F-tile Architecture and PMA and FEC Direct PHY IP User Guide

ID 683872
Date 12/15/2021
Public

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2.2.6. FEC Placement Rules

  • A single FEC core can be used to implement up to four different hard IP interfaces each with a different FEC type. For example, it is possible to have two RS-FEC(528, 514) mode 25GbE hard IP interfaces and one RS-FEC(544, 514) mode 50GbE hard IP interface in one FEC core. Refer to the respective hard IP protocol user guides for supported FEC types.
  • All FEC-enabled hard IP interfaces in a FEC core must use the same system PLL.
  • Four FEC-enabled hard IP interfaces using a st_x1 configuration can be placed in one FEC core. The PMA location of these hard IP interfaces need not be contiguous.
  • For designs using one FEC-enabled hard IP interface using a st_x2 , st_x4 , or st_x8 configuration, the FEC streams must be contiguous.
  • In st_x2 configurations, the streams must be the top two or the bottom two, not the middle two, of a FEC core. Nor can they straddle FEC cores. For example, the two streams can be either Stream0 and Stream1 or Stream2 and Stream3 but not Stream1 and Stream2 and not Stream3 and Stream4.
  • All four streams in a st_x4 configuration must be in one FEC core.
  • All eight streams in a st_x8 configuration must be in two FEC cores.
  • For 200GbE and 400GbE, FEC must be enabled: LL FEC and KP FEC are the available FEC modes.
  • F-tile does not allow FEC for 40GbE.
  • Firecode FEC is only available for 25GbE.
Figure 33. FEC-Enabled Configuration Example with Multiple Interfaces Example 1
Figure 34. FEC-Enabled Configuration Example with Multiple Interfaces Example 2

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