Re: [lp-wan] I-D Action: draft-ietf-lpwan-coap-static-context-hc-06.txt

[Laurent Toutain <[e-mail]>]

On Fri, May 3, 2019 at 6:34 PM <[e-mail]> wrote:

> Dear authors,
>
> I've read draft-ietf-lpwan-coap-static-context-hc-06 .
>

thank you very much Dominique,

Here are a few comments so far. I haven't seriously read OSCORE and
> examples yet.
> Overall, you are not using MUST and SHOULD. Is this intended because of
> the informational status?
>

yes, rule gives a lot of flexibility and the compression mechanism depends
of the
usage. The goal of the document is to explain how to apply compression to
CoAP
protocol.

Thanks for the correction, this document is in the standard track not
informational.



> Technical
> - I did not understand the last paragraph of 4.5 CoAP Token fields.
>

In SCHC when you don't know the field size at the rule creation, you can
define the field as variable.
For instance :
FID.                    FL MO.     CDA
CoAP.URI-path. var ignore value-sent

in that case, the var keyword in the Field Length will make the compression
send the length (in byte)
before the value of the field.

A CoAP Token has almost the same behavior as a URI-path, but the length and
the value are stored
at 2 differents place in the CoAP Header.

The paragraph says that instead of var function to describe the length, a
tkl function must be used. The
tlk function indicates that the length is stored in the CoAP TKL field. The
receiver must use this value
to determine the value sent on the radio.



> - I did not understand the first sentence of 5.3.1, Variable length
> Uri-Path and Uri-Query. Do you mean "not" known?


yep, changed.


> Also, I think the
> following sentence no longer applies "and the LSB CDA must not carry any
> value."
>

yes, that a remain of an older version of SCHC rule, suppressed in the draft



> - 6.3 No-Response: "If the value is not known, ...". I guess you mean the
> opposite.
>

right, not has been removed


> - 6.4 Time Scale: "If the value is not known, ...". I guess you mean the
> opposite.
>
>
>
idem

>
> Editorial
> - Section 1 Introduction: "The context is said static since the field
> description composing the Rules and the context are not learned during the
> packet exchanges but are previously defined." Context used twice, sentence
> needs rewriting.
>

suppressed context: old reference.



> - many more English writing nits, I will do a Pull Request on GitHub.
>

we did the merge.

>
> Best regards
> Dominique
>
> Le 05/02/19 15:00, « lp-wan on behalf of [e-mail] »
> <[e-mail] on behalf of [e-mail]> a écrit :
>
> >
> >A New Internet-Draft is available from the on-line Internet-Drafts
> >directories.
> >This draft is a work item of the IPv6 over Low Power Wide-Area Networks
> >WG of the IETF.
> >
> >        Title           : LPWAN Static Context Header Compression (SCHC)
> >for CoAP
> >        Authors         : Ana Minaburo
> >                          Laurent Toutain
> >                          Ricardo Andreasen
> >       Filename        : draft-ietf-lpwan-coap-static-context-hc-06.txt
> >       Pages           : 29
> >       Date            : 2019-02-05
> >
> >Abstract:
> >   This draft defines the way SCHC header compression can be applied to
> >   CoAP headers.  The CoAP header structure differs from IPv6 and UDP
> >   protocols since CoAP
> >   use a flexible header with a variable number of options themselves of
> >   a variable length.  The CoAP protocol is asymmetric in its format
> >   messages, the format of the header packet in the request messages is
> >   different than in the response messages.  Most of the compression
> >   mechanisms have been introduced in
> >   [I-D.ietf-lpwan-ipv6-static-context-hc], this document explains how
> >   to use the SCHC compression for CoAP.
> >
> >
> >The IETF datatracker status page for this draft is:
> >https://datatracker.ietf.org/doc/draft-ietf-lpwan-coap-static-context-hc/
> >
> >There are also htmlized versions available at:
> >https://tools.ietf.org/html/draft-ietf-lpwan-coap-static-context-hc-06
> >
> https://datatracker.ietf.org/doc/html/draft-ietf-lpwan-coap-static-context
> >-hc-06
> >
> >A diff from the previous version is available at:
> >
> https://www.ietf.org/rfcdiff?url2=draft-ietf-lpwan-coap-static-context-hc-
> >06
> >
> >
> >Please note that it may take a couple of minutes from the time of
> >submission
> >until the htmlized version and diff are available at tools.ietf.org.
> >
> >Internet-Drafts are also available by anonymous FTP at:
> >ftp://ftp.ietf.org/internet-drafts/
> >
> >_______________________________________________
> >lp-wan mailing list
> >[e-mail]
> >https://www.ietf.org/mailman/listinfo/lp-wan
>
>
>
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