From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-x22c.google.com (mail-qt0-x22c.google.com [IPv6:2607:f8b0:400d:c0d::22c]) (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 E7BCB3BA8E for ; Tue, 12 Jun 2018 02:55:11 -0400 (EDT) Received: by mail-qt0-x22c.google.com with SMTP id l10-v6so17555079qtj.0 for ; Mon, 11 Jun 2018 23:55:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc :content-transfer-encoding; bh=IZ60/9CVvBT9o70NR7vEtCsZdQyVmLCQc6hk2BUzQ4A=; b=iyNiA+CsXpn4RagARkjvpnG0frNxmsdmJIhhyjLo196wbUzNOUhV+a5jCkgd2oHiOc mHu8BBRJ79cfAl6pQncB9cf0VHTZTxt3QzPJ8exYyJc8ENxD6WOl1jOpzWp6QX4OHFp/ uUkNHvxA0UfszeIq7A0RvTfuze+kTEXd3L+uvWpNB4PAkhUrLnG1lNGXqeKkHN23+zPV /KW4z3EU4zKxIzP5sG7LHZqqtseMtdjScNP0Cp06dNltWHHkK+s37tG0EkGjbbXPULvm qNyWLhZIQe13IzL4h66oNiQA2Sm76MEthKroiLJQ6BS3OEwyCLHLQUZEXepnl3h5srFO psJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc :content-transfer-encoding; bh=IZ60/9CVvBT9o70NR7vEtCsZdQyVmLCQc6hk2BUzQ4A=; b=VF24cIu34bUDaZ6OJTeAE6Cmf1Qdl1G5Xm6vu2OORcQVg+jaSSOc71zTv4U2iBk6k1 L5s0PCjEhbx2m06sowj/2J9b35Bd4lGM+IVVMVMBnJ7nMGVXzeobDyF5fxAo/9xEkzwg rQUrKqmSsBBUwrtXYFKSQ2VsJ0d6KIpLKfibBHWer37KOkyOZDhmqHkwwyAvJ/W3WnbA ifnKVVnJyaZ3uaoPqVwyRQCNn3Fa978Q/mse4bagmX+s3/PaAbfAElsHEkW+4yGWOE3q iXhnGVfSoJLKqyvw0cEASTuXiS6xDH2+HlxcOpDz43HtGYec559Iqrv2QLXHYHg6AiG8 xqxw== X-Gm-Message-State: APt69E3aFiV3U2H4wfpAXexLz95/5+Ra0I631sS+lwyDSo8Wb5X0PDI2 aKTb9TP2yPNtCurLyelCjjUt5JLsqP6BZzk2tAA= X-Google-Smtp-Source: ADUXVKLF4C8xTHaaBeZysyZYY6VmLUq1NrIzRlCYrydDV1nfKZBOpxdpHr4zUptWmXsYyxKFE+Nu7Zv7kqCOP2AF9XQ= X-Received: by 2002:aed:24fb:: with SMTP id u56-v6mr2300330qtc.203.1528786511487; Mon, 11 Jun 2018 23:55:11 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:aed:24f0:0:0:0:0:0 with HTTP; Mon, 11 Jun 2018 23:55:10 -0700 (PDT) From: Dave Taht Date: Mon, 11 Jun 2018 23:55:10 -0700 Message-ID: To: Kevin Darbyshire-Bryant Cc: bloat , Geoff Huston Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Bloat] geoff huston's take on BBR X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Jun 2018 06:55:12 -0000 On Mon, Jun 11, 2018 at 10:58 PM, Kevin Darbyshire-Bryant wrote: > > >> On 11 Jun 2018, at 22:27, Dave Taht wrote: >> >> https://ripe76.ripe.net/presentations/10-2018-05-15-bbr.pdf > > Fascinating! > > " =E2=80=A2 BBR changes all those assumptions, and could potentiall= y push many networks into sustained instability > > =E2=80=A2 =E2=80=93 We cannot use the conventional network contr= ol mechanisms to regulate BBR flows > > =E2=80=A2 Selective packet drop just won=E2=80=99t create back pressure o= n the flow=E2=80=9D > > And I keep on seeing questions on whether BBR understands ECN - if not=E2= =80=A6. well I think we see the results. I think geoff goofed in his testing of BBR, starting all flows at the same time, thus syncing up their probing periods. Real traffic is not correlated this way. (I made the same mistake on my initial bbr testing) I do agree that bbr treats aqm drops as "noise", not backpressure. And bbr scares me. I look forward very much to bbr one day soon doing some sort of sane, conservative, response to ecn marks. PS having fq on the link makes cubic and bbr cohabitate just fine. fq_codel vs bbr behavior was reasonable, though bbr lost a lot more packets before finding a decent state. > Cheers, > > Kevin D-B > > 012C ACB2 28C6 C53E 9775 9123 B3A2 389B 9DE2 334A > --=20 Dave T=C3=A4ht CEO, TekLibre, LLC http://www.teklibre.com Tel: 1-669-226-2619