From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-x12a.google.com (mail-lf1-x12a.google.com [IPv6:2a00:1450:4864:20::12a]) (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 839E83CB36 for ; Mon, 12 Aug 2019 19:37:09 -0400 (EDT) Received: by mail-lf1-x12a.google.com with SMTP id b17so75449704lff.7 for ; Mon, 12 Aug 2019 16:37:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=+Ms2Y5f+rezCsv4ykyhwMA3M3ZdS40RgwnzRnL+Tnsc=; b=eA/9zAX0t82eAuxIr2bD+xQdIsdPtUPc0GyiT4DV+N4i+UgUiSK4Hhw/veKRnQx4nj VcDaKHWcgtR/+QPp8agGDpbatNZqc5iFSRZfi7+9Eu1Ohze/J6T8cyDUFCTdRE+iDzfz K1BjfGtOFRZxnAHqBYt2RrwFWKuIc/1J4K9AtLxqQUEf96oQU2DZjRynKED62En2+NRA Fi0Ip7cCj3ETg+LfyPvP1C9YvNyZ+/BrePRAgjomQ3shrmQapAkBUFZQryJATCdVnRsh dBC77PN5xpiQkTMVG6kIt85MCW8TEnBa5dQNFKAdHN+hrRRhc2JXAztD6wSccdvYRl8t gpQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=+Ms2Y5f+rezCsv4ykyhwMA3M3ZdS40RgwnzRnL+Tnsc=; b=oWGr5GE/6Ars2Q431ExCmvBinkM1gKh3gUh42eeeBYabsrKnRVwv4kiK60gZSyAWTr yEgggvu6jp+KyC2RV7y+tByv14EqhxxDdOVaws3P8hTpCS4L5YjaUw9ciYJt2YoT0BEo rfKuaTX/i3mEQqW2OfM314VySxFQBVQQ5NH0JmvIAFBj5vkwPo6VehigmELHpbUCDOBg bofoi7t84U9cZvX76oTJKLi3GhFZxwCaCR8L8Cx3sGqHuNWzfgo6tJa++X4AxtPfqNgo QutqVumujYg32NhBB1Voab1LxJ8uqkMogn41hREzZO41UR/ls9i2MveLkqF/Tjwewmo8 ebSw== X-Gm-Message-State: APjAAAUKPk2D3Fb9mYrWVRmISSxQVSyOZO+0k1BN8Mg1WWcvTkyDafDi q8XLsonZqUlBPrkdyIyX36s= X-Google-Smtp-Source: APXvYqypoYOfcBFw9YrdlUhtfDWZthDsk0Lbn8NvH1N9fOVuq2Rqc5B5rRz72XttDUwIl96JsQhWog== X-Received: by 2002:ac2:550c:: with SMTP id j12mr16494086lfk.171.1565653028485; Mon, 12 Aug 2019 16:37:08 -0700 (PDT) Received: from jonathartonsmbp.lan (83-245-237-193-nat-p.elisa-mobile.fi. [83.245.237.193]) by smtp.gmail.com with ESMTPSA id r68sm19259668lff.52.2019.08.12.16.37.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 12 Aug 2019 16:37:07 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) From: Jonathan Morton In-Reply-To: Date: Tue, 13 Aug 2019 02:37:06 +0300 Cc: ECN-Sane Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Dave Taht X-Mailer: Apple Mail (2.3445.9.1) Subject: Re: [Ecn-sane] cautionary tcp tale 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: Mon, 12 Aug 2019 23:37:09 -0000 > On 13 Aug, 2019, at 12:30 am, Dave Taht wrote: >=20 > https://www.snellman.net/blog/archive/2017-07-20-s3-mystery/ TL;DR summary: Buggy checksum recalculation in a cable modem caused minor packet loss = (through rejection at the receiver). In the absence of TCP Timestamps, = the retransmissions of these lost packets were identical and triggered = the same bug. Result, connections to certain particular servers which = had the unusual property of disabling TCP Timestamps would quickly = stall. I think a tool could be made to watch a sample of received traffic for = this pattern: incorrect checksums where the correct checksum is the same = each time (though different per deployment). How much network equipment = exhibits this bug? - Jonathan Morton=