From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.17.22]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 6E40721F1FC for ; Thu, 19 Dec 2013 05:13:34 -0800 (PST) Received: from u-081-c036.eap.uni-tuebingen.de ([134.2.81.36]) by mail.gmx.com (mrgmx102) with ESMTPSA (Nemesis) id 0MSp1l-1W3i8s3Qfd-00Rti0 for ; Thu, 19 Dec 2013 14:13:31 +0100 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) From: Sebastian Moeller In-Reply-To: <52B2D93B.6050501@imap.cc> Date: Thu, 19 Dec 2013 14:13:33 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: References: <34E77F64-739C-49E4-B8A4-6ABBEAE4174B@gmail.com> <8DB84101-C942-49C4-99F0-6C9319961297@gmail.com> <22176178-A50F-48F2-A3A1-D3853764AD0E@gmail.com> <0E267F91-3CC8-48F4-92C0-AD8BACA98FCC@gmail.com> <1FA2FD44-D715-4B50-BB5A-BAF61070970B@gmx.de> <31B5B61B-4E58-4C5E-8F33-710CCE0918F4@gmail.com> <52B2D917.6080006@imap.cc> <52B2D93B.6050501@imap.cc> To: Fred Stratton X-Mailer: Apple Mail (2.1510) X-Provags-ID: V03:K0:329nU1cVqW4TXFiBvNCUeMPMrTDNKUzn13nsXKOmv/D2VUaMW6h iWRr81/xv5CTidMhkpRXWtplNoKspVytRMqLIC2agoQ/w4k1C1ETnndc8pGShmG69C2eAnm 5BiXZYRUw00zaLMa7tFNysUaBcrMWnuZJ/mIz6tGJP7hpXC1g8FksGtkOfuONbHRTtmQIJV NaghIIu47w7Wnxd7ng66g== Cc: cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] cerowrt-3.10.24-5 dev build released 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: Thu, 19 Dec 2013 13:13:34 -0000 Hi Fred, On Dec 19, 2013, at 12:32 , Fred Stratton wrote: >=20 > On 19/12/13 11:31, Fred Stratton wrote: >> 3 comments. >>=20 >> Presumably you want these changes for some future use of the = interface by a wider audience, rather than current users of ceroWRT. Oh, my goal is not so much "world domination" but rather making = the link layer adjustments first class citizens in cerowrt's guy; if = this should make it into openWRT I would not be unhappy, but it is not = one of my personal goals. >>=20 >> There is an requirement for this less sophisticated user to turn AQM = on for ADSL. There are far more ADSL users than those who use fibre or = cable. In the UK, offered a choice, about only 25 per cent of ADSL = users migrate to fibre. The figure for cable is 10 per cent. This is in = a fairly open market with competition. >>=20 >> I would argue that the default should be 'on'. Ah, the DSL users really do need to set the right overhead as = well for the link layer adaptation to work well, otherwise the padding = of the packet due to the quantization is wrong (not a total loss if the = number of packets is large enough this could/should average out). So I = am not sure whether default on will lead to happiness all around. >>=20 >> You state the choice in the interface pull down should be 'ethernet = or 'atm'. Currently it is 'ethernet' or 'adsl', which semantically makes = more sense, even though it uses a mystic, undocumented tc-stab option, = namely 'adel'. Well, I changed it to ATM in the last version, as that is what = is relevant for the link layer. So if in the future ADSL3 uses PTM we do = not care :) Adel, did I write that? If so I can assure you I intended to = write ADSL in lower case, it is just my on-line spell checker that = corrects me badly... >>=20 >> The 'adsl' option appears to work, which is why I advocate it. for tc and the kernel atm and adsl are the same, just two = different names for the same thing. I think we should use ATM instead of = ADSL for reasons hinted at above. =20 >>=20 >> Finally, the fourth of these 3 comments... >>=20 >> OpenWRT developers are working on the TP-LINK TD-W8970, a gateway = device containing a Lantiq SoC. The device is cheaper in Europe than the = US for a change. Cheaper is good, but the other specs do not seem to exciting, = 64MB ram 8Mb rom, only 2.4GHz radio (given the flakiness of both 2.4 and = 5GHz I think it nice to have options :) ) >>=20 >> Lantiq apparently have open-sourced their code, and the device will = be able to connect to the internet via ADSL2 or VDSL2, extending its = capabilities. >>=20 >> Your interface will need to be modified again for a gateway device, = rather than a router. What is the difference between a gateway device and a router? Best Regards Sebastian >>=20 >>=20 >> On 19/12/13 10:49, Sebastian Moeller wrote: >>> Hi Rich, >>>=20 >>>=20 >>> On Dec 19, 2013, at 05:12 , Rich Brown = wrote: >>>=20 >>>> Hi Sebastian, >>>>=20 >>>>>> Perhaps we could extend the Interface configuration page to add a = =93Link uses DSL/ADSL:=94 checkbox right below the Protocol dropdown. = Default would be off, but when customers go to the GE00 interface to = enter their PPPoE/PPPoATM/ISP credentials, they=92d see this additional = checkbox. Checking it would feed that info to the AQM tab. (And perhaps = there could be a link there either to the AQM tab, or to the wiki for = more information.) >>>>> I am happy to include a link to a wiki, but I guess we first = need a wiki page :) >>>> Is this a challenge? Well, I accept! :-) >>>>=20 >>>> = http://www.bufferbloat.net/projects/cerowrt/wiki/Setting_up_AQM_for_CeroWr= t_310 is a draft. I recycled the images from a previous message and = wrote the least amount that I could that is likely to be true. >>> This is great, thanks a lot. I have made a few changes to the GUI = yesterday, which hopefully improve the usability, so if the new GUI = passes muster with the cerowrt crowd, the screenshots will need to = change as you note on top. >>>=20 >>>> Please send me comments (or edit the page directly, if you have = permissions.) >>> I do not have edit permissions, so I just comments here. >>>=20 >>> Basic settings: >>> Why 85% as starting point? And can we give instructions how to = measure "degradation in performance", so that non-technical users have a = chance to actually optimize their own system? >>>=20 >>> Queueing Discipline: >>> Maybe we can add a link to the mail list page = (https://lists.bufferbloat.net/listinfo/cerowrt-devel)? >>> Also can we note that it is recommended to turn ECN off for the = egress, as we handle packets before the bottleneck and dropping packets = actually allows us to send other more urgent packets , while on ingress = it is recommended to turn ECN on, as the packets have cleared the = bottleneck already, and hence dropping has no bandwidth advantage = anymore. Both dropping and ECN should have the same effect on TCP = adaptation to the path capacity. >>>=20 >>> Link Layer Adaptation: >>> I think the first question is: Do I have an ATM carrier between = your modem and your ISP's DSLAM? This typically is true for all ADSL = variants. >>> The second question is: Do I have overhead on the link outside of = Ethernet framing? This typically is true for users of PPPoE and PPPoATM = and even Bridging I think. >>>=20 >>> If the answer to any of these questions is yes, one needs to = activate the link layer adaptations. >>> In case of pure overhead select ethernet, in case of ADSL select = ATM. >>> Fill in the per packet overhead in byte (see: = http://ace-host.stuart.id.au/russell/files/tc/tc-atm/, = http://web.archive.org/web/20100527024520/http://www.adsl-optimizer.dk/ = and http://www.faqs.org/rfcs/rfc2684.html). If the overhead truly is = zero and no ATM carrier is used, then select "none" for link layer = adaptation. (I changed this page, so the tc_stab htb_private selection = is under advanced options, and there is a selection of "none", = "ethernet", and "none" in the first drop down box, "none" disables the = link layer adaptation. Also the drop down box contains some information = which selection is relevant for which cases). >>>=20 >>> What=92s going on here? Why do I need this?: >>> I think we should mention that only with the proper link layer = selected and the overhead specified cerowrt is able to assess how large = each packet is on the link to the ISP, and only then the shaping is = deterministic. (For ATM users without the adaptations the shaper is = stochastically too optimistic about the link capacity (which is too say = the shaper is too optimistic about the effective packet sizes)). >>>=20 >>> Best Regards >>> Sebastian >>>=20 >>>=20 >>>=20 >>>> Thanks. >>>>=20 >>>> Rich >>> _______________________________________________ >>> Cerowrt-devel mailing list >>> Cerowrt-devel@lists.bufferbloat.net >>> https://lists.bufferbloat.net/listinfo/cerowrt-devel >>=20 >=20