Hi Dave, I pruned the CC list as I am out of my league here and want to restrict the radius of my embarrassment to those that already know my level of incompetence before hand.
That said, having read through the L4S architecture description and the related appendices of draft-ietf-tsvwg-ecn-l4s-id-05 I came to the conclusion, that this is a mess. The L4S project proposes a really wide-ranging change of basically the internet (but allow a concurrent operation with legacy probably to cater to the fact that an internet-wide flag-day seems daunting to organize). But then they chicken out when figuring out how to differentiate between their new and the old by proposing to use ECT(1) for a purpose outside of its nominal purpose namely explicit congestion notification, why not think bolder? If the plan is to change everything the feasibility can not hinge upon the ability to re-using one old legacy bit, can it... Conceptually it seems much cleaner to use ECT(1) for congestion notification directly (there are already proposals out there and SCE just added another fully back-ward compatible one) and find another way to mark l4s traffic, sure that is going to be hard and inconvenient, but if you set out to change the internet that is par for the course. IMHO they would do more good if they actually fought for a better use of the 6 DSCP bits instead. (say by splitting into two groups of 3 bits, one group for reduced diffserv and one group for new features, that would even allow for concurrent use of the inevitable L5S and L6S ;) ). Especially since as far as I can understand l4s actually would like to have a more gradual congestion information stream than classic ECN, and since they need to modify DCTCP anyway to make it save for the wider internet, replacing its ECN response should be well inside the scope of work they already have on their list. If I sound a bit miffed, it is because after reading https://tools.ietf.org/html/draft-ietf-tsvwg-l4s-arch-03 I do not have the feeling they are trying to build abetter internet, but rather that they are building an internet where I can be a better "product" and customer of newfangled services, and I do not look forward to such a facebooky future with much enthusiasm. I hope that the discussion in Prague go well and a compromise/consense can be hashed out as I see different implementations duking it out here, but the overall goal of the competitors seems quite compatible, improving the internet by focussing on latency. Best Regards Sebastian > On Mar 15, 2019, at 11:46, Dave Taht <dave.t...@gmail.com> wrote: > > Bufferbloat.net's ecn-sane working group members have a co-ordinated response > to your efforts brewing but it's not ready yet. We have a worldwide team of > linux and freebsd developers co-ordinating on landing code for our competing > proposal "Some Congestion Experienced", which we submitted to tsvwg last > sunday. > > That draft is under continuous revision, here: > > https://github.com/dtaht/bufferbloat-rfcs/blob/master/sce/draft-morton-taht-tsvwg-sce.txt > > Our Linux and FreeBSD team is also flying into prague for SCE presentations > at netdevconf and ietf. > > Some background to this: after the L4S/TCP Prague/and dualpi experiments > appeared stalled out indefinitely in the IETF, and with our own frustration > with IETF processes, bufferbloat.net project members publicly formed our own > working group to look into the problems with ecn, back in august of last year. > > Its charter is here: https://www.bufferbloat.net/projects/ecn-sane/wiki/ > > We were unaware, until last month, that the cable industry had 16 months back > gone and formed its own private working group also, and was intending to turn > the tcp prague/l4s/dualpi IETF "experiments" into an actual DOCSIS standard. > > Our SCE proposal appears to be backward compatible with the existing 10s-100s > of millions of ecn-enabled fq_codel[1] and sch_cake[2] deployments, and > doesn't require any changes to any RFC3168 tcps (or any tcp-friendly > congestion control) at all in order to basically work. tcp-prague is subtly > incompatible with that, and dualpi, more so. Our proposal is different also, > it proposes some receiver side changes in order to get the full benefit of > SCE while remaining backward compatible with the existing meaning of the CE > codepoint. > > In either case, either approach essentially permanently redefines the ECT_1 > codepoint incompatibly, once and for all, and for all time. This is a final > battle over the meaning of a single bit in IP, and I expect the debates to be > as difficult as the ones described in https://www.ietf.org/rfc/ien/ien137.txt > - I would really, really, really prefer that they stay technical and not veer > into politics, but I have little hope for that. > > The members of the ecn-sane working group are delighted to finally hear that > running code for tcp-prague might land this ietf, and look forward to finally > testing the whole l4s/tcpprague/dualpi architecture in conjunction with the > flent.org 's and irtt's exhaustive suite of tests and servers in the cloud in > the coming months, both against our existing, deployed, fq_codel, fq_pie, > cake and pie derived solutions and our new SCE proposal. We hope to finally > be able to write new tests for flent in particular, that can show tcpprague > off in the ways that are important to those developing it. Flent has some > basic dctcp tests, but nothing that can get down below a 20ms sample rate on > modern hardware. (currently. It's easy to add tests, flent is written in > python) > > We also hope that more test tools and implementations in ns2 and ns3 show up > for tcpprauge and dualpi show up soon also, from members of those projects. > > Note: sunday's dual-pi linux submission was kicked back from the linux > networking developers due to some technical and legal problems with linux > net-next HEAD ( https://patchwork.ozlabs.org/patch/1054521/ ) , and I do > hope that a corrected version lands soon, so we can safely test it with > current versions of OpenWrt, etc. > > Finally, running code. Will we find consensus? > > Thx! > > > [1] https://tools.ietf.org/html/rfc8290 > [2] sch_cake was available for 3 years out of tree and was mainlined last > august, in linux 4.19. It is partially described by "Piece of CAKE: A > Comprehensive Queue Management Solution for Home Gateways" > "https://arxiv.org/pdf/1804.07617.pdf > > A second paper describing its fq_codel-derived "cobalt" AQM algorithm is > awaiting publication in a peer reviewed journal. It has been part of openwrt > and the related sqm-scripts for many years and is widely deployed on multiple > commercial products, such as those from eero and evenroute. > > Cake has a docsis specific mode which we longed for cablelabs to evaluate. > > > On Fri, Mar 15, 2019 at 2:33 AM Bob Briscoe <i...@bobbriscoe.net> wrote: > Forwarding to tcpm & iccrg - apologies if you were already on one of the > lists that received this. > > Olivier has been working hard on integrating the pieces of a Linux > implementation of TCP Prague, and is close to having a version ported against > the tip of the Linux mainline tree. This is his request for more people to > get involved. > > > Bob > > > -------- Forwarded Message -------- > Subject: [tcpPrague] Implementation and experimentation of TCP > Prague/L4S hackaton at IETF104 > Date: Wed, 6 Mar 2019 10:26:05 +0000 > From: Tilmans, Olivier (Nokia - BE/Antwerp) > <olivier.tilm...@nokia-bell-labs.com> > To: hackat...@ietf.org <hackat...@ietf.org>, tcppra...@ietf.org > <tcppra...@ietf.org> > CC: dleb...@google.com <dleb...@google.com>, Joakim Misund > <joakim.mis...@gmail.com>, Bob Briscoe <resea...@bobbriscoe.net>, Quentin De > Coninck <quentin.deconi...@uclouvain.be>, François Michel > <francois.mic...@uclouvain.be>, Mirja Kuehlewind > <mirja.kuehlew...@tik.ee.ethz.ch>, Maxime Piraux > <maxime.pir...@uclouvain.be>, Olga Albisser <o...@albisser.org>, Fabien > Duchêne <fabien.duch...@uclouvain.be>, De Schepper, Koen (Nokia - BE/Antwerp) > <koen.de_schep...@nokia-bell-labs.com> > > Hi all, > > We'll be working on the "TCP Prague" congestion control/L4S architecture > during the IETF-104 hackaton. > This topics aims at accelerating the work that started during the IETF93 > (coincidentally also in Prague), in order to get TCP Prague to an 'usable' > state—i.e., meet the safety requirements and have supporting materials (e.g., > VMs, labs) to let people experiment with it. Depending on people's interest, > prototyping something similar for QUIC is another possible output. > > Details and links to resources/supporting drafts are available at > https://trac.ietf.org/trac/ietf/meeting/wiki/104hackathon#tcp-prague and > copied below. > Additionally, few topics will presented during netdev 0x13 the week before. > > See you in Prague. > > Best, > Olivier > > > Implementation and experimentation of TCP Prague/L4S > > * Champion > * Olivier Tilmans <olivier.tilmans at nokia-bell-labs.com> > * Projects > * Prototype the "TCP Prague" congestion control on Linux > * Finalize the implementation of accurate ECN (draft conformance), and port > it on Linux v5.x * Build tooling around L4S to let people experiment with the > technology (e.g., virtual machine, or mininet labs) > * Work towards "QUIC Prague" > * Resources > * TCP Prague > * Repository — https://github.com/L4STeam/tcp-prague > * Requirements — > https://tools.ietf.org/html/draft-ietf-tsvwg-ecn-l4s-id-05#page-21 > * Upcoming netdev talk — > https://netdevconf.org/0x13/session.html?talk-tcp-prague-l4s > * Accurate ECN > * Specs — https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-07 > * Implementation for Linux v4.17 — https://github.com/mirjak/linux-accecn > * Past netdev talk — > https://www.netdevconf.org/2.2/session.html?kuhlewind-accecn-talk > * Paced Chirping * Repository — https://github.com/JoakimMisund/PacedChirping > * Upcoming netdev talk — https://netdevconf.org/0x13/session.html?talk-chirp > * L4S architecture > * Specs — https://tools.ietf.org/html/draft-ietf-tsvwg-l4s-arch-03 > * DualPI2 AQM > * Specs — https://tools.ietf.org/html/draft-ietf-tsvwg-aqm-dualq-coupled-08 > * Repository — https://github.com/L4STeam/sch_dualpi2_upstream > * Upcoming netdev talk — > https://netdevconf.org/0x13/session.html?talk-DUALPI2-AQM > * RITE Project — https://riteproject.eu/dctth/#code > _______________________________________________ > tcpPrague mailing list > tcppra...@ietf.org > https://www.ietf.org/mailman/listinfo/tcpprague > _______________________________________________ > iccrg mailing list > ic...@irtf.org > https://www.irtf.org/mailman/listinfo/iccrg > > > -- > > Dave Täht > CTO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-831-205-9740 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat _______________________________________________ Bloat mailing list Bloat@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/bloat
