[En-Nut-Discussion] Slight problem with UDP

[Paolo Simoncelli]

Hi Ole,

Thanks for your reply,

>In your current configuration it might be possible that the first UDP
>packet is send out before the arp challenge / response is finished, so
>your pc does not have a complete arp table right at the beginning of
>your program... (on the pc side).

So you think that it's a pc-side problem?
things should go like this:

en		     pc

ARP whois pc ?
                      ARPr here i am
UDP take this one !
                      ARP whois en ?
ARP let me think ...
                      uhmm ... no one replies drop that %$%ih
ARPr here i am	     nice to meet you !

then, they live long and prosper ...



I have not much debugging aid, but i have tried to
"UDP flood" my server, with another pc, and i have lost
no first packet, so it seems more a "slow" reply from ethernut

maybe en ARP replying task is switched too early, before completing
ARP challenge so UDP packet is sent too early to the server

I am not that deep into ARP, so i don't know whether the responding
side knows if the querying side has got his reply or if all is left
to timeouts

next days i will setup a more deep test, anyway this seems a well
known behaviour, with a workaround too ;-) !

sorry for the spam at the end of my messages

Ciao!
Paolo