I have a router 3640. There are two E1 boards connected in this equpament, therefore I have several wans. There are multiple NATs configured on this equipament already, so the ethernet port is the outside interface and I cannot change this configuration.
I have a RAS and its default gateway is the 3640 ethernet port, stations that are connected to RAS and need to access Internet must be use one of three different IP addresses ( 22.214.171.124, 126.96.36.199 or 188.8.131.52 ) as your proxy server. I need to configure one NAT that can be able to translate these destinations addresses to 10.6.1.15.
The inside and outside interfaces are the ethernet interface, I hve used NAT on a Stick, It solved my problem in part, so far the best I could do was NAT from one to one.