Re: [dhcwg] Last Call: <draft-ietf-dhc-anonymity-profile-06.txt> (Anonymity profile for DHCP clients) to Proposed Standard

Lorenzo Colitti <lorenzo@google.com> Mon, 22 February 2016 02:18 UTC

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From: Lorenzo Colitti <lorenzo@google.com>
Date: Mon, 22 Feb 2016 11:17:50 +0900
Message-ID: <CAKD1Yr15EYQdS3XR4zenqmpBn2K2Zue2a+mMz1m+Vw54ou7zZQ@mail.gmail.com>
Subject: Re: [dhcwg] Last Call: <draft-ietf-dhc-anonymity-profile-06.txt> (Anonymity profile for DHCP clients) to Proposed Standard
To: Brian Haberman <brian@innovationslab.net>
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Cc: IETF Discussion <ietf@ietf.org>, dhc-chairs@ietf.org, Christian Huitema <huitema@huitema.net>, iesg@ietf.org, draft-ietf-dhc-anonymity-profile@ietf.org, "dhcwg@ietf.org" <dhcwg@ietf.org>
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On Tue, Feb 16, 2016 at 9:29 PM, Brian Haberman <brian@innovationslab.net>
wrote:

> > Well, section 4 of draft-ietf-dhc-anonymity-profile-07 says:
> >
> >    The choice between the stateful and stateless scenarios depends on
> >    flag and prefix options published by the "Router Advertisement"
> >    messages of local routers, as specified in [RFC4861].  When these
> >    options enable stateless address configuration hosts using the
> >    anonymity profile SHOULD choose it over stateful address
> >    configuration, because stateless configuration requires fewer
> >    information disclosures than stateful configuration.
> >
> > That seems pretty close from what you want, at least as far as "stateful
> DHCPv6" is concerned.
>
> I would agree that the above text covers what I interpret as Lorenzo's
> concern.
>

My concern is not with the intent, it's with the wording.

The business of this draft is to provide guidance to implementers. I am an
implementer: I wrote the DHCP client currently used in a host OS, and while
said OS does not yet support DHCPv6, I am likely to involved with that as
well if/when that happens. So I am squarely in the target audience for this
document - but as has become clear from this thread, I did not understand
the text correctly, even though I was actually paying attention It took a
specific response from Christian and an explanation from a colleague before
I actually understood what the implications were for host behaviour. We
should try to ensure other implementers do not misunderstand the text like
I did, by making it clearer.

Let me suggest text again:

   When these options enable stateless address configuration (i.e., when
   the A flag in a Prefix Information Option is set to 1) hosts using the
   anonymity profile SHOULD perform stateless address configuration
   and SHOULD NOT use stateful DHCPv6, because stateless configuration

I don't see how that text is different from the text that's already in the
draft, except it actually provides clear guidance. Why not use it?