Re: [MMUSIC] Magnus Westerlund's Discuss on draft-ietf-mmusic-t140-usage-data-channel-12: (with DISCUSS)

[Christer Holmberg <[e-mail]>]

Hi,
    
    > I think the below proposal improves the scope description so it would be good to include.

    Done :)

    https://github.com/cdh4u/draft-datachannel-t140/pull/56/commits/a6a5ed91c20439bab709c89cfba725656e0bb22a

    Regards,

    Christer
 
    
    
    On Thu, 2020-04-09 at 11:08 +0000, Christer Holmberg wrote:
    > Hi Magnus,
    >     
    > >    I will clear my discuss as I think I strayed beyond the discuss criteria
    > > due
    > >    missing the sentence in the prior sub-section. 
    > >    
    > >    I think the text would clearer if one took slightly more consideration
    > > for under
    > >    what conditions in offers or answers the normative language will apply.
    > > For
    > >    exmaple. When an a=dcmap:3 with a subprotocol="t140" attribute is
    > > included ...
    > >    
    > >    This is of course statement dependent and I will not spend my time on
    > > suggesting
    > >    rewording of all of these. 
    > 
    >   
    > What about the following change:
    > 
    > OLD:
    > 
    > 	"This section defines the SDP considerations that are specific to a
    > T.140 data channel."
    > 
    > NEW:
    > 
    > 	"This section, and its subsections, define the SDP considerations that
    > are specific to a T.140 data channel,
    > 	  identified by an SDP 'dcmap' attribute [I-D.ietf-mmusic-data-channel-
    > sdpneg]  with a "t140" 
    >                 attribute parameter value."
    > 	
    > Regards,
    > 
    > Christer
    > 
    >     
    >     
    >     On Tue, 2020-04-07 at 15:05 +0000, Christer Holmberg wrote:
    >     > Hi,
    >     > 
    >     >  ----------------------------------------------------------------------
    >     >  DISCUSS:
    >     >  ----------------------------------------------------------------------
    >     >         
    >     >     >>>    Section 4.1:
    >     >     >>>    
    >     >     >>>       The offerer and answerer MUST NOT include the max-retr or
    > the
    >     > max-
    >     >     >>>       time attribute parameters in the 'dcmap' attribute.
    >     >     >>>    
    >     >     >>>    This is just an example of a issue that is exists in
    > basically all
    >     > of the
    >     >     >>>    RFC 2119 terminolgy using sentences in this section. The
    >     > formulation is that
    >     >     >>>    the offerer or answerer must do something with attributes or
    >     > parameters of
    >     >     >>>    the dcmap attribute. However, it is not stated to be specific
    > to
    >     > the dcmap
    >     >     >>>    attribute that specifically specify something for a T.140
    > SCTP
    >     > stream. I
    >     >     >>>    think that scope restriction needs to be made more explicit
    > for
    >     > these RFC 2119
    >     >     >>>    statements. Else they would have applicability as soon as one
    >     > support
    >     >     >>>    this specification.
    >     >     >>   
    >     >     >> The last sentence of Section 4 says:
    >     >     >> 
    >     >     >> "This section defines the SDP considerations that are specific to
    > a
    >     > T.140 data
    >     >     >> channel."
    >     >     >
    >     >     > So why is that last and not first? 
    >     > 
    >     >     It is the last sentence of the parent section (4), and covers the
    >     > procedures in the section, including the subsections (4.x). This wording
    > has
    >     > been used multiple times before.
    >     > 
    >     >     But, if you think it is more clear, I could say "The following sub
    >     > sections define the SDP considerations....".
    >     > 
    >     >     > So isn't this all scoped based on that there is an dcsmap line
    > with a
    >     > subprotocol line stating t140 either included in an
    >     >     > offer that one is generating or responding to as an answerer? 
    >     > 
    >     >     Correct, and Section 4.1 describes the SDP details on how to
    > indicate a
    >     > T.140 data channel, using the dcmap attribute.
    >     >     
    >     >     > As you see I am undertain if the sentence is sufficient to scope
    > this
    >     > correctly.
    >     >     > Are there statement that are relevant outside of the scope of
    > actually
    >     > offering
    >     >     > or answering a T140 offer? I think part of the uncertainty is if
    > there
    >     > are
    >     >     > aspect that my be wrongly interpreted if one support T140 but it
    > is not
    >     > actively
    >     >     > included? 
    >     > 
    >     >     The procedures in section 4 (including the sub sections) only apply
    > to
    >     > T140.
    >     > 
    >     >    Regards,
    >     > 
    >     >    Christer
    >     > 
    >     > 
    >     > 
    >     > 
    >     >     Cheers
    >     >     
    >     >     Magnus Westerlund 
    >     >     
    >     >     
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    >     >     
    >     >     
    >     >     
    >     -- 
    >     Cheers
    >     
    >     Magnus Westerlund 
    >     
    >     
    >     ----------------------------------------------------------------------
    >     Networks, Ericsson Research
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    >     Ericsson AB                 | Phone  [phone]
    >     Torshamnsgatan 23           | Mobile [phone]
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    >     
    >     
    -- 
    Cheers
    
    Magnus Westerlund 
    
    
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