The 800G RS-FEC core supports monitoring of the symbol error rate (SER) for link degradation as required by Clause 172.2.5.3 of IEEE 802.3df-2024.
When rx_degrade_enable is High, the error rate
is monitored over consecutive windows consisting of rx_degrade_interval codewords. If the number of symbol errors observed
during such a window exceeds the value specified on the rx_degrade_act_thresh port, the rx_degraded_ser flag goes High. If the error count accumulated during any
subsequent window is below the value specified by the rx_degrade_deact_thresh when the end of the window is reached, rx_degraded_ser goes Low.
Changes to the degrade thresholds take place immediately whenever the values on
the ports are changed. The activation threshold must always be greater than or equal to
the deactivation threshold to ensure correct behavior. Changes to the degrade interval
must only be made when rx_degrade_enable is Low. The symbol error rate
is only monitored while the FEC receiver is aligned and the RS decoder is active.
The enablement and settings of the monitoring are shared and apply to all 800G ports.