1. Home
  2. Cisco Systems
  3. Static NAT Question

Static NAT Question

Network 1 --> Router1 --> Router2 --> Network 2 --> Router3 --> Network

3

Network 1 has a subnet of 172.16.5.0/24 Network 2 has a subnet of 172.16.8.0/24 Network 3 has a subnet of 172.16.1.0/24

I need network 1 to communicate with network 3. Router 3 only accepts packets from the 172.16.8.0 network. I need to NAT network 1 at router

2 to translate my 172.16.5.0 packets into 172.16.8.0 packets. I do not control router 3 and the people who do control it will not make any changes to it.

I made the serial interface on router 2 (it connects to router 1) the NAT outside interface. I made the ethernet interface on router 2 the inside interface (though I don't think this makes any difference).

The only other configuration I made was this line:

IP NAT outside source static 172.16.5.165 172.16.8.44 (I am only interested right now in NATting this one IP address).

When I show ip nat translations, I see the proper translation, but I can't ping nor access anything on the other network. I do not get any debug ip nat information at all (like it's not translating). I THINK it's because the router sees the return packet as 172.16.8.44 and doesn't think to route it back through (as it's on the same network as it's interface) but I am not sure. I thought this was the entire point of NAT.

Any ideas or solutions? Thanks.

Reply to
paul.demay
Loading thread data ...

Make the interface that connects to router 1 the inside interface, and make the interface that connects to router 3 the outside interface.

ip nat was designed to work most easily with the source being nat'd on the way out to the "outside", and with the destination being de-nat'd on the way in from the "outside".

Reply to
Walter Roberson

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.