Keith Moore writes:
> > I agree 100% with Micehls' point - assigning unique IDs to sites for use in
> > site-local addresses moves the site-local addresses into a globally
> > routable address space, with the additional feature that those addresses
> > are provider independent. The result would be an address space that is
> > site-local by (potentially unenforceable) executive fiat rather than by
> > technical design.
>
> this sounds like a feature to me, because it would allow hosts using
> such addresses to have their traffic routed between sites without NAT.
>
> private addresses were a bad idea; we should not repeat them in v6.
So it seems to me that what's at issue here is what
is the lesser of evils. I think one thing which we should
all be able to agree about is that local addresses
regardless of original intent will be used to access
global address space. The basic problem here is
renumbering -- and the fact that people don't
want to do that. Since, its a tragedy of the commons
problem, there is simply nothing we can do
about this unless we create the Address Police
who can arrest and execute those recalcitrant
addressing scofflaws.
Thus, we have the two options: site locals which
are actually globally unique could relatively
easily be made globally routable by simply
advertising the prefix. The downside here is
prefix aggregation doesn't happen. For large
sites, this is probably not a big problem, but
for small sites it could be a huge issue.
The other alternative is essentially NAT/ALG's.
We all know how that works, and what it does
to the net.
The thing I don't understand is whether the
address aggregation problem introduced by a
new class of globally unique addresses is
really any worse than the existing problems
with route aggregation, and specifically about
mobility and multihoming. It's quite possible
that we could make things significantly worse
by introducing a new class of routing prefixes,
but as far as I understand, the ultimate fix
for routing table explosion isn't especially
well understood, and it may require its own
set of draconian measures *regardless* of
site locals. On the other hand, we know for
absolute certain that NAT's completely pooch the
end to end principle and are well known evil.
I guess I come down slightly in favor of
avoiding the known evil in favor of the
potentially unknown evil, but as they say,
ignorance is bliss.
Mike
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