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Hierarchy Level


Enable or disable pre-forward error correction (FEC) bit error rate (BER) monitoring.

With pre-FEC BER monitoring enabled, when the configured pre-FEC BER signal degrade threshold is reached, the PIC stops forwarding packets to the remote interface and raises an interface alarm. Ingress packets continue to be processed. If pre-FEC BER monitoring is used with MPLS fast reroute or another link protection method, then traffic is rerouted to a different interface.

You can also configure backward fast reroute to insert local pre-FEC BER status into transmitted OTN frames, notifying the remote interface of signal degradation. The remote interface can use the information to reroute traffic to a different interface. If you use pre-FEC BER monitoring together with backward fast reroute, then notification of signal degradation and rerouting of traffic occurs in less time than that required through a Layer 3 protocol. To configure backward fast reroute, include the backward-frr-enable statement at the same hierarchy level.


When you configure pre-FEC BER signal degrade monitoring, we recommend that you configure both the signal-degrade-monitor-enable and backward-frr-enable statements.

You can also configure the pre-FEC BER thresholds that raise or clear a signal degrade alarm and the time interval for the thresholds. If the BER thresholds and interval are not configured, the default values are used. Include the ber-threshold-signal-degrade value, ber-threshold-clear value, and interval value statements at the [edit interfaces interface-name otn-options signal-degrade] hierarchy level to configure the BER thresholds and time interval. See Understanding Pre-FEC BER Monitoring and BER Thresholds for more information about pre-FEC BER monitoring and determining BER threshold settings.


By default, pre-FEC BER signal degrade monitoring is disabled.


signal-degrade-monitor-enable—Enable pre-FEC BER signal degrade monitoring.

no-signal-degrade-monitor-enable—Do not enable pre-FEC BER signal degrade monitoring.

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 13.2.