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

From: "Michel Py" <[email-masked]>
Date: Wed, 27 Nov 2002 09:51:48 -0800

Keith,

>> Michel Py wrote:
>> So what is the difference between this new GUPI block
>> and GUSLs, except that you want a possible evolution
>> to globally routable for the new GUPI block?

> Keith Moore wrote: 
> problems with GUSLs as an alternative to GUPIs:
> - the proposed uses of PI globals change too many
>   assumptions about how SLs were to be used to reuse
>   the FEC0::/10 prefix for that purpose.  

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. The scope would not be global, although it would
go behind the site's boundaries.

> - there were too many conflicting or intractable
>   assumptions about SLs anyway

Assumptions in current drafts?

> - we need PI globals that can be routed between sites
> by private agreement anyway.

We need _something_ that can be routed between sites by private
agreement only. This does not need to be global.

>> The obvious answer is that we create a new block _then_, not now.
> no, because we need the block now to solve the problems with SLs.

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. Everybody would be better off having them use site-locals and
try to limit the damage.

Michel.

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From: Keith Moore <[email-masked]>
Date: Wed, 27 Nov 2002 12:58:08 -0500

> when two sites connect. 

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.

> Assumptions in current drafts?

yes.
 
> agreement only. This does not need to be global.

I'm convinced it's easier to make things work (especially DNS PTR lookups)
if they are globally unique than if they are only probably unique.

> 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?

Keith