Change VIP address

You need to enter the Virtual IP and Virtual host name during a clusterware installation. These information are stored in the OCR and different components within RAC depends on these VIPs.
If for any reason you want to change the VIP, you may do it using ifconfig and srvctl utilities.
The following steps are performed to change the VIP address.

Step 1: Confirm the current IP address for the VIP

$ ifconfig - a

Step 2: Stop all the resources that are dependent on the VIP on that particular node.

$ srvctl stop instance -d DB -i db1
$ srvctl stop asm -n node1
$ su - root

# srvctl stop nodeapps -n node1

Step 3: Verify that VIP is no longer running.

$ ifconfig -a

The output must be blank. If any interface is listed, it means there are components that is dependant on VIP is still running. Stop those resources.

Step 4: Change /etc/hosts file

Edit the /etc/hosts file with the new ip address and hostname.

Step 5: Modify the nodeapps and provide the new VIP address using srvctl.

$ su -root

# srvctl modify nodeapps -n node1 -A 192.168.4.41/255.255.255.0/eth0

where 192.168.4.41 is the new IP address and 255.255.255.0 is the subnet mask
and eth0 is the interface you want your VIP to use.

Step 6: Start the nodeapps again

# srvctl start nodeapps -n node1

Step 7: Repeat step 1 -6 on the other available nodes.

Step 8: Modify the IP address in the tnsnames.ora and listener.ora files.

Thanks