Configure PAT with extendable on interface with dynamic IP

[thyan0001]

I am trying to configure PAT with extendable option (for FTP) on a Cisco 881G. The outside interface is a 3G card with a dynamic IP address assigned to it. So what I'd like to do is assign the PAT rule to the interface name like this:  

ip nat inside source static tcp 192.168.1.10 21 interface Dialer2 21 extendable

(192.168.1.10 is the address of the local FTP server behind the 881G.)

But IOS doesn't seem to allow the extendable option when using interface name. Any suggestions on how to tackle this?

[cadet alain]

Hi,

Do you really need the translation to be extendable? if so then you'll have to use an IP and not the interface and in this case you should ask your ISP for one more IP for your PAT.

Regards

Alain