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 TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id B95643B29D; Sun, 1 Dec 2019 14:32:50 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1575228761; bh=TTBDx49VxaB/K9+syRlELAneJcZ06rVVkZsl8Rj+fWM=; h=X-UI-Sender-Class:Subject:From:In-Reply-To:Date:Cc:References:To; b=A2TYtMYGzGs9RkIAXgUhG7+z9HljxwxQ5MVVMDyTPZ4Kf4q/A+LvT8AEr+w59oaMd 7ZKgFrNVe/yGtwtTdujIDNDQ6T/3Xb+K9Y599Mh206AQJGOJHuAitgbu/mEQCo/bQZ QtnRLv5qvdIJsiPjFDIsBB69IXTOjkCPTcleogco= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from hms-beagle2.lan ([95.116.232.196]) by mail.gmx.com (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1N1fis-1heLrt2rwO-011wtz; Sun, 01 Dec 2019 20:32:41 +0100 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) From: Sebastian Moeller In-Reply-To: Date: Sun, 1 Dec 2019 20:32:40 +0100 Cc: Carsten Bormann , ECN-Sane , bloat Content-Transfer-Encoding: quoted-printable Message-Id: References: <63E9C0E4-C913-4B2F-8AFC-64E12489BC65@gmail.com> <297503679.4519449.1575069001960@mail.yahoo.com> <54C976BC-DEC7-4710-9CFF-0243559D9002@gmail.com> <156EA284-C01D-4FAA-89F4-DB448795F7FC@gmx.de> <385CF47C-17AD-4A62-9924-068E1485FFD5@gmail.com> <8C5FD2CE-D24F-4998-A636-8F85279C67BA@gmail.com> <02703449-D6CE-497D-BDBD-D79542D0EACF@gmx.de> <349F14BC-683C-431E-BE8F-8574880F04B9@gmail.com> <337C951B-1812-4F20-89CE-F8B6BCF3B7C8@gmx.de> To: Jonathan Morton X-Mailer: Apple Mail (2.3445.104.11) X-Provags-ID: V03:K1:5QClpkUQfzO0NORFjRqmOegIfyBd99mvtFBW0Bae62rU9fS4EUJ KcaBiR85uaWRZCckV1rzHVXA4cqpr6zHV3m3A9G3xhEUg4nzhjwWZyl9iYAfYTv3lhq9+YY nIXtxblKC7y405mQMZSOYkeQ1g1ZY3C5PEZS//a+KUDEzoK7BBFfjqGyHVBGVPP2NPz+EaC 3nfrMesr6YW01NiGSkR5Q== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:SapoS/wDxjs=:FCKkDocprSoz5oWxsBZWee NbLaL6fpbeztV4pwWWIaOb9BRs/8RN0wivalfRq+iGSIb3mC38D/xf6CZW0jWDhXqHmHiSa7W YWr1s6p4rN5XzH5g1MCKQyesFi+Lzydqg4x+Fe362q7lAWq4QTjweyOMB81siysdaQXdxT7AV ihmZxddHFHbqwrG5QE9nKxNPIyTLaiGNGBnj3kAIB1rtGTYEvVywK1SAPFoFKi5uQnWnsjLTQ UApeXO5FPMHKOQCScg7n5hHMvHXp4uXVdYBYUv3VqLmIuqdEM+ahwtbAJmuBYmBOy3mDPgTLz 7ln1jZWGVYeFzcrm1gVrVx1Z1wtFwZYBOfQSXpmJDPROnf72pyRDR4Bve1A5JMqCi7fFsShNA rHm1C0ng6GPBiMy1gn0yTqskAkt+xdrydgk5kArH2RtGWL++KZ9/fsIlPCx6YIrtCfQi8FfS7 GLbBW7QPomcFJHzb46tKDxvkoYLn3xzaVOVD3zQDTGIL2gv/3FxC/SZXaf7NB9jxpIResAMlY 3Pg32fSj4KqG2fsVo75R3djnb0Dna1GIpC08qaUEduQ+9Qx/pmTVDLq7e3vqNjedM7NuXvqG5 kTaDY35v2rAFmboJLkobMqkCMSc3wE7DhAXCfhr77jUJDxt3rXpcfUVQgNYQVzny+xAeU+wl0 EAnTBLBL/zRWsewtyqB1XGMDY36u2Wim96xMc9gwsBXELiHIVw7oXpFyaKuVMCtFm4W+iULsO sbRl48E+WTPPJr7L42cPjQGrucMKd6FR/kNG5e2m0aZ6/Q8tnolUNGGXjWx8RsEFUJT6WdCEf AYI5Kn8EFn9viCiyrQra09KXhVTOh+jJ238haDwv8kUS60xrkwGUrWF1mDaq5HAat362kIa33 Nmg2vr27hD5cnlR6K/uKuJBpYfc6xnLQ2NvnKLjXV02oxmbADYKaRJt4I34I3TjMtOPVyKWBT HHIjqLHffe71A6qF5eoNoizLkU5FRA7cLymO3KbjPzomYoUM161iwADPHGj8zPIlhNJnfSrU+ ik+QXYZwlls0bEHfb3Q8XBaFhu3tgAffS3RI/9UumDOyeMrXlDTA2M41fu1vv1KmlUjBgTWWx g4rt2b4MsgqGOb3uT8YrHe4ha4uHT+YlcoCrzLRCCTXbBKKJWvetHG4Laih1zZJE0AZO5wEyQ fVdaccHWA5vi2BmrQc3u50lk2Fs96uVnZE2aLw64sDLduR95mlNkasfLV2zkhHE11L8s9MFZG p3MsPHbTjhstu26V5LfpPorQoqt6vGGzC1vINLet446ZeIkdi4KA3EgsfBXU= Subject: Re: [Ecn-sane] [Bloat] sce materials from ietf X-BeenThere: ecn-sane@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Discussion of explicit congestion notification's impact on the Internet List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Dec 2019 19:32:51 -0000 Hi Jonathan, > On Dec 1, 2019, at 20:27, Jonathan Morton = wrote: >=20 >> On 1 Dec, 2019, at 9:03 pm, Sebastian Moeller = wrote: >>=20 >>> If less feedback is observed by the sender than intended by the AQM, = growth will continue and the AQM will increase its marking to = compensate, ultimately resorting to a CE mark. =20 >>=20 >> Well, that seems undesirable? >=20 > As a safety valve, getting a CE mark is greatly preferable to losing = congestion control entirely, or incurring a packet loss as the other = alternative congestion signal. Well, yes, I fully agree, I was referring to the "less feedback = is observed by the sender than intended" part; I think it is great that = SCE is safe by design in this regard. > It would only happen if the SCE signal or feedback were seriously = disrupted or entirely erased - the latter being the *normal* state of = affairs when either endpoint is not SCE aware in the first place. >=20 >> Am I right to assume that the fault tolerance requires a relative = steady ACK stream though? >=20 > It only needs to be sufficient to keep the TCP stream flowing. If the = acks are bursty, that's a separate problem in which it doesn't really = matter if they're all present or not. And technically, the one-bit = feedback mechanism is capable of precisely reflecting a sparse sequence = of SCE marks using just two acks per mark. >=20 >> I fully agree that if ACK thinning is performed it really should be = careful to not loose information when doing its job, but SCE hopefully = can deal with whatever is out in the field today (I am looking at you = DOCSIS uplinks...), no? >=20 > Right, that's the essence of the above discussion about relative = feedback error, which is the sort of thing that random ack loss or = unprincipled ack thinning is likely to introduce. "unprincipled ack thinning" nice description. >=20 > Meanwhile, an ack filter that avoids dropping acks in which the = reserved flag bits differ from its successor will not lose any = information in the one-bit scheme. This is what's implemented in Cake = (except that not all the reserved bits are covered yet, only the one we = use). So, to show my lack of knowledge, basically a pure change in = sequence number is acceptable, any other differences should trigger ACK = conservation instead of filtering? Best Regards Sebastian >=20 > - Jonathan Morton >=20