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

["Christian Huitema" <[e-mail]>]

On Friday, February 12, 2016 12:48 PM, Fred Templin wrote
> > From: dhcwg [mailto:[e-mail]] On Behalf Of ???? (> JINMEI,
Tatuya)
> >
> > Brian Carpenter called for an attention to Section 4.5.2 of the draft...
> > so I'm responding to it.
> >
> > 4.5.2.  Prefix delegation
> >
> >    The interaction between prefix delegation and anonymity require
> >    further study.  For now, the simple solution is to avoid using prefix
> >    delegation when striving for anonymity.  When using the anonymity
> >    profiles, clients SHOULD NOT use IA_PD, the prefix delegation form of
> >    address assignment.
> >
> > I'm not sure what Brian tried to indicate in his message, but at least
> > this section looks vague to me about the rationale for the "SHOULD
> > NOT".  It's not obvious to me how IA_PD is worse than IA_NA in terms
> > of privacy.  Is this a "SHOULD NOT" simply because the "interaction"
> > (is not yet fully understood and) requires further study?

Yes, exactly that. There was some anxiety that prefix delegation requires
understanding to whom the prefix is delegated. There are also potential side
effects if prefix are reassigned quickly to random nodes. All that needs
further study before we can make a recommendation. We can certainly add a
bit of text to make that more clear.

> I don't have a strong opinion on the "SHOULD NOT" in this paragraph, but
it is
> very important that this guidance not be taken out of context. This
document
> is only about clients that wish to remain anonymous, which does not apply
to
> all use cases.

Yes. Also, we can add text explaining that once these problems are better
understood and the IETF agrees on the proper way to handle anonymous prefix
delegation, clients MAY use the agreed upon solution. Which is kind of
redundant, but if you guys prefer it that way, why not.

-- Christian Huitema