Subject: [6lo] Adam Roach's Discuss on draft-ietf-6lo-nfc-13: (with DISCUSS and COMMENT)

From: Adam Roach via Datatracker <[email-masked]>
Date: Wed, 13 Mar 2019 17:04:27 -0700

Adam Roach has entered the following ballot position for
draft-ietf-6lo-nfc-13: Discuss

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DISCUSS:
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Thanks to everyone who has worked on this document.

I generally agree with Benjamin's discuss points, and in particular agree with
his comment that it's kind of hard to figure out how all these pieces work
together. I have an additional issue that is somewhat related to some of the
points he raised, but which is (I think) not completely covered.

I'm really confused about what the purported privacy properties of this
protocol are. In section 4.3 (which I *think* talks about globally-routable IP
addresses, although this is a bit unclear), the document says:

   such an IID SHOULD guarantee a stable IPv6 address
   because each data link connection is uniquely identified by the pair
   of DSAP and SSAP included in the header of each LLC PDU in NFC

(Aside: this "should" is a simple statement of fact, not a described behavior of
the protocol, and so the use of RFC-2119-style all-caps is not appropriate.)

The presence of "a stable IPv6 address" inherently implies the ability to
track devices.

Then, in section 7, I find the following text:

   ...the short address of
   NFC link layer (LLC) is not generated as a physically permanent value
   but logically generated for each connection.  Thus, every single
   touch connection can use a different short address of NFC link with
   an extremely short-lived link.

This text seems to imply that addressing information is, in general, not stable,
which appears to flatly contradict the text in section 4.3.

Please clarify, in section 4.3, what the duration of stability of these
identifiers is.

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COMMENT:
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ID Nits reports:

  == Unused Reference: 'RFC4291' is defined on line 697, but no explicit
     reference was found in the text

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§1:

>  IPv6 is an ideal internet
>  protocols owing to its large address space

Nit: "protocol"