Mitigating the effects of SLAAC renumbering events (draft-ietf-6man-slaac-renum)

Wed Aug 31 10:35:17 UTC 2022

Folks,

We have been discussing the potential problems associated with SLAAC 
renumbering events for a while now -- one of the most common cases being 
ISPs rotating home prefixes, and your devices ending up with 
stale/invalid addresses.

We have done quite a bit of work already:

   * Problem statement: https://datatracker.ietf.org/doc/html/rfc8978
   * CPE recommendations: https://datatracker.ietf.org/doc/html/rfc9096

But there's still some work to do to address this issue: The last 
remaining it is to improve SLAAC such that hosts can more gracefully 
deal with this renumbering events.

In that light, IETF's 6man has been working on this document: 
https://www.ietf.org/archive/id/draft-ietf-6man-slaac-renum-04.txt

And we have proposed a simple algorithm for SLAAC (an extension, if you 
wish) that can easily help, as follows:

     If you (host) receive an RA that contains options, but not all
     of the previously-received options/information, simply send a
     unicast RS to the local-router, to verify/refresh that such missing
     information is still valid. If the information is stale, get rid of
     it.

I presented this algorithm at the last IETF meeting 
(https://youtu.be/eKEizC8xhhM?t=1308).

(You may find the slides here: 
https://datatracker.ietf.org/meeting/114/materials/slides-114-6man-improving-the-robustness-of-stateless-address-autoconfiguration-slaac-to-flash-renumbering-events-00)

Finally, I've sent draft text for the specification of the algorithm 
here: 
https://mailarchive.ietf.org/arch/msg/ipv6/KD_Vpqg0NmkVXOQntVTOMlWHWwA/

We would be super thankful if you could take a look at the draft text 
(i.e., 
https://mailarchive.ietf.org/arch/msg/ipv6/KD_Vpqg0NmkVXOQntVTOMlWHWwA/) 
and provide feedback/comments.

If you can post/comment on the 6man wg mailing list 
(https://www.ietf.org/mailman/listinfo/ipv6), that´d be fabulous.
But we'll appreciate your feedback off-line, on this list, etc. (that'd 
still be great ;-) )

Thanks in advance!

Regards,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont at si6networks.com
PGP Fingerprint: F242 FF0E A804 AF81 EB10 2F07 7CA1 321D 663B B494