Re: /128 address allocation and "localized IPv6 address space exhaustion", was RE: Brokenness of specs w.r.t. client behavior with M&O bits

Mark Smith wrote:
> 
> I'm curious as to why you think this might be the case?
> 
> From what I understand, fixed length addresses were chosen for a few
> reasons (a) only CLNS had variable length addresses, verses every other
> protocol that didn't (e.g. applelalk, IPv4, IPX etc.), so there was
> much more limited experience with variable length addresses, (b)
> people tended to use fixed length CLNS addresses within their
> organisation anyway, to be operationally simpler and (c) it made
> building hardware forwarding ASICS etc. much simpler.
> 
> I can't see why IPv6 having variable length addresses would have
> prevented people creating NAPT66 if /128s were allocated.
> 

Human hoarding instinct combined with old practices from the IPv4 days.
 You can see similar behaviour in areas where the PSTN uses fixed-length
numbers (e.g. North America) versus those there the PSTN uses
variable-length numbers (e.g. Germany).

Yes, people tended to use fixed-length addresses within their
administrative domain, but that is exactly the issue: the crossing of
administrative domains.  With a fixed-length address, each "owner" is
going to try to control the address space as much as possible, even if
it doesn't make sense.  With variable-length addresses, each "owner"
will chop off as much as they feel they need, and knowing they don't
have to worry about it.

	-hpa