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From: MK <stardust496@gmail.com>
To: netdev@vger.kernel.org
Subject: empty ack packets
Date: Fri, 10 Sep 2010 01:12:44 -0400	[thread overview]
Message-ID: <AANLkTimkvDsqY==1JQRhH54+P7yAzFX4omYN0r9+_mi=@mail.gmail.com> (raw)

Hello list,

I am looking at a tcpdump and I see that very very frequently, after
receiving a segment, my tcp is sending an empty ack back in a matter
of several (around 20 - 50) microseconds. And then after several more
microseconds, my tcp is sending some valid outgoing data. I am trying
to understand why it decided to send an empty ack back when that ack
could potentially have been delayed by microseconds and get
piggybacked on the outgoing data.

>From the code, it appears that the delayed ack timeout is 40 millisecs
so it is likely not the delack timer that is causing this. (And I do
not have the quickack option)

This is RHEL5 (2.6.18) kernel.

Does anybody have an idea as to what is happening?

Thanks a lot!!

             reply	other threads:[~2010-09-10  5:12 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-10  5:12 MK [this message]
2010-09-10  5:29 ` empty ack packets Mitchell Erblich
2010-09-10  7:06 ` Hagen Paul Pfeifer
2010-09-10 10:57   ` MK

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