4.5.2. CRC Checking
The MAC RX computes the CRC-32 checksum over frame bytes received and compares the computed value against the CRC field in the receive frame. If the values do not match, the MAC RX marks the frame invalid by setting avalon_st_rx_error to 1 and forwards the receive frame to the client. When the CRC error indicator is asserted, the external logic is expected to drop the frame bytes.