E-Tile Transceiver PHY User Guide

ID 683723
Date 4/01/2024
Document Table of Contents

2.2.6. Reed Solomon Forward Error Correction (RS-FEC) Parameters

The Native PHY IP Core supports RS-FEC (528, 514) and (544, 514). You can enable this functionality by selecting the Enable RS-FEC option in the Datapath Options section of the GUI.
Figure 28. GUI with Enable RS-FEC Option Selected

RS-FEC merging is not supported with more than one Native PHY IP instance. A Native PHY IP with an RS-FEC block enabled uses the whole RS-FEC block, even if it uses only one channel in the IP. You can use dynamic reconfiguration to utilize the same RS-FEC block for implementation on different protocols.

The RS-FEC IP core supports the following modes:

  • 32GFC/ CPRI 24G (x1, x2, x3, x4)
  • 128 GFC
  • 25GE FEC Direct (x1, x2, x3, x4)
  • 100 GbE
  • Interlaken 7
Table 26.  RS-FEC Mode Configurations
Supported Mode RS-FEC Code Type FEC Mode Alignment/Scrambling/Transcoder Mode Transcoder Bypass
32GFC/ CPRI 24G (x1, x2, x3, x4) NRZ (528, 514) Fractured Fibre channel Not bypassed
128 GFC Aggregate Fibre channel Not bypassed
25GE FEC Direct (x1, x2, x3, x4) Fractured Basic Not bypassed
100 GbE Aggregate Basic Not bypassed
Interlaken PAM4 (544, 514) Aggregate Fibre channel Bypassed
Figure 29. RS-FEC Options
Table 27.  RS-FEC Parameters
Parameter Value Description
Enable aggregate mode On/Off  
RS-FEC Clocking Mode

EHIP clock

Clock 0

Clock 1

Clock 2

Clock 3

No Clock

Sets the clocking mode for the RS-FEC block. For some RS-FEC topologies, the clock selection is fixed. In all other cases, this control selects the TX adapter clock used to clock the RS-FEC block.
First RS-FEC Lane





Selects the first RS-FEC lane to be used. There are four lanes in the RS-FEC block. When the RS-FEC block is in fractured mode, any of the four lanes may be selected as the first lane. For multiple channel Native PHY IP core instances with the RS-FEC block enabled, the RS-FEC lanes used must be contiguous and must fit within a single four-channel RS-FEC block.
Alignment/Scrambling/Transcoder Mode

Basic Mode

Fibre-Channel Mode

Basic Mode selects Ethernet-like mode for a specific lane. The transcoder is not bypassed, alignment or codeword markers are used for alignment of the RS-FEC block, and the PN-5280 scrambling is disabled.

Fibre-Channel Mode selects Fibre-Channel mode for RS-FEC lanes. Fibre-channel mode disables RS-FEC alignment/codeword markers. Selecting Fibre-Channel mode also selects PN-5280 scrambling when in fractured mode.

CPRI Mode is identical to Fibre-Channel mode with respect to the RS-FEC operation.

Transcoder Bypass Lane

Not Bypassed


Selects the transcoder mode for RS-FEC lanes.
  • Not bypassed: The transcoder is not bypassed.
  • Bypassed: Bypasses the transcoder to enable a user-defined transcoder implemented in the FPGA.
7 The Interlaken mode requires a special string in the quartus.ini file to enable its functionality. For more details, contact My Intel support.