Our network is composed of a Cisco 2610 router which connects to our ISP and the other end (inside) connects to a switch and then from the switch we connect to a Cisco ASA 5510. Also from the switch we connect to a couple of servers that have public IPs. (Please see attached diagrame with fake IP addresses)
On the router we also have an ethernet port configured for 192.168.1.0/24 network. This network uses NAT to allow users to connect to internet and that's all we use it for. The IP address: 18.104.22.168 on the outside interface of the router is used for NAT (overload).
As you can see we two different subnets, one from the ISP to our router and the inside public subnet which we use for our servers.
For some reason, the ISP wants to give use only one subnet (outside and inside of the router will be on the same subnet).
How can I configure the router to "route" from outside to inside if both sides are in the same subnet? (I call it "route" because routing means there are two different subnets.
If it is possible please send me some link to some info where I can study this further.
I would appreciate any suggestion.