From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail2.tohojo.dk (mail2.tohojo.dk [77.235.48.147]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 2457E21F29F for ; Wed, 25 Feb 2015 02:24:57 -0800 (PST) X-Virus-Scanned: amavisd-new at mail2.tohojo.dk Sender: toke@toke.dk DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toke.dk; s=201310; t=1424859889; bh=cqU3QYpGG0NMuZF5s5S6niNu3h0yRYpplwcE1uKR7Vg=; h=From:To:Cc:Subject:References:Date:In-Reply-To; b=gvigrDE0wT4pOd8XmO0o+6DGuJgXs0E+SNyE7w/6ttH1Q95f5sNBqFGDPyi4lJy2u BHbd26euMdW12WQj4yHU0MPI0H+C5a8FF6OAfIXSsx3me+jGxD/22zSqxfcZGAy/HQ lr9jtnLfXtmASL6si9d2B+4sham5adGEh73DyLsM= Received: by alrua-kau.kau.toke.dk (Postfix, from userid 1000) id 698DE3E35C9; Wed, 25 Feb 2015 11:24:48 +0100 (CET) From: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: Michael Welzl References: <201502250806.t1P86o5N011632@bagheera.jungle.bt.co.uk> <4A80D1F9-F4A1-4D14-AC75-958C5A2E8168@gmx.de> <3F47B274-B0E4-44F2-A434-E3C9F7D5D041@ifi.uio.no> Date: Wed, 25 Feb 2015 11:24:48 +0100 In-Reply-To: <3F47B274-B0E4-44F2-A434-E3C9F7D5D041@ifi.uio.no> (Michael Welzl's message of "Wed, 25 Feb 2015 10:10:46 +0000") Message-ID: <87twyaffv3.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Cc: Alex Elsayed , "bloat@lists.bufferbloat.net" Subject: Re: [Bloat] RED against bufferbloat X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Feb 2015 10:25:26 -0000 Michael Welzl writes: > but that's FQ (or FQ_CoDel's changed FQ variant), much more than the > AQM mechanism in use (as we have also seen presented by Toke at the > last ICCRG meeting). Well, actually, that presentation did also include an evaluation of the AQMs in an asymmetrical scenario. And that shows that while generally ARED does perform fairly well, it tends to be a bit on the aggressive side. In the asymmetrical case this results in too many drops on the slow side of the asymmetrical link (typically upload), hurting throughput in the other direction due to lost ACKs. There's also some other issues in there, with PIE and CoDel in particular, most notably their reactions when conditions change: it can take tens of seconds for the algorithms to get queueing latency under control in this case. Slides for the IETF presentation available here: http://www.ietf.org/proceedings/91/slides/slides-91-iccrg-4.pdf There's also a longer version of the talk (from the Stanford Netseminar) available on Youtube: https://www.youtube.com/watch?v=kePhqfKA3SM > But this discussion is about AQM mechanisms, not (changed)FQ. While the academic side of me enjoys studying AQMs (and I'm still far from anything resembling a thorough understanding of them), the practical "I just want my network to work" side of me has become increasingly convinced (in part by doing the experiments in the above mentioned talk) that FQ is more important than AQM in many scenarios. As such, I think that excluding FQ from the conversation is mostly of, well, academic interest ;) -Toke