Link degrade monitor: Pre-FEC BER Fast reroute (BIP8)

Pre-FEC bit error rate (BER) fast reroute (FRR) uses the pre-forward error correction (pre-FEC) BER as an indication of the condition of an OTN link. When the pre-FEC BER degrade threshold is reached, the interface stops forwarding packets to this interface and raises an interface alarm. Ingress packets continue to be processed. You can optionally enable backward FRR to inject the local pre-FEC status into the transmitted OTN frames, notifying the remote interface. The remote interface then reroutes traffic to a different interface. When backward FRR is enabled, notification of signal degradation occurs in less time than through a Layer 3 protocol.