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

[Philip Homburg <[e-mail]>]

>A better mitigation is to affect the preferred and possibly the valid
>lifetimes in response to consecutive RAs from the same router that lack
>the original (stale) prefix. e.g., after two consecutive RAs that do not
>contain the existing prefix, reduce the preferred lifetime. After two
>additional RAs, reduce the valid lifetime.

I think that to avoid confusion it is probably best to have 3 documents:
- one that describes host behavior. I think that what you describe above would
  fit in such a document. There is a lot we can do to make hosts more robust.
- one that describes CPE behavior. If the CPE explicitly deprecates old
  prefixes then that solves the problem with CPE reboots. Having
  more sensible lifetimes fits in such a document, but I don't think it
  provides a solution. It just reduces some secondary effects such as
  stale prefix build up.
- Finally, a document for ISPs describing how to best provide prefixes 
  using DHCPv6-PD. 

I think all 3 approaches are needed:
- a host doesn't want to rely on a cheap CPE doing its job.
- a quality CPE can provide better support for hosts today. There will always
  be ISPs that do flash renumbering
- finally a quality ISP may have a need to renumber customers and would like
  to do so without breaking things.