Dave,
Reordering your comments slightly.,..
--On Thursday, 11 October, 2007 11:07 -0400 Dave Crocker
<dcrocker@xxxxxxxx> wrote:
> To repeat: At some point, it would help to take history as
> being instructive, rather than to dismiss attempts at
> considering alternatives.
>
> This might not change the situation with IPv6, but it could
> have an effect on other, future work.
It is hard to predict the future. It is almost equally hard to
draw firm conclusions from the fairly recent past, especially
when drawing those conclusions requires understanding the
counterfactual implications of various choices. I agree that
history is instructive and should not be ignored, but think we
should hesitate to jump to conclusions about what it tells us.
> The approach to IPv6 could have been vastly more incremental,
> so as to make its adoption vastly less disruptive. But you
> have to start by considering the benefits of such an approach.
>
> Brian, the approach to IPv6 ignored protecting the installed
> base and ignored finding a way to have the lowest possible
> barriers to adoption. As 15 years of non-adoption has
> demonstrated, the value proposition for adopters also was not
> compelling.
Examining a value proposition requires asking both the question
"how hard, expensive, or risky is it for me to do this?" and
"how do I benefit if I do?". Larger benefits justify larger
investments; a perception of few benefits may not justify even a
small investment. From that perspective, even small changes to
something that is perceived as working satisfactorily involve
risks of bugs and disruption. There is no way to make a change
zero-cost and zero-risk.
Certainly it is reasonable to hypothesize, as you are doing,
that decisions about transition and compatibilities with IPv6
created a bad value proposition by making transition too
complicated and costly. But it is equally reasonable to
hypothesize that the error lay in our failure to address enough
other issues -- to solve enough other problems -- to create real
"pull" for making changes, no matter how cheap those changes
appeared to be.
Would IPv6 have been more successful had the solution addressed
fundamental routing issues more directly? If it somehow made
small-site multihoming more straightforward and plausible? If
it incorporated a solution to the semantic and management issues
implied by RFC 3514? If it solved some other real or imagined
problem with IP? If we had simultaneously overhauled TCP to
support more connection-agile or address-insensitive use of
applications?
As things have turned out, we've pretty much ended up with "IPv4
with more bits". Selling that one to the community is hard
except on the basis of either an anti-NAT campaign or one based
on the imminent falling of the sky. The former is made more
difficult by the observation that most user organizations do not
perceive that they are suffering real harm from NATs (whether
that perception is correct or incorrect is irrelevant) and more
difficult yet by concerns that IPv6 will not eliminate some of
the factors that cause NATs. The latter is made more difficult
by too many prior predictions, some unrealistic over-marketing,
and an inability to see the sky moving downward and accurately
and convincingly anticipate the dire effects of its coming down.
Can one demonstrate that, given those factors, an easier
transition process would have made a significant difference?
Possibly it would have, but I don't think there is any way to be
convinced.
On the other hand, had IPv6 offered more than what the market
seems to see as a mostly-theoretical improvement (elimination of
NATs) and avoidance of a future address space catastrophe) --
some obvious advantages to those who who already have deployed
IPv4 installations and the address space needed to support
them-- would we have seen wider adoption? Again, there is no
way to know for sure but, if the answer is "yes", then it is
hard to guess how much difference a slightly easier transition
would have made.
So, let us by all means look at history and try to learn its
lessons. But let us also be sure we know what those lessons
actually are, rather than using the historical argument to
justify a position that may not be supported by the evidence.
best,
john
_______________________________________________
Ietf@xxxxxxxx
https://www1.ietf.org/mailman/listinfo/ietf