Re: [rtcweb] SRTP/AVPF/TCP in draft-ietf-rtcweb-transports-01

Magnus Westerlund <> Mon, 07 October 2013 08:20 UTC

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Date: Mon, 07 Oct 2013 10:21:10 +0200
From: Magnus Westerlund <>
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Subject: Re: [rtcweb] SRTP/AVPF/TCP in draft-ietf-rtcweb-transports-01
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On 2013-10-03 19:09, Parthasarathi R wrote:
> Hi Harald/Magnus,
> Thanks for the clarification.  Please clarify whether TCP/RTP/SAVPF will
> be registered in IANA as separate MMUSIC specification or any another
> simple mechanism exists to add IANA registry.

I think we might need a MMUSIC or AVTCORE SDP field proto cleanup
document. It is not only TCP/RTP/SAVPF that is missing, also AVPF and
SAVP is missing.

But, before diving into this. Are there really consensus that we will
use IP/TCP/RFC4571 framing/RTP(SAVPF) rather than using TURN over TCP to
get a stack saying IP/TCP/TURN/RTP(SAVPF)?

Their SDP identification are quite different. The later uses m= lines
indicating RTP/SAVPF with the TURN part in the ICE candidates.

> I’m interested in seeing the usage of DTLS key exchange for SRTP within
> TCP/RTP/SAVPF profile. Even though DTLS is designed for connectionless
> protocol, I assume that it works with TCP (connection oriented) protocol
> as well. The optimized version of TCP/RTP/SAVPF shall use TLS as a SRTP
> key exchange mechanism. Please correct me in case I’m missing something.

In that case you definitely need an MMUSIC document. This as we need to
figure out if using TLS to represent DTLS was a misstake as I think you
need to separate DTLS and TLS when sent over TCP for the different
purposes in that case.


Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVM
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