[svlug] TCP checksum ignored?

J C Lawrence claw at kanga.nu
Sun Mar 23 09:42:25 PST 2003


On Sun, 23 Mar 2003 18:12:44 +0200 
Ira Abramov <lists-svlug at ira.abramov.org> wrote:

> for the second time in 4 months I bump into a blade in one of our
> blade servers that ignores TCP packet errors quitely.

> Scenario: files pulled over TCP (http, ftp) to the machine (mobile
> Pentium 3, Intel e1000 interface) get there with a different md5sum
> each time. tried both with machines on the same subnet as well as
> remote. the second interface on that same blade works fine. I have no
> other conclusion to reach but that the faulty interface not only
> changes the occasional bit in the data, but both ethernet and TCP
> error detection tests fail.

> Is there a possibility that in order to cut CPU overhead, the kernel
> defaults not to check crc32 on TCP packets? I saw this with three
> different kernel versions as well, from SuSE, RH and virgin 2.4.20
> from kernel.org.

Have you checked in the reverse direction -- files transfered FROM the
suspect box?  I'd tend to be more suspicious of RAM or DASD errors.

-- 
J C Lawrence                
---------(*)                Satan, oscillate my metallic sonatas. 
claw at kanga.nu               He lived as a devil, eh?		  
http://www.kanga.nu/~claw/  Evil is a name of a foeman, as I live.



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