netdev - Re: TCP fast retransmit

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Message-ID: <C2C333F1-98FD-41FB-9CFA-EDE9F363CABF@mpi-bpc.mpg.de>
Date:	Fri, 9 Dec 2011 14:34:17 +0100
From:	"Esztermann, Ansgar" <Ansgar.Esztermann@...-bpc.mpg.de>
To:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: TCP fast retransmit


On Nov 25, 2011, at 17:36 , Eric Dumazet wrote:

> Could you send a sample pcap of such problem, but please include full
> tcp sesssion, from the first SYN packet, up to packets following
> restransmits.

OK, I've got a dump now. It is rather large (>300MB), so it's probably not a good idea to send it to the list. Instead, you can find it here:
http://wwwuser.gwdg.de/~aeszter/tcpstream.pcap

The capture has been taken in the sender, 10.208.9.87, with a capture filter on the receiver's IP address. OS is:
% uname -a
Linux mwolf 2.6.37.6-0.9-default #1 SMP 2011-10-19 22:33:27 +0200 x86_64 x86_64 x86_64 GNU/Linux

The first "strange" retransmission is in frame 166859, following ACKs in frames 166849 .. 166858. 

If I can do anything to reduce the amount of data, I will of course do so.

> A diff of "netstat -s" taken before your session and after your session
> on receiver would help too, if receiver is not a loaded machine of
> course.

Attached.

Thanks a lot,

A.

-- 
Ansgar Esztermann
DV-Systemadministration
Max-Planck-Institut für biophysikalische Chemie, Abteilung 105

Download attachment "netstat.diff" of type "application/octet-stream" (4185 bytes)