Re: [IPv6] Second Working Group Last Call for <draft-ietf-6man-rfc6724-update>

[Ted Lemon <[e-mail]>]

On Wed, Apr 10, 2024 at 12:11 PM Kyle Rose <krose=[e-mail]>
wrote:

>  * At my sites I am fine with preferring GUA->GUA over ULA->ULA, in large
> part because I don't have any names that map to both types of address.
>

It seems to be the case that your setup would work just fine with the new
required behavior, if we required it, no?

 * I regard seeing or attempting to use unreachable ULA (e.g., discovered
> in global DNS or found in other configuration) as a configuration error
> that should be resolved by fixing the source of the unreachable addresses.
>

This is true. I think we should take that text out of the document.
However, it's not a reason to not want to prefer ULAs over GUAs.

The reason to prefer known ULA<->known ULA over GUA<->GUA is that it
enables sites to reliably number internally with a ULA and for that ULA to
then be used for internal communication in preference to GUAs, which may be
renumbered arbitrarily as ISP contracts change or at the whim of the ISP,
for that matter. This is a serious usability issue both for homes and for
enterprise sites, as was discussed earlier when we were debating the NPT66
draft.

So I'm curious whether your objection is because you don't care about the
ULA-in-the-DNS case (I don't either!) or whether you knew about the
benefits of enabling local ULAs to be preferred over GUAs and consider
these to be not compelling enough for us to write the document in such a
way that we might one day soon be able to rely on hosts we care about
behaving this way. Or do you think we should just always prefer ULAs over
GUAs (sounds like no)?

I think it makes sense that you wouldn't care about this feature—I can't
imagine it being useful for an ISP—but do you really care so much about
/not/ requiring this that you'd take this capability away from sites that
would benefit (greatly, IMHO) from it?