IP fragmented

From: Benedykt Kroplewski (mlody@popnet.pl)
Date: Sat Jan 29 2000 - 04:59:18 EST

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    Hi

    I have written a driver to the new hardware. It is serial, synchronous,
    ISA
    based, communication card but it doesn't meter now. It is mmio driven with
    IRQ's without DMA on the ISA.

    I send pure TCP/IP packets without any hardware headers etc... It's like
    point-to-point through completely transparent hardware.

    When I send a packet which is smaller or equal to the actually set MTU
    value then everything work perfectly.

    The problem starts when I try to send a packet which is grater then
    actually set MTU.

    As expected, the larger packet is fragmented into smaller parts and it
    goes to the second machine. It is received by the second machine but it is
    lost in system. It looks like the second computer does not glue fragmented
    packets....!

    But if I send fragments with delay (udelay(1000)) or more then the second
    computer recognizes it sometimes and responds properly.
    Normal packets below MTU size don't need any delay.

    When I set larger value of MTU I can ping with the packet size up to the
    new MTU.

    Again, when I send packets of a size less then MTU then it works great.

    I attached source files here. Please look at it, maybe I miss something or
    I don't know about some additional issues.

    Please help.

    Regards,
    Benedykt Kroplewski



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