Changing/redirecting IP

Hello,

Please advise me on the following.

I have 2 tunnels - one IPSec (Lan-LAN) and one OVPN (Mikrotik is OVPN client; the OVPN server is in it’s LAN).
Now the OVPN is used for backup only.

Users connect to the server share using the IPSec tunnel, but when it’s down i have to change their hosts file on workstations in order to point to different ip address.

The question is: how can i force Mikrotik to replace the requests to IP 10.0.0.10 (being the IPSec IP of the destination server) to go to 20.0.0.20 (being the OVPN IP of the destination server).

1 to 1 mapping

http://wiki.mikrotik.com/wiki/Manual:IP/Firewall/NAT#1:1_mapping

Thank you. That was it!