Re: [aqm] TCP ACK Suppression
"Richard Scheffenegger" <rs.ietf@gmx.at> Wed, 07 October 2015 16:05 UTC
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From: Richard Scheffenegger <rs.ietf@gmx.at>
To: Mikael Abrahamsson <swmike@swm.pp.se>, "Bless, Roland (TM)" <roland.bless@kit.edu>
References: <alpine.DEB.2.02.1510060748480.8750@uplift.swm.pp.se> <D2394BB6.548C5%g.white@cablelabs.com> <0A452E1DADEF254C9A7AC1969B8781284A7D9B66@FR712WXCHMBA13.zeu.alcatel-lucent.com> <5614D4B8.5060403@kit.edu> <alpine.DEB.2.02.1510071246550.8750@uplift.swm.pp.se>
Date: Wed, 07 Oct 2015 17:57:38 +0200
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Cc: "LAUTENSCHLAEGER, Wolfram (Wolfram)" <wolfram.lautenschlaeger@alcatel-lucent.com>, Greg White <g.white@CableLabs.com>, aqm@ietf.org
Subject: Re: [aqm] TCP ACK Suppression
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[as individual] Hi Mikael, ACK thinning will interfere with the ACK clock of the sender; a good recipie to require much more buffering at the bottlneck hop of that session (since the sender will start bursting out TCP data packets at it's line rate, rather than the bottleneck link rate). So, if your goal is to have the sender send out TCP data segments at the bottleneck rate, you'd not want to ACK too many segments at once... Of course, the drawback is your observation, that TCP (over Ethernet) typically requires 64 bytes of ACK per 2x 1448 bytes, or about 1:45 uplink/downlink bandwidth). Others have already pointed out some relevant RFCs in this thread too... Best regards, Richard ----- Original Message ----- From: "Mikael Abrahamsson" <swmike@swm.pp.se> To: "Bless, Roland (TM)" <roland.bless@kit.edu> Cc: "LAUTENSCHLAEGER, Wolfram (Wolfram)" <wolfram.lautenschlaeger@alcatel-lucent.com>; "Greg White" <g.white@CableLabs.com>; <aqm@ietf.org> Sent: Wednesday, October 07, 2015 12:51 PM Subject: Re: [aqm] TCP ACK Suppression > On Wed, 7 Oct 2015, Bless, Roland (TM) wrote: > >> Oh, I hope that this is an exception. Such kind of optimizations may >> cause a lot of trouble since a link layer device is interfering with >> transport layer semantics. We all know that exactly these kinds of >> interference eventually end up in problems with end-to-end transparency >> and deployment of new protocol options. At least it interferes with the >> ACK clocking expectation of some congestion control algorithms... > > Personally, I think you're going to see more and more of this. There are > mulitple shared access medium where you're allowed to send only part of > the time, and it's someone else who tells you when you may send. > > So if you're sitting there with 100 ACK packets all nicely ACKing > increasing values indicating no packet loss, and now you're allowed to > send, why not just kill 99 of those ACK packets? > > While I agree with you on principle, these kinds of mechanisms cut the > amount of ACK traffic down by factor 15-30, meaning I can download at 250 > megabit/s and only have a few hundred kilobit/s of upstream ACKs, instead > of 5-10 megabit/s of ACKs. That's a huge opimization for any kind of > asymmetric and/or time slot access medium such as ADSL, LTE, DOCSIS, PON > and I'm sure there are others. > > Btw, what is the reason for TCP doing ACKs for every 2 packets in > steady-state, even with window sizes in the hundreds of kilobytes or even > megabytes? I would prefer if the TCP host stack sent fewer ACKs instead of > trying to optimize this at the access routing device. > > -- > Mikael Abrahamsson email: swmike@swm.pp.se > > _______________________________________________ > aqm mailing list > aqm@ietf.org > https://www.ietf.org/mailman/listinfo/aqm
- [aqm] TCP ACK Suppression Mikael Abrahamsson
- Re: [aqm] TCP ACK Suppression Greg White
- Re: [aqm] TCP ACK Suppression Mikael Abrahamsson
- Re: [aqm] TCP ACK Suppression LAUTENSCHLAEGER, Wolfram (Wolfram)
- Re: [aqm] TCP ACK Suppression Bless, Roland (TM)
- Re: [aqm] TCP ACK Suppression Mikael Abrahamsson
- Re: [aqm] TCP ACK Suppression Clark Gaylord
- Re: [aqm] TCP ACK Suppression Steve Bauer
- Re: [aqm] TCP ACK Suppression Francini, Andrea (Andrea)
- Re: [aqm] TCP ACK Suppression Richard Scheffenegger
- Re: [aqm] TCP ACK Suppression Greg White
- Re: [aqm] TCP ACK Suppression Bless, Roland (TM)
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression David Collier-Brown
- Re: [aqm] TCP ACK Suppression Jonathan Morton
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression Richard Scheffenegger
- Re: [aqm] TCP ACK Suppression Yuchung Cheng
- Re: [aqm] TCP ACK Suppression Jonathan Morton
- Re: [aqm] TCP ACK Suppression Jonathan Morton
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression Greg White
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression Yuchung Cheng
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression Christian Huitema
- Re: [aqm] TCP ACK Suppression Rick Jones
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression Christian Huitema
- Re: [aqm] TCP ACK Suppression David Collier-Brown
- Re: [aqm] TCP ACK Suppression Simon Barber
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression Yuchung Cheng
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression Greg White
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] TCP ACK Suppression Simon Barber
- Re: [aqm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Dave Taht
- Re: [aqm] [tcpm] TCP ACK Suppression Jonathan Morton
- Re: [aqm] [tcpm] TCP ACK Suppression Jonathan Morton
- Re: [aqm] [tcpm] TCP ACK Suppression Simon Barber
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Jonathan Morton
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Mikael Abrahamsson
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression Greg White
- Re: [aqm] [tcpm] TCP ACK Suppression Joe Touch
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang
- Re: [aqm] [tcpm] TCP ACK Suppression David Lang