[address-policy-wg] Just say *NO* to PI space -- or how to make it less destructive

> So there shouldn't be PI for ISPs either, I guess. Only to Peering 
points
> (one per RIR). Would make the routing table so much cleaner. Completely
> impractical? Why is it possible for end sites then?

Now that is a very interesting suggestion. If you assume
that multiple peering points in a single city have rich 
and cheap interconnection, you could extend this idea
to one prefix per city with a population greater than
100,000. There are about 5000 such cities in the world
so we are talking about 5000 prefixes. Of course, each
of these cities serves a larger surrounding area with
various services and such services often reach across
national borders. For instance, the inhabitants of Kehl
and Offenburg in Germany are likely to use services in
Strasbourg, France such as the Opera du Rhin, shopping,
etc. 

If you consider these large cities as centres of gravity
for the surrounding area, then these 5000 cities cover
almost all of the populated surface of the Earth. What
could we do with 5000 such routes in the global routing 
table?

Well, for one thing, we could offer an almost unlimited
number of PI IPv6 address blocks to ever business or
organization that feels the need to multihome in order
to secure the separacy plus resiliency that need in
their network connections. All of those PI blocks would
be invisible in 4999 of the world's cities because those
cities will only see the single city prefix. We then have
solved the routing table scaling problem by dividing
and conquering. There still could be some localised issues
in some cities, but it is much simpler for a group of
local ISPs to sort out a local issue than it is for everybody
in the world to agree on the one true routing solution.

The best part of this solution is that it requires no
protocol changes, no new code in routers, and works with
all existing IPv6 technology. It can be implemented entirely
by changing RIR allocation rules, and ISP business practices.
This is not a "flag day" situation either. There is no need
to stop issuing and using provider aggregatable addresses.
These new geo-topo aggregatable addresses can coexist in the
same network. Some ISPs will choose to only assign one kind
of addresses, either classic PA or new geo-topo addresses. Others
will use both and use the newer ones to provide new services.

The only area where business practices needs to change is
inside a single city aggregate where the ISPs inside that
aggregate have to agree on how to exchange traffic and how
to deal with the hot-potato nature of geo-topo routing. 
Each city is free to come up with its own variation on this
as long as they do not deaggregate the city aggregate address
block outside of bilateral peering agreements. In other words,
ISPs in London will see only a single route to all of the geo-topo
space in Paris unless they have specific bilateral agreements
with Paris ISPs.

Remember we have reserved 7/8ths of the IPv6 address space in
order to be able to implement these types of new addressing schemes.
The main problem to be solved in order to deploy this, other
than general agreement on the scheme, is how to size each of the
5000 city aggregate blocks. Geographers and economists would likely
find this easy work, but we have to make contact with them, explain
the problem, and ask for their analyses.

> Won't take long until the first ISPs fall. And then more and more will 
have
> to. There is no strong community, apart from those customers with
> lots-o-money.

Most businesses only survive and thrive because they serve their 
customers well. Any ISP that expects to have a strong future must
understand the needs of their customer base and then organize their
company resources to serve those customers. This means that ISPs who
see this as a battle of the PROVIDERS (with PA addresses) against the
END USERS (with subnets assigned from PA blocks) are doomed. Providers
have to look at this problem from the end user point of view and then
find some solution that meets the end user needs while at the same
time offering the ability for the provider to continue providing
valuable services.

In general, as you point out, these situations are like a steamroller
and end user demand will win out in the end. However, we can avoid a
period of chaos and instability if the providers take the lead and
manage an orderly transition to the new network order.

--Michael Dillon