NAT pool and outside interface

Lessons Discussion
#1

When working with NAT, does the IP Address on my outside interface have to be part of the same subnet for my range of NAT pool IP Addresses? Or, can I have a configuration such as the following:

int s0/0/0
ip address 209.165.201.1 255.255.255.252
ip nat outside

int fa0/0
ip address 10.1.1.1 255.255.255.0
ip nat inside

ip access-list TEST2
permit 10.0.0.0 0.255.255.255

ip nat pool TEST 209.165.200.241 209.165.200.245 prefix-length 29
ip nat inside source TEST2 pool TEST overload

And if the subnet of my pool of IP Addresses can vary from the IP Address configured on s0/0/0, what about that configuration needs to be changed to allow a successful ping (and translation) from a device on my private LAN (10.1.1.0/24) to the 209.165.201.0/30 network?

Thanks.

#2

It doesn’t have to be an IP address on your outside interface, you could use a different range in the pool.

There’s two things you should do though:

  • Create a loopback interface and configure the subnet there that you use in the pool.
  • Advertise this subnet or use a static route on the other side.

Rene