Subject: Re: -current sendmail cancer in IPv4-only kernel
To: Steve Deering <>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: current-users
Date: 05/08/2000 16:59:35
In message <v04220801b53cd0113399@[]>,
Steve Deering writes:

>At 2:34 PM -0700 5/7/00, Jonathan Stone wrote:
>>Even Steve Deering has always said that IPv6 may never be deployed.
>I don't follow this mailing list (someone forwarded your message to me),
>but it looks like you are seriously distorting my words.  I have indeed
>often publicly expressed my worry that IPv6 won't succeed in taking over
>from IPv4, due to the inertia of the installed base and the apparent
>preference by many for short-term hacks and loss of IP functionality,
>rather than doing what needs to be done to really fix the problems.  But
>whenever I say that, I am also quick to point out that I am pessimistic
>by nature (that way, I am never disappointed, and often pleasantly
>surprised) and that, nonetheless, the chances of success are high enough,
>and the alternative of just letting the Internet decay is irresponsible
>enough, that I continue to put my own time and effort into making IPv6
>Using those concerns of mine to support your argument for an "IPv6-free
>system" is disingenuous.  


If that's the way you read my message, then I owe you an apology.
However, I didn't intend to distort your words, and I dont think I
did. Widescale IPv6 deployment is not a sure thing even yet, and
(as you note) you are often quick to say so.  I dont think that was
misrepresentation.  But if you do, you have my apology, and (I hope)
you've clarified your position adequately.

But the problem I'm addressing is a different one.

Some people within the NetBSD community have suggested that
NetBSD no longer needs to support IPv4-only configurations.
That is what I'm objecting to.  If you re-read what I wrote
in that perspective, it may make more sense.

>I don't know exactly what's being proposed, but I can't imagine anyone
>is proposing to do anything to prevent the continued use of IPv4 on
>NetBSD systems.  

That depends on whether you mean IPv6-plus-IPv4 "dual stack" setups,
or IPv4-only setups.  People have been  breaking the latter, and 
others have suggested that it become NetBSD policy to not support
IPv4-only systems.    That makes some of us rather unhappy.

>So what technical problem are you trying avoid by having
>an "IPv6-free system"?

The current state of IPv6 at Stanford is such that last time
anyone I know tried to turn on an IPv4-plus-IPv6 box, they could
no longer resolve hostnames.  (This was under OpenBSD, not NetBSD,
but the KAME code in both platforms is very, very similar.)

As for the technical problems with IPv6: yes, we can turn on IPv6 in
trivial configurations today. But there are still technical issues
with IPv6, where doing what IPv4 does today is (as far as I know) 
at best an open research problem.  If you're interested in discussing that,
I'd prefer to move it to email, or at least to a venue where it's

And I'm sorry to be the bearer of ill-wind, but yes, as it happens, I
do seem to be meeting more and more people who see IPv6 acutally
diplacing of IPv4 as increasingly unlikely.  Again, that'd be better
discussed via email or elsewhere.