Hi David,
On Jan 7, 2014, at 12:08 , David Personette <[email protected]> wrote: > I'm in the US, but live in a relatively rural area. My only internet options > are DSL and satellite. The local provider is Century Link (it used to be > Sprint, but they sold their copper phone business off). I have the fastest > service that they offer (based on distance from the DSLAM), 4 down / .5 up. And you are not alone, a considerable percentage of the population wherever you look is hanging on such connections. So cerowrt should really help those folk as well as luckier ones. > > I have had SmokePing monitoring my latency to the first hop outside my > network for over a year now (I've been on CeroWRT the whole time). My > baseline (no load) latency is 31ms. I used to have AQM throttling back to 80% > of my already pathetic bandwidth. I would still regularly see periods lasting > minutes to hours when latency would be 80 - 120ms. > > I only recently grokked what you were talking about with tc_stab since I got > back from the holidays with the family, I set things up as you suggested for > Fred (nfq_codel, "target 25ms" in advanced egress, ATM, per packet overhead > 40, The exact number depends on the encapsulation your ISP uses, 40 is right for a typical PPPoE over LLC/SNAP connection, if that is correct for your link you are fine, otherwise contact me if you want to empirically find out the proper value for your link. > and set my SQM bandwidth limits to 95%). Since the 30th my "worst case" > latency has been 41ms. the fq_codels really are great if in control of the bottleneck, really good work by bright people! > Plus I get to use more of my actual bandwidth. Well, that I am not so sure. By enabling link layer ATM the router will automatically take care of the ATM cell overhead for you (basically reducing the effective rate to ~90% of the link, in other words you get the same effect by shaping to 90%). It will also handle the per packet overhead and the nasty potential padding of the last ATM cell (both have a stronger effect on small packets and are hard to actually account for by static rate reduction; link layer ATM comes again to the rescue by taking these two into account individually for each packet based on the packet size). So effectively 95% with link layer adjustments might mean a lower wire rate than 80% without; the important thing is that with the link layer adjustments the link capacity is estimated correctly avoiding the modem's and the DSLAM's buffers to fill and cause buffer bloat. > I REALLY wish that I'd made the time to read your emails about setting up the > ATM overhead earlier. Oh, I can understand, when I learned about this some years ago (by stumbling over Russel Stuart's website and Jesper Brouer's thesis) it immediate changed my internet experience (I was on a 3 down / 0.5 up connection at that time). :) Best Regards Sebastian > > Thank you. > > -- > David P. > > > > On Mon, Jan 6, 2014 at 9:27 AM, Sebastian Moeller <[email protected]> wrote: > Hi Fred, > > > On Jan 6, 2014, at 15:22 , Fred Stratton <[email protected]> wrote: > > > The line rate is 11744/1022 kb/s, but changes moment to moment. SNR is 12.1 > > decibel. I am using 11000/950 kb/s as settings. > > So 100 * 11000 / 11744 = 93.66% of downlink line rate and 100* 950 / > 1022 = 92.95 % of uplink line rate; quite impressive given the common wisdom > of 85% :). > > > > I shall try your suggestion when there is something worth watching live, > > to provide a valid comparison, which may not be before 21:30 CET on Sunday. > > Oh, take your time, this is really not essential, butit would be a > nice data point for figuring out how important the correct overhead estimate > really is in real life, theory being theory and all… > > Best Regards > Sebastian > > > > > On 06/01/14 14:12, Sebastian Moeller wrote: > >> Hi Fred, > >> > >> > >> On Jan 6, 2014, at 10:52 , Fred Stratton <[email protected]> wrote: > >> > >>> I have been operating the latest build with 6relayd disabled. The henet > >>> /48 I have been allocated is subnetted correctly, presumably by dnsmasq. > >>> > >>> I adopted the suggestions to use nfq_codel and an egress target of 25ms , > >>> with an overhead of 40 on a PPPoE connection. I chose to watch the first > >>> 2 episodes of the 3 part third series of 'Sherlock', live on iPlayer, and > >>> these streamed correctly and uninterrupted for 90 minutes. This was not > >>> previously possible. (Quite whether they were up to the standard of > >>> previous episodes is another matter.) > >>> > >>> I can watch iPlayer with little stutter whilst downloading Arch Linux by > >>> torrent, downloading other files at the same time. > >>> > >>> So, for a relatively slow ADSL2+ line, the current build works well. > >> Out of curiosity, to what percentage of the "current line rate" (you > >> know the one reported by your modem) you shaped up- and downlink? And in > >> case you have too much time on your hand, how does the same feel with an > >> overhead of 10 (to see how bad an overhead underestimate would feel for a > >> user), since you currently happen to have a quite sensitive subjective > >> latency evaluation system set up :)… > >> > >> Best Regards > >> Sebastian > >> > >>> > >>> On 06/01/14 03:29, Dave Taht wrote: > >>>> On Sat, Jan 4, 2014 at 10:40 AM, Fred Stratton <[email protected]> > >>>> wrote: > >>>>> Link Names: > >>>>> > >>>>> For consistency, if ADSL is used as a portmanteau term, them VDSL > >>>>> should be > >>>>> used as the equivalent for VDSL and VDSL2. > >>>>> > >>>>> CeroWRT has to decide whether it is an experimental build, or something > >>>>> that > >>>>> will eventually be used in production, so these decisions can be made > >>>>> consistently. > >>>> Well, what I was aiming for was for us to get the sqm scripts and gui > >>>> up to where they were better than the standard openwrt qos scripts and > >>>> then push them up to openwrt to where they could be more widely > >>>> deployed. > >>>> > >>>> Aside from being able to dynamically assign priorities in the gui, we > >>>> are there. Except that nfq_codel is currently getting better results > >>>> than fq_codel at low bandwidths, and I'm tempted to pour all of > >>>> simple.qos into C. > >>>> > >>>> As for cero's future - certainly since all the snowden revelations > >>>> I've been going around saying that "friends don't let friends run > >>>> factory firmware". I would like a stable build of sqm and cerowrt to > >>>> emerge, and to then go off and work on improving wifi. Regrettably > >>>> what seems to be happening is more backwards than forwards on the > >>>> former, and ramping up on the ath9k and ath10k is taking more time > >>>> than I'd like, and it seems likely I'll be working on those primarily > >>>> on another platform and only eventually pushing the results out to > >>>> cero, mainline kernel > >>>> > >>>> So it's still at the "keep plugging away" point for sqm, ipv6, cero in > >>>> general, with the stable release always just out of sight. > >>>> > >>>> Tackling the ipv6 problem is next on my agenda on cero, and getting a > >>>> test suite going is next on my day job. > >>>> > >>>>> I concur with your ADSL setup suggestion as default. I have been > >>>>> running the > >>>>> Sebastian Moeller ping script overnight to calculate ADSL overhead for > >>>>> the > >>>>> last several days. After several hours of curve fitting using Octave, an > >>>>> overhead result is displayed. This novel approach works well. > >>>> It would be nice to get to where we could autoconfigure a router using > >>>> tools like these with no human intervention. This includes bandwidth > >>>> estimation. > >>>> > >>>>> The overhead for the particular setup I use was 40 for PPPoE, and 10 for > >>>>> PPPoA. > >>>>> > >>>>> The default you suggest is a suitable starting point, I suggest. > >>>>> > >>>>> > >>>>> On 04/01/14 18:16, Rich Brown wrote: > >>>>>> QUESTION #5: I still don’t have any great answers for the Link Layer > >>>>>> Adaptation overhead descriptions and recommendations. In an earlier > >>>>>> message, > >>>>>> (see > >>>>>> https://lists.bufferbloat.net/pipermail/cerowrt-devel/2013-December/001914.html > >>>>>> and following messages), Fred Stratton described the overheads carried > >>>>>> by > >>>>>> various options, and Sebastian Moeller also gave some useful advice. > >>>>>> > >>>>>> After looking at the options, I despair of giving people a clear > >>>>>> recommendation that would be optimal for their equipment. > >>>>>> Consequently, I > >>>>>> believe the best we can do is come up with “good enough” > >>>>>> recommendations > >>>>>> that are not wrong, and still give decent performance. > >>>>>> > >>>>>> In this spirit, I have changed Draft #3 of the “Setting up SQM” page to > >>>>>> reflect this understanding. See > >>>>>> http://www.bufferbloat.net/projects/cerowrt/wiki/Setting_up_AQM_for_CeroWrt_310 > >>>>>> > >>>>>> ADSL/ATM link: Choose “ADSL/ATM", and set Per Packet Overhead > >>>>>> to > >>>>>> 40 > >>>>>> VDSL2 link: Choose “VDSL”, and set Per Packet Overhead to 8 > >>>>>> Other kind of link (e.g., Cable, Fiber, Ethernet, other not > >>>>>> listed): Choose “None (default)”, and set Per Packet Overhead to 0 > >>>>>> > >>>>>> NB: I have changed the first menu choice to “ADSL/ATM” and the second > >>>>>> to > >>>>>> “VDSL” in the description. I would ask that we change to GUI to reflect > >>>>>> those names as well. This makes it far easier/less confusing to talk > >>>>>> about > >>>>>> the options. > >>>>>> > >>>>>> As always, I welcome help in setting out clear recommendations that > >>>>>> work > >>>>>> well for the vast majority of people who try CeroWrt. Thanks. > >>>>>> > >>>>>> Rich > >>>>>> _______________________________________________ > >>>>>> Cerowrt-devel mailing list > >>>>>> [email protected] > >>>>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel > >>>>> _______________________________________________ > >>>>> Cerowrt-devel mailing list > >>>>> [email protected] > >>>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel > >>>> > >>> _______________________________________________ > >>> Cerowrt-devel mailing list > >>> [email protected] > >>> https://lists.bufferbloat.net/listinfo/cerowrt-devel > > > > _______________________________________________ > Cerowrt-devel mailing list > [email protected] > https://lists.bufferbloat.net/listinfo/cerowrt-devel > _______________________________________________ Cerowrt-devel mailing list [email protected] https://lists.bufferbloat.net/listinfo/cerowrt-devel
