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Duplicate NAT entries

I have a router with 2 ethernets that translates addresses. Periodically a user from LAN A is given the same NAT address as another user on LAN A. I have to perform a #clear IP Nat trans x.x.x.x on each entry and wait for the users to reconnect. This always fixes the fault. The router was a 2500 and I have now replaced it with a 3640 with the same config but the problem still persists. The dyanimc NAT pool is not being used up. Has anyone had similar problems?


Re: Duplicate NAT entries

Hi Chris

yes I had exactly the same problem with a 3640 router (but only 1 ethernet port). I was looking for a workaround and found Cisco Bug CSCdp84147. You should upgrade your IOS to one of the latest releases [12.1(3) at least]. BUT if you don't want to upgrade your IOS you can do what I did to solve this:

Dynamic NAT translations have a default session timeout of 24 hours. I changed this value to 8 hours by means of 'ip nat translation timeout 28800' command where 28800 are seconds (8 hours). This command completely solved my problem.

You can take a look on this command at:


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