From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailout-de.gmx.net (mailout-de.gmx.net [213.165.64.23]) by huchra.bufferbloat.net (Postfix) with SMTP id 31E1121F09D for ; Mon, 30 Jul 2012 13:25:36 -0700 (PDT) Received: (qmail invoked by alias); 30 Jul 2012 20:25:35 -0000 Received: from tsaolab-fw.caltech.edu (EHLO [192.168.50.16]) [131.215.9.89] by mail.gmx.net (mp024) with SMTP; 30 Jul 2012 22:25:35 +0200 X-Authenticated: #24211782 X-Provags-ID: V01U2FsdGVkX18VmNRu6oMVtOsIvaTvBCN05gzC6waj7Ea9SyTcud Gln1FhZep+tI26 Mime-Version: 1.0 (Apple Message framework v1278) Content-Type: text/plain; charset=us-ascii From: Sebastian Moeller In-Reply-To: Date: Mon, 30 Jul 2012 13:25:33 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: William Katsak X-Mailer: Apple Mail (2.1278) X-Y-GMX-Trusted: 0 Cc: cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] ADSL Issue (PPPoE) 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, 30 Jul 2012 20:25:37 -0000 Hi William, On Jul 30, 2012, at 11:34 AM, William Katsak wrote: > Hello, >=20 > I am playing with a CeroWRT (3.3.8-6) router on my vacation in Russia = and am > seeing some weird behavior with simple_qos.sh that I am unsure if I > should attribute to a > bug, or to an Internet connection that is "just that bad". >=20 > Background: > - The router is on my wife's parents' ADSL line (according to the = modem, > ~3000/500). The modem is a D-Link DSL-2500U. >=20 > - Even though the link is 3000/500, and I can get speedtest.net to > report 2.5mbps/0.42mbps on a clean connection (direct or Cero with no > QOS on), as soon as I use a host that is outside of Rostelecom (local > service), it drops to 0.9/0.4mbps. This is consistent with Netalyzr > test: Upload 430 Kbit/sec, Download 970 Kbit/sec. This suggests that > even though the DSL link is higher bitrate, the ISP doesn't have the > outgoing bandwidth or is rate-limiting it somehow. >=20 > - I don't necessarily intend to leave the router running Cero here, > but I want to get a handle on the latency situation, as it makes Skype > pretty messy...I am hoping to roll what I learn into a more stable > build of OpenWRT. >=20 > I have tried several different configurations of the modem including: > 1) Default: Modem does PPPoE and hands out 192.168.1.xxx addresses. I > tried just letting Cero route through that address. > 2) PPP-IP extension: This has the effect of the modem handling the > PPPoE connection and handing out the single "real" IP address over > DHCP. In this case Cero would see the Internet IP on ge00. > 3) Bridging: Allow Cero to establish the PPPoE connection and manage = it. >=20 > Right now I am in PPP-IP extension mode on the modem, and GUI QOS on > the router. This seems to be reliable and also keeps the latency down, > although I would imagine that PPPoE on the router and the GUI QOS > would be fine too, but obviously I would rather use simple_qos. >=20 > The problem: >=20 > When I try simple_qos.sh, I see this: >=20 > insmod: can't insert 'cls_fw': File exists > insmod: can't insert 'sch_htb': File exists > RTNETLINK answers: No such file or directory > RTNETLINK answers: No such file or directory >=20 > If I run it again, the RTNETLINK errors go away...I assume this is > just an annoyance. >=20 > This gives me super stable ping times, etc. but a lot of websites hang > loading, and the connection is unusable. If I reboot the router, the > connection works fine again, although the high latency comes back. >=20 > So, with all that out there, I have some questions with simple_qos: >=20 > 1) If I am using PPPoE on the router, do I need to do IFACE=3Dpppoe-ge00= > or still just ge00? > 2) Should I set PPOE to "yes"? Since your DSL connection is running PPPOE you should set PPOE = to yes in any case IF your DSL connection uses ATM as link layer (most = probable). This will just make sure that the shaper calculus the right = packet seizes to account against your link rates. But check against = http://ace-host.stuart.id.au/russell/files/tc/tc-atm/ to figure out the = prier value for overhead, as that depends on the specifics of your DSL = connection. I found that = http://www.linuxhowtos.org/manpages/8/tc-stab.htm also is quite = interesting to read to better understand the overhead parameter. But = unfortunately simple_qos does not (yet) use the generic tc-stab method = but the atm link layer adjustments specific for HTB. (Since I am on = cable right now I have no way of testing whether the tc-stab method also = works with HTB). Especially for small packets (like VoIP) if you do not = account for the the fact that ATM always sends out integer 48byte cells = and will pad if necessary, you will cause severe queueing way below = reaching the nominal link rate, as the shaper does not account for a) = the padding nor b) the 5byte ATM overhead per ATM-cell (at least I think = that is the case). You should do this in any case so that shaping actually has a = chance to work reliably and repeatably independent on the size = distribution of your shaped packages. > 3) Is it possible that no matter what I do, the buffers at the speed > drop between Rostelecom and their bandwidth provider is hurting me > somehow? If I understand correctly, yes this is going to hurt you, so if = your intended VoIP traffic leaves the Rostelecom net you might need to = specify 974/430 for the shaped rates instead of 3000/512. But that = sounds like something that is easy to test. Since your achievable uplink = (430) is still quite close to your link rate (500) I would still = recommend to look at getting link layer and overhead specified correctly = in simple_qos. > 4) If 3, what to do other than yell at them? As an emergency stop-gap measure shape your rates to what the = network path you are most interested in can deliver? That said I, isn't = that what codel is supposed to do automatically??? >=20 > Overall, is anyone using Cero with a PPPoE connection with good > results? What kind of configuration do you have? No, but I used cerowrt with a bridged ATM-based DSL connection = in the past which shares most of the issues with PPPOE over ATM. BTW = stock openwork does not account properly for ATM either so if you switch = to openwork you will need to edit some of the QOS scripts to work well = with DSL. (Last time I looked the "calculate overhead" checkbox did = something statistic I failed to fully understand). >=20 > Sorry for the info dump, but if there is indeed a problem going on > with PPPoE connections, I am more than willing to be a guinea pig > until August 10th. I would appreciate any ideas! Oh, by the way I have some half done octave program to figure = out the actual overhead from a ping sweep, let me know if you are = interested... Best Regards Sebastian >=20 > Thanks! >=20 > -Bill Katsak > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel