Re: [6lo] Benjamin Kaduk's Discuss on draft-ietf-6lo-minimal-fragment-12: (with DISCUSS and COMMENT)

Benjamin Kaduk <kaduk@mit.edu> Thu, 05 March 2020 15:41 UTC

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Date: Thu, 05 Mar 2020 07:41:25 -0800
From: Benjamin Kaduk <kaduk@mit.edu>
To: "Pascal Thubert (pthubert)" <pthubert@cisco.com>
Cc: The IESG <iesg@ietf.org>, "6lo-chairs@ietf.org" <6lo-chairs@ietf.org>, "carlesgo@entel.upc.edu" <carlesgo@entel.upc.edu>, "draft-ietf-6lo-minimal-fragment@ietf.org" <draft-ietf-6lo-minimal-fragment@ietf.org>, "6lo@ietf.org" <6lo@ietf.org>
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Subject: Re: [6lo] Benjamin Kaduk's Discuss on draft-ietf-6lo-minimal-fragment-12: (with DISCUSS and COMMENT)
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On Wed, Mar 04, 2020 at 06:07:31PM +0000, Pascal Thubert (pthubert) wrote:
> Dear Benjamin
> 
> Many thanks for your  review this time again!
> 
> I answered the track question separately (with you and Mirja), this is a conscious discussion that was debated with Suresh in Singapore, we decided for STD track and made the changes accordingly.
> 
> Let's address the DISCUSS first, more tomorrow on the COMMENTs
> 
> > ----------------------------------------------------------------------
> > DISCUSS:
> > ----------------------------------------------------------------------
> > 
> > I think we need to be more explicit (whether inline or by reference) about
> > what "Secure joining and the Link-Layer security that it sets up"
> > (Section 7) entails in terms of ensuring that access to the LLN is only available
> > to authenticated and authorized entities.  It might be worth doing so as
> > explicit assumptions or an applicability statement early in the document
> > (e.g., the Introduction).
> 
> For one thing, in https://tools.ietf.org/rfcdiff?url2=draft-ietf-6lo-minimal-fragment-05.txt text was moved that makes this unreadable.

Oh, yes, that would make a difference.

> Changed the first paragraph of the intro to:
> "
>    The original 6LoWPAN fragmentation is defined in [RFC4944] for use
>    over a single Layer 3 hop, though possibly multiple Layer 2 hops in a
>    mesh-under network, and was not modified by the [RFC6282] update.
>    6LoWPAN operations including fragmentation depend on a Link-Layer
>    security that prevents any rogue access to the network.
> "

Assuming this is meant to replace the "Secure joining and [...]" text, this
looks good.

> > 
> > Also, in Section 2.3 we refer to the datagram_tag plus layer-2 sender address
> > as being "a globally unique identifier for the datagram", but I think this can
> > only hold within some time-bounded window (e.g., the lifetime of the
> > packet), since the tag space is finite and reuse somewhat inevitable.
> 
> This is certainly correct was better make it explicit. What about:
> "
>    datagram_tag:  An identifier of a datagram that is locally unique to
>       the Layer 2 sender.  Associated with the MAC address of the
>       sender, this becomes a globally unique identifier for the datagram
>       within the duration of its transmission.
> 
> "
> 
> Please let me know if that addresses your DISCUSS so I can move on with the COMMENTS

Yes, that sounds good.

Thanks!

-Ben

> Many thanks again!
> 
> Pascal