I manage a bunch of routers... on some, the outside-to-inside port address translation statements are set up like this:
ip nat inside source static tcp 192.168.10.69 25 188.8.131.52 25 extendable
(184.108.40.206 is my outside public IP assigned to FastE4)
while other routers are set up like this:
ip nat inside source static tcp 192.168.10.69 25 interface FastEthernet4 25
Both ways work fine, although I prefer the latter way in case FastEthernet4's IP address changes. Are there any real significant difference or are they really just the same?
1.You are right , it is used in case IP Address of NAT interface change , you don't have to change that address in NAT statement
2.Other important thing is , in case you are using DHCP to acquire IP address for Fastethernet interface ( i.e you are making your router as DHCP client) , then also your later method comes handy , as again you don't have to worry about the IP address , DHCP server will allocate "interface" keyword will take care of everything.
HTH...rate if helpful..
Not aware of any significant difference. They achieve the same thing.