Subject: RE: assignment of GUPI [RE: Taking two steps back (Was: Re: onequestion...)]

From: "Michel Py" <[email-masked]>
Date: Wed, 27 Nov 2002 10:45:06 -0800

Keith,

>> Michel Py wrote:
>> GUSL does not create PI globals. As its name implies,
>> it creates globally unique site-locals, which would
>> avoid NAT and/or renumbering when two sites connect.

> Keith Moore wrote:
> I don't think we should use FEC0::/10 for these.  Those
> were intended as site-local addresses, and people have
> ideas that these have security properties, that
> applications should favor them, etc.  Making SLs globally
> unique and routing them between sites amounts to an
> architectural change - but more importantly it conflicts
> with assumptions that are already built into some
> applications and into people's minds.

Okay, you convinced me. GUSL is good for mergers, but if it is used for
inter-site communications it's an architectural change.

>> You are missing the point. If network administrators
>> do not like restricted SLs, they will use 2002:0A00::/24
>> instead, a one-way ticket to NAT. 

> humbug.  this is too fanciful to have any credibility.
> why should network adminis pick an obscure prefix when
> we are making much better and more obvious solutions
> available?

Because they want addresses that are not publicly routable, and nothing
you can say will change this.

Here's the dilemma: if the scope of GUPI is global, how could you
guarantee that people won't pay their ISPs to leak the GUPI address in
the defaultless routing table?

The big difference is that with GUSL we would have extended the scope to
friendly sites, not to global. The risk of GUSL ending up global PI
could be managed.

With GUPI, you are asking for a blank check. If GUPI addresses leak
unaggregated in the global routing table, we have recreated the IPv4
swamp and possibly killed IPv6. How do you plan to manage this risk?

Risk / benefit analysis: Solving problems with site-locals only is not a
big enough carrot to take the risk of recreating the swamp. Make the
carrot bigger.

Michel.

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From: Keith Moore <[email-masked]>
Date: Wed, 27 Nov 2002 15:12:20 -0500

> you can say will change this.

Well, maybe we'll end up making GUPIs not publically routable.
I guess I'd like to hear more about this rationale from others, though - 
it makes less sense to trust unrelated parties to filter your traffic
than it does to trust your own border filters (or your ISPs, or both).

> the defaultless routing table?

If people don't want their addresses to be publically routable,
why would they pay their ISPs to route them?

> friendly sites, not to global. The risk of GUSL ending up global PI

I don't see how this is changed by a decision to not use FEC0::/10
for globally unique addresses.
 
> swamp and possibly killed IPv6. How do you plan to manage this risk?

It's a complex question, and I don't want to gloss over it.  

However, a lot of the perceived risk seems to have to do with the idea 
that ISPs will let their routing performance degrade rather than raise 
their prices.  So maybe if we could get widespread agreement on minimum 
acceptable routing performance (e.g. convergence times) then the market
would take care of the rest by making it so expensive to advertise
a PI prefix globally that few would do it.

But there still seems to be an inherent conflict between those who 
are demanding non-routable addresses (is anyone else demanding this?)
and those who want GUPIs to be routable.  If there's really sufficient
demand for both maybe we need separate blocks.

Keith