Re: [MMUSIC] Data channel dcsa attribute usage and IANA

[Paul Kyzivat <[e-mail]>]

On 8/29/19 5:49 AM, Roni Even (A) wrote:
> Hi,
> 
> I think that dcsa(subprotocol) would have been enough, at least based on 
> channel-sdpneg document, maybe Paul can help

I'm sorry that this is coming up so late. In retrospect I think it 
deserved more discussion about how this is to work. IIRC this got tucked 
in quite some time ago, early in the definition of dcsa.

I don't recall why both forms are shown. I don't know what "dcsa" alone 
would mean. The guess it could be a wildcard meaning that it can be used 
with all subprotocols. But that doesn't make any sense to me.

So I'm inclined to only use the "dcsa(subprotocol)" form. Perhaps we 
should file an errata against rfc4566bis as soon as it becomes an RFC.

	Thanks,
	Paul

> Roni
> 
> *From:*Christer Holmberg [mailto:[e-mail]]
> *Sent:* Thursday, August 29, 2019 12:25 PM
> *To:* Roni Even (A); [e-mail]; [e-mail]
> *Cc:* [e-mail]
> *Subject:* Re: [MMUSIC] Data channel dcsa attribute usage and IANA
> 
> Hi,
> 
> One question for clarification:
> 
> Section 8.2.4.1 of RFC4566bis says:
> 
>        “Usage Level: Usage level(s) of the attribute.  This MUST be one or
> 
>        more of the following: session, media, source, *dcsa and*
> 
> *      dcsa(subprotocol)*.”
> 
> …and in the Table in Section 8.2.4 it says:
> 
> “dcsa,dcsa(msrp)”
> 
> Q1: Why does it need to say both ‘dcsa’ and ‘dcsa(subprotocol)’? Isn’t 
> it enough with ‘dcsa(subprotocol)’?
> 
> Regards,
> 
> Christer
> 
> *From: *mmusic <[e-mail] 
> <mailto:[e-mail]>> on behalf of Christer Holmberg 
> <[e-mail] <mailto:[e-mail]>>
> *Date: *Thursday, 29 August 2019 at 11.27
> *To: *"Roni Even (A)" <[e-mail] 
> <mailto:[e-mail]>>, "[e-mail] 
> <mailto:[e-mail]>" <[e-mail] <mailto:[e-mail]>>
> *Cc: *"[e-mail] <mailto:[e-mail]>" 
> <[e-mail] <mailto:[e-mail]>>
> *Subject: *Re: [MMUSIC] Data channel dcsa attribute usage and IANA
> 
> Hi,
> 
> Thanks for the information! The last paragraph clarifies it.
> 
> So, draft-t140-usage-data-channel will update the IANA registry for the 
> SDP attributes used inside the SDP dcsa attribute.
> 
> Regards,
> 
> Christer
> 
> *From: *"Roni Even (A)" <[e-mail] <mailto:[e-mail]>>
> *Date: *Thursday, 29 August 2019 at 11.08
> *To: *Christer Holmberg <[e-mail] 
> <mailto:[e-mail]>>, "[e-mail] 
> <mailto:[e-mail]>" <[e-mail] <mailto:[e-mail]>>
> *Cc: *"[e-mail] <mailto:[e-mail]>" 
> <[e-mail] <mailto:[e-mail]>>
> *Subject: *RE: Data channel dcsa attribute usage and IANA
> 
> Hi Christer,
> 
> To add to Paul’s response
> 
> Look at the last 2 paragraphs of section 5.2.1 
> https://tools.ietf.org/html/draft-ietf-mmusic-data-channel-sdpneg-28#section-5.2.1
> 
> Roni
> 
> *From:*mmusic [mailto:[e-mail]] *On Behalf Of *Christer 
> Holmberg
> *Sent:* Wednesday, August 28, 2019 1:33 PM
> *To:* [e-mail] <mailto:[e-mail]>
> *Cc:* [e-mail] <mailto:[e-mail]>
> *Subject:* [MMUSIC] Data channel dcsa attribute usage and IANA
> 
> Hi,
> 
> Section 7.2 of draft-ietf-mmusic-msrp-usage-data-channel updates the 
> IANA registry for the SDP ‘setup’ attribute, by indicating that it can 
> be used inside an SDP ‘dcsa’ attribute.
> 
> Do we really need to update the IANA registry for all SDP attributes 
> that can be included in an ‘dcsa’ attribute???
> 
> There is no text in draft-mmusic-data-channel-neg about having to modify 
> the IANA registry for such attributes.
> 
> Regards,
> 
> Christer
> 
> 
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