Subject: [MMUSIC] Draft new version: draft-ietf-mmusic-sdp-bundle-negotiation-06

From: Christer Holmberg <[email-masked]>
Date: Mon, 7 Apr 2014 08:06:17 +0000

Hi,

We have submitted a new version (-06) of BUNDLE.

As you will see, the document has been re-structured quite a bit. The main reason for that was to align the SDP offer/answer procedures with the RFC 3264 structure (I had to do that for another draft, so I decided to do the same thing also for BUNDLE - rather now than when we reach WGLC).

The draft does have a dependency on an RTP header indicator, and the completion of draft-ietf-mmusic-sdp-mux-attributes, but otherwise there are currently no BUNDLE specific open issues.

Regards,

Christer

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From: Colin Perkins <[email-masked]>
Date: Wed, 9 Apr 2014 11:55:14 +0100

Christer,

Section 8.1.1 starts:

   By default, all RTP based media within a BUNDLE group belong to a
   single RTP session [RFC3550].  Multiple BUNDLE groups will form
   multiple RTP Sessions.

   NOTE: The usage of multiple RTP sessions within a BUNDLE group, or
   the usage of a single RTP session that spans over multiple BUNDLE
   groups, is outside the scope of this specification.  Other
   specification needs to extend the BUNDLE mechanism in order to allow
   such usages.

   When a single RTP session is used, all bundled "m=" lines
   representing RTP based media share a single SSRC numbering space
   [RFC3550].

I suggest rephrasing this as:

   All RTP-based media within a single BUNDLE group belong to a 
   single RTP session [RFC3550]. Multiple BUNDLE groups will form 
   multiple RTP sessions, one per bundle group.

   Since a single RTP session is used for each bundle group, all 
   “m=“ lines representing RTP-based media in a bundle group will 
   share a single SSRC numbering space [RFC3550].

Similarly, in the Introduction, I suggest changing:

   The default assumption is that all Real-Time Protocol (RTP) [RFC3550]
   based media flows associated with a BUNDLE group belong to the same
   RTP Session [RFC3550].  Future extensions can change that assumption.

to

   All Real-time Transport Protocol (RTP) [RFC3550] based media flows 
   associated with a single BUNDLE group belong to a single RTP session 
   [RFC3550].

The rationale for this change is that supporting multiple RTP sessions on a single 5-tuple is a significant change to RTP, for example to introduce a shim-layer, that did not receive consensus in AVTCORE. These changes align the bundle draft with that decision, and reword the text for clarity.

Colin

On 7 Apr 2014, at 09:06, Christer Holmberg <[email-masked]> wrote:
> As you will see, the document has been re-structured quite a bit. The main reason for that was to align the SDP offer/answer procedures with the RFC 3264 structure (I had to do that for another draft, so I decided to do the same thing also for BUNDLE – rather now than when we reach WGLC).
>  
> _______________________________________________
> mmusic mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/mmusic

-- 
Colin Perkins
http://csperkins.org/

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From: Martin Thomson <[email-masked]>
Date: Wed, 9 Apr 2014 09:34:03 -0700

Looks easier to read.

On 9 April 2014 03:55, Colin Perkins <[email-masked]> wrote:
> Multiple BUNDLE groups will form

...unless they happen to be the same RTP session seen from different
perspectives.

---

From: Christer Holmberg <[email-masked]>
Date: Wed, 9 Apr 2014 18:40:03 +0000

Hi,

>Looks easier to read.

I'm glad to hear that :)

> ...unless they happen to be the same RTP session seen from different perspectives.

Not sure I understand.

Regards,

Christer

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From: Martin Thomson <[email-masked]>
Date: Wed, 9 Apr 2014 12:49:02 -0700

>> ...unless they happen to be the same RTP session seen from different perspectives.

The definition of RTP session is such that you could be seeing the
same session on two 5 tuples and yet be ignorant of this fact.

a  a
 \ /
  |
  b

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From: Colin Perkins <[email-masked]>
Date: Wed, 9 Apr 2014 21:39:31 +0100

> same session on two 5 tuples and yet be ignorant of this fact.

Right. A better phrasing might be “Disjoint BUNDLE groups will form multiple RTP sessions, one per bundle group”?

-- 
Colin Perkins
http://csperkins.org/

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 10 Apr 2014 11:00:26 +0000

Hi,

> Right. A better phrasing might be "Disjoint BUNDLE groups will form multiple RTP sessions, one per bundle group"?

Whatever makes you happy :)

Regards,

Christer