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UDP MTU Fragmentation on a STM32

MTasso
Associate

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:

MTasso_0-1734066441653.png

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

thanks

2 REPLIES 2
STea
ST Employee

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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yes it is:

MTasso_0-1734114881209.png