Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds

[Fernando Gont <[e-mail]>]

On 25/10/19 14:59, Ted Lemon wrote:
> On Oct 25, 2019, at 1:52 PM, Fernando Gont <[e-mail]
> <mailto:[e-mail]>> wrote:
>> The "flash renumbering" could also happen if the CPE was trying to kind
>> of the right thing, the ISP does not employ stable prefixes, and the CPE
>> happens to crash and reboot. Some CPEs also reportedly do a "release"
>> when rebooted.
> 
> That’s probably a bug.   If the CPE has a valid lease, and the prefix is
> still working, it should continue to advertise it until its valid
> lifetime expires. 

Normally CPEs keep no state in stable storage about that.


> The ISP DHCP server should be giving the router two
> prefixes if it’s being renumbered: the preferred one, and the one that’s
> still valid but not preferred anymore.

The reality is that, we have all sort of things in the echosystem. So if
the network is to be robust, while we can and do improvements were
possible/needed. That said, there should be smarts on the hosts to cope
with these scenarios gracefully (hope for the best, plan for the worst).

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492