[lwip-users] Broadcast packets breaking my network traffic

[Caglar Akyuz]

Hi all,

I have an annoying problem which took my whole week and I have no
solution in my hand still.

I have many lwIP devices(6 to 12) which are connected to a PC through a
hub. I'm transferring ~66 kbytes/sec(992 bytes at every 16msec) from
each device to the PC, all the devices running at the same time. In some
place at some random time, maybe 5 mins or 5 hours, data transfer is
getting currupted such that for a period of approx. 200 msecs no
messages(packets) flying around. Then after 200 msecs, devices continue
sending packets to the PC. On the ethereal log, it's seen that this
happens right after an arp query by the PC. (or some other broadcast packet)

In my port, sys_arch_protect is implemented by disabling interrupts. I'm
using raw api(TCP) with lwIP 1.1.0. I suspect that this may be a phy
issue. I tried to switch to half-duplex mode with no help. Since I see
lost TCP segments in the ethereal log, I suspect that lwIP is sending
packets but they are not reaching the other end for some reason.

Where do yo think the problem can be? In my application code, my port's
ethernet driver, in my physical layer?

Thanks for your help,
Caglar AKYUZ


P.S. : Some test results:

1) Problem is not happening on a direct cable connection(without a hub)
2) Problem is happening with various hubs.
3) If I use a Linux PC, problem is rarely seen, with a Windows PC the   
   problem is more frequent.
4) All the devices losing connection at the same time.
5) If I use static arp entries in Linux, all goes well. I can not test

   this on Windows since Windows has a strange static arp understanding.