Re: [Dart] multiplexing different media types
Harald Alvestrand <harald@alvestrand.no> Sun, 15 June 2014 07:18 UTC
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Date: Sun, 15 Jun 2014 09:18:09 +0200
From: Harald Alvestrand <harald@alvestrand.no>
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To: "Paul E. Jones" <paulej@packetizer.com>, dart@ietf.org, Eric Rescorla <ekr@rtfm.com>
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Subject: Re: [Dart] multiplexing different media types
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(Adding EKR to thread to get a definitive DTLS answer) On 06/15/2014 06:52 AM, Paul E. Jones wrote: > Harald, > > >> "SCTP ... can be multiplexed with one or more RTP sessions". Actually >> we can only multiplex SCTP with a single RTP session. There have been >> proposals that would allow multiplexing of multiple RTP sessions >> (each containing multiple media flows) over a single 5-tuple, but >> these were not accepted. > > Your draft (draft-ietf-rtcweb-transports) says: > > RTCWEB implementations MUST support multiplexing of DTLS and RTP over > the same port pair, as described in the DTLS_SRTP specification > [RFC5764], section 5.1.2. All application layer protocol payloads > over this DTLS connection are SCTP packets. > > I had a question about this as we discussed the DART draft. I assumed > the only DTLS connection would be one used for key negotiation for > SRTP. Is that not the case? Would there be multiple DTLS connections > multiplexed? If so, how would one be differentiated from another? EKR is the expert here. As I understand it, the key material for DTLS-SRTP is derived from the session keys from the DTLS session. This does not in any way affect the usage of the same DTLS session for passing DTLS data. > > As for RTP Session multiplexing, it's interesting to hear that > proposals are dead. Is there a proposal for multiplexing different > media types (e.g., audio and video) within the same RTP Session, > then? RFC 3550 discourages that, but it was my understanding that > browser makers wanted to multiplex the different media types somehow. > What's the plan? draft-ietf-avtcore-multiplex-guidelines covers the RTP aspects. draft-ietf-mmusic-sdp-bundle-negotiation has the details on SDP. The only thing in RTP itself that prevents such multiplexing is the words in RFC 3550; technically there is no barrier at the RTP level. At the SDP level things are a bit more complex, which is why -bundle- isn't an RFC yet. > > Paul > -- Surveillance is pervasive. Go Dark.
- [Dart] Commentary on draft-york-00 Harald Alvestrand
- Re: [Dart] Commentary on draft-york-00 Dan York
- Re: [Dart] Commentary on draft-york-00 Ben Campbell
- Re: [Dart] Commentary on draft-york-00 Harald Alvestrand
- Re: [Dart] Commentary on draft-york-00 Black, David
- Re: [Dart] Commentary on draft-york-00 Harald Alvestrand
- Re: [Dart] Commentary on draft-york-00 Black, David
- Re: [Dart] Commentary on draft-york-00 Ruediger.Geib
- Re: [Dart] Commentary on draft-york-00 Black, David
- Re: [Dart] multiplexing different media types Paul E. Jones
- Re: [Dart] multiplexing different media types (wa… Paul E. Jones
- Re: [Dart] multiplexing different media types Harald Alvestrand
- Re: [Dart] multiplexing different media types Harald Alvestrand
- Re: [Dart] multiplexing different media types Paul E. Jones
- Re: [Dart] multiplexing different media types Paul E. Jones
- Re: [Dart] multiplexing different media types Paul E. Jones
- Re: [Dart] Commentary on draft-york-00 Ruediger.Geib
- Re: [Dart] multiplexing different media types Harald Alvestrand
- Re: [Dart] multiplexing different media types Eric Rescorla
- Re: [Dart] multiplexing different media types Eric Rescorla
- Re: [Dart] multiplexing different media types Eric Rescorla
- Re: [Dart] multiplexing different media types Eric Rescorla