An unsuccessful frame reception might take the form of a runt frame or a frame with
an incorrect FCS. In this case, the bad frame is received and the signal
rx_axis_tuser is asserted to the client at the end of
the frame. It is then the responsibility of the client to drop the data already
transferred for this frame.
The following conditions cause the assertion of
rx_axis_tlast along with
rx_axis_tuser = 1 signifying a bad_frame:
- FCS errors occur.
- Packets are shorter than 64 bytes (undersize or fragment frames).
- Frames of length greater than the maximum transmission unit (MTU) size programmed are received.
- Any control frame that is received is not exactly the minimum frame length.
- The XGMII data stream contains error codes.
Figure 1. Frame Reception with Errors – 32-bit
Figure 2. Frame Reception with Errors – 64-bit