Re: [v6ops] A common problem with SLAAC in "renumbering" scenarios

[Richard Patterson <[e-mail]>]

On Mon, 25 Feb 2019 at 18:37, Fernando Gont <[e-mail]> wrote:
> Agreed. That said, with the current default lifetime values, things
> become tricky:
> At least in theory, you should be sending such RAs for "Valid Lifetime"
> seconds. With a default of one month, that means that, in theory, you
> should be sending such RAs for a month. And if there are multiple
> crash-and-reboot events, you should advertise each of the stale
> prefixes. (I assume the CPE just records the last one)

I get your reasoning, but I'm not sure if it's quite as dire as that,
a single RA update with PrefLifetime of 0 should in theory suffice,
but then we get in to discussing the reliability of ICMPv6 messaging.
(as you have done in draft-gont-6man-slaac-renum-02 )

In my head, an address with the higher Preferred Lifetime should be
selected over one with a lower value, however I couldn't find any
recommendation as such in RFC6724, is this stipulated anywhere else?
 If not, would an update to 6724 that introduces a Preferred Lifetime
comparison as a tie-breaker help?  i.e. When deciding between multiple
non-deprecated source addresses, always pick the address with the
highest Preferred Lifetime?