On 08/27/2014 05:39 PM, Christian Kreibich wrote:
> Hi folks,
> 
> What's the level of checksum offloading support in the ixgbe driver?
> With driver version 3.21.2, I seem to be able to enable/disable checksum
> offloading via ethtool (3.1). I have it enabled ...
> 
> $ ethtool -i eth6
> driver: ixgbe
> version: 3.21.2
> firmware-version: 0x61bd0001
> bus-info: 0000:08:00.0
> supports-statistics: yes
> supports-test: yes
> supports-eeprom-access: yes
> supports-register-dump: yes
> 
> $ ethtool -k eth6
> Offload parameters for eth6:
> rx-checksumming: on
> tx-checksumming: on
> [...]
> 
> ... but when I replay a pcap trace whose packets have broken IP and TCP
> checksums on this machine via tcpreplay, the checksums remain incorrect
> according to tcpdump on a different, packet-receiving machine. Shouldn't
> the transmitting driver be fixing them?
> 
> Or am I barking up the wrong tree here and this is a tcpreplay problem,
> rather than a driver one?
> 
> Thanks for any insights,
> -C.
> 

Last I knew tcpreplay doesn't request any checksum offloading.  It just
replays the packets as they are.

The receiving side should however identify them as checksum errors and
hand the frames off to the stack for verification that the checksum is bad.

Thanks,

Alex


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