Subject: Re: HEADS UP! Default value of ip6_v6only changed
To: NetBSD OS PMC <>
From: William Allen Simpson <>
List: current-users
Date: 10/28/2003 04:54:30
NetBSD OS PMC wrote:
> The default value of ip6_v6only (sysctl net.inet6.ip6.v6only) has
> been changed.  The new value brings us closer in line with current
> RFC-defined behavior and practices.
> Itojun still has significant concerns about the new default behavior.
> His concerns have been well-documented in
> Best Regards,
> NetBSD OS PMC (core)

The draft is well founded.  I strongly opposed the translation/mapping 
of IPv4 into IPv6 a decade ago.  There was a whole working group 
devoted to the project, and AFAIK, the WG failed interoperability and 
was disbanded. 

The stack should use IPv4 or IPv6 on a per host basis, as indicated by 
its DNS *and* the availability of IPv6 infrastructure, but not both 
concurrently (for a host).  Of course, there could be IPv4 and IPv6 
concurrently (dual stack approach).

Craig Metz is a sharp fellow, and has been working on IPv6 
implementation since the beginning.  We all respect itojun (of course). 

RFCs are not gospel.  RFC-2133/2553/3493 has evolved over time, and is 
"Informational".  The new IPV6_V6ONLY is only in the most recent 
version, and the default value of "off" is manifestly wrong.  

Please leave the default value as "on", as recommended by 
William Allen Simpson
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