Client may want to use different port for SSH for DR machines.
How to use non standard SSH port to configure passwordless SSH for DR machines?
Follow the below instructions:
Create ~root/.ssh/config on each box and add:
Host DR1HOSTNAME
Port 16107
Host DR2HOSTNAME
Port 16107
Host DR3HOSTNAME
Port 16107
Repeat above step for ~dradmin/.ssh/config for each DR node.