UDP MTU Fragmentation on a STM32

MTasso · ‎2024-12-12

I'm using the LWIP library and STM32F407. I’m trying to send a 1860 bytes through Ethernet using UDP protocol, exceeding the Ethernet MTU (1500 bytes) so my data is fragmented. I´ve used some programs to test If I could read UDP stream, but nothing works. No problem to read packets under 1500byte (with no fragmentation) with my host application or other.. However, I can see the traffic generated by this packet using Wireshark:

There is any way to read this fragmented Data properly, configuring some parameter of the LWIP library?

thanks

STea · ‎2024-12-13

Hello @MTasso ,

Ensure that the IP reassembly feature is enabled in the lwipopts.h file (#define IP_REASSEMBLY 1). This feature allows LWIP to reassemble fragmented IP packets.
Regards

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MTasso · ‎2024-12-13

yes it is:

STea · ‎2024-12-30

Hello @MTasso ,
did you manage to get it working? if yes it would be great to share for other community users.

if not, maybe you can check if there are any similar cases in the FreeRTOS and lwIP forum.
Regards

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