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Wireshark-users: [Wireshark-users] Large Packages although TSO is off

From: Estanislao Gonzalez <estanislao.gonzalez@xxxxxxx>
Date: Fri, 24 Sep 2010 15:35:26 +0200
 Hi,

I've been reading a lot lately, but I still can't find the source of my problem.

For example this is a captured package at eth0:

6249	10.090368	remote.ip	local.ip	TCP	51402>  50383 [ACK] Seq=56628006 Ack=1578 Win=9216 Len=18824 TSV=240912663 TSER=21362093

These are the current settings:
# ethtool -k eth0
Offload parameters for eth0:
Cannot get device udp large send offload settings: Operation not supported
rx-checksumming: on
tx-checksumming: on
scatter-gather: off
tcp segmentation offload: off
udp fragmentation offload: off
generic segmentation offload: off
generic-receive-offload: off

(I've already tried turning checksumming also off)

The TCP options are set to avoid reassembling streams and not to validate checksums.

If MTU is set to 9000 for the receiver, and 1500 for the sender, why am I still seeing large packages?

Any idea?

Thanks,
Estani

--
Estanislao Gonzalez

Max-Planck-Institut für Meteorologie (MPI-M)
Deutsches Klimarechenzentrum (DKRZ) - German Climate Computing Centre
Room 108 - Bundesstrasse 45a, D-20146 Hamburg, Germany

Phone:   +49 (40) 46 00 94-126
E-Mail:  estanislao.gonzalez@xxxxxxx