Subject: RE: globally unique site local addresses

From: "Michel Py" <[email-masked]>
Date: Sat, 23 Nov 2002 13:40:35 -0800

> Mark Smith wrote:
> Lack of absolute guarantees of globally unique site local
> addressing is a bit of a "stick" that will prevent people
> from trying to use their globally unique site locals for
> global communications, as per Brian Zill's concerns.

I have voiced these concerns myself earlier, and they are valid.
However, this stick is really not big and would not prevent these
addresses to leak in the defauless route if there is no other
enforcement mechanism.

> I also like the fact that his model doesn't require any
>  interaction with a registry of some sort, and any
> associated costs ie. his model is "good enough and free",
> rather than "perfect and not-free".

There is room for both models at the same, and "good enough" is not
going to be good enough for everybody.

Michel.

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From: Margaret Wasserman <[email-masked]>
Date: Sat, 23 Nov 2002 20:35:12 -0500

>going to be good enough for everybody.

I would need to see a very compelling case for why two types
of globally-unique/provider-independent addressing are needed
before I would like to see two models.

I think that one of the benefits of globally-unique/provider-
independent addresses over site-locals is that it is possible
to tell (when one is leaked in any of the possible ways)
exactly where the address came from...  This would, of course,
work best if the addresses were actually unique, rather than
mostly-unique.

Margaret

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From: Pekka Nikander <[email-masked]>
Date: Sun, 24 Nov 2002 21:01:21 +0200

> before I would like to see two models.

"Good enough" ones are easy to generate without too much human
intervention, for example, without any connection to the
registry.  OTOH, they are not necessarily unique, and therefore
not "good enough" for some people.  IMHO, both types are needed.

> work best if the addresses were actually unique, rather than

Requiring that everybody registers their GUPI addresses will
not make everyone to register them.  OTOH, you could argue that
if we mandate registration, and someone uses some prefix
without registering them, it's their problem.

In any case, a modest suggestion:  Let's separate the GUPI
prefix generation and registration processes, and make them
sequential.

The prefix generation could be a semi-automatic hashing based
process, generating  a prefix that is only statistically unique.
If real uniqueness is required, the administrator could take the
generated prefix and attempt to register it against a modest fee.
It that succeeds, good.  If that particular prefix is already
taken, the admin can generate a new prefix and try again.

Registration would require not only registering the prefix but
also showing the input.  That would discourage people from
hoarding "easy" prefixes or adjacent prefixes, since looking
for suitable hash input for such prefixes would not be that
easy.  Furthermore, if really needed, the fee can be gradually
raised as the registry starts to fill up, thereby discouraging
new registrations.

The basic benefit of this method is that there would be only one
way of generating GUPI addresses, and that would be an easy one.
Additionally, the method would initially keep the GUPI prefix
space sparce and evenly distributed; that might be advanteous.
For example, deferring regisration of one's prefix would not be
that risky, since the probability of succeeding later would be
still fairly high.

--Pekka Nikander

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From: Pekka Savola <[email-masked]>
Date: Sun, 24 Nov 2002 22:46:12 +0200 (EET)

> not "good enough" for some people.  IMHO, both types are needed.
[...]

Whether "completely unique" is required epends on what they're to be used
for.

Myself, I can't see _any_ reason why anyone would require complete
uniqueness (except for being able to globally route them, which is a
problem I don't think we should be pursuing here).

"Nearly enough uniqueness" with about 38 bits is more than enough.  Even
with the birthday paradox, where all the networks would be interconnected,
about hundreds of thousands of sites would have to all-interconnected,
thousands with a very good probability of uniqueness.

But sure, e.g. reserving fee::/12 (pun intended :-), fef::/12 reserved)  
manual assignments would be ok, but I think people would just not use them
at all, or use them for entirely wrong purposes -- which is why
registering them should not be free.

-- 
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