Re: [MMUSIC] Eric Rescorla's No Objection on draft-ietf-mmusic-sdp-bundle-negotiation-51: (with COMMENT)

[Christer Holmberg <[e-mail]>]

Hi,

> I will let Adam confirm his intent, but I read the “initial SDP offer” section as talking about the initial _SDP_ offer”. It says the 
> initial offer _MAY_ contain one or more “a=rid” lines. The "Modifying the Session” section then goes on to say that such an 
> offer MAY change the number of RID lines in use. I argue that going from zero to one or more RID line counts as changing the number of RID lines in use.

The MAYs are not the issue. The "initial offer" section contains a list (7 bullets) of considerations when adding a rid attribute. The same list is not present in the "modifying session" section. Does that mean they only apply if one is adding a rid attribute in the initial offer of a session??? In my opinion they apply to whenever a new rid attribute is added - whether it's in the initial offer, or a subsequent offer, of a session.

>In the case of BUNDLE, I don’t think we are talking about a complete restructure. Just recognize the difference between invoking 
>bundle in the initial SDP offer vs subsequent SDP offers. That probably means adding a few sentences to the “Initial SDP offer” and 
>“Modifying the Session” sections.

What sentences?

Regards,

Christer




> On 21 May 2018, at 18.37, Christer Holmberg <[e-mail]> wrote:
> 
>> Hi,
>> 
>>>> It is also important to remember that this affects virtually every SDP attribute we define, >> unless there are cases where "initial offer" always means the initial offer of a session, i.e., >> it is not possible to introduce an attribute later in a session.
>>> 
>>> I'm not following your logic here. Can you give an example?
>> 
>> Assume I establish a session, with audio and video.
>> 
>> The initial offer will contain the m- lines, and associated SDP attributes, for audio and video.
>> 
>> Later in the session, I send a subsequent offer, adding a BFCP m- line.
>> 
>> When setting the SDP attributes associated with the BFCP m- line, I will now use the "initial offer" procedures for those attributes, because it is the initial offer for those attributes (while a subsequent offer for the SIP session).
>> 
>> Regards,
>> 
>> Christer
>>