[En-Nut-Discussion] Slight problem with UDP
Paolo Simoncelli
simonp at email.it
Tue Nov 3 13:34:35 CET 2009
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
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