You can define multiple interfaces for Redundant Interconnect Usage by classifying the role of interfaces as private either during installation or after installation using the
oifcfg setif command. When you do, Oracle Clusterware creates from one to four (depending on the number of interfaces you define) highly available IP (HAIP) addresses, which Oracle Database and Oracle ASM instances use to ensure highly available and load balanced communications.
The Oracle software (including Oracle RAC, Oracle ASM, and Oracle ACFS, all 11g release 2 (18.104.22.168), or later), by default, uses the HAIP address of the interfaces designated with the private role as the HAIP address for all of its traffic, enabling load balancing across the provided set of cluster interconnect interfaces. If one of the defined cluster interconnect interfaces fails or becomes non-communicative, then Oracle Clusterware transparently moves the corresponding HAIP address to one of the remaining functional interfaces.
For example, after installation, if you add a new interface to a server named
eth3 with the subnet number 172.16.2.0, then use the following command to make this interface available to Oracle Clusterware for use as a private interface:
$ oifcfg setif -global eth3/172.16.2.0:cluster_interconnect
While Oracle Clusterware brings up a HAIP address on
eth3 of 169.254.*.* (which is the reserved subnet for HAIP), and the database, Oracle ASM, and Oracle ACFS use that address for communication, Oracle Clusterware also uses the 172.16.2.0 address for its own communication.
Do not use OIFCFG to classify HAIP subnets (169.264.*.*). You can use OIFCFG to record the interface name, subnet, and type (public, cluster interconnect, or Oracle ASM) for Oracle Clusterware. However, you cannot use OIFCFG to modify the actual IP address for each interface.
Oracle Clusterware uses at most four interfaces at any given point, regardless of the number of interfaces defined. If one of the interfaces fails, then the HAIP address moves to another one of the configured interfaces in the defined set.
When there is only a single HAIP address and multiple interfaces from which to select, the interface to which the HAIP address moves is no longer the original interface upon which it was configured. Oracle Clusterware selects the interface with the lowest numeric subnet to which to add the HAIP address.
Oracle Grid Infrastructure Installation Guide for your platform for information about defining interfaces