If you have more than one Control Station (for failover) on your VNX system, then you can configure an alias IP address which will connect you through to whichever control station is available, rather than connecting directly to either control station.
ssh to your control station as nasadmin, then su to root user.
Check existing IP alias configuration if any.
$ /nas/sbin/nas_config -IPalias -list
Create the IP alias address, same address range and subnet:
$ /nas/sbin/nas_config -IPalias -create 0
Do you want slot_0 IP address <xxx.xxx.xxx.1> as your alias? [yes or no]: no
Please enter an IP address to use as an alias: xxx.xxx.xxx.3
Repeat first command above to see it in the list, and you can also check the IP alias appears in network settings under eth3:0. You can also check IP addresses assigned to your control stations eth1:0 and eth2:0 using this command.
# /sbin/ifconfig eth3:0
Finally, start a new ssh session and attempt to connect to the VNX via the alias IP address.