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TCC_2
Level 10
Level 10

Core Issue

It is not possible to remove or change the Network Address Translation (NAT) configuration if there is an active NAT in the NAT table.


Resolution

Clear the NAT table prior to making any changes to the NAT configuration by choosing any one of these options:

  • Issue the clear ip nat translation command and then replacing the NAT configuration quickly, before any new NAT entries are populated into the translation table due to active NAT traffic. To do this, create a script with the configuration commands written in a text format. For example:

    clear ip nat translation *
    config terminal
    no ip nat pool old pool name

    ip nat pool new pool 

  • Disable the NAT on the router by removing the ip nat inside or ip nat outside commands on the interfaces. Then clear the translation table and change the configuration.
       

For more information, refer to How to Change the Dynamic NAT Configuration, Verifying NAT Operation and Basic NAT Troubleshooting.


Comments
Drew T
Level 1
Level 1

Whilst i'm not new to NAT nor cisco, I've come across one that I cannot remove the NAT from. I remove the ip nat in/out statements from each interface to totally disable nat. I remove all the nat config but one line and clear the nat translation table and verify (multiple times) that it is indeed empty. There are no static nor dynamic nat entries in the config or table, yet I still get:

"router(config)#$no ip nat inside source route-map nat-route-map pool nat-pool overload

Dynamic mapping in use, do you want to delete all entries? [no]: yes

%Error: Dynamic mapping still in use, cannot remove

router(config)#^"

Any ideas on this? This is literally the only 'ip nat' command in the entire config, and it still won't delete. Short of a reload and re-try, is there any way? I can't really reload this router very easily (it's a border router).

netvigator
Community Member

I have the same problem and same results from no ip nat inside/outside, no ip nat static.

Any suggestions?

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