Ethernet Subsystem Intel® FPGA IP User Guide

ID 773413
Date 4/03/2023
Public
Document Table of Contents

5.1.5. Flow Control

Table 39.  Flow Control Signals
Signal Name Direction Description
i_p<n>_tx_pause In

Asserted to send a pause XOFF frame.

Only functional if pause flow control is enabled.

Note: For 10G/25G channels, i_tx_pause must be held for more than 205 ns to ensure the request is captured by the MAC.

This signal is not available when Enable SFC/PFC Queue Buffering parameter is enabled.

i_p<n>_tx_pfc[7:0] In

Used to send a PFC XOFF frame for the corresponding priority queue. Only functional if priority flow control is enabled.

Note: For 10G/25G channels, i_tx_pfc must be held for more than 205 ns to ensure the request is captured by the MAC.

This signal is not available when Enable SFC/PFC Queue Buffering parameter is enabled.

o_p<n>_rx_pause Out Indicates that a pause XOFF frame was received.

This signal is not available when Enable SFC/PFC Queue Buffering parameter is enabled.

o_p<n>_rx_pfc[7:0] Out

Indicates that a PFC XOFF frame was received for the priority queue q, where q is the bit number that was asserted.

This signal is not available when Enable SFC/PFC Queue Buffering parameter is enabled.

PFC TX and RX queue status signals with PFC feature Enabled
p<n>_tx_pfc_watermark [7:0] Out

Indicates the PFC TX queue watermark.

  • 1'b1: Data fill level in the queue is above threshold
  • 1'b1: Data fill level in the queue is below threshold.
p<n>_rx_pfc_stall [7:0] In

Indicates stall on the PFC RX queue.