Forward Error Correction (FEC) works by adding redundant bits to a data stream to enable the recipient to detect and correct errors or omissions in the data stream.
FEC can be beneficial in reducing packet loss in the event of a fault on a tail technology, particularly when transmitting over xDSL. However FEC will not fix the underlying issue with the technology and will compromise capacity as the total amount of data will be reduced due to the addition of the redundant parity bits.
FEC is therefore potentially useful whilst a diagnostic process is being followed, and to temporarily ameliorate stability issues on a faulty link whilst a permanent fix is being delivered.
The most useful use case for FEC is when using mobile solutions (especially 4G) as the underlay technology in an SD-WAN. The inherently unstable latency of mobile data streams can be mitigated through the deployment of forward error correction within the INF.
When aggregating multiple mobile connections together, FEC can deliver improved stability and therefore data transfer rates and resilience.