Subject: [AVTCORE] I-D Action: draft-ietf-avtcore-rtp-multi-stream-07.txt

From: [email-masked]
Date: Mon, 09 Mar 2015 12:50:05 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories.
 This draft is a work item of the Audio/Video Transport Core Maintenance Working Group of the IETF.

        Title           : Sending Multiple Media Streams in a Single RTP Session
        Authors         : Jonathan Lennox
                          Magnus Westerlund
                          Qin Wu
                          Colin Perkins
	Filename        : draft-ietf-avtcore-rtp-multi-stream-07.txt
	Pages           : 25
	Date            : 2015-03-09

Abstract:
   This memo expands and clarifies the behaviour of Real-time Transport
   Protocol (RTP) endpoints that use multiple synchronization sources
   (SSRCs).  This occurs, for example, when an endpoint sends multiple
   media streams in a single RTP session.  This memo updates RFC 3550
   with regards to handling multiple SSRCs per endpoint in RTP sessions,
   with a particular focus on RTCP behaviour.  It also updates RFC 4585
   to update and clarify the calculation of the timeout of SSRCs and the
   inclusion of feedback messages.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-avtcore-rtp-multi-stream/

There's also a htmlized version available at:
http://tools.ietf.org/html/draft-ietf-avtcore-rtp-multi-stream-07

A diff from the previous version is available at:
http://www.ietf.org/rfcdiff?url2=draft-ietf-avtcore-rtp-multi-stream-07

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

---

From: Magnus Westerlund <[email-masked]>
Date: Mon, 9 Mar 2015 21:11:50 +0100

WG,
(As Author)

We this version of the draft is a significant changed version. We have
attempted to resolve all open issues one way or another.

- We have made a proposal for how many (4) initial (zero delay) compound
RTCP packets one is allowed to send in a unicast session.

- Clarified about the impact and suitable mitigation for sessions not
having updated their avg_rtcp_size calculation for aggregates.

- The Scheduling algorithm for aggregated packets have seen a number of
modifications:

  * Update of the assignment of tp. Simulations of cases where SSRCs
where removed from endpoint showed that there was significant issue with
drift, that could cause a endpoint to go quite for many RTCP reporting
intervals (over 50 intervals was found in simulation). This caused us to
go to common tp value for all included SSRCs that is set to an average
of intended transmission times.

  * Rules for handling AVPF properly, by setting T_rr_last as well as
discsussing that T_rr_int suppression shall not be used when calculating
transmission time. Also that suppressed updates of tp is simply set to
tc as currently specified.

  * Updated discussion of the impact of this scheduling algorithm

- Rules for determining if one is an point-to-point session or a
multiparty based on CNAMEs and RTCP reporting groups.

- Rules for how to include a feedback packet in another report in case
it can't trigger an early sending of a suitable SSRC.

- Clarifications that different media rates may occur within a media
type also.

- Removed the TBD and open issues that promised typical examples for
RTCP parameters. We authors are of the opinion that it is more important
to get this specification finished in its normative parts, then to spend
more time on writing example and case studies.

I hope you will take the time to read it completely and comment on the
state of the draft.

We have requested agenda time to further discuss the implications and
resulting behaviour of the changes in the scheduling algorithm. If there
are particular aspects you have questions on, don't hesitate to send a
question.

Cheers

Magnus Westerlund
(As author)

On 2015-03-09 20:50, [email-masked] wrote:
> _______________________________________________
> Audio/Video Transport Core Maintenance
> [email-masked]
> https://www.ietf.org/mailman/listinfo/avt
> 
> 

-- 

Magnus Westerlund

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