Re: PIO Lifetimes (was: Re: draft-ietf-6man-slaac-renum: Heuristics to deprecate stale information)

[Ted Lemon <[e-mail]>]

I summarized because I'm just repeating things we've already discussed.
When a new router shows up, we use that as a signal that the link may have
changed. We probe our old routers using unicast RS. If they answer, great,
if not, we deprecate their information. That takes care of the problem of
continuing to use stale information. Secondly, the draft already places
constraints on how long we will consider a router to be alive if we haven't
heard from it. If we don't hear from it over that time period, then we
flush its information. So the problem that you described of the table
growing without bound is taken care of as well. I suppose we could add a
heuristic that if the table exceeds an implementation-dependent size limit,
the oldest router may be flushed to make room for a newer router. Perhaps
that's already in the spec—I'd have to go look.

On Thu, Aug 18, 2022 at 2:35 AM Vasilenko Eduard <
[e-mail]> wrote:

> >1. if we see evidence that the old router isn't there, prefer the new
> router.
>
> How?
>
> >2. Don't keep stuff around forever, even if the router tells us to.
>
> Do not understand the use case.
>
>
>
> I do not understand these too general statements.
>
> If you would propose what exactly you have in mind (ND modification)
>
> Then I would be capable to judge:
>
> 1.       Is it useful?
>
> 2.       Is it related to “flush renumbering”?
>
>
>
> Reminder, we have stale information that we need to deal with. The problem
> that we are not aware that the information is stale.
>
> RFC 6059 proposes to keep even more stale information. Hence, RFC 6059 is
> not related to the “flush renumbering”.
>
>
>
> Eduard
>
> *From:* Ted Lemon [mailto:[e-mail]]
> *Sent:* Thursday, August 18, 2022 5:46 AM
> *To:* Fernando Gont <[e-mail]>
> *Cc:* Vasilenko Eduard <[e-mail]>; [e-mail]
> *Subject:* Re: PIO Lifetimes (was: Re: draft-ietf-6man-slaac-renum:
> Heuristics to deprecate stale information)
>
>
>
> Right. Combining these two mechanisms should synergize well. To
> oversimplify:
>
> 1. if we see evidence that the old router isn't there, prefer the new
> router.
>
> 2. Don't keep stuff around forever, even if the router tells us to.
>
>
>
> On Wed, Aug 17, 2022 at 10:41 PM Fernando Gont <[e-mail]>
> wrote:
>
> On 17/8/22 06:57, Vasilenko Eduard wrote:
> > Hi Ted,
> > I still do not agree that it makes sense to collect the big table of
> stale ND information.
> > Because after PIO preferred has been put to 0. PIO validity may be still
> 1 month.
>
> Well, part of the issue there is that the PIO lifetimes should be
> sensible. -- that's why we have a recommendation in that regard.
>
> Thanks,
> --
> Fernando Gont
> SI6 Networks
> e-mail: [e-mail]
> PGP Fingerprint: F242 FF0E A804 AF81 EB10 2F07 7CA1 321D 663B B494
>
>