Re: [v6ops] draft-moreiras-v6ops-rfc3849bis-00

Mark Andrews <marka@isc.org> Mon, 12 August 2013 00:33 UTC

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To: "Antonio M. Moreiras" <moreiras@nic.br>
From: Mark Andrews <marka@isc.org>
References: <5207D42F.2030302@nic.br> <5207E319.6070601@nic.br> <B66D2D0C-DE6D-49CC-A87A-7C65B5360DB4@delong.com> <52082128.5090503@nic.br>
In-reply-to: Your message of "Sun, 11 Aug 2013 20:41:28 -0300." <52082128.5090503@nic.br>
Date: Mon, 12 Aug 2013 10:27:40 +1000
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Cc: Alejandro Acosta <aacosta@rocketmail.com>, v6ops@ietf.org
Subject: Re: [v6ops] draft-moreiras-v6ops-rfc3849bis-00
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In message <52082128.5090503@nic.br>br>, "Antonio M. Moreiras" writes:
> On 11/08/13 19:29, Owen DeLong wrote:
> > I support the idea. It might be worth also asking for a ULA Doc slice at th
> e same time.
> > I think a /48 is probably sufficient for most ULA examples.
> > 
> > But I think it would be good to be able to write up ULA examples and traini
> ng that use
> > actual ULA prefixes intended for documentation.
> 
> I agree. An organization could generate an ULA prefix specifically to
> use in a course, or document. But it could be copied and used in
> production environments. This would break the "global uniqueness", and
> could lead to other problems.

FUD.

You either do the correct thing and generate your own prefix or you
don't and copy one and hope that no one else has copied it that you
are connecting to.  Having a reserved prefix will not help you here.

ULA are not "globally unique", they are locally unique with a
extrememly low probability of collision when *locally* connecting.
If you use them in a global context (i.e. publish to the world in
AAAA records) without some global differentiator you will cause
problems.

All a documentation prefix will do is have one potentially toxic
prefix compared to a handful of potentially toxic prefixes.  There
are 1099511627776 prefixes in fd00::/8.  Even if there were thousands
of documentation prefixes the odds of you hitting one when generating
your own prefix are astronomically small.  Additionally the more
prefixes that are used in documentation the less toxic a particular
prefix will be.

Mark

> It would be nice to have a specific ULA documentation prefix.
>
> I would suggest a prefix with the L bit cleared, easy to remember, and
> maybe slightly shorter than /48. For example FC00:0:D0C0::/44.
> 
> []s
> Moreiras.
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
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