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checksum error sending UDP packets with 1 or 2 payload bytes

Former Member

The test was run on a zed board. when UDP packets with 1 or 2 bytes payload are sent from a zed board to a PC, the packets are not received by the PC. Tcpdump on the PC shows checksum errors. Any packets with 3 bytes or more payload size work fine. Sending from the PC to the zedboard with 1 or 2 bytes payload size is also fine.

This seems like a hardware and Ethernet driver error. Does anyone have similar experience with that and/or have any idea how to fix it?

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    Hi,
    I've got the same issue on zynq7020 board.
    did you manage to figure out where the problem is ?
    Regards,
    Alin

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    What operating system/driver are you using?  What speed is your Ethernet connection?

     

    Also what rev ZedBoard and which version of the Xilinx tools are you using?

     

    -Gary

  • 0

    Hi, Gary.

    Ethernet speed is 1000 mbps. Do you think the issue can be ethernet speed related ?
    The operating system is not LINUX, but a RTOS.
    Board revision is "HW-Z7-ZC702 REV 1.0". I'm not using any Xilinx tools.

    I can get it working only if the application layer places 0s in the corresponding UDP checksum field. The HW seems to take into accout also the UDP checksum field when computing UDP checksum for packets with 1 or 2 bytes payload data length. Maybe the HW doesn't have enough time to clear UDP checksum field in the packet because for 3 data bytes or more checksum offloading works pretty fine or maybe this issue is about data alignement.

    I think the first post in this thread it's about a different operating system and of course a different ethernet driver. It seems to me like we have 2 operating systems (and 2 different ethernet drivers) having the same issue.

    With Best Regards,
    Alin