Subject: RE: "unique enough" [RE: globally unique site local addresses]

From: "Michel Py" <[email-masked]>
Date: Mon, 25 Nov 2002 08:51:45 -0800

Pekka,

>> Michel Py wrote:
>> My $0.02 about the hash/random/collision issue:
>> It's a non-issue.

> Pekka Nikander wrote:
> I would agree with you, but only if I shared the same
> view of the GUPI prefix usage.

This much is clear. However, I think the use you envision for GUPI is
dangerous and will lead to NAT, which is also clear in the opinion you
expressed about GUPI encouraging or discouraging NAT.

In the example you use, a SOHO configuring their network, use of GUPI is
a disaster, IMHO. Site-locals are not for SOHO sites, they need to talk
to the public Internet. These people need to use global addresses. I
don't challenge the need for globally unique PI addresses, but this
would be GAPI not GUPI.

As I mentioned before, we MUST NOT encourage the use of site-locals for
people that don't understand their limitations, and this certainly
applies to the SOHO example you used.

GUPI still is site-local addresses, which are not routable on the public
Internet, and will be successful in enterprises only if the comfort
level of the administrator as reached the level that he is happy with
the enforcement of non-routability. Back to what started this, the main
four characteristics of GUPI are:

1. No fee and/or low fee.
2. No registration and/or easy registration.
3. Globally unique.
4. Not globally routable.

I don't challenge the need for globally routable, globally unique
identifiers. As a matter of fact, the scheme I proposed for GUPI is a
spin-off GAPI. That being said, this is not the same battle.

In the case of GUPI, we already have a block allocated for it:
FEC0::/10. If we don't change the purpose of the block which is
site-locals, there is a shorter path to success than GAPI that would
require IANA to allocate a new block and is full of issues concerning
the explosion of the global routing table.

My message is: one problem at a time. GUPI is achievable short-term, not
GAPI. Let's focus on what we can do now, which is globally unique, not
globally routable and when this hurdle has been cleared then we can
process towards globally unique and globally routable.

Michel.

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From: Tim Chown <[email-masked]>
Date: Mon, 25 Nov 2002 23:47:07 +0000

> applies to the SOHO example you used.

So how do I print to my net printer in between connections to my ISP when
I get a different prefix each time I connect?  I want some kind of addresses
to use locally equivalent to Net10.   Not for NAT, but to communicate 
internally while offline.

I think this discussion has forgotten a lot of the pro/con points made in
the previous 500-mail thread, and at Atlanta :)

tim

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From: Pekka Nikander <[email-masked]>
Date: Tue, 26 Nov 2002 10:31:39 +0200

Michel,

> applies to the SOHO example you used.

I can understand your point.

There is just one thing that I want to repeat:

   If you give people something that is globally unique and
   stable, that is, something that looks, smells and tastes
   as globally unique stable identifiers, they will start to
   use them as such, sooner or later.

   We should not underestimate the desirability of such
   identifiers in the face of changing prefixes.

Not all innovation is limited within the IETF.

--Pekka

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From: Pekka Savola <[email-masked]>
Date: Tue, 26 Nov 2002 11:51:20 +0200 (EET)

> Not all innovation is limited within the IETF.

I agree 100%.

We should not try to make globally unique site-locals too attractive, 
because, well, they're not _meant_ to be attractive.

We have globals in IPv6, you know.  I'd actually like to use _globals_,
not some site-local addresses.

(in the random site-id proposal, the uniqueness probability may even be 
high to prevent this..)

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords