From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x231.google.com (mail-wm0-x231.google.com [IPv6:2a00:1450:400c:c09::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 76AF53B2A2 for ; Mon, 21 Nov 2016 06:27:24 -0500 (EST) Received: by mail-wm0-x231.google.com with SMTP id a197so140958495wmd.0 for ; Mon, 21 Nov 2016 03:27:24 -0800 (PST) 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=bSJuVUpaBLoXJMda96Aa6CE3gg6I2JGT/Fi2hdGsWI4=; b=cpuuoUrnnt1Md2mIWxOL4VWYHVMT31ax2rTxFJ2IsvoLVMv3Fw9gmJtipKensqxhaJ JUHYIo5Rx2cNcYEBOLZ8tlSVQsUHXPZBW/A+StgGDpxqsA3LGaZwT2EmuE2c3YNmAD0g FiEVYbHLQE4Hs5k/vMjvof0PGRTTM9waLj/S9F+lAliyA0y+f0SXK9zvz3QXnjwHlejS fug7PQ4KLT+Dx2QG0ZHx2FNeBLKK87d4jR9Z+zk0kr9lQsons/4IeClw855W4x8DzLZJ FYmCRy/TbnJjGxAm2eIlqvAAlMcqVFgQpSTu5KjzuPeNVssIfXhHPwhEGubW8aLlY3HE jo1g== 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=bSJuVUpaBLoXJMda96Aa6CE3gg6I2JGT/Fi2hdGsWI4=; b=HlVNPSZWbbV//3nvMK3Nqw50uMFseN3e0IiY+hhbGruQqpJHm3/ECYuP1jy2oAuY0e 1fnDU4dSwPT1h+UxWkSWGI5VgVZzog+2XvStRAWoBuU5SEefr41O6ijHoQhjTqK/xfIO y1mSg6dIKsBsiYPcK6HvVox9E3ItCW80ouO2S2ztH0b54A0nKCNSpFfVF1lzQN/WeTUH iQWWvdx8PkskhP/3qGSQ4AbpGo9ykgfJmTyaMaG6OPty6tabNCZuxSYGvuLRKR3Ynlmb xuWI7ymHEpAtJHgnwxuC9jqDrtMP8O3/60DBJh9qxsYxv5JLtHLd+cD8kAfuldwFY2am n/eA== X-Gm-Message-State: AKaTC02baTje++Fzz1LZdIL7hdr9DwKyPluqnqW3Xp/3501QerLCjZJM4pF4XM+gpn/ZLA== X-Received: by 10.25.104.2 with SMTP id d2mr2930171lfc.95.1479727643433; Mon, 21 Nov 2016 03:27:23 -0800 (PST) Received: from [192.168.100.13] (37-33-82-144.bb.dnainternet.fi. [37.33.82.144]) by smtp.gmail.com with ESMTPSA id 64sm5274586ljf.17.2016.11.21.03.27.22 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 21 Nov 2016 03:27:22 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) From: Jonathan Morton In-Reply-To: Date: Mon, 21 Nov 2016 13:27:21 +0200 Cc: make-wifi-fast@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <97DE7A30-F225-4B9C-B84B-DD3C38F35A69@gmail.com> References: To: Loganaden Velvindron X-Mailer: Apple Mail (2.3124) Subject: Re: [Make-wifi-fast] 3g/4g with fq_codel & mobility X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 21 Nov 2016 11:27:24 -0000 > On 21 Nov, 2016, at 13:16, Loganaden Velvindron = wrote: >=20 > I have one of those gl.inet 6416a board. It runs fq_codel on the > USB-3g dongle modem interface, and it runs very well at rest. >=20 > I put it inside a car, and while driving, I notice some induced = latency: >=20 > https://www.dslreports.com/speedtest/6354936 >=20 > Can someone who has some understanding of 3g/4g internals shed some > light ? Could the 3g/4g modem be buffering due to varying strength of > the signal or due to handover in base station ? Usually such dongles don=E2=80=99t give direct access to the 3G modem = interface. Instead they provide an Ethernet or PPP interface, and do a = conversion internally. Ethernet emulation is more common of late, = possibly due to the rise of 4G. Running fq_codel on such a device without a shaper relies on the buffers = in *both* the dongle itself and the driver for the emulated Ethernet = device having appropriately sized buffers in aggregate. This is = virtually never the case. And that=E2=80=99s just for the upload = direction. In the download direction you are relying on buffers in the provider=E2=80= =99s network and the cell tower. Fq_codel on your own hardware has no = effect here. To solve these problems you have to take control of the bottleneck, ie. = to move it to a location you control using a pair of shapers (one in = each direction). That=E2=80=99s what I do, using Cake of course. The = difficulty is then in determining the link speed to shape at, as that = will change based on propagation conditions, interference, distance, and = antenna orientations. It=E2=80=99s a difficult problem, and one that is so far inadequately = solved. - Jonathan Morton