GTS Ethernet Intel® FPGA Hard IP User Guide

ID 817676
Date 10/12/2024
Public
Document Table of Contents

4.4.3.2. Connect the RX MAC Flow Control Interface

All iteface sigals ae clocked by the i_clk_tx clock. Fo 10GE/25GE chaels, all iteface sigals ae asychoous.

Table 32.  RX MAC Flow Cotol Iteface
Sigal Name Width (bits) Desciptio
o_x_pause 1 bit Whe asseted, stop sedig Etheet fames o the TX MAC cliet iteface sice the IP coe eceived a PAUSE XOFF fame.
o_x_pfc[7:0] 8 bits Whe a bit is asseted, stop sedig Etheet fames o the TX MAC cliet iteface fo the coespodig pioity queue sice the IP coe eceived a PFC XOFF fame.

The o_x_pause ad o_x_pfc[7:0] pots o each chael ae asseted whe thei emote lik pate sets oe o moe of the queues to a o-zeo pause quata.

Figue 36. Example of o_x_pause Togglig
I the above diagam, o_x_pause is asseted because the emote lik pate seds a PAUSE XOFF equest. The quata cout fom the PAUSE XOFF equest emais high i o_x_pause util it expies.
  • Whe a PAUSE XOFF equest is eceived ad Stop TX taffic whe lik pate seds pause paamete is eabled i GUI, the TX MAC stops sedig taffic.
  • Whe a PAUSE XOFF equest is eceived ad Stop TX taffic whe lik pate seds pause paamete is disabled i the GUI, the TX MAC seds taffic. o_x_pause deassets o evey valid cycle i the IP. The width of the pulse idicates the umbe of cycles of pause equied.
Figue 37. Example of o_x_pfc[7:0] Togglig
  • Fo all chaels, oe quata is woth multiple cycles of pause. Each quata is woth 512 cycles.
  • o_x_pfc is asseted whe the emote lik pate seds a PFC XOFF equest. I the diagam below, a PFC (Pioity Flow Cotol) equest is set fo queue[0], ad the late fo queue[6].
Note: The same PFC packet ca set multiple queues. The PFC quata coutes cout dow o each valid cycle. Theefoe, the pulse width shows the legth of the taffic pause ecessay fo each queue. The PFC quata values ca be cofigued usig PFC_Pause_quata egistes. Refe to the Agilex™ 5 Etheet Itel® FPGA Had IP Registe Map fo moe ifomatio.