In evaluating FEC, if you see FEC corrected errors but no uncorrected errors, what does that indicate?

• A. No issues; FEC is not needed.
• B. FEC corrected errors indicate there are detectable transmission errors being corrected by FEC.
• C. The presence of FEC corrected errors with zero uncorrected errors suggests the link is experiencing errors that FEC is correcting.
• D. The link is down.

Answer: (C)

Forward Error Correction adds extra bits so the receiver can detect and fix a certain number of bit errors without asking for retransmission. When you see errors that FEC has corrected but no errors that remain uncorrected, it means the channel was noisy and introduced some errors, but those errors were within what the FEC code can fix. The data is being recovered successfully, so the link is operating with FEC doing its job rather than being completely faulty. If there were uncorrected errors, that would indicate the channel exceeded FEC capability or a deeper issue; here the absence of uncorrected errors shows the system is handling the noise effectively.