Site local

[Iljitsch van Beijnum <iljitsch@muada.com>]

I'm now writing some text about short-term router/policy solutions.

Kurt (or should I say Kurtis?) raised the question how many multihomers
there are now in IPv4. There are three answers:

1. We don't know
2. Not all that many
3. It's not relavant, it's the long-term growth that's the problem

One reason the current number of multihomers is relatively low is
probably because it is relatively hard to do. Another is the
availability of alternatives. Both of this has the potential change. As
more and more people start to multihome it will become a matter of
routine, this can become a snowball-effect. In IPv4, people have
relatively small address blocks and use NATs. In IPv6, the address
blocks are huge and not as many people will use NATs, so even though
IPv6 has better renumbering support, it is quite likely renumbering will
actually be harder than in IPv6. Renumbering 60k subnets is simply
prohibitively expensive using current numbering, naming and security
mechanisms. This will be an incentive for people to "serially multihome"
and insist on portable address space.

But now there is an interesting development in the IPv6 working group:
they reached consensus it is a good idea to look at globally unique,
non-routable (although this part was immediately challenged) address
space to replace/complement current site local scoped addresses.

If large enterprises can use this type of address space for all their
internal stuff, renumbering becomes much easier as there are no security
issues: globally routable addresses from an ISP are never trusted, use
site local for internal stuff = no need to change filters when
renumbering. The main renumbering issue that remains is that of the DNS
interaction, maybe along with pushing a new /48 down the internal
network. These seem relatively solvable.

In my opinion, this along with host-multihoming solutions should be
enough to lower the need for multihoming by injecting a globally visible
/48 into the routing table a good deal.

Comments?

Does this mean we should annex the globally unique site local effort and
work on that in this wg?

Iljitsch