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NVI (Nat Virtual Interface) port forwarding issues.

BigDawgFelton
Level 1
Level 1

Hey guys,

I recently ran into issues browsing to an internal FTP server via the outside interfaces IP address. This was using the legacy NAT settings using the nat inside and nat outside commands on the appropriate interfaces. Port forwarding works from the outside just as expected. However using the outside and inside commands limits the feature I need which is getting to the server by the external IP.

I recently read that you can configure Nat Virtual Interfaces by using the "ip nat enable" on the NAT interfaces. I configured it based on documentation I read and it was working great. When doing a "show ip nat nvi translations" I are my entries for my port forwards where they should be.

Now the weird thing......

When I reboot the router I see my port forward information not in "show up nat nvi translations" but in the "show ip nat translations" instead. All other traffic shows that it was NATed using the nvi interface and not traditional NAT. Also I can browse the the server from outside or inside using the external IP address. If I reconfigure and "clear ip nat nvi translations *" and "clear ip nat translations *" everything works again until I reboot the router.

Please help. The router I have this configured on is an 831 router running 12.4. I'm not sure of the exact image at the moment. Could this just be a bug?

Thanks, Elton

Sent from Cisco Technical Support iPhone App

1 Reply 1

Peter Paluch
Cisco Employee
Cisco Employee

Hello Elton,

I am trying to catch back on your issue.

When I reboot the router I see my port forward information not in "show  up nat nvi translations" but in the "show ip nat translations" instead.  All other traffic shows that it was NATed using the nvi interface and  not traditional NAT. Also I can browse the the server from outside or  inside using the external IP address. If I reconfigure and "clear ip nat  nvi translations *" and "clear ip nat translations *" everything works  again until I reboot the router. 

I don't understand this description. Does the reloaded configuration differ from the configuration before the reload? Do you experience any connectivity problems after the reboot, apart from seeing the translations in a wrong output? When you say "if I reconfigure" - what exactly do you reconfigure? Do you replace existing commands with different commands?

Can you post the current config?

Best regards,

Peter

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