Date: Wed, 14 Dec 2011 22:17:41 +0100 From: Andrea Venturoli <ml@netfence.it> To: pyunyh@gmail.com Cc: freebsd-net@freebsd.org Subject: Re: Intel 82550 Pro/100 Ethernet and TSO troubles Message-ID: <4EE91275.3060808@netfence.it> In-Reply-To: <20111214195918.GC11426@michelle.cdnetworks.com> References: <4EE8FA10.8090502@netfence.it> <20111214195918.GC11426@michelle.cdnetworks.com>
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On 12/14/11 20:59, YongHyeon PYUN wrote: > AFAIK the firmware of controller has no known TSO issue so it > indicates a bug in driver. > What makes me wonder is ICMP ECHO packet should not be affected by > TSO and I have no clue at this moment. I wasn't talking about ICMP ECHO. What happened was: a) the client connected to my server, advertising a TCP MSS of X; b) my server started sending with packets larger than X (possibly it misinterpreted MSS size???); c) an ICMP packet arrived, asking my server to send packets no larger than Y (I guess it was ignored); d) my server kept resending the same (too big) packets; e) it eventually reduced packet size, but it was still larger than Y; ... Wireshark showed some wrong checksums (I believe on the ICMP packet, but I might remember wrong). Of course this made a bell ring and removing TSO solved everything. > (Here, I assume you've > captured packets on receiver side since bpf sees packets before > hardware computes checksum.) Yes, although I don't have them anymore. > If you have a reliable way that reproduces the issue, let me know. I can turn TSO on again, save the packets and send them to you. I just hope nothing changes on the Internet in between the server and the client. Let me know if you need/want this and I'll arrange in the next few days. bye & Thanks av.
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