From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x231.google.com (mail-lf0-x231.google.com [IPv6:2a00:1450:4010:c07::231]) (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 DA0863B2BC; Sat, 4 Jun 2016 15:55:13 -0400 (EDT) Received: by mail-lf0-x231.google.com with SMTP id s186so8276339lfs.1; Sat, 04 Jun 2016 12:55:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=TJuoScbQu5XUH02YcNHSH3AbtMun8Z3Fk/w1r/0sCuo=; b=BNN5FgzMT7PvXn6haikjXaesTTtcQwRQHIAvjleQSKjBpKYt7QdOtQTv4GUSN2PvHU VAArRBDfp2lUXwpzGRLAnWoR48vkKF8KrRNFg5KGVgZYJIdSIebrYGhsMNHXqgiGJXLm IY6Gm1DIVbfFvUowfyuYQS6OoXSu4eATn4vdEz3bDilR0cMudND4S5Jy4W6FZBsjs3yD o8IZKL2WEkwPjxoDfLUC/dxl9+OqbU054tvjgdgDfNlaPQEC2CKECupvxixi/PtNQk1O UdL8joKSwD6Zv+072ux/sAFxK6fbal3e/Ta6z21Jq1Np984Mvce+J6M44hl/gQRTD5wR PpUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=TJuoScbQu5XUH02YcNHSH3AbtMun8Z3Fk/w1r/0sCuo=; b=cCF9c6bkwcegcqFvN7gWNVPSe0cvKrRjAplihB/AMOBL/Tjeg4McesLPFe8yFaWRe6 vZnyfFhkzLsMdAbtK6PN0Wj4/26hEAuqnv65vZ6pNICYktXUxsiNxwCs3gx0kQApcLdY hM3MQOK8kV57b0NNdwzSW0IIPnfMzVOh9YEoWhY/UNfRNw33N5ZDMtwytTuPvqwsQg1C ePoKBnapSlh51olHZ6Tes8v/8K7fh/XfDx5WiB/2dI1tPj+3hcaEPqp6XljPEUybiDZi ptw4Dew11OYaaM8DzdtNWffHA3zJhKhOS9yr/u3yl8TUiiJwAMydJQAxEvm5usF5MBLz JAJg== X-Gm-Message-State: ALyK8tK3cs+y5nZGiBkGOnKPztk9fz8oHynilS6SCjYFYohztcD0nWa7WX/8v/7JpAstoA== X-Received: by 10.25.134.2 with SMTP id i2mr2073643lfd.1.1465070112579; Sat, 04 Jun 2016 12:55:12 -0700 (PDT) Received: from [192.168.100.11] (37-33-56-85.bb.dnainternet.fi. [37.33.56.85]) by smtp.gmail.com with ESMTPSA id o75sm1113534lfi.9.2016.06.04.12.55.11 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 04 Jun 2016 12:55:11 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) From: Jonathan Morton In-Reply-To: <1465062599.2968.11.camel@edumazet-glaptop3.roam.corp.google.com> Date: Sat, 4 Jun 2016 22:55:01 +0300 Cc: Noah Causin , Andrew McGregor , cake@lists.bufferbloat.net, "codel@lists.bufferbloat.net" Content-Transfer-Encoding: quoted-printable Message-Id: References: <22371476-B45C-4E81-93C0-D39A67639EA0@gmx.de> <857AEE56-E7DB-4981-B32E-82473F877139@gmail.com> <8AB0D25D-C1CA-45F1-889E-2F73CF8C44F7@gmail.com> <323AFC22-A092-4F59-8197-AF21EF73FD58@gmail.com> <274D3A0FA900FD47AA6B56991AAA32FDC5529FC8@wtl-exchp-1.sandvine.com> <574478B4.7080103@taht.net> <39F38477-A877-4C1B-9B7F-BB3358425F17@gmail.com> <0eb223f9-2873-7f53-c2ce-c6867ddec17c@gmail.com> <48A25043-19E2-4BB7-B634-A4003F7BE6F8@gmail.com> <01BEA343-7C07-46FA-8DC4-07BF26309FC8@gmail.com> <10d58240-e106-ff1f-a038-df5bc0ee7a36@gmail.com> <1465062599.2968.11.camel@edumazet-glaptop3.roam.corp.google.com> To: Eric Dumazet X-Mailer: Apple Mail (2.3124) Subject: Re: [Cake] [Codel] Proposing COBALT 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: Sat, 04 Jun 2016 19:55:14 -0000 > On 4 Jun, 2016, at 20:49, Eric Dumazet wrote: >=20 > ECN (as in RFC 3168) is well known to be trivially exploited by peers > pretending to be ECN ready, but not reacting to feedbacks, only to let > their packets traverse congested hops with a lower drop probability. In this case it is the sender cheating, not the receiver, nor the = network. ECN Nonce doesn=E2=80=99t apply, as it is designed to protect = against the latter two forms of cheating (and in any case nobody ever = deployed it). Given that it=E2=80=99s *Valve* doing it, we have a good chance of = convincing them to correct it, simply by explaining that it has an = unreasonable effect on network latency and therefore game performance = while Steam is downloading in the background. This is especially = pertinent since several of Valve=E2=80=99s own games are notoriously = latency-sensitive FPSes. COBALT should turn out to be a reasonable antidote to sender-side = cheating, due to the way BLUE works; the drop probability remains steady = until the queue has completely emptied, and then decays slowly. = Assuming the congestion-control response to packet drops is normal, BLUE = should find a stable operating point where the queue is kept partly full = on average. The resulting packet loss will be higher than for a dumb = FIFO or a naive ECN AQM, but lower than for a loss-based AQM with a = tight sojourn-time target. For this reason, I=E2=80=99m putting off drafting such an explanation to = Valve until I have a chance to evaluate COBALT=E2=80=99s performance = against the faulty traffic. - Jonathan Morton