All of Jims presos are licences under one of the creative commons licenses.
Mine would be, too, if I had bothered to mark them as such. I will go back and correct this. Feel free to reuse whatever you like, with the caveat that all these presos do reflect enhanced thinking and research over time, and sometimes contain errors or ideas that have been revised. Original libreoffice and powerpoint sources for jim's stuff are at http://mirrors.bufferbloat.net/ Mine are mostly at: http://www.teklibre.com/~d/bloat/Talks/ - the linuxcon talk is not up in source form because I wanted to illustrate several of the graphs better. On Mon, Nov 26, 2012 at 2:11 AM, Richard Brown <[email protected]> wrote: > Folks, > > I am planning to give a talk about Bufferbloat to the local Linux User Group > next week (http://dlslug.org). All this traffic on the list is fantastic, > because it gives me a lot of background on the current state of bufferbloat. > I've pulled together a bunch of general questions about CeroWrt that I would > like to be able to cover if they come up: > > - Is it true that the latest CeroWrt is Sugarland 3.3.8-26 from > mid-September? (My router is using this build - r33460.) Yes. A lot of updates have accumulated, I do hope to get a new release out soon and start up 3.6.x+ development. I'm extremely encouraged by what is in 3.6 and later. I note there is a nasty hole in the sugarland config that new users should close immediately on a new install. http://www.bufferbloat.net/issues/411 > - I see the "QoS" item in the Network tab of the web GUI. Is this important > for Sugarland? Or does some other router configuration take care of this now? Openwrt QoS works ok on ipv4 traffic. (yes, it uses fq_codel). However the simple_qos.sh script I have been prototyping works on everything and seems to be mildly better. In part that's due to handling ipv6 traffic correctly, and possibly due to the fact it has "nfq_codel" in it, rather than fq_codel, which is a respin of fq_codel using the latest ns2 model of codel behind it, which differs in some important respects. It was obvious after working on that that better benchmarks were needed, which has been a focus these past 2 months. simple_qos.sh does require manual configuration, however, and testing for an accurate bandwidth estimate is problematic even with the rrul test. I would really like someone to make this available via a gui, and more people to beat on it... (and I'll rename this ceroshaper in the next release) And: I would prefer to stress to all audiences that this stuff is WIP, and try to get them to understand that the goal is to do smart queueing over top the smallest possible amount of buffering, and a multitude of factors can lead to sub-optimal results. rather than "install this script on your random hardware, expect magic". Or: "Download this firmware, expect magic". As one example, I was completely blindsided the other day, when working with david woodhouse, by the new GRO network offload "feature", on his device, which wedges enormous packets into the stack. That needs to get turned off on linux based routers, generally. Somehow. Preferably, automatically. (I am delighted that multiple ADSL folk, including david, just made a huge dent in adsl latencies over on the netdev mailing list) > - What's the relationship between the QoS GUI item above and the debloat.sh > and simple_qos.sh scripts that have been mentioned on this list? What's the > best practice here for getting a router up and running? the debloat (written in lua) script in the ceropackages repository makes sure that various latency inducing network offloads (on by default in linux) are OFF. I recently learned that the GRO offload could induce a problem, I don't remember if that's off in sugarland. It runs on ALL interfaces by default in cerowrt.... People trying to make debloating a router work on other platforms than cerowrt, should modify that script to run on all their interfaces. Or... debloat.sh is a simpler version of debloat that doesn't do all the stuff debloat does, yet, but works on debian/ubuntu. It needs to be better, turning off gro for example on ALL devices, and I like that it lacks the lua dependency. I incidentally note that I no longer remember what's in sugarland for simple_qos and debloat, what I am fiddling with now is not checked in. I think a difference is that I'm using a different quantum, am only using ecn on ingress. > > - I can see how the CeroWrt de-bloating algorithms help protect against bad > latency when I'm *uploading* big files. I'm not sure whether using CeroWrt > with its CoDel/FQ/SFQ/etc. helps when I'm downloading big files, though. What > can I say about this? Most shapers in the world try hard to address ingress and egress. It is very byzantine to configure the default ingress shaper "IFB", but that's what is done. Shaping ingress traffic has been one of the few places where I have seen ECN give a benefit. ECN on egress, seems to be a lose at most bandwidths I've tried. The right place for ingress shaping, however, really is at the head end or dslam. > > - I believe the default DNS server in Sugarland is dnsmasq, Bind ate way too much memory. Writing a gui for it proved nearly impossible. Dnsmasq has evolved over the past year to include a nifty AAAA and dhcpv6 naming scheme (and added dhcpv6, and has nearly enough functionality to replace the radvd daemon now). I'm very happy with the directions dnsmasq is going. (I'd really like to get some help on getting AHCP into it) > not bind. Is DNSSEC enabled by default? DNSSEC is temporarily gone. Simon kelly of dnsmasq is making some progress towards making it fit into dnsmasq. As he lacks time and resources on his side, I can't give an estimate as to arrival time, but I'm sure it will be a lot more tiny and more web configurable, whenever it's done. There's partial DNSSEC support in a branch of dnsmasq, patches would be welcomed.... I learned this week that dnsmasq is the default dns/dhcp server in android, for tethering, and is also heavily used in libvirt and various clustering solutions. That's in addition to near dominance of the linux based home router market... And for all that market penetration, (at least 1/4 of the internet) simon and his crew have made such solid software, in their spare time, as for nobody to know who they are. It's sad, and frustrating... I admit that I like a few features of bind, such as views, and nsupdate... Bind can be optionally installed via installing bind-latest and bind-latest-config via opkg. I certainly plan to leave bind available for those that want it, but going forward, unless MBs of ram drop from the sky for free for everyone, it's not going to be the default in cerowrt. > Also: there's a report (Bug #411) that says that DNS is leaking internal > names to the outside world. What's the best advice for closing this? ("list > notinterface 'ge00'" is one recommendation…) yes. EVERYBODY please do that. > > - I've been assembling information about the various de-bloating techniques > implemented in CeroWrt. It seems that Infoblox has recently reorganized their > blogs, and the links published earlier this week have all broken. Here are > updates: > > http://www.infoblox.com/community/blog/application-analysis-using-tcp-retransmissions-part-1 > http://www.infoblox.com/community/blog/application-analysis-using-tcp-retransmissions-part-2 > http://www.infoblox.com/community/blog/router-buffer-tuning > http://www.infoblox.com/community/blog/rethinking-interface-error-reports Thx. > My plan is to give a little of the science behind bufferbloat mitigation and > also put in a plug for CeroWrt. Any topics I haven't already mentioned that I > should? Thanks! > > Rich Brown > Hanover, NH USA > _______________________________________________ > Cerowrt-devel mailing list > [email protected] > https://lists.bufferbloat.net/listinfo/cerowrt-devel -- Dave Täht Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html _______________________________________________ Cerowrt-devel mailing list [email protected] https://lists.bufferbloat.net/listinfo/cerowrt-devel
