Re: [rtcweb] Comments on draft-ietf-rtcweb-data-channel-07

Magnus Westerlund <> Tue, 25 February 2014 10:58 UTC

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Date: Tue, 25 Feb 2014 11:58:43 +0100
From: Magnus Westerlund <>
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Subject: Re: [rtcweb] Comments on draft-ietf-rtcweb-data-channel-07
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On 2014-02-23 10:54, Barry Dingle wrote:
> In reference to your first _Section 1 comments_, I agree that we need to
> clearly differentiate the SRTP media and the SCTP media. (Note - SRTP -
> not RTP !)

So SRTP is an extension of RTP, in fact it is a profile, or rather two
(RTP/SAVP or RTP/SAVPF). I wrote RTP because I meant no specific RTP
configuration here, it can be any of the profiles and any of the
extensions. I know and fully support that RTCWEB uses RTP/SAVPF for RTP
transported media, however in the wider context and possible other usage
of the defined mechanism this may or may not be true. Therefore I see a
need to be generic in that discussion. If one want to emphasize the SRTP
part, then use (S)RTP.

> I agree that there could be real-time media that can be sent over SCTP
> Channels are still meet the criteria for 'real-time' as being 'received
> within a few hundred milliseconds of being generated' - see WebRTC
> Overview section 2.4.
> Maybe we need to differentiate the Channel types - and then refer to the
> data going over those Channels. For instance,if we define "SRTP
> Channels" and "SCTP Channels", we could then refer to 'SRTP Channel
> media' which would have a specific meaning.

Well, around RTP we aren't discussing "channels" at all. Thus, this
becomes very ambiguous to what it means, unless you have a definition to
go along with it.

In the context of a PeerConnection we can have one or more RTP session.

Also, I don't know what an SCTP channel is. There is an SCTP
association, which is something between two endpoints. On top of this we
have the SCTP Data channels. So what are you missing or want from these


Magnus Westerlund

Services, Media and Network features, Ericsson Research EAB/TXM
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