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boundary="Apple-Mail=_9D0A3503-24EA-4608-BD9B-2AE36C8B29C5"; protocol="application/pgp-signature"; micalg=pgp-sha256 MIME-Version: 1.0 X-OriginatorOrg: darbyshire-bryant.me.uk X-MS-Exchange-CrossTenant-Network-Message-Id: 35a90f23-3c07-46d7-cd48-08d5d68e5e72 X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Jun 2018 09:15:29.9894 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 9151708b-c553-406f-8e56-694f435154a4 X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR07MB3966 Subject: Re: [Cerowrt-devel] [Bloat] Invisibility of bufferbloat and its remedies X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 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: Wed, 20 Jun 2018 09:15:34 -0000 --Apple-Mail=_9D0A3503-24EA-4608-BD9B-2AE36C8B29C5 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On 20 Jun 2018, at 09:07, Sebastian Moeller wrote: >=20 > Hi Kevin, >=20 >=20 >> On Jun 20, 2018, at 09:12, Kevin Darbyshire-Bryant = wrote: >>=20 >>=20 >>=20 >>> On 20 Jun 2018, at 00:41, Jonathan Morton = wrote: >>>=20 >>>> On 19 Jun, 2018, at 11:34 pm, valdis.kletnieks@vt.edu wrote: >>>>=20 >>>> Do we have a good cookbook on how to determine the set-rate? >>>=20 >>> On DSL, the sync rates in each direction should usually be readable = from the modem; they are typically reported on the router's status page. = The advertised rate is less reliable, to say the least. >>=20 >> I=E2=80=99ve been experimenting with this hack in sqm-scripts to do = just that = https://github.com/ldir-EDB0/sqm-scripts/commit/a71ab1c9acd75d6e9254360e83= 2ac7b6f9514e88 originally on my parents DGN3500 and currently on my on = BT HomeHub5a test line. >=20 > Clever (I see how you chiseled data_rates() into shape here, = respect)! Even though I believe that this is not pppoa specific and = should probably check whether /lib/functions/lantiq_dsl.sh exists. = Actually this code will also work on VDSL2 links... (and we should also = be able to extract the encapsulation atm or ptm). >=20 > if [ "pppoa-wan" =3D "$IFACE" ]; then > if [ -f "/lib/functions/lantiq_dsl.sh" ] : then > ... > fi > fi >=20 > But would it not be simpler to call /etc/init.d/dsl_control status | = grep -e "Data Rate:" or somesuch? Cureently openwrt only supports = lantiq/intel modems, but if broadcom modems should ever be supported I = venture a guess they will not use /lib/functions/lantiq_dsl.sh to = generate the stats output ;) (not that there is a guarantee that = dsl_control would exost and generate compatible output). >=20 >=20 > But I believe that this is not that helpful as a mode to automatically = set the bandwidth*, as I assume that most ISPs will shape the downstream = bandwidth upstream of the DSLAM (if just to avoid having a DDOS against = one user taking down the whole DSLAM). In my case my ISP even shapes the = upstream, which is somewhat more puzzling. It looks like a cool way to = deal with variable sync (either after a re-sync due to say DLM action or = due to SRA) so how about polishing this a bit and including this as pure = informational line in the log? >=20 >=20 > *) if this is to be made automatic by say allowing to scrape bandwidth = from the modem we would need additional setting for setting the shaper = percentage. I wonder whether all of this is worth it though, given that = the number of users running sqm on devices in control of the dsl-modem = is going to be miniscule, no? >=20 >>=20 >> It fails to work if the ISP does rate banding (BT 20CN does this, BT = 21CN doesn=E2=80=99t) where downstream is limited to a rate below = downstream sync rate. I guess a lookup table could be implemented. >=20 > I predict that a lookup table is going to be constantly out of = date, especially since at least my ISP is a moving target in both the = shaper settings as well as the actual overheads (on the plus side they = started to send the applicable net bandwidth as part of the pppoe = negotiations (but failed to document how those rates are actually to be = interpreted ;) win some loose some)). >=20 >=20 > Final thought, how about just using this on the luci side to give = hints about the sync bandwidth in the GUI (like displaying the value of = either sync for xdsl or the speed for ethernet devices (speed in ethtool = parlance, so 10Mb/s, 100Mb/s, ...)) that will not be as smooth as your = solution, but should also be more robust against doing the wrmg thing = automatically? Or am I overcomplicating things again. What part of =E2=80=98hack=E2=80=99 didn=E2=80=99t you understand? ;-) Luci is a =E2=80=98bad=E2=80=99 idea in that setting it there = effectively makes the rate fixed again=E2=80=A6. and line resyncs do not = remain static, so it needs to be a hotplug type solution. The commit isn=E2=80=99t perfect=E2=80=A6it was never meant to make it = into the wild=E2=80=A6I explored 2 years or so ago to see if something = like that could be done but was foiled by a BT 20CN banding plan. But = the seed of an idea is there. To grow it needs watering by someone who = can code. Incidentally luci sqm scripts typo (and possibly worse/not intended) = "Create log file for this SQM instance under = /var/run/sqm/${Inerface_name}.debug.log. Make sure to delete log files = manually.=E2=80=9D =E2=80=98Inerface_name=E2=80=99. - and I=E2=80=99m not sure if that = isn=E2=80=99t supposed to be expanded to the actual interface name in = use - I tried fixing the typo but when the name expansion still didn=E2=80= =99t work and I had no idea how to fix that=E2=80=A6. I got distracted = by something else :-) --Apple-Mail=_9D0A3503-24EA-4608-BD9B-2AE36C8B29C5 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEASyssijGxT6XdZEjs6I4m53iM0oFAlsqGzAACgkQs6I4m53i M0ozzxAAk57AxEyFju2ScCzSwWZLXZh+DM7J+o3LT3s+Jp6b84wqakXCIq5FN65l HS6eeniGVnc45SWNqGnuJ0WG3arI0HHHLFuQyvAqfVEkFlJh0qdYiekiAjt3nkOA EVyPmwUYGownj2z3xF6EMALZj4oIYbCfJR/Xph8Ybd4SpJXzqf0dHxGyM7YdVFai M57Dj5hKhEUOTy5KpJHZquUi1fuoOHtSpnLirkyIY8wGpRn8vHqnDbtVE0NiY/Hn jFlNz7nfDnUQeYz2OC6rtLZj5/r2v3bMwgSMvL525R2zZHvosJmR0/opgW9jnduk bZGwitZbN7LeuRMD2H0NoVi4TXLfUETsRPaz9x4F89f8yj4UJmgzVpMoxyZSbCdB 8Jkt6PYkMff74ufrpXoKIaXx3ReKP1eDC50gsYiA0ywk4QNQrCS/ezyQ6kF04fir z52rYzoDH1iBYCwB4IUoyEsj49KewScRiOYcLeeoFkPBmVCqC9s4JMVaQ/np4kc6 H8ZR253VdRco50T2OUGx9j+q45RwE80TsRMKSREodxChPHOD0SbdPzFm80F+cLdk X1A6+vb5ZZdMGPbmEW7oyrFomtKeH+97+ksKQumzip/wmtO3GhaolFeTF1gbzQEt IGn49yA+NSSAhMt5KpWSTgRKWfsbMJtxbFL5cMrSbusScrmJdvA= =j4NS -----END PGP SIGNATURE----- --Apple-Mail=_9D0A3503-24EA-4608-BD9B-2AE36C8B29C5--