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Re: [Perc] Drop support for E2E RTP header extensions

Nils Ohlmeier <nohlmeier@mozilla.com> Mon, 24 April 2017 20:57 UTC

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From: Nils Ohlmeier <nohlmeier@mozilla.com>
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Date: Mon, 24 Apr 2017 13:57:30 -0700
In-Reply-To: <aef9a32f-f761-c9e8-de99-57c4acfd5088@gmail.com>
Cc: Richard Barnes <rlb@ipv.sx>, Jonathan Lennox <jonathan@vidyo.com>, "perc@ietf.org" <perc@ietf.org>
To: Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com>
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Subject: Re: [Perc] Drop support for E2E RTP header extensions
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> On Apr 24, 2017, at 08:57, Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com> wrote:
> 
> RTP header extensions are negotiated on the SDP O/A, so not all endpoints may support same header extension, and even if they support same set of extensions, they may be negotiated with different ids. So it is impossible to support RTP header extensions E2E except in the scenario in which all endpoints support same subset of extensions and happens to be negotiated with same id.

The topic of header extensions has been discussed in the past at the first perc interim meeting on 2016-01-11. I suggest reading the meeting minutes and materials from that meeting: https://datatracker.ietf.org/group/perc/meetings/ <https://datatracker.ietf.org/group/perc/meetings/>
It appears at the time discussion on RTCP had not concluded yet. But I don’t think that the conclusion of doing RTCP hop-by-hop only changes substantially the arguments to allow end-to-end header extensions.

I assume nobody disagrees that negotiating end-to-end header extension is not easy. But it is purely a signaling problem. I don’t see a technical reason why the media plane should dis-allowed it.
As it is a signaling issue it also means that every PERC conferencing solution is free to remove end-to-end header extension from the signaling if it wants to make it’s life easier.

Best
  Nils Ohlmeier

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