If you enable the Avalon-ST adapters for the Low Latency Ethernet 10G MAC IP core, you may observe an underflow error on the TX path.
This issue affects versions 13.1 and 14.0 of the Low Latency Ethernet 10G MAC.
A patch is available to fix this issue for Quartus® II software versions 13.1 and 14.0. Download and install the patch from the appropriate link below:
This issue will be fixed in a future version of the Low Latency Ethernet 10G MAC.