NAT works on some devices on same network, but not others

[slilley92]

This is weird. We have NAT configured to translate the IP address of some ATM machines to 172.16.95.x network before passing to the company that drives our ATMs. Here is a sample of the config on our router at their site:

ip nat inside source static 172.16.57.200 172.16.95.3

ip nat inside source static 172.16.24.200 172.16.95.4

ip nat inside source static 172.16.106.200 172.16.95.11

ip nat inside source static 172.16.38.200 172.16.95.7

Here's what is happening: 172.16.106.200 is not being translated to 172.16.95.11 before being passed to the ATM company. They put a protocol analyzer on and see packets coming from 172.16.106.200. I tried translating a couple of other devices from the 172.16.106.x network over to 172.16.95.x; some work, some don't. I do not understand. Has anyone seen anything like this before??

Thank you,

Steve

[rwiesmann · Accepted solution]

Hi Steve

It sounds really a bit strange. Thought first that maybe the packets come from different interfaces and you maybe forgot the ip nat inside/ip nat outside comand.

What is the ios you are running?

Regards

Roger

[slilley92]

Roger! That is exactly it! I just figured this out before I read your response. We have 2 PVCs on the frame circuit to the router in question; I had ip nat inside defined on the primary but not the secondary. Once I added 'ip nat inside' to the secondary, NATing started occuring immediately! I feel like a real idiot, but on the plus side, I learned something. And maybe this conversation will help someone else who is as dumb as I am!

Thank you,

Steve