This KB provides information about Forward Error Correction (FEC) support on the EX4100 Series.
FEC is supported for 25G and 10G speed.
FEC CL91 (RS-FEC) is supported for 25G and FEC CL74 (Fire-Code) and CL108 is supported for 25G port speed
FEC CL74 is enabled by default for 25G and other FEC values are supported and can be configured
Interfaces with LR optics doesn’t support FEC
Configuration CLI: #set interface <interface name> gigether-options fec <fec108/fec91/fec74/none>