I know this is a basic routing question, but I can't remember what I need to do for my specific situation. I have a new T1 to a branch location that is running on a 192.168.0.0/24 network and our local network is a 192.168.0.0/16. I'm having a hard time conceptualizing how traffic generated from our local net destined to a 192.168.0.0/24 is going to make it to the remote location. I'm not sure if this is considered an overlapping network and the key is in using NAT. Thanks in advance for the help.
This does not confuse the issue and does help to clarify what is going on. As long as there are not addresses assigned on your side in the range 192.168.0.1 through 192.168.0.254 then it can work to use 192.168.0.0/24 at the branch. It will work because examination of the routing table always looks for the longest match.
Before I explain further I would like to point out one thing. Consider the prefixes
we might look at them and say that they are both 192.168.0.0 and are the same. But to the router and its routing logic they are different because they have different masks and they identify different address blocks.
So to make an example if you do show ip route you might get output that says that 192.168.0.0/16 is reachable through on fastethernet0/0 and that 192.168.0.0/24 is reachable through on serial1/1. And if your user on the LAN of site A sends a packet to address 192.168.0.44 then the router will know that it matches the more specific route in the table and will forward out the serial interface. And if that user sends a packet to 192.168.3.2 then the router will know that it matches the less specific route in the table and will forward out the fastehternet interface.
For this to work both site A and the branch must have entries in their routing table for both the /16 and the /24 subnets. (and in this case you would not need address translation)