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Incorrect behavior when send/received small Ethernet frame

Question asked by Alexandre FROISSARD on Jun 12, 2020
Latest reply on Jul 8, 2020 by Etienne Alepins

Hello,

 

I have a behavior than I don't understand, I send a Ethernet frame for ENET0 to ENET1 (they are connected together by a wire). When I send a frame bigger or equal to 88 Bytes everything work correctly, but if I try to send a frame smaller, at the reception the RxBD data length field is equal to 1520 bytes (value of the MRBR register).

The ENETs are in store and forward mode, the FIFO threshold are the default value.

The Ethernet configuration is RGMII 100Mbits/s.

I use the legacy buffer descriptor and the option to compute the CRC and send it by the MAC is activated.

 

Is someone has an idea about why I have this behavior?

 

Best regards

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