Re: slaac-renum: New rev of draft-gont-6man-slaac-renum (Fwd: New Version Notification for draft-gont-6man-slaac-renum-08.txt)

Philip Homburg <pch-ipv6-ietf-6@u-1.phicoh.com> Tue, 19 May 2020 15:25 UTC

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To: ipv6@ietf.org
Cc: Fernando Gont <fgont@si6networks.com>
Subject: Re: slaac-renum: New rev of draft-gont-6man-slaac-renum (Fwd: New Version Notification for draft-gont-6man-slaac-renum-08.txt)
From: Philip Homburg <pch-ipv6-ietf-6@u-1.phicoh.com>
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In-reply-to: Your message of "Tue, 19 May 2020 03:38:18 -0300 ." <8354111a-7d3f-ecfa-bcf1-baaae27209ee@si6networks.com>
Date: Tue, 19 May 2020 17:24:33 +0200
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In your letter dated Tue, 19 May 2020 03:38:18 -0300 you wrote:
>https://www.ietf.org/internet-drafts/draft-gont-6man-slaac-renum-08.txt

I disagree with Section 4.1.2. Host should not try to second-guess routers.
So host should keep preferred and valid lifetimes unchanged.

In Section 4.5, I think it is bad to hardcode knowledge about ULAs 
in detecting stale prefixes. In my opinion that shows that the
algorithm is fragile. And note that this applies to all hosts.

So there might be other circumstances where some prefixes are special. A
site may have multiple ULA prefixes that have different meaning. The
same applies to regular global unicast.

So in my opinion the best way forward is to only expire prefixes quickly
if the host knows that the router sends all information in one RA.
Hosts can easily detect if a router uses one RA or multiple RAs.