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

[Sergio Garcia Murillo <[e-mail]>]

On 24/04/2017 17:52, Richard Barnes wrote:
>
>
> On Mon, Apr 24, 2017 at 11:46 AM, Sergio Garcia Murillo 
> <[e-mail] 
> <mailto:[e-mail]>> wrote:
>
>     On 24/04/2017 17:38, Jonathan Lennox wrote:
>
>             On Apr 24, 2017, at 6:36 AM, Sergio Garcia Murillo
>             <[e-mail]
>             <mailto:[e-mail]>> wrote:
>
>             Hi all,
>
>             I have seen no more activity regarding the E2E RTP header
>             issue.
>
>             Is there a consensus that they can't be supported and that
>             there is no use case for them? Does anyone have a
>             different view? Should this be discussed and agreed on
>             next virtual interim meeting?
>
>         At previous virtual interims, I believe the consensus was that
>         no one had a current use case for E2E RTP header extensions;
>         however, if we didn’t support them, retrofitting them into the
>         protocol later would be extremely difficult.  Thus, we
>         (reluctantly) decided to support them.
>
>         If they turn out to complicate the protocol too much, I
>         suppose this can be revisited.
>
>
>     Hi Jonathan, thanks for the heads up.
>
>     Apart of making protocol complex, the way that rtp header
>     extensions are supported on double encryption won't work on E2E
>     mode except on the most trivial scenarios. 
>
>
> Since we're talking about E2E protection, it seems like the only 
> scenario is "the header travels unmodified from sender to receiver".  
> It seems like this is supported in the simplest way possible; all the 
> E2E headers are grouped together, before the OHB.  Beyond the OHB, you 
> can do whatever you want.
>
> What advanced scenarios are not supported here?

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.

Best regards
Sergio