From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) by huchra.bufferbloat.net (Postfix) with ESMTP id 921F621F151 for ; Mon, 17 Jun 2013 00:30:31 -0700 (PDT) Received: from u-090-csam110a.zmbp.uni-tuebingen.de ([134.2.90.47]) by mail.gmx.com (mrgmx102) with ESMTPSA (Nemesis) id 0M5a9E-1UQBmG35WS-00xZ8s; Mon, 17 Jun 2013 09:30:29 +0200 Content-Type: text/plain; charset=iso-8859-1 Mime-Version: 1.0 (Mac OS X Mail 6.5 \(1508\)) From: Sebastian Moeller In-Reply-To: <8738shrd0p.fsf@toke.dk> Date: Mon, 17 Jun 2013 09:30:18 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <00B68282-44B0-4392-8AEF-68144A50D94E@gmx.de> References: <8738shsx3w.fsf@toke.dk> <87vc5drhdj.fsf@toke.dk> <87bo75rgp5.fsf@toke.dk> <8738shrd0p.fsf@toke.dk> To: =?iso-8859-1?Q?Toke_H=F8iland-J=F8rgensen?= X-Mailer: Apple Mail (2.1508) X-Provags-ID: V03:K0:GTWdrdds6INK16971T1ZBW0kXak4GZG/VnVF2/zXrC626XUpsRG 6fD6iPWqrkbdOWcVaxmXIxrqCGvhHVCGRk7g6z+VGyOl5eAFAHF4I8dgncupGSpkscspVxt A5min7G/7Knfs085jQHtQfsXewEkjR96CmU3+K4W9qA4u4ncgXrr2YVy8bDMPZrnVcTefFX mBoSALV8tNZjk9hFHJLBg== Cc: cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] trivial 6in4 fix(?) X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 Jun 2013 07:30:32 -0000 Hi Toke, On Jun 16, 2013, at 22:55 , Toke H=F8iland-J=F8rgensen = wrote: > Sebastian Moeller writes: >=20 >> As far as I can tell at least VDSL typically means VDSL2 and that >> probably means PTM instead of ATM. In essence this means you do not >> have to deal with ATMs 48 payload bytes per 53 byte cell transport >> inefficiencies. So all you need to deal with is per packet overhead. >> Then again I am sure you probably know that already. (Sidenote, as = far >> as I understand (so not very far) using ATM for DSL connections with >> POTS service in the lower frequency range never made much sense at >> all, the 5 byte ATM header typically was constant and by that just >> ballast and the 48 byte quantization on the last mile never came with >> any benefits, but I digress) >=20 > Right, thanks. So that means the overhead is constant per (ethernet) > package? That is my interpretation, I am still waiting for vdxl = deployment in my area so I have no actual hands-on experience yet. = Honestly, I think the best thing to do is not so much assume ATM or lack = of ATM, but simply measure it :) (while VDSL offers PTM, it can also = operate over ATM if the telco wishes, so vdsl is technically not = guaranteed to be free of ATM). If you collect a large quantity of pings = to the nearest IP address ouside of your control for 16 to 113 byte ping = sizes (say 100 packets at each size) you should be able to see a step = profile in the RTTs for an ATM carrier (with two steps) and no steps = (but rather a ramp) for no PTM.=20 Best Sebastian >=20 > -Toke