Re: A common problem with SLAAC in "renumbering" scenarios

FWIW, I think the reason that the only way to renumber IPv6 networks is
(mostly) there is no way to explicitly communicate the user prefixes from
the CPE to the network. I think most deployments inject routes based on
DHCPv6 PD snooping, and the implementations of that generally only support
one injected route per DHCPv6 client.

On Wed, Feb 20, 2019 at 4:46 PM Ole Troan <otroan@employees.org> wrote:

> Top posting. Two points here.
>
> 1) Flash renumbering breaks stuff. Especially for people running servers.
> Allowing people to host and own their own content in their own networks
> would do a lot more to protect people’s privacy rather than changing
> addresses. So let’s agree that the problem you want to solve is a
> misconfiguration/error case, not recommended operational practice.
>
> 2) We should always strive to make mechanisms more robust. Your suggested
> point solution already have alternative broader solutions. E.g. MPMH host
> or added rules in SAS. It might be worth looking at the more general
> problem.
>
> Ole
>
>
> > On 20 Feb 2019, at 06:34, Fernando Gont <fgont@si6networks.com> wrote:
> >
> >> On 20/2/19 01:54, Ole Troan wrote:
> >>
> >>
> >>>> On 20 Feb 2019, at 04:35, Fernando Gont <fgont@si6networks.com>
> wrote:
> >>>>
> >>>> On 20/2/19 00:11, Ole Troan wrote:
> >>>>
> >>>>
> >>>>>> On 20 Feb 2019, at 03:50, Fernando Gont <fgont@si6networks.com>
> wrote:
> >>>>>>
> >>>>>> On 19/2/19 10:08, Ole Troan wrote:
> >>>>>> Nick,
> >>>>>>
> >>>>>>> On 19 Feb 2019, at 13:57, Nick Hilliard <nick@foobar.org> wrote:
> >>>>>>>
> >>>>>>> Ole Troan wrote on 19/02/2019 12:22:
> >>>>>>>> Indeed. Wonder how these pesky mobile phone operators manage to
> >>>>>>>> deliver the same telephone number to a user, for years. Across
> >>>>>>>> different providers and contracts.
> >>>>>>>> I can’t think this argument is anything but a strawman.
> >>>>>>>
> >>>>>>> Ole,
> >>>>>>>
> >>>>>>> if recommending static IP addressing is an idea that 6man wants to
> push, you'll need to reach out to the security and ops areas to get their
> input on this.  I'm not sure this is an issue that 6man can resolve fully.
> >>>>>>
> >>>>>> It’s been the IPv6 addressing model for at least 20 years, so I
> think the other areas have had ample time to provide their input.
> >>>>>
> >>>>> For the reasons stated in draft-gont-6man-slaac-renum, I don't think
> >>>>> this affects the discussion we are having. But, out of curiousity,
> >>>>> where's the "addressing model" you are referring to documented?
> >>>>
> >>>> I can’t see slaac-renum tackling these issues.Which reasons are you
> referring to?
> >>>
> >>> A significant percentage of IPv6 deployments don't employ static
> >>> prefixes but dynamic prefixes. That's a deployment reality.
> >>
> >> There’s a defined way to do IPv6 renumbering, which involves
> overlapping new and old prefixes.
> >
> > There's a defined way to do *planned renumbering*, you might argue.
> > That's not what we are trying to address here -- even when the
> > improvements we propose end up helping in that area, anyway.
> >
> >
> >
> >> There seems to be some people arguing that renumbering without an
> overlap is a supported case in IPv6. It is not.
> >>
> >> That is although related, not the problem you are looking at.
> >
> > There's a variety of reasons for which a prefix may become stale without
> > explicit signaling. Jen has provided a more thorough list here:
> >
> https://tools.ietf.org/html/draft-linkova-6man-default-addr-selection-update-00
> > .
> >
> > What triggered our I-D is one of the cases in Jen's list, where a CPE
> > crashes and reboots. Version -01 of our I-D elaborates on many things
> > that contribute to the problem.
> >
> > What we have right now is a system that is not robust. We want to
> > improve robustness. The outcome of burying our heads into sand will most
> > likely be people complaining about IPv6, and IPv6 connectivity failing
> > and hosts falling back back to IPv4 (thanks to HE).
> >
> > Modulo folks that seem to be in favor of improving things, so far I seem
> > to have read:
> >
> > * CPE vendors are shipping crap
> > * ISPs are clueless in what they build
> > * Some of us miss some clues about IPv6
> > * The 37% of network suffering from these issues are just marginal.
> >
> > I don't think the above is doing us any favours. Actually, it seems a
> > lot like "problem solving" in
> > https://images-na.ssl-images-amazon.com/images/I/416cjJcmM-L.jpg . I'd
> > rather honor the "E" in IETF.
> >
> > Thanks,
> > --
> > Fernando Gont
> > SI6 Networks
> > e-mail: fgont@si6networks.com
> > PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
> >
> >
> >
> >
>
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