Tse mac

XOFF pause frames have pause quanta value 0xffff. If you don't send another pause frame before the pause timer expires in the Ethernet tester then the tester will start transmitting again. You want to set holdoff_quant to something less than 0xffff, which is the default value. I would set it to something like 0x8000 and see how that works. With that setting the MAC should send an XOFF pause frame every 16ms (if running at 1Gbps) as long as the Rx FIFO stays above the rx_section_empty threshold.