Subject: RE: Consensus on what? RE: CONSENSUS CALL: Deprecating Site-Local Addressing

From: "Dave Thaler" <[email-masked]>
Date: Wed, 2 Apr 2003 13:44:03 -0800

I agree with Michel, and hence in a way I guess I object to the
wording of the question. 

Per Margaret's clarification
> People who spoke at the mike, but did not express
> an opinion during the show of hands, may express their YES/NO opinion
now
> on the list.
I'm still entitled to give a response on the list, which I'm still
reserving based on the details of the actual proposal.

As I mentioned at the mike during the meeting, to deprecate site-locals,

you need to either:
a) remove the ability to _automatically_ address disconnected and
   intermittently-connected sites, or
b) specify how to automatically address them.

My reading of the opinions expressed during the meeting was that people
agreed that disconnected and intermittently connected sites should be
supported.

However, during the meeting, no one gave any proposals for (b).
One or two people (Dino Farinacci was one, and maybe Erik was another?) 
gave proposals for how to _manually_ number them as an administrator,
but that's not a solution for zero-config environments where site-locals
may be used today (e.g. a simple home gateway).

Hence, I'm assuming that most people responding with "Yes deprecate"
mean (b) without knowing if the result would be as bad as site-locals,
in which case they're no better off.  Since I admit I don't yet know
if it would be as bad (or heaven forbid, worse), I abstained from 
raising my hand at the time.

Can someone quickly give a proposal or two for (b) before the consensus
call deadline?  If I see a reasonable proposal, I'm likely to
respond YES.

Otherwise I'll be forced to respond NO until a detailed proposal
appears.  

It seems like at the moment we're being asked for a consensus on an idea
which may or may not prove to be practical (although we obviously hope
it is
practical)!

-Dave

> -----Original Message-----
> From: Michel Py [mailto:[email-masked]]
> Sent: Tuesday, April 01, 2003 2:21 PM
> To: Margaret Wasserman; [email-masked]
> 
> Margaret / Bob,
> 
> What is this consensus about? I was hoping that the mailing list would
> be asked to express their opinions _after_ a text to deprecate
> site-local addressing had been submitted to the working group. In the
> current situation, this consensus if there is one would be good only
to
> accept text as a working document. This document that still has to be
> seen then should go to WG last call.
> 
> Where is the doc to deprecate site-local addressing?
> 
> Michel.
> 
> 
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---

From: Brian E Carpenter <[email-masked]>
Date: Thu, 03 Apr 2003 15:23:18 +0200

Dave Thaler wrote:
...
> b) specify how to automatically address them.
...e.
> call deadline?  

I think we've heard several, all in the class of picking a short prefix
(and it could still be FEC0::/10) and expanding it to /48 by adding
almost-certainly-unique bits, such as

- bits derived from GPS location at an arbitrary point inside the site
- bits derived from the date & time at the instant you want a prefix
- bits derived from an IEEE address of an arbitrary device inside the site
- pseudo-random bits of some kind
- bits supplied from a central allocator of some kind

Clearly, mileage may vary with any of these but I can't see any
fundmental problem, as long as we only require a very high
probability of uniqueness rather than a formal guarantee.

   Brian