6to4 nat question

Bernhard Schmidt berni at birkenwald.de
Thu Apr 30 15:13:06 CEST 2009

Hi Tom,

> We operate our own AS including ipv6. Now I wanted to provide
> a "carrier grade" ipv4 => ipv6 nat gateway for our whole ipv4 network
> (a /19).


> But it didn't nat the answer packet back to ipv6.

What software version are you using? I had success with a very similar 
configuration on 12.4(15)T6 (2821), but it did not work after an upgrade 
to 12.4(20)T. Also even with 12.4(15)T, I occasionally had to reload the 
system after changing NAT-PT settings before it started working. Other 
lessons learned with that software version are IPv4 and IPv6 must not be 
on the same interface and overloading the IPv4 NAT pool didn't work.

Also, in the line

 > ipv6 nat prefix 2A02:C00:0:FFFF:FFFF::/96 v4-mapped v6v4global

I'm referencing a non-existing IPv6 access-list after v4-mapped, I'm not 
exactly sure why but since it is called "NOTCONFIGURED" in my config I 
assume I had a reason for it :-)


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