Hi Dave, I was just told that I am allowed to distribute the code freely. I will upload it to GitHub and will send you the link as soon as I am done with it. As for the AQM test, I set the QDisc to FQ-CoDel, CoDel, and CAKE, but none worked on CORE. In contrast, RED and PIE worked as expected. As far as I know, the major difference between these two groups of AQMs is the time when the packets are dropped. But I am not 100% sure it was the cause. I may somehow test FlexiS or FlexiR (FlexiS adapted to the receiver side) on a testbed with various AQMs. But it will be toward the end of the adaptation I guess :) Best regards, Qian On Thu, Apr 7, 2022 at 8:52 AM Dave Taht wrote: > On Tue, Apr 5, 2022 at 8:44 AM Qian Li wrote: > > > > Dear Dave, > > > > Thank you for your interest in my work. > > > > I have read another paper authored by D. Rossi at el. presenting the > priority inversion problem of LEDBAT when it is used together with AQM. And > it has become one of the factors that motivated me to devise a new LBE CC > that can preserve low priority even when AQM is used. > > We'd given up hope circa 2014 as of the publication of the paper I > cited, and moved on. > > >However, I could not test FlexiS with CoDel on the CORE emulator probably > because CoDel drops packets at the dequeue time. > > I don't really understand that statement. > > > More tests should be done to verify that FlexiS does preserve low > priority in the presence of various AQM algorithms. > > Yes. until fairly recently I had had a testbed setup that allowed > testing of various tcps and aqm systems, but its been in storage since > covid. > > > I am now adapting FlexiS to the receiver side. The main motivation to do > so is that there might be HTTP/TCP proxies between the sender and the > receiver. A receiver side LBE CC and make the connection between the proxy > and the receiver LBE. In this work, I am going to tackle some open issues > with FlexiS. For example, I am going to test if trend analysis can be done > based on one way delay so that the throughput is less affected by ack path > congestion. And I am going to evaluate various techniques to reduce rate > below 2 mss per RTT. This may include what you have suggested -- use small > packets and sub-packet window. I am also interested in using pacing to slow > down sending rate and maybe more alternative solutions. > > Cool! > > > > > I don't have a git tree for the source code mainly because I don't know > if I am allowed to publish the code as open source. If you are interested > in the source code, I can ask the University of Oslo if I am allowed to > distribute it freely? > > I would hope they would allow publication. The world is full of half > baked projects that if only someones new also stepped in, were > completed. An example of this is BBR which originally was about half > what it is today, until source was released among the right people. > > > > > Best regards, > > Qian > > > > > > > > On Sun, Apr 3, 2022 at 6:38 AM Dave Taht wrote: > >> > >> Dear Qian: > >> > >> Pretty promising paper. I liked that it tackled congestion on the ack > >> path, among other things. > >> > >> > https://www.techrxiv.org/articles/preprint/TCP_FlexiS_A_New_Approach_To_Incipient_Congestion_Detection_and_Control/19077161/1/files/33905018.pdf > >> > >> I like also that you tackled, inter-rtt fairness, and, ledbat's > >> latecomer advantage problem, and in fig 9, the basic problem with > >> delay based LBE vs AQMs (in that ledbat degrades to reno)... [1] > >> > >> Towards your conclusion... > >> > >> I have always disagreed with the "don't reduce segment size" crowd, > >> btw. If you have a rate where you need to go below 2mss, it doesn't > >> hurt the network to reduce the size of the packet, and you can keep > >> the signal strength up by reducing that size and continuing to sample > >> rtt, to respond quickly. > >> > >> Even if you are only passing a single byte of data, by lowering this > >> below everyone else's 2mss noise floor, you still eventually win, and > >> also you occupy space in packet fifos, reducing overall latency, as > >> bytes=time. IMHO. > >> > >> elsewhere, sub-packet windows are being experimented in bbrv2, I'm > >> told, but not in LBE. > >> > >> I'm also a big believer in packet pacing, and I think this is the > >> first paper I've seen that attempted LBE with it. Thx! > >> > >> Got a git tree? > >> > >> [1] do wish you'd had cited > >> https://perso.telecom-paristech.fr/drossi/paper/rossi14comnet-b.pdf > >> > >> -- > >> I tried to build a better future, a few times: > >> https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org > >> > >> Dave Täht CEO, TekLibre, LLC > > > > -- > I tried to build a better future, a few times: > https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org > > Dave Täht CEO, TekLibre, LLC >