Some flavors of optical ethernet do have FEC: https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/implementation-optics-wp.

Some flavors of optical ethernet do have FEC: https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/implementation-optics-wp.html https://www.cisco.com/c/en/us/products/collateral/interfaces...