Configuring Bit-Error-Triggered Section Switching
This section describes how to configure bit-error-triggered section switching.
Usage Scenario
Bit errors caused by optical fiber aging or optical signal jitter may exist on carrier networks. These bit errors may result in the interruption of services with high quality requirements. In a scenario in which services travel along an LDP LSP and LDP auto fast reroute (FRR) is configured for the LDP LSP, you can configure bit-error-triggered LDP LSP switching to protect services against bit errors.
To do so, you only need to enable bit error detection on interfaces along the primary and backup paths of the LDP LSP and set the switching type of each interface as trigger-section. If an interface encounters a bit error event after you configure bit-error-triggered LDP LSP switching, the interface changes its status to Down and triggers route convergence, which in turn triggers LDP LSP switching.
Pre-configuration Tasks
Before configuring bit-error-triggered section switching, complete the following tasks:
Enable Bidirectional Forwarding Detection (BFD) globally.
Procedure
- Run system-view
The system view is displayed.
- Run interface interface-type interface-number
The interface view is displayed.
- Run trap-threshold crc-error packet-error-ratio alarm-threshold coef-value pow-value [ resume-threshold rsm-coef-value rsm-pow-value ] [trigger-lsp |trigger-section]
Bit error detection is enabled, and the thresholds for triggering bit error event alarms are set.
To enable bit-error-triggered LDP LSP switching to take effect, you must specify trigger-section.
To enable bit-error-triggered trunk update to take effect, you must specify the switching type, either trigger-lsp or trigger-section
The alarm-threshold value equals alarm-coe multiplied by 10-alarm-pow. If the BER detected by a trunk member interface exceeds the alarm-threshold value, the trunk member interface reports an alarm indicating that a bit error event has occurred.
The resume-threshold value equals resume-coe multiplied by 10-resume-pow. If the BER detected by a trunk member interface falls below the resume-threshold value, the trunk member interface reports an alarm indicating that the bit error event is over.
The resume-threshold value cannot be greater than the alarm-threshold value.
If you do not specify the resume-threshold value, the system automatically uses tenth of the alarm-threshold value as the resume-threshold value.
- Run commit
The configuration is committed.
Checking the Configurations
After an interface along the primary or backup paths of an LDP LSP encounters a bit error event, run the following commands to check the configurations:
Run the display interface interface-type interface-number command. The command output shows that the link protocol status of the interface that has encountered the bit error event is DOWN(bit-error-detection down).
Run the display mpls lsp command. The command output shows LDP LSP configurations.
Before a bit error event occurs, run the tracert lsp ip destination-address mask-length command. The command output shows that the LDP LSP uses the primary path to transmit services.
After a bit error event occurs, run the tracert lsp ip destination-address mask-length command. The command output shows that the LDP LSP uses the backup path to transmit services.