e1000-devel  

Re: [E1000-devel] rx_csum_offload_errors counter questions

Jesse Brandeburg
Fri, 10 Feb 2012 11:10:55 -0800

On Sat, 2012-02-11 at 01:24 +0700, Bokhan Artem wrote:
> 11.02.2012 0:23, Jesse Brandeburg пишет:
> 
> 
> Thanks!
you're welcome!

> 
> >> Does it count L2 or L3 errors?
> >  This counter is mostly for L3 or L4 errors (IP checksum, TCP checksum)
> 
> 
> Does it counts all tcp and udp csum errors regardless of destination of 
> packets?

yes, if the packet's data doesn't match the checksum it is reported.
you should check your netstat -s output on those routers and compare to
the NIC stats.

> >> Does the driver counts packets with bad csums which will be routed then?
> > it is unlikely that the packet will be routed as it will likely be
> > dropped by the upper layers.
> 
> We have several routers in chain and rx_csum_offload_errors in incoming 
> traffic on all of them. It was interested for me why this happens.

it seems maybe you have a device downstream of you that is sending
packets with bad checksums a lot.  What is the percentage of packets
received that have a bad checksum? My guess is that a certain percentage
of internet traffic will always have bad checksums, due to lots of
causes, some due to DoS style attacks, others just due to normal signal
issues.

If you wish you can disable all hardware checksums with ethtool, and see
if the OS reports about the same rate of errors.  It will increase CPU
and possibly lower packet rate of your router however :-)



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