IP fragmented

From: Benedykt Kroplewski (mlody@popnet.pl)
Date: Fri Jan 28 2000 - 13:40:15 EST


I have written a driver to the new hardware. It is serial, synchronous,
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
to the second machine. It is received by the second machine but it is
It looks like the second computer does not react on it when receives

But if I send fragments with delay (udelay(100)) 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.

Benedykt Kroplewski

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