Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.


ASA5505: PAT IP Protocol 41 to inside host


Is there a way to have ASA forward protocol 41 to an inside host? The ASA has only 1 public ip address.

I have a router (on the ASA inside interface) doing ipv6-in-ip tunneling to a host on the internet. I keep getting 305006 translation errors.

ASA 8.0(2)


Erik Tamminga


Re: ASA5505: PAT IP Protocol 41 to inside host

I think the signature for protocol 41 is disabled by default and the alarm level is informational. you may check for sig ID 1007 and see that it is disabled. If you want to forward this protocol over a vpn tunnel then you may have to use NAT-T. Following link may help you


Re: ASA5505: PAT IP Protocol 41 to inside host

I think my question was not understood correctly. Let me rephrase my question.

Internet -> ASA5505 -> C871

My C871 has an tunnel interface configured to tunnel IPv6 in IPv4 to an IPv6 tunnel broker on the internet.

My ASA has only one public assigned IP adres.

ASA is configured to do PAT for all internal hosts.

Tunnel interface on C871 sends out tunneled packets using ip protocol 41 (ipv6-in-v4).

My ASA complains about not being able to translate protocol 41 and is thus forwarding the traffic untranslated (which obviously doesn't get to it's destination).

Question: How can I have my ASA forward IP protocol 41 traffic to my C871?

I can forward ALL traffic, but that's not what I want. I still want to utilize my ASA's (SSL-)VPN features.

(The network in question is a personal engineering network, otherwise it would be designed differently ofcourse).


Erik Tamminga

CreatePlease to create content