Due to a problem with the design examples, the following design variants will see underflow errors when tested with packets that are more than 4100 bytes long:
1) 10M/100M/1G/10G Ethernet Design Example
2) 1G/10G Ethernet Design Example
This error is caused by the size of the external FIFO buffer between the MAC and traffic controller. The size, 8 x 512 bytes, is too small, causing the Avalon-ST valid signals to be de-asserted during the frame transmission.
Users will observe corrupted packets and CRC error reported by the packet monitor.