Re: [rtcweb] An input for discussing congestion control (Fwd: New Version Notification for draft-alvestrand-rtcweb-congestion-00.txt)
Henrik Lundin <hlundin@google.com> Mon, 19 September 2011 08:02 UTC
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References: <4E649FBD.1090001@alvestrand.no> <4E734E89.5010105@ericsson.com> <4E766C4C.2020201@jesup.org> <CAEdus3LcjV9x+gLdZm5vwKhh-ge6xzfWSEB_NxcHe1Gz_5DZ8g@mail.gmail.com> <4E76F544.1040108@jesup.org>
Date: Mon, 19 Sep 2011 10:04:47 +0200
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From: Henrik Lundin <hlundin@google.com>
To: Randell Jesup <randell-ietf@jesup.org>
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Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] An input for discussing congestion control (Fwd: New Version Notification for draft-alvestrand-rtcweb-congestion-00.txt)
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Add me to the bof members list. /Henrik L On Mon, Sep 19, 2011 at 9:54 AM, Randell Jesup <randell-ietf@jesup.org>wrote: > Open question to the list: should the congestion-control-geeks discuss > here on the > list the nitty-gritty details required to build the requirements and > especially to design > and debate a possible proposed "baseline" congestion-control algorithm? > > We can certainly do that detailed discussion by email and come back with a > draft; I had been planning to do it by email, but recent discussion on > rtcweb > made me think I should ask for opinions on this. Given the structure, if > there's > any significant support for "on-the-list" I'll do that. Realize though > that they may > get pretty long and detailed without really touching on the larger issues > being > discussed here. > > Right now the bof members to discuss this and propose a draft would be > myself, > Harald, Justin, Stefan Holmer and Magnus. > > > On 9/19/2011 3:06 AM, Stefan Holmer wrote: > > On Mon, Sep 19, 2011 at 12:10 AM, Randell Jesup <randell-ietf@jesup.org>wrote: > >> On 9/16/2011 9:26 AM, Magnus Westerlund wrote: >> >>> 1. Section 3: As delay based congestion control has been tried a number >>> of times and meet with less than stellar success I wonder if you have >>> any understanding of how this relates to the issues previously >>> encountered: >>> >> Do you have any pointers to these earlier attempts? My separate >> experience >> with this class has been extremely successful, though perhaps with a set >> of >> real-world use-cases that don't cover the situations you're referring to. >> My understanding is that Radvision's NetSense is very similar from their >> description of it. >> >> > I'm interested in any references you may have as well. > > > > I doubt you'll find many/any, as the first published discussion I saw of > delay-sensing > congestion control for RTP data was Radvision's posts about Netsense last > year > and in their Android webcasts; and that was pretty detail-free until their > recent > blog posts. There's plenty of un-published experience with them at various > companies > I believe.... Not just Google and Radvision. > > > > >> >> - Stability (especially on short RTTs) >>> - How it competes with TCP flows, which was a real issues for TCP Vegas >>> but may be less of an issue here. >>> >> Perhaps Google can comment here about what tests they've done. If >> anything, >> this class of algorithm when faced with aggressive TCP flows will >> eventually >> have problems, because TCP will tend to fill up the buffers at the >> bottleneck. >> Since this algorithm senses buffers starting to fill up, it will tend to >> back >> off before TCP is likely to see a loss event. Now, it's more complex than >> that of course, and multiple flows make it more complex still. It's also >> sensitive to the adaptation rate of this algorithm and speed of backoff. >> If I remember, TFRC tends to back off more slowly than TCP but also >> increase >> more slowly; I suspect Google's algorithm is similar. >> > > As you're saying, it will always be hard for delay based congestion > control algorithms to compete with a packet loss based algorithm. The delay > based algorithm will detect over-use much earlier than the packet loss based > one, and that's basically what we've seen in the tests we've been running as > well. I do think we would benefit from more tests in this area. For > instance, we might want to go with an additive increase approach rather than > the current one which is multiplicative, this would likely help improve the > algorithms self fairness as well. > > > Probably; additive increase is probably better, or possible using a > fraction-of- > predicted-bandwidth increase. If you use additive increase, it should > probably be > partly proportional to the maximum "good" bandwidth seen during the > connection. > This provides some needed scaling of the ramp-up rate to the absolute > magnitude > of bandwidth available. > > > -- > Randell Jesuprandell-ietf@jesup.org > > > _______________________________________________ > rtcweb mailing list > rtcweb@ietf.org > https://www.ietf.org/mailman/listinfo/rtcweb > > -- Henrik Lundin | WebRTC Software Eng | hlundin@google.com | +46 70 646 13 41
- [rtcweb] An input for discussing congestion contr… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Magnus Westerlund
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Stefan Holmer
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Varun Singh
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Tim Panton
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Varun Singh
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi
- Re: [rtcweb] An input for discussing congestion c… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi
- Re: [rtcweb] An input for discussing congestion c… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Dzonatas Sol
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi
- Re: [rtcweb] An input for discussing congestion c… Harald Alvestrand
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Jim Gettys
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Ingemar Johansson S
- Re: [rtcweb] An input for discussing congestion c… Henrik Lundin
- Re: [rtcweb] An input for discussing congestion c… Randell Jesup
- Re: [rtcweb] An input for discussing congestion c… Stefan Holmer
- Re: [rtcweb] An input for discussing congestion c… Soo-Hyun Choi