Subject: [MMUSIC] BUNDLE TEXT: Answerer Procedures (29th May)

From: Christer Holmberg <[email-masked]>
Date: Wed, 29 May 2013 11:39:54 +0000

Hi,

Based on the e-mail and interim discussions, I've tried together some "Answerer Procedures" text for BUNDLE.

For now, I would request that people mainly focus on the technical stuff, and if some text is unclear. I WILL align the usage of "m=" line and "media description" :)

Also note that examples will be added later.

Regards,

Christer

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6.4.  Answerer Procedures

6.4.1.  General

   This section describes how an Answerer, when it receives an SDP Offer
   including a BUNDLE group, generates the associated SDP Answer.

   When an Answerer receives an SDP Offer which includes a BUNDLE group,
   and the Answerer accepts the offered BUNDLE group, the Answerer MUST
   generate an SDP Answer according to the procedures in Section 6.1 and
   this section.

6.4.2.  RFC 5888 restrictions

   Based on the rules and procedures in RFC 5888, the following
   restrictions also apply to BUNDLE groups in SDP Answers:

   o  1) A BUNDLE group must not be added to an SDP Answer, unless the
      same BUNDLE group was included in the associated SDP Offer; and

   o  2) An SDP "m=" line must not be added to a BUNDLE group in the SDP
      Answer, unless it in the associated SDP Offer was included in the
      same BUNDLE group.

6.4.3.  Offerer Bundle Address Selection

   In the SDP Answer, the Answerer selects the bundle address for the
   Offerer, based on the address information received in the associated
   SDP Offer, using the mid value.  The mid value associated with the
   "m=" line in the SDP Offer that represents the bundle address MUST in
   the SDP Answer be located first in the mid value list added to SDP
   group:BUNDLE attribute associated with the BUNDLE group.

   From the associated SDP Offer, the Answerer SHOULD choose the bundle
   address associated with the mid value located first in the mid value
   list included in the SDP group:BUNDLE attribute associated with the
   BUNDLE group, unless:

   o  1) The mid value represents an "m=" line with a port zero value in
      the SDP Offer; or

   o  2) The mid value represents an "m=" line with a port zero value in
      the SDP Answer.

   OPEN: The decision for allowing a media description with port zero
   values inside a BUNDLE group is pending on update for RFC 5888.

6.4.4.  Answerer Bundle Address Selection

   In the SDP Answer, the Answerer selects its local bundle address.
   Each "m=" line included in a BUNDLE group MUST contain identical
   address information.  The only exception is the usage of a zero port
   value for an "m=" line, which is allowed eventhough another port
   value number is used for other "m=" lines in the BUNDLE group.

   OPEN: The decision for allowing a media description with port zero
   values inside a BUNDLE group is pending on update for RFC 5888.

   In a subsequent SDP Answer, the Answerer MAY change its local bundle
   address, as long as each "m=" line included the BUNDLE group contain
   identical address information.

   For a given BUNDLE group, the Answerer MUST NOT assign the bundle
   address to "m=" lines that are not included the BUNDLE group, or to
   "m=" lines that are included in another BUNDLE group.

6.4.5.  Rejecting A BUNDLE Media Description

   When generating the SDP Answer, if the Answerer wants to reject media
   associated with an "m=" line in the BUNDLE group, it will add a zero
   port number value to the "m=" line, according to the procedures
   defined in RFC 3264.

   OPEN ISSUE: It is FFS whether it is allowed to include a port zero
   media descriptions in a BUNDLE group.

6.4.6.  Removing a media description from a BUNDLE group

   When generating the SDP Answer, if the Answerer wants to remove an
   "m=" line from a BUNDLE group (without rejecting the "m=" line),it
   MUST NOT include the "m=" line in a BUNDLE group.  In addition, the
   SDP Answer MUST not add its local bundle address to the "m=" line.

   An Answerer MUST NOT, in the SDP Answer, remove an "m=" line from a
   BUNDLE group, unless the "m=" line had unique address information in
   the associated SDP Offer.

   NOTE: The reason for the restriction above is that, if the "m=" line
   would be removed from the BUNDLE group, the address information would
   be identical to the "m=" lines remaining in the BUNDLE group.

   OPEN: The decision for allowing a media description with port zero
   values inside a BUNDLE group is pending on update for RFC 5888.

---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 29 May 2013 10:23:12 -0400

Christer,

This seems good to me, pending polishing the language.

I trust when you say "address information" you mean:
- the port in the m-line
- the address in the c-line
- associated ICE information

Obviously it would be cumbersome to mention all of that each time you 
need to refer to address information. So I'm expecting you will coin a 
term (e.g., "address information") and provide a definition of it.

	Thanks,
	Paul

On 5/29/13 7:39 AM, Christer Holmberg wrote:
> Hi,
>
> Based on the e-mail and interim discussions, I’ve tried together some
> ”Answerer Procedures” text for BUNDLE.
>
> For now, I would request that people mainly focus on the technical
> stuff, and if some text is unclear. I WILL align the usage of “m=” line
> and “media description” :)
>
> _______________________________________________
> mmusic mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/mmusic
>

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 30 May 2013 06:27:37 +0000

Hi,

> Obviously it would be cumbersome to mention all of that each time you need to refer to address information. So I'm expecting you will coin a term (e.g., "address information") and provide a definition of it.

Yes. There is going to be a separate section which describes that more in detail. 

Thanks!

Regards,

Christer

On 5/29/13 7:39 AM, Christer Holmberg wrote:
> stuff, and if some text is unclear. I WILL align the usage of "m=" 
> line and "media description" :)
>

---

From: Kevin Dempsey <[email-masked]>
Date: Thu, 30 May 2013 09:18:27 +0100

Can we add that the answerer must also ensure that it can de-mulitplex the
media it will receive? That is, it must either agree to a de-mulitplex
scheme that was offered (either in the SDP, such as SSRC signalling,  or
external signalling) or ensure that there is no PT overlap in the bundle by
not including certain PTs or by unbundling one or more m-lines.

On 30 May 2013 07:27, Christer Holmberg <[email-masked]>wrote:

> need to refer to address information. So I'm expecting you will coin a term
> (e.g., "address information") and provide a definition of it.
>

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 30 May 2013 08:26:58 +0000

Hi Kevin,

> Can we add that the answerer must also ensure that it can de-mulitplex the media it will receive? That is, it must either agree 
> to a de-mulitplex scheme that was offered (either in the SDP, such as SSRC signalling,  or external signalling) or ensure that 
> there is no PT overlap in the bundle by not including certain PTs or by unbundling one or more m-lines.

For sure we will have to add text also about that. The reason I didn't add anything yet is because we don't have a clear outcome of that discussion yet :)

Thanks!

Regards,

Christer

On 30 May 2013 07:27, Christer Holmberg <[email-masked]> wrote:
Hi,

Thanks!

Regards,

Christer

---

From: "Cullen Jennings (fluffy)" <[email-masked]>
Date: Thu, 30 May 2013 17:37:48 +0000

Looks good to me

On May 29, 2013, at 5:39 AM, Christer Holmberg <[email-masked]> wrote:

> Hi,
>  
> Based on the e-mail and interim discussions, I’ve tried together some ”Answerer Procedures” text for BUNDLE.
>  
> For now, I would request that people mainly focus on the technical stuff, and if some text is unclear. I WILL align the usage of “m=” line and “media description” :)
>