hw tcp v4 csum failed

hw tcp v4 csum failed

[Doruk Fisek]

Hi,

 I am getting "hw tcp v4 csum failed" errors using a BCM5701 ethernet
adapter with the tigon3 driver in a vanilla 2.4.20 kernel.

 There seems to be no apparent problem (probably because of low-load).

 What can be the cause of these errors?

                               Doruk

--
FISEK INSTITUTE -- http://www.fisek.org

Re: hw tcp v4 csum failed

[David S. Miller]

On Sun, 27 Jul 2003 10:02:46 +0300
Doruk Fisek <dfisek@fisek.com.tr> wrote:

> Hi,
> 
>  I am getting "hw tcp v4 csum failed" errors using a BCM5701 ethernet
> adapter with the tigon3 driver in a vanilla 2.4.20 kernel.
> 
>  There seems to be no apparent problem (probably because of low-load).
> 
>  What can be the cause of these errors?

Nothing need to be done.

They are usually happening because of one of two things:

1) The other host computed an incorrect checksum.
2) Something between the foreign host and your's corrupted
   the packet.

Both of which are normal events and so you can ignore the
message safely.

Re: hw tcp v4 csum failed

[James Stevenson]

> Hi,
> 
>  I am getting "hw tcp v4 csum failed" errors using a BCM5701 ethernet
> adapter with the tigon3 driver in a vanilla 2.4.20 kernel.
> 
>  There seems to be no apparent problem (probably because of low-load).
> 
>  What can be the cause of these errors?
 
if it isnt a software problem.

Its probably a problem releated to the cable or surrounding
interference on the cable.

a) loose connection either on back of machine or @ the hub / switch etc..
b) there is a large power supply sitting very close to the cable.
   i have seen the transformers on scanners / printers etc.. strong enough
   todo this is the cable gets wrapped around it

	James 

Re: hw tcp v4 csum failed

[Jamie Lokier]

James Stevenson wrote:
> >  I am getting "hw tcp v4 csum failed" errors using a BCM5701 ethernet
> > adapter with the tigon3 driver in a vanilla 2.4.20 kernel.

> Its probably a problem releated to the cable or surrounding
> interference on the cable.

This is an ethernet adapter.  It means that interference problems
should cause CRC32 errors, and the packets will be dropped/logged at
the MAC layer, and the TCP checksum not checked.  The MAC layer CRC32
is strong enough that TCP checksum errors should be exceedingly rare,
unless the interference is very bad and a very large number of packes
are being submitted.

Perhaps the error message is not really indicating TCP checksum errors?

-- Jamie