allows creation of more than one IP label and address on the same network interface. IPAT via IP aliases uses the gratuitous Address Resolution Protocol (ARP) capabilities available on many types of networks.

When a resource group containing the service IP label falls over from the primary node to the target node, the service IP labels are added (and removed) as alias addresses to the base IP addresses on an available NIC. This allows a single NIC to support more than one service IP label placed on it as an alias. Therefore, the same node can host more than one resource group at the same time.

When there a multiple interfaces on the same node connected to the same network, and those interfaces are not combined into a Ethernet Aggregation, all boot addresses must all be on different subnets. Also, any persistent addresses or service addresses must be on different subnets than the boot addresses.

Because IP aliasing allows coexistence of multiple service labels on the same network interface, you can use fewer physical network interface cards in your cluster. Upon fallover, PowerHA® SystemMirror® equally distributes aliases between available network interface cards.