Low Latency Ethernet 10G MAC Intel® FPGA IP User Guide

ID 683426
Date 3/01/2022
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4.6.2.1. PFC Frame Reception

When the MAC RX receives a PFC frame from the remote partner, it asserts the avalon_st_rx_pfc_pause_data[n] signal if Pause Quanta n is valid (Pause Quanta Enable [n] = 1) and greater than 0. The client suspends transmission from the TX priority queue n for the period specified by Pause Quanta n. If the MAC RX asserts the avalon_st_rx_pfc_pause_data[n] signal in the middle of a client frame transmission for the TX priority queue n, the client finishes sending the current frame and then suspends transmission for the queue.

When the MAC RX receives a PFC frame from the remote partner, it deasserts the avalon_st_rx_pfc_pause_data[n] signal if Pause Quanta n is valid (Pause Quanta Enable [n] = 1) and equal to 0. The MAC RX also deasserts this signal when the timer expires. The client resumes transmission for the suspended TX priority queue when the avalon_st_rx_pfc_pause_data[n] signal is deasserted.

When the remote partner sends more than one pause quanta for the TX priority queue n, the MAC RX sets the pause quanta n to the last pause quanta received from the remote partner.