Using NAT and PAT Together

The pool of available “real” addresses can be made up of multiple global statements. To augment a pool of global addresses with a PAT option, use the same nat_id in the global statements. When the pool contains both a global pool and a PAT designation, first the addresses from the global pool are used, and then the next connection uses the PAT address. Whenever a global pool address becomes available, the next connection takes that address.

In this example, a class C-sized global pool is augmented by a PAT argument using the outside interface IP address. All traffic that can’t be handled by the 1.1.3.0/24 network will be translated using PAT.

Pix(config)# global (outside) 3 1.1.3.0 netmask 255.255.255.0
Pix(config)# global (outside) 3 interfacePix(config)# nat (inside)3 0 0