Hello guys
I'm pretty sure you hardly every face on problems like mines.
We have a DNS Server in our Site B . There are two different path to achieve our services in site B ( I mean we connect site A and B with 2 path of MPLS and Internet as backup). So, DNS Server answers queries with addresses of Global interfaces with Round Robin. Imagine DNS Server answer with address of MPLS link and this link is down so client can't access to destination. Here I want to change Destination of packet if the destination is not reachable. Something like combination of Route-map , IP SLA and NAT together .
You may be confused. So break my question to a simple example :
Computer A with source ip of 10.10.10.1 wants to talk with destination server with address of 20.20.20.20(MPLS address of Site B) . So Com A sends packet to default gateway. Here, default gateway should check 20.20.20.20 availability. if it's not available , change the destination to 30.30.30.1 ( Internet address of site B).
I guess it's not possible to check availability and changing address at the same time . So I tried to change destination without any attention about link availability. but it didn't work:
access-list 101 permit ip any host 20.20.20.20
ip nat pool trans 30.30.30.1 30.30.30.1 prefix-length 24
ip nat inside destination list 101 pool trans
interface f0/0 ( default gateway of internal users) ==> ip nat inside
interface f0/1 ( public interface ) ==> ip nat outside
