Monday, May 2, 2011

Howto remove old NAT configuration from Cisco router

Recently I came upon a situation where my ISP has assigned me a static IP - instead of L2TP dialer (Virtual PPP Interface in Cisco) I was using before ...
Anyway, I started to remove old and irrelevant NAT settings that were associated with my old dialer ,but when I've tried to configure the new NAT settings I got an error:
%Dynamic mapping in use, cannot change

After scratching my head for awhile I found the solution.

To remove old NAT settings on Cisco router you need to 

1)Clear all old NAT translations
router#clear ip nat translatiom *

2)Disable old NAT pool settings
router(config)#no ip nat pool public_access netmask

3)And finally, disable the translation:
router(config)#no ip nat inside source list 1 pool public_access overload

From this point you can safely configure the new NAT settings.