Re: [ledbat] LEDBAT doesn't help sharing network beyond home gateway
Sampo Syreeni <decoy@iki.fi> Fri, 29 July 2011 01:20 UTC
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Date: Fri, 29 Jul 2011 04:19:57 +0300
From: Sampo Syreeni <decoy@iki.fi>
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To: Bob Briscoe <bob.briscoe@bt.com>
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Cc: Janardhan Iyengar <jana.iyengar@gmail.com>, "ledbat@ietf.org" <ledbat@ietf.org>, tsv-area IETF list <tsv-area@ietf.org>
Subject: Re: [ledbat] LEDBAT doesn't help sharing network beyond home gateway
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On 2011-07-28, Bob Briscoe wrote: > I said in a residential network, LEDBAT won't yield to traffic sharing > any queue upstream of your own home gateway queue. > > LEDBAT's target delay is 150ms. Target delay, but also a one designed to mimic the minimum delay over the whole path? No? A users's upstream cable modem being the most typical and biggest part of that, but still, isn't the protocol about the whole? Shouldn't it then in theory be that LEDBAT quenches towards the minimum total delay, regardless of where the bottleneck might be? Any higher up, faster, less congested buffers ought to be totally neglected in the process because the lower, more filled up dominate the e2e delay calculation? If not, then the quenching ought to happen because of the more congested link/filled up buffer, that is *now* causing the extra delay beoynd the minimum sensed. > The root cause is the fixed 150ms target delay. So what I (we?) am missing is that with very fast networks the protocol should be able to asymptotically go to zero latency, while staying nice and crowd-stable? Are there other, statistical considerations beyond this? > If LEDBAT yielded to others, users would reject it. They absolutely would not. In fact, they don't: it's in current use and is rapidly being adopted by the numbers, as uTP, within uTorrent (and others). > We could design a LEDBAT-like protocol that yields to others in any > queue. But no-one would want it (yet). Incidentally, a goal of ConEx > is to incentivise deployment of LEDBAT-like protocols. The suffix > '-like' means that they would benefit from yielding to anyone, not > just your family in your home. Yes. So I at least am missing something. I'm sorry to ask for looking a bit stupid, but... What *am* I missing, really? -- Sampo Syreeni, aka decoy - decoy@iki.fi, http://decoy.iki.fi/front +358-50-5756111, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
- [ledbat] LEDBAT doesn't help sharing network beyo… Bob Briscoe
- Re: [ledbat] LEDBAT doesn't help sharing network … Rolf Winter
- Re: [ledbat] LEDBAT doesn't help sharing network … Murari Sridharan
- Re: [ledbat] LEDBAT doesn't help sharing network … Sampo Syreeni
- Re: [ledbat] LEDBAT doesn't help sharing network … arvid
- Re: [ledbat] LEDBAT doesn't help sharing network … Woundy, Richard