Re: [rtcweb] draft-alvestrand-one-rtp-00.txt ICE usage
Paul Kyzivat <pkyzivat@alum.mit.edu> Fri, 12 August 2011 15:56 UTC
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Date: Fri, 12 Aug 2011 11:57:14 -0400
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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To: Harald Alvestrand <harald@alvestrand.no>
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Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] draft-alvestrand-one-rtp-00.txt ICE usage
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Trimming, and changing subject On 8/12/11 11:20 AM, Harald Alvestrand wrote: > On 08/12/11 16:55, Paul Kyzivat wrote: >> On 8/12/11 2:45 AM, Harald Alvestrand wrote: >>> On 08/11/11 20:47, Paul Kyzivat wrote: >>>> On 8/11/11 7:32 AM, Harald Alvestrand wrote: >>>>> I have taken some of the information I learned from the discussions in >>>>> Quebec City about the issues of putting video and audio into the same >>>>> RTP session and created a draft from them outlining a solution to the >>>>> problem of signalling this configuration using SDP. >>>>> >>>>> Comments welcome, including the recommended context for processing the >>>>> document; in a few days I'll send the same note to AVTCORE and/or >>>>> MMUSIC. >>>> >>>> Harald, >>>> >>>> A few questions/comments: >>>> >>>> 1) If ICE is being used, how do you expect it to be handled on the 2nd >>>> m-line? Since one of the goals of multiplexing on a single rtp session >>>> is to minimize ICE processing, one would hope only to do ICE on the >>>> first of the grouped m-lines. But if the answerer doesn't support this >>>> grouping, then the ICE will be needed on the others. >>> I tried to be explicit that if negotiation is successful, only the ICE >>> parameters from the first section listed in the A=group:TOGETHER would >>> be used: >> >> Sure. But if the other side *doesn't* support TOGETHER, then ICE will >> need to be negotiated independently for each m-line. And for that to >> work, the port for the 2nd m-line but be active, other ICE candidates >> identified and included for it, etc. >> >> ISTM the implications of that need further explanation. >> (I'm not an expert on ICE. If I were, maybe this would be obvious.) > There are 2 possible things to do for the offerer: > - Start ICE procedure on all ports when sending the offer > - Wait until the answer comes back, and either start ICE procedure on > one port (if the responder understood TOGETHER), or start the ICE > procedure on all ports (if the responder did not understand TOGETHER) > > The first alternative is a number of milliseconds faster, but others > should chime in on whether that's significant or not. (I don't know much about ICE, so just call me on it if I say something stupid) IIUC, there are some aspects of ICE that MUST be done before sending the offer. Specifically that involved gathering the candidate list, which may involve assignment of multiple local ports, interactions with a TURN server, etc. I don't think everything can be deferred until the answer is received. (I suppose one approach would be for the initial offer to set the port to zero in all but the first m-line. Then, once the first answer is received, indicating whether TOGETHER is supported, another offer can be generated, using appropriate ICE based on whether using TOGETHER or not. But that does start to get complex.) Thanks, Paul
- [rtcweb] Fwd: I-D Action: draft-alvestrand-one-rt… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Paul Kyzivat
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Ross Finlayson
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Paul Kyzivat
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Paul Kyzivat
- [rtcweb] Combining attributes (Re: Fwd: I-D Actio… Harald Alvestrand
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt ICE … Paul Kyzivat
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Randell Jesup
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt ICE … Randell Jesup
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Justin Uberti
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt ICE … Paul Kyzivat
- [rtcweb] draft-alvestrand-one-rtp-00.txt and inte… Christer Holmberg
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt and … Christer Holmberg
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt and … Harald Alvestrand
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt and … Christer Holmberg
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Harald Alvestrand
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Randell Jesup
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Colin Perkins