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

On Thu, Oct 3, 2013 at 10:09 AM, Parthasarathi R <partha@parthasarathi.co.in
> 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’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.
>

Yes, this should work. It will use the RTP-over-TCP framing for the DTLS
records (i.e. 16-bit-length prefix). I don't think if it makes sense to
support TLS instead of DTLS in this case since there are no guarantees that
the TCP transport will be lossless (i.e. if the TCP buffers fill, endpoints
may choose to start dropping packets instead of continuing to buffer).

> ****
>
> ** **
>
> Thanks****
>
> Partha****
>
> ** **
>
> *From:* Harald Alvestrand [mailto:harald@alvestrand.no]
> *Sent:* Thursday, October 03, 2013 8:50 PM
> *To:* Magnus Westerlund
> *Cc:* Parthasarathi R; rtcweb@ietf.org
> *Subject:* Re: SV: [rtcweb] SRTP/AVPF/TCP in
> draft-ietf-rtcweb-transports-01****
>
> ** **
>
> On 10/03/2013 07:22 AM, Magnus Westerlund wrote:****
>
> Harald, ****
>
> ** **
>
> Yes you are missing something. The registry you pointed at are the one for RTP profiles. The one containing the combinations with transport are SDP specific. ****
>
> ** **
>
> http://www.iana.org/assignments/sdp-parameters/sdp-parameters.xhtml#sdp-parameters-2****
>
>
> Thanks!
>
> For consistency's sake, shouldn't all the SDP parameters that contain
> "RTP" also be listed in the RTP registry?
>
> I'm thinking that -transport- may have to grow an IANA section that
> registers TCP/RTP/SAVPF, and it needs to decide whether to register it in
> one or both.
>
> (Of course, the TCP/ prefix is only used in some of the examples in the
> RFC defining RTP over TCP - as a matter of taste, I don't like having
> protocol in the profile name, so would be happy not doing so if the SDP
> experts say this is OK by the rules, but then I need to adjust the language
> to not use the word "profile" in this place.)
>
>
> ****
>
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