It is due to the reason that frame count signal does not count the length of pause frame.
The following patch provides a solution to enable frame count signal that does count the length of pause frame when pause frame forward is disabled while received.
Please download the appropriate Quartus® II software version 10.0SP1 patch 1.210 from the following links:
You must either have previously installed the Quartus II 10.0 SP1 software or must install the Quartus II 10.0SP1 software before installing this patch. Otherwise, the patch will not be installed correctly and the Quartus II software will not run properly.
After you install the patch please regenerate your Triple Speed Ethernet MegaCore® before you compile your design.