From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 9F6B43B2A0 for ; Thu, 2 Jun 2016 11:42:55 -0400 (EDT) Received: from [172.17.3.79] ([134.76.241.253]) by mail.gmx.com (mrgmx002) with ESMTPSA (Nemesis) id 0LdYxu-1brDAn2J5m-00imZJ; Thu, 02 Jun 2016 17:42:51 +0200 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) From: moeller0 In-Reply-To: Date: Thu, 2 Jun 2016 17:42:50 +0200 Cc: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , cake@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <6F215C7B-D4B2-484B-B728-61E0B83FF30E@gmx.de> References: <574FFE52.1040501@darbyshire-bryant.me.uk> <2A84540D-AA30-4BD0-AF9A-5510EA00B7E8@gmail.com> <87a8j3fyxc.fsf@toke.dk> To: Jonathan Morton X-Mailer: Apple Mail (2.2104) X-Provags-ID: V03:K0:Xwnz/OhWWnpuFyDsg8E55uGzqtcm+3jXjYMM/NWTMZ046P30ZMw gqTRCoKhZlzoHRGxVN4RBPKmhLROk/BAVqP77QxteTSbpVElkXThBKSV9J7bxbHceKdxK8d YHUqW6sg0jdqrQcLbU0+R6rAuVnmjg2pYLzquvSOfn3JZ0ic4BZkZG3GMrnOY/HBm2INNrh LOqm0DbzJrxXBg3g+uk1w== X-UI-Out-Filterresults: notjunk:1;V01:K0:u5Bt6gAjFck=:Hs6I205qmusMlsrK4WPByb KYs1NTxUa0SIf1P10tezmbgs4PX9uF+PNh/Zx/wQXPlNhbPnfYAa3JcUvrMIe9YVODhfz6wcl LSIwXufRaapQ/Dl8K4uhqeDlldgDHLV0K1oIX6C5UhvC4BcPXja6Tc6K9TNfvWDIJfcy+VewL 4lC3EQIadW4eCuOUMXReZ1pTjRH2wwL6WlBR4Pvld7odzf4IzOFfDUEfkhA3cg+mDNy2bzjOX F28C0vNH6VV6NLrNJBkzqsTKApwJNWmLdJxAYY5OD8XT27BDlbOxhJBhQI4ktbmDhI6iuH0xR kLYAYFV0LA/eArE4v5crX4beccDgHpSGFu7XD9pyYI8l+V9yfKeRCS4sMnmFi7+rMPEm8Hp9U nuycYNSsqSYigZpTANmCU3dNRXc1WfgAlvtG91ofe2DM1UDaFpwz4TG1gcsRoaLqh1NHNh+DA mJGPm2zIIXariXacF1zItCiAWJ305QmPncPc0DloE7l62WTNf7zdLgOFvNJpWmMLebN5KI6Ud aqTgb1hA7Zz+ASNwwELQZ0NJRTNonWh99ozLMPWPlrY6skDcg4Gm0Jd1TkyQRCmEGmtX91k8x nZND0Ctjg+qqEgZYRUnMUp6OR6IFdJoK37x4owwxf+CJyx+5mzFnOYlOgGEhBo14O8y9vm/Ou diaOhtUWbDNeF2WtslKaWkYp64n8WH1IZ+mWQa3tFL43NjEFBYxgd7WBy6OFKdfLbIsMXZzxt bmE1Lx+D5rHCIQ56IsA014WD+zuOQYbUaU+RLFxWpHD2642FMasiMaVra+2DkOFoIkH4BJy9H 8ihfQja Subject: Re: [Cake] cake/tc - removal of atm/ptm/ethernet specific overhead keywords X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 02 Jun 2016 15:42:56 -0000 Hi Jonathan, > On Jun 2, 2016, at 16:49 , Jonathan Morton = wrote: >=20 >>> It would be nice if LuCI could infer information about the likely >>> overheads from the rest of the configuration, and apply (or suggest = & >>> default) the correct keywords in sqm-scripts. That would make the >>> feature much more widely used. >>=20 >> We can probably do this for the most common cases, but am not so sure >> it's unambiguous when to pick what. If someone can supply a couple of >> examples of configuration where we are fairly certain we know what to >> pick, I can look into how that can be inferred in luci=E2=80=A6 >=20 > The most obvious cases are where there is an ADSL or VDSL modem built = into the router, as there is on my Buffalo WBMR (though I don=E2=80=99t = currently have a working ADSL line to demonstrate a live example). SQM = on the WAN-facing interfaces which (directly or indirectly) use that = modem should then infer the PPP and ATM modes from the modem=E2=80=99s = configuration, which I know is visible to LuCI in some form. >=20 > It=E2=80=99s slightly less obvious what to do with a standalone = router, where there is a separate modem handling the PPP endpoint, thus = the WAN interface appears in all respects to be Ethernet. For this = case, an easy way of setting the =E2=80=9Cconservative=E2=80=9D, = =E2=80=9Cbridged-ptm" or =E2=80=9Cpppoe-ptm=E2=80=9D keywords should do = the trick, perhaps with =E2=80=9Cconservative=E2=80=9D being the sane = default. The PTM keywords are better suited to VDSL installations. I = suspect cable and cell modems may work best *without* overhead = compensation. I do not agree that these are too helpful unless the user = already has lots of knowledge, but then they are hardly an improvement = on =E2=80=9Coverhead N=E2=80=9D. >=20 > As for the =E2=80=9Cconservative=E2=80=9D keyword, it assumes ATM = encapsulation and exactly one ATM cell of inner encapsulation overhead, = the latter exceeding all known combinations of inner encapsulation used = in practice (except for bizarre cases involving IP-in-IP tunnelling). = It=E2=80=99s intended to be a reasonable default where it is known or = suspected that encapsulation is in use, but no specifics are known. So far I have not encountered overhead >=3D 48, that is true. = But I have also never seen a blue whale, which I do not want to be = interpreted as me doubting their existence. In reality 48 bytes still = seems like a likely upper bound for per-packet overhead on an ATM link, = so of all the keywords, conservative might survive, if renamed = =E2=80=9Cconservative_adsl=E2=80=9D or =E2=80=9Cconservative_atm=E2=80=9D.= =E2=80=9Cpppoe-ptm=E2=80=9D however is a good example for an = under-defined keyword=E2=80=A6 what exactly is this supposed to entail? >=20 > Sebastian seems to have more detailed information about what = encapsulation combinations are actually in use in Germany, and can = doubtless advise on how these show up in LuCI on an ADSL router. Not at all, some details of the encapsulation are not easily = extractable from the typical modem=E2=80=99s dsl-information tab. My = attempts at measuring the per-packet-overhead culminated in what I = documented under https://github.com/moeller0/ATM_overhead_detector and = https://github.com/moeller0/ATM_overhead_detector/wiki I stopped = believing this is =E2=80=9Csimple=E2=80=9D a long time ago; I also = failed to come up with a method to measure the actual overhead on VDSL = links=E2=80=A6 Best Regards Sebastian >=20 > - Jonathan Morton >=20 > _______________________________________________ > Cake mailing list > Cake@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cake