Oracle Clusterware requires that each node is connected through a private network. You can also called cluster interconnect.
It used for established communication between all the nodes present in the cluster.
Note:
1. Oracle RAC (RDBMS) interconnect uses must be the same interface that Oracle Clusterware uses with the host name
2. Do not configure the private interconnect for Oracle RAC on a separate interface that is not monitored by Oracle Clusterware.
Note:
1. If you configured HAIP on eth0 and eth1, and want to replace eth1 with eth3, then you do not have to stop Oracle Clusterware.
2. If you want to add another set of interfaces such as eth2 and eth3 to your HAIP configuration then you need to stop the Oracle Clusterware.
Following are the steps to change a network interface and its associated subnet address by using the OIFCFG command:
1. Check the Clusterware is running on all nodes
olsnodes -s
mycluster1 Active
mycluster2 Active
mycluster3 Active
2. Check replacement interface is configured and operational at level of operating system on all nodes.
-- For linux
ifconfig
-- For windows
ipconfig
3. Add the new interface to the cluster
providing the name of the new interface and the subnet address
oifcfg setif -global if_name/subnet:cluster_interconnect
4. if you change the Oracle ASM network, then update the Oracle ASM listener
srvctl update listener -listener listener_name -asm -remove -force
srvctl add listener -listener listener_name -asmlistener -subnet subnet
5. Remove the subnet address by providing the name and subnet address
oifcfg delif -global if_name/subnet
--Example
oifcfg delif -global eth1/10.10.0.0
6. Verify the setting
$ oifcfg getif
eth2 10.220.52.0 global cluster_interconnect
eth0 10.220.16.0 global public
7. For change the private network, then stop Oracle Clusterware on all nodes by running command on each node.
crsctl stop crs
8. When you stop Oracle Clusterware then de-configure the deleted network interface.
ifconfig down
9. Restart Oracle Clusterware by running command on each node of the RAC.
crsctl start crs
For more reference:
https://docs.oracle.com/en/database/oracle/oracle-database/18/cwadd/oracle-clusterware-administration.html#GUID-8A7E30F0-6D43-46CC-B453-6C8806886052