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Re: [tcpm] TCP tuning

John Heffner <johnwheffner@gmail.com> Wed, 03 February 2010 22:11 UTC

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Date: Wed, 03 Feb 2010 17:11:41 -0500
Message-ID: <1e41a3231002031411u57a79ffas1fa77988e83343c0@mail.gmail.com>
From: John Heffner <johnwheffner@gmail.com>
To: Murali Bashyam <MBashyam@ocarinanetworks.com>
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Cc: "tcpm@ietf.org" <tcpm@ietf.org>
Subject: Re: [tcpm] TCP tuning
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On Wed, Feb 3, 2010 at 5:03 PM, Murali Bashyam
<MBashyam@ocarinanetworks.com> wrote:
> Any idle period higher than the RTT between HTTP requests tends to reset the cwindow down to the restart window. This hurts persistent connections too. What's the motivation for this, can we have a different slope while reducing the window instead of resetting all the way down?


This is because you lose the ack clock.  Otherwise, when resuming
sending you'll send a line-rate burst of the full BDP, which will
often overflow queues and cause loss and/or large delay spikes.  There
is currently no pacing mechanism in TCP to smooth out such bursts.

  -John

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