GTS Ethernet Intel® FPGA Hard IP User Guide

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

A.2.3.1. Conditions Triggering XOFF Frame Transmission

The GTS Etheet Itel® FPGA Had IP suppots etasmissio. I etasmissio, the IP coe etasmits a XOFF fame peiodically, extedig the pause time, based o sigal values.

The TX MAC tasmits PAUSE XOFF fames whe oe of the followig coditios occus:

  • Cliet equests XOFF tasmissio—A cliet ca explicitly equest that XOFF fames be set usig the i_tx_pause ad i_tx_pfc[7:0] sigals.
    • Whe i_tx_pause is asseted, a PAUSE XOFF fame is set to the Etheet etwok whe the cuet fame tasmissio completes.
    • Whe i_tx_pfc is asseted, a PFC XOFF packet is tasmitted with XOFF equests fo each of the Queues that has a bit high i the sigal. Fo example, settig i_tx_pfc to 0x03 seds XOFF equests fo Queues 0 ad 1.
  • Host (softwae) equests PAUSE XOFF tasmissio—Settig the pause equest egiste tigges a equest that a PAUSE XOFF fame be set. Similaly, settig the PFC equest egiste tigges PFC XOFF fame equests fo the selected Pioity Queues.
  • Retasmissio mode—If the etasmit hold-off eable bit has the value of 1, ad the i_tx_pause sigal emais asseted o the pause equest egiste value emais high, whe the time duatio specified i the hold-off quata egiste has lapsed afte the pevious PAUSE XOFF tasmissio, the TX MAC seds aothe PAUSE XOFF fame to the Etheet etwok. The same mechaism applies to PFC. While the IP coe is paused i etasmissio mode, you caot use eithe of the othe two methods to tigge a ew XOFF fame: the sigal o egiste value is aleady high.
Note: Itel ecommeds that you use the flow cotol pots to backpessue the emote Etheet ode.