Hi Ingemar, I was to make that very same point; from my earlier collaboration with Mirja and Brians efforts, I think the prevalence of gear that still uses a notion of a TOS byte, and rewrites it for a L4 flow is actually higher than ECN impacting connection set up etc.
So, on some paths you may believe you negotiate ECN, but one half-link may bleach the IP-header ECN bits. Again, this is detectable for the receiver (currently, no mechanism to convey this info back to a TCP sender), and affected sessions would revert back to loss-based CC. Such ECN-unresponsive, loss-responsive flows may pose an issue to AQMs that do some differentiated handling of ECN vs non-ECN packets though... Best regards, Richard > -----Original Message----- > From: iccrg [mailto:[email protected]] On Behalf Of Mirja Kühlewind > Sent: Montag, 29. Juni 2015 14:56 > To: Ingemar Johansson S > Cc: [email protected]; [email protected]; Dave Taht ([email protected]); > Bob Briscoe ([email protected]); [email protected]; > [email protected] > Subject: Re: [iccrg] ECN issues > > Hi Ingemar, > > we did only test connection setup up and some small transmissions so far. > We did not measurement anything with longer connection though. However, > from these results I'd also say there are no mayor issues anymore. There > are still some boxes that overwrite the IP ECN bits because they still > think it's part of the ToS field. However, those cases are rather easy to > detect because all packets should have the same marking. Linux implements > an easy fallback where ECN is disabled if the SYN is ECN marked. That's > probably not the perfect solution but mostly helps the problem. > > Mirja > > > > Am 25.06.2015 um 21:02 schrieb Ingemar Johansson S > <[email protected]>: > > > > Hi > > > > And thanks all for the info both on and off list. I believe that I have > enough information. The main objective for me was to get an understanding > how serious the issues that various boxes in the middle (e.g NATs/FWs ) > mess with the ECN bits really is. Seems to me, based on the info I > received thus far that this is becoming more and more an non-issue ?. > > > > Realized that I have seen the below paper before, somehow I mixed it > > up with the older paper, have to blame it on my own teflon-memory ... > > Thanks for refreshing my memory > > > > /Ingemar > > > >> -----Original Message----- > >> From: Mirja Kühlewind [mailto:[email protected]] > >> Sent: den 25 juni 2015 19:31 > >> To: Ingemar Johansson S > >> Cc: [email protected]; [email protected]; Bob Briscoe > >> ([email protected]); [email protected]; Dave Taht > >> ([email protected]); [email protected] > >> Subject: Re: ECN issues > >> > >> Hi Ingemar, > >> > >> there is a newer paper we published last year (and gave a quick > >> presentation at the last ICCRG meeting): > >> > >> http://wan.poly.edu/pam2015/papers/4.pdf > >> > >> https://www.ietf.org/proceedings/92/slides/slides-92-iccrg-1.pdf > >> > >> In the mean time we did more measurements using BitTorrent clients > >> instead. The results are very similar. We might be able to quickly > >> present some new results at the next session (if the session takes > >> place and there is still space). > >> > >> Does this help or are you looking for some specific information? > >> > >> Mirja > >> > >> > >>> Am 24.06.2015 um 13:34 schrieb Ingemar Johansson S > >> <[email protected]>: > >>> > >>> Hi > >>> > >>> I wonder, is there any new data around that gives any ideas how > >>> large the > >> issues with ECN really are ?. > >>> > >>> Issues that I am interested are ECN black holes and faulty remarking > >>> of ECN fields > >>> > >>> The last one I have seen is this paper by Mirja, Brian and Sebastian > >>> Neuner > >>> http://www.ict-mplane.eu/sites/default/files/public/publications/311 > >>> ec > >>> ndeployment.pdf > >>> > >>> Is there any new data available ?. > >>> > >>> /Ingemar > >>> ================================= > >>> Ingemar Johansson M.Sc. > >>> Senior Researcher > >>> > >>> Ericsson AB > >>> Wireless Access Networks > >>> Labratoriegränd 11 > >>> 971 28, Luleå, Sweden > >>> Phone +46-1071 43042 > >>> SMS/MMS +46-73 078 3289 > >>> [email protected] > >>> www.ericsson.com > >>> > >>> "No man has a good enough memory > >>> to be a successful liar" > >>> Abraham Lincoln > >>> ================================= > > _______________________________________________ > iccrg mailing list > [email protected] > https://www.irtf.org/mailman/listinfo/iccrg _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
