Re: tcp troughput weirdness

From: Noritoshi Demizu (demizu_at_dd.iij4u.or.jp)
Date: 07/12/05

  • Next message: Danny Braniss: "Re: tcp troughput weirdness" 
    Date: Tue, 12 Jul 2005 19:20:42 +0900 (JST)
To: David Malone <dwmalone@maths.tcd.ie>

    (I am sorry if you have received this e-mail. I'm resending this
     because it seems the previous one was lost.)

    > TCP inflight limiting is supposed to guess the bandwidth-delay
    > product for a TCP connection and stop the window expanding much
    > above this.

    (Just to clarify..)
    TCP inflight limiting has a dedicated variable "snd_bwnd".
    And min(tp->snd_wnd, tp->snd_cwnd, tp->snd_bwnd) limits
    the amount of data to be sent.

    > However, some of the guys I know that work on TCP dynamics reckon
    > that they can they can come up with situations where inflight
    > limiting will break. Unfortunately, I haven't had time to talk
    > this through with them. I guess you may have found one of those
    > situations ;-)

    I experienced such situations with DragonFlyBSD. I put examples
    where inflight limiting reduces throughputs at the following pages.

      http://www.demizu.org/~noritosi/memo/2005/0706/
      http://www.demizu.org/~noritosi/memo/2005/0711/

    Sorry, all senders in those examples are DragonFlyBSD.

    Regards,
    Noritoshi Demizu
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