Re: [lwip-users] Consecutive calls to sendto() and recvfrom() functions

[pekez]

Thank you both Sergio and David for your answers.

Now, I tried next things:

1) included Davids proposed solution, that is added sleep of 1 sec after 
the first packet is sent by client. This make app almost work, but it 
still behaves randomly. For example, most of the time client succesfully 
sends all 4 packets, and receives all 4, but third received packet 
doesn't have the right payload (in this example, it receives 'h' instead 
of 'g'). ZYNQ server did sent 'g' from app layer (I don't know how to 
check it from lower layers). Sometimes, client doesn't receive the last 
packet at all, but third packet has the right payload ('g'). Sometimes 
app works completely how it should.

2) included Davids solution in PC client + set IP_DEBUG and LWIP_DEBUG 
options in LWIP library. Guess what? In this case the app works always 
as it should (at least so far). Maybe all those prints give the server 
app enough time to process everything or something, I am really not sure 
how that can affect the app.

ARP_QUEUEING option is set to true by default in LWIP.

Sergio, can you just explain what you mean by third sentence, how can I 
check all those things (port, driver) and what is known-to-work app?

I forgot to mention that everything works completely fine all the time 
when I send from client 1 message and then receive 1 message, and vice 
verca at server. So problems occur only when I want to send/receive more 
messages consecutively.


On 28.10.2016 15:41, Sergio R. Caprile wrote:
> If you have lost messages, you should run a capture and see what comes 
> out and what not, maybe there is an ARP operation taking place while 
> you believe messages are being lost.
> You should check your port and your layer-2 driver with a 
> known-to-work application.
>
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