Forward error correction (FEC) is a method of correcting certain data transmission errors that occur over noisy communication lines, thereby improving data reliability without requiring retransmission. FEC is helpful for applications that are sensitive to packet loss or corruption, such as audio, VoIP, and video conferencing. With FEC, the receiving firewall can recover lost or corrupted packets by employing parity bits that the sending encoder embeds in an application flow. Repairing the flow avoids the need for SD-WAN data to fail over to another path or for TCP to resend packets. FEC can also help with UDP applications by recovering the lost or corrupt packets, since UDP does not retransmit packets.