Natting does not mandate that the networks need to be directly connected.
For example
(10.10.10.0/24)R1 <--> R2 <--> R3(100.100.100.0/24)
On R3 you can configure
ip nat pool MYNAT 100.100.100.20 100.100.100.20 prefix-length 24
ip nat inside source list 100 pool MYNAT overload
!
access-list 100 permit ip 10.10.10.0 0.0.0.255 any
interface
ip nat inside
interface
ip nat outside
This sort of situation can be generally seen on the perimeter firewall facing the interanet which translates all the internal address to a glabal public ip pool for routing over the internet and the source networks are mostly not dorectly connected
HTH
Narayan
