Re: [v6ops] I-D Action: draft-gont-v6ops-ipv6-addressing-considerations-00.txt

[Eduard Metz <[e-mail]>]

It's indeed about the uniqueness of the prefix.
In terms of RFC4007 ULAs do not have a global scope, but are (or may be)
unique beyond link-local scope. There is not really a label for this it
seems

Apart from that ULA is hard to catch in terminology, I don't think there is
any disagreement

On Wed, Jan 6, 2021 at 3:10 AM Fernando Gont <[e-mail]> wrote:

> On 5/1/21 13:08, Gert Doering wrote:
> > Hi,
> >
> > On Tue, Jan 05, 2021 at 02:24:14PM +0100, Eduard Metz wrote:
> >> Maybe the last column should be "Applicable to Internet" (no / no / yes)
> >> or something along these lines. I assume the point here is to indicate
> that
> >> link-local and ULA cannot be used on the Internet.
> >
> > What is "the Internet"?
> >
> > We're an ISP, so if we use ULAs on our infrastructure, outside any
> > firewalls (but not announcing to other ASes, or leaking packets) - is
> > that "used on the Internet" or not?
>
> Agreed that "Applicable to Internet" is probably not a good taxonomy.
>
> The proper (and useful) taxonomy is that of "scope". ULAs clearly don't
> have a global scope (as per the definition in RFC4007).
>
> Given a ULA prefix (say, fd12:3456:7890:abcd::/64), it doesn't globally
> (and uniquely) identify a link. Similarly, nobody is in the position of
> publishing a ROA or restricting which AS can originate packets from such
> prefix.
>
> IMO, generating the "Global ID" of ULAs from a PRNG does reduce the
> possibility of collisions *when a limited number of ULA-based networks
> are interconnected* -- but the birthday paradox tells you can't expect
> the ULA prefixes to be globally unique. There's more to "global scope"
> than simply asserting that if you interconnect, say, two networks the
> chances of colliding prefixes will be small.
>
> Thanks,
> --
> Fernando Gont
> SI6 Networks
> e-mail: [e-mail]
> PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
>
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