Enabling Forward Error Correction
The Forward Error Correction (FEC) functionality reduces the loss of traffic packets in links, especially for UDP applications, and the number of retransmissions, which lead to delays, and also recovers received data on the CPE device. Data recovery is provided by redundant encoding of the data stream on the device on the sending side.
We recommend using FEC on noisy links to reduce the packet loss and increase the speed of TCP connections.
The sender CPE encodes the stream of traffic packets egressing into the tunnel, adding redundant packets. The use of encoding on the sending and receiving sides may cause delays due to extra data processing. You can configure the degree of redundancy in the settings of the SD-WAN Controller or when you enable FEC.
The receiving CPE device buffers traffic packets received through the tunnel and decodes them, recovering lost packets, if possible. The general diagram of FEC is shown in the figure below.
FEC diagram
You can enable FEC on an individual tunnel. The tunnels are displayed in a common table in the Tunnels section; in the graphical topology in the Topology section; and in the CPE device configuration on the Tunnels tab. Only tunnels built using the particular CPE device are displayed in the configuration of that device.
To enable FEC on a tunnel, use the following instructions: