Source nat can be done using a pool of ip addresses. Suppose, I have a pool of 64 public ip addresses and I configure my nat enabled router so that whenever packets are sent outside, source nat all connections using this pool of addresses.
Now, my question is that, what am I doing with these addresses actually? Are they all configured in my router interfaces? Or they are for just source nat purpose(I advertise reachability of those addresses by some protocol)?
As far as I can tell on Linux both approaches are possible. As long as the responses get back to the box doing the NAT it really doesn't matter whether it's through explicit routes or through allocating multiple IPs to the internet-facing interface. The NAT engine is hit before any routing decisions (including the decision on whether to accept the packet locally) are made.
Other implementations may be less flexible.
It's depend upon your requirement actually . Source nat ensure souce IP addresse translation to configured translated IP address . The translation IP address can be single interface allocated ip address . Or pool of ip address
==> When Configuring single IP address allocated to interface i is referred as Port address translation (PAT)
==> When Configuring multiple IP address translation to single private ip address is referred as dynamic NAT translation.
