Error message

Unanswered Question
Oct 4th, 2007

My ASA 5510 constantly receives the following message, hundreds in a day.

Does anyone know what this message means?

Thank you!

<163>:Oct 04 14:22:31 EDT: %ASA-session-3-305006: regular translation creation failed for protocol 41 src inside: dst outside:

I have this problem too.
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Jon Marshall Thu, 10/04/2007 - 10:47

Hi David

Protocol 41 is used by IPv6. So for IPv6 to get across the IPv4 internet it needs to encapsulate the IPv6 packet inside an IPv4 packet and for this it uses protocol 41.

However if you are using PAT on your firewall then it will not be able to do a translation for this because there are not any TCP/UDP port numbers.

It may be harmless, it may not. What is the host and does it have any IPv6 software running on it ?



davidwu2007 Mon, 01/07/2008 - 07:02

Hi Jon,

Sorry, I don't see your message until now.

Host is a Windows Vista machine.


Jon Marshall Mon, 01/07/2008 - 07:08


Better late than never :)

I believe Vista runs IPv6 by default so that would explain it.


davidwu2007 Mon, 01/07/2008 - 08:32

Thanks Jon,

My only concern now is that why Ip address keeps trying to connect to outside

from the Vista machine.


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