mengjiansh...@163.com wrote:
Use Wireshark to monitor the traffic between the tcp client ip and the machine running lwip example_app. I notice sometimes lwip example_app gets a packet but Wireshark doesn't, sometimes Wireshark gets a packet but lwip example_app doesn't. The SYN packet from the tcp client shows in Wireshark but not in lwip. It's weird because Wireshark uses the same WinPcap library as lwip does.
Typically this is due to the NIC driver does IP/UDP/TCP checksum on TX on it's own. Hence an app will see packets with wrong checksums. (WinPcap and NPcap (?) gets the packets in the TX-path before the NIC can add the checksum). Enter the Network card advanced settings dialogue and turn some/all of these off. Thus forcing Winsock to do the checksum. You can probably let the RX checksum offloading be enabled. Depends on your CPU speed. BTW. please use shorter text-lines next time. -- --gv _______________________________________________ lwip-users mailing list lwip-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/lwip-users
