From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.17.21]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 0223721FA65 for ; Thu, 3 Sep 2015 11:14:24 -0700 (PDT) Received: from hms-beagle.home.lan ([217.237.68.126]) by mail.gmx.com (mrgmx103) with ESMTPSA (Nemesis) id 0LjquD-1YwIGT3JHt-00bsju; Thu, 03 Sep 2015 20:14:20 +0200 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) From: Sebastian Moeller In-Reply-To: Date: Thu, 3 Sep 2015 20:14:19 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <330FB5B1-B42F-4475-AFA2-C0303D916C00@gmx.de> References: To: Jonathan Morton X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:1kr5wmbdMCIpRwUkoccP71dUd8D/VEsEdnIzbew2UvwtdKYg4Fk sMHIgstu6TMkgVXu8KOJ+JtIUBVDEk/Tu2MnZXg60yDdc3ySnRYazN8Ahas6ZhAE562IdD0 VUYRZ38d+H2LjVT0xxHh4dpq2vpzcn45NhnUw+eEBmxIMYuDwHzRhWO6OPtgDXEIbJZu3D1 Jwla+gIK/NXG4bP0H5Vhg== X-UI-Out-Filterresults: notjunk:1;V01:K0:G+SCWufpeyQ=:wsHvZcksukHgrZR3krFrJa YVEhCp9O/VNohluUuH3GQHBBTuPxbdXYfxjI37dNQqweN3XPo5HYIQKPz0z3qFl0xP4CUMQ92 Z29+gl3PnsC8KpqQ31UP6IQZ0EYTZghUXr646epDPjCL08uvOkALluGLePS0oE+LovDDqNRzw Rse6fCYfSx/EdhWXu+EkPbDJrdbLUL8vE8Lm70zFSLj03/Dymb9mKYMmMBRXUG+YmyFjMGOfW qF/l2J/2/KEnAdTk6GZwS3mK8aE5mzrUmTDxFvhI4XS6TvPcnmaRVMirCx09hk3o3+mbEOBVa y+6r7EhRZtQ9BszUiGiVlDXtR2SEW7X5BTCTdlaaVOlmXWMbz+6XcBf7OrpwlmLcPmZQxeG58 K9UGErNxucOMVtXD4OAlE3V/Lz9bwRXJ5wjqmJ8nPF/Gon43csNPor8u5JIHn6W5YRr/g6Tua AAzwtqIaXoV6vQbwCekH54balNg+edHHg1EbjEHIe3V5quy2WkmIQQsu6nbZ6aWmHxxmb8Gk3 /wagLwbwgjJFx53bBkpai28wPoRQBUNknjHyeDfQifqQN2RvqroJ8AubZ8KAyd/ZRAC0x5Otb f5+zZigDMl9YAc1v3Ih8zksn4s8ZDOIu5ewFk/nhemiuFMJFl6XZZDMUXqgKIEJKyMweawnhK krx2iC2uXhnlYADrdo8g0KWbtdSaLZoa1dp/ltFqIrtN/TvixdGBu5LTNAgaaZp3q9h5eKeJu cvfbzXM15Xesw1pNe8kMBRwnKnibHfWOQWe1nQ== Cc: cake@lists.bufferbloat.net Subject: Re: [Cake] pppoe-ptm overhead calculation question X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 03 Sep 2015 18:14:47 -0000 Hi Jonathan, On Sep 3, 2015, at 20:02 , Jonathan Morton = wrote: > I'm getting the distinct impression that VDSL1 & VDSL2 are completely = different technologies with the misfortune of sharing an acronym and = physical medium. That is a decent way of putting it. VDSL2 has the advantage of = coming late to the party and avoiding some of the then obvious warts of = VDSL1; also VDSL1 ist not compatible with ADSL-lines in the same DSLAM = and hence probably on the define world wide. There are some deployments = in Asia and parts of the rest of the world (according to wikipedia) = VDSL2 seems to have struck mor resonance with telco ISPs and hence seems = more prevalent.. > It's certainly far too easy to confuse data about one for the other. It certainly is, it does not help that ITU documents are = decidedly not fun to read... >=20 > Ideally, I'd like to see measurements on a real line to corroborate = one way or the other. =20 The good thing is that I outlined the approach to measure this: = create a traffic shaper close to line-rate, saturate the shaper with = to-be-expanded-bytes packets and measure latency under load. For VDSL2 = all should be well (or as well as with not-to-be-expanded bytes as = payloads), for HDLC latency should rise quickly and badly (my first = approximation would be that the on-the-wire-size doubles, so the shaper = is toast by then). > However, the use of a fixed-size word frame does sound much more = elegant than HDLC. 64/65 encoding is not too bad actually 1.5% overhead independent = of the number of packets is decent=85 Best Regards Sebastian >=20 > - Jonathan Morton