Question about TCP Checksum errors

From: Larry Finger
Date: Sat Dec 17 2011 - 18:18:34 EST


In https://bugzilla.novell.com/show_bug.cgi?id=718736, a user reports that his network using an RTL8188CE becomes very slow under "heavy" load. This condition started when he updated from openSUSE 11.4 to 12.1. The kernels involved are 2.6.37 and 3.1. I am unable to duplicate the problem.

Packet capture with Wireshark shows that the slow down is due to retransmissions due to TCP checksum errors. I found nothing to explain the situation with a Google search, thus I am asking here.

I put heavy in quotes because the traffic is from a web browser to yahoo.com, thus the potential throughput is not very high.

As far as I know, this checksum is generated in a higher layer of the network stack, and that data is just passed through the 802.11 layer, and the wireless driver. Is this correct? Anyone have any ideas on where to look for the problem?

Thanks,

Larry
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