IPv6 address space shortages (was: Re: A simple question)

--On Sunday, 27 April, 2003 22:24 -0700 Bill Manning 
<bmanning(_at_)ISI(_dot_)EDU> wrote:
> % As John Klensin pointed out on this same list several weeks
> ago % (and I'm sure he said it better than I will), the
> decision to % use ambiguous local addressing in IPv4 (i.e. RFC
> 1918 addresses) % was partially motivated by the desire to
> conserve IPv4 address % space.  In IPv6, we don't have an
> address space shortage, so there % is no reason to introduce
> architectural complexity to conserve % address space.
> %
> % Margaret
>
>         "dont' have an address space shortage..." - Margaret
>         -YET-
>         IPv4 didn't have one either, in its early days.
Bill, regardless of what other features are there and what other 
justifications might exist, the primary problem and hence design 
goal that brought IPv6 into existence was "not enough address 
space".   If we can (even in our paranoid moments) reasonably 
anticipate running out of space, then it is time to send the 
IPv6 addressing architecture back to the drawing board and 
replace it with something that supports variable or 
extensible-length addresses.   I really can't imagine a rational 
enterprise voluntarily deciding to convert to IPv6 if they are 
told it only has a lifetime of NN years, where NN is less than 
at least a major fraction of a century.
For that purpose, I think "running out of space" can be defined 
as finding ourselves with a need to adopt allocation policies or 
strategies (now or later) that force people into non-unique 
addresses to conserve space.
It seems to me that if you, or anyone else, wants to make the 
case that the IPv6 address space isn't going to be large enough, 
you need to do so explicitly and immediately (five years ago 
would have been better, but maybe we know more now).   While I, 
personally, would have preferred extendable length addresses, it 
feels to me that saying "yet" at this stage in the game is just 
pointless sniping unless you are willing to argue for calling a 
halt at this stage and redesigning.
   regards,
       john