I have an issue where we have a private network, 10.199.0.0/24. This traffic NATs to a single DHCP assigned address on the outside interface of Cisco 1841. The 1841 can be connected to our netowrk or it can be connected to an external ISP. When in station, the IP address the 1841 receives is a routable IP address and thus we only have to NAT once. 10.199.0.0/24 to routable address.
However, when connected to the external ISPs, a NAT has to be performed at the 1841 and then again at the cable/DSL modem. How do I configure my outside interface to be able to handle this extra occurance of natting? Currently, we are able to ping from a laptop on the inside network to the 192.168.1.254 address on the backside of a CABLE/DSL Modem. If we put the DNS address of 192.168.1.254, we can actually resolve names using the external ISP. But we cannot surf the web or ping open sites like yahoo.com.
Any help would be appreciated.