Today I also did the same tests at my home network. Obviously different router, and devices on the network.
Here happens something different. The router sends ARP requests to my microcontroller (the exact opposite), the microcontroller responds normally, but the router doesn't seem to receive the response, thus it keeps sending the same request again and again. (This time for some reason the microcontroller does not send the ARP request at all... Only responds) Again the controller sends the UDP packet with no response. *Fotis Panagiotopoulos* *--* *AMCO S.A.* 25 Amfiaraou st. PO 10442, Athens, Greece Tel: +30 210 5907000 ext. -34 <%2B30%20210%205907000%20ext.%20-36> | Fax: +30 210 5912711 e-mail: [email protected] | web: http://www.amco.gr On Tue, Aug 16, 2016 at 5:27 PM, Fotis Panagiotopoulos <[email protected]> wrote: > No the ARP requests are send at the beginning of the transmission. As I > stated the problem appears only when I try to access a server outside of my > local network. > > I coded LWIP to send some data through UDP. Before the UDP connection, as > it is normal it decides that the traffic should be send to the router (I > followed the code till here with my debugger), then it realises that it > doesn't know the address of the router, and sends the ARP request, that > however is never responded. > > When the router responds to another ARP request, generated by another > device on my network, LWIP knows the MAC and tries to send the UDP packet, > again with no response. Obviously this will happen at a random time (the > app 30 secs delay I mentioned above). > > It seems that the router has something personal with my microcontroller... > > > > *Fotis Panagiotopoulos* > > > *--* > > *AMCO S.A.* > > 25 Amfiaraou st. PO 10442, Athens, Greece > Tel: +30 210 5907000 ext. -34 <%2B30%20210%205907000%20ext.%20-36> | Fax: +30 > 210 5912711 > e-mail: [email protected] | web: http://www.amco.gr > > On Fri, Aug 12, 2016 at 9:40 PM, [email protected] <[email protected]> > wrote: > >> Fotis Panagiotopoulos wrote: >> >>> As I see in wireshark, when my microcontroller sends an ARP request >>> about my gateway it does not receive any response. It continues sending the >>> same request for about 30 secs (the time I wasn't seeing any UDP traffic), >>> and then it starts sending the UDP packet. >>> >> >> Sorry if I ask the wrong questions, but I haven't been monitoring this >> thread fully. >> >> When are the ARP requests sent? In the middle of a transfer? Can you get >> us a pcap of that period? If it's in the middle of a transfer, it could >> well be that the ARP cache timed out and that there is some kind of bug in >> that handling for you. Which version if lwIP are you using again? (Again, >> sorry if I ask something already asked before...) >> >> >> Simon >> >> _______________________________________________ >> lwip-users mailing list >> [email protected] >> https://lists.nongnu.org/mailman/listinfo/lwip-users >> > >
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