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

Fernando Gont fgont at
Wed Aug 31 12:40:03 CEST 2022


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:
   * CPE recommendations:

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:

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

I presented this algorithm at the last IETF meeting 

(You may find the slides here:

Finally, I've sent draft text for the specification of the algorithm 

We would be super thankful if you could take a look at the draft text 
and provide feedback/comments.

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

Thanks in advance!

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

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