From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id D7CC721F1C3; Tue, 19 May 2015 09:26:08 -0700 (PDT) Received: from u-088-d142.biologie.uni-tuebingen.de ([134.2.88.142]) by mail.gmx.com (mrgmx003) with ESMTPSA (Nemesis) id 0MYg42-1YguOf2Kwc-00VRfA; Tue, 19 May 2015 18:25:31 +0200 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Content-Type: text/plain; charset=windows-1252 From: Sebastian Moeller X-Priority: 3 (Normal) In-Reply-To: <1431961775.459218261@apps.rackspace.com> Date: Tue, 19 May 2015 18:25:25 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <154EF843-C6D4-47C8-B306-90C23C469212@gmx.de> References: <8C015B1B-EFBA-4647-AD83-BAFDD16A4AF2@netapp.com> <14d5800ec08.27f7.e972a4f4d859b00521b2b659602cb2f9@superduper.net> <1431919815.385726792@apps.rackspace.com> <55597353.2010408@superduper.net> <14d67011de0.27f7.e972a4f4d859b00521b2b659602cb2f9@superduper.net> <1431961775.459218261@apps.rackspace.com> To: dpreed@reed.com X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:Hud0ItAGgUxWR7LAhT9XkwSGGLENGxm07zqf1hJLCM6gLWdB4ON w59xHCK99ns5PpnxSeh1XzYlj+i3nQp4GyPFz41sdvBV+i7dXQfjd4ITyvJF4PfhET5Q3RA 0Nfm7KiP29UjkXF+LzRX0B2Iy6pfTH4EXexQ8rw6o6B2rhNJ+fOrQGPCFskLNiCrcBynKjJ Z9iQ7KcpT1/N+Xr+FOACg== X-UI-Out-Filterresults: notjunk:1; Cc: "Klatsky, Carl" , Simon Barber , cake@lists.bufferbloat.net, "Eggert, Lars" , cerowrt-devel , bloat Subject: Re: [Cerowrt-devel] [Cake] [Bloat] heisenbug: dslreports 16 flow test vs cablemodems X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 May 2015 16:26:53 -0000 Hi David, On May 18, 2015, at 17:09 , dpreed@reed.com wrote: > I'm curious as to why one would need low priority class if you were = using fq_codel? Are the LEDBAT flows indistinguishable? =20 Well, as far as I can tell fq_codel treats all flows the same, = but we want LEDBAT flows to basically scavenge the left-overs, not get = their fair share on the table ;). Updates by the way are not the best = example for this kind of problem as some updates are urgent enough to = post-pone everything else for. > Is there no congestion signalling (no drops, no ECN)? The main reason = I ask is that end-to-end flows should share capacity well enough without = magical and rarely implemented things like diffserv and intserv. As far as I can tell bit torrent tries to do two things: 1) open = up quite a number of parallel ingress and egress flows and 2) keep that = traffic out of the way of other traffic. fq_codel interferes with how 2) = is implemented. Currently, the best of the flawed work-arounds is to = have bit torrent tell the network that it should be treated as LEDBAT = using TOS bits. This is flawed as we have no gurateee whatsoever on the = sanity of TOS bits on our networks ingress (and often networks will = re-map the TOS bits anyway, so on ingress the LEDBAT TOS signal might = not be in the packets any more, and since one man=92s ingress is another = man=92s egress, basically using TOS bits for keeping bit torrent in the = background is a loosing proposition). That said I watched a ripe talk by = Peter Lothberg where he proposed for the carriers (DTAG in his case) to = encode their TOS bits into the IPv6 addresses and simply ignore the IP = TOS bits, so they will not need to re-map those as they are totally = neutral for DTAG planned internal network. (And interestingly in DTAG=92s = IPv6 network RRUL test packets from sweden keep their TOS bits fully = intact). Best Regards Sebastian >=20 >=20 > On Monday, May 18, 2015 8:30am, "Simon Barber" = said: >=20 > I am likely out of date about Windows Update, but there's many other = programs that do background downloads or uploads that don't implement = LEDBAT or similar protection. The current AQM recommendation draft in = the IETF will make things worse, by not drawing attention to the fact = that implementing AQM without implementing a low priority traffic class = (such as DSCP 8 - CS1) will prevent solutions like LEDBAT from working, = or there being any alternative. Would appreciate support on the AQM list = in the importance of this. >=20 > Simon >=20 > Sent with AquaMail for Android > http://www.aqua-mail.com >=20 > On May 18, 2015 4:42:43 AM "Eggert, Lars" wrote: >=20 > On 2015-5-18, at 07:06, Simon Barber wrote: > Windows update will kill your Skype call. >=20 > Really? AFAIK Windows Update has been using a LEDBAT-like = scavenger-type congestion control algorithm for years now. > Lars > _______________________________________________ > Cake mailing list > Cake@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cake