Span loss
Span loss is the optical signal loss over a fiber span between two network nodes. It is measured by comparing power levels at the transmitting (Tx) and receiving (Rx) ports, typically in decibels (dB). If span loss exceeds thresholds, alarms like "Span Loss Value Out Of Range" are triggered.
Span loss calculations
The span loss calculation is an automatic process for determining span losses between NCS 1014 nodes. The span loss verification algorithm calculates span loss by comparing power measurements at the line TX/RX port at the far-end and the line RX/TX port at the near end. If the span loss is not within configured thresholds, the algorithm raises the "Span Loss Value Out Of Range" alarm.
Span loss reporting
The span loss application periodically reports the span loss value for a span every few seconds. If there are changes in span loss, such as those caused by variations in fiber loss, the application typically updates the span loss value between 10 to 30 seconds after the value has stabilized.
Span loss verification reports these values:
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OSC span loss
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Signal span loss
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Span loss
OSC span loss
RX OSC span loss: This is the difference between the received OSC signal power at the near end and the transmitted OSC signal power at the far-end. It refers to the fiber entering the LINE RX port.
TX OSC span loss: This is the difference between the transmitted OSC signal power at the near end and the received OSC signal power at the far-end. It refers to the fiber exiting the LINE TX port.
Signal span loss
RX signal span loss: This is the difference between the received C-band signal power at the near end and the transmitted C-band signal power at the far-end. It refers to the fiber entering the LINE RX port.
TX signal span loss: This is the difference between the transmitted C-band signal power at the near end and the received C-band signal power at the far-end. It refers to the fiber exiting the LINE TX port.
Span loss
RX span loss: This measurement is the difference between the received total power at near-end and transmitted total power at far-end.
TX span loss: This measurement is the difference between the transmitted total power at near-end and received total power at far-end.
Configure span loss thresholds
Use this task to configure span loss thresholds
Before you begin
Procedure
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Step 1 |
Use the commands optical-line-control and controller ots R/S.I/P to enter the optical applications configuration mode and select the controller on which the span loss thresholds need to be configured. The span loss can be configured only controller ots on R/S/I/0. Example: |
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Step 2 |
Use the keywords span-loss min value and span-loss max value, to configure the minimum and maximum span loss threshold values. Example: The example sets the minimum threshold to 0.0 dB and the maximum threshold to 42.0 dB. The system raises a SPAN-LOSS-OUT-OF-RANGE alarm when 'Rx span loss' is greater than the maximum threshold or lesser than the minimum threshold. |
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Step 3 |
Commit the changes and exit all the configuration modes. Example: |
View the span loss measurements
Use this task to view the various span loss measurements.
Procedure
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Use the show olc span-loss command to view the various span loss measurements. Example: The entries, highlighted in bold, show the span loss measurements. |
Verify span loss configurations
Use this task to verify the span loss configurations.
Procedure
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Verify the configured values using the show running-config optical-line-control controller ots command. Example: The entries, highlighted in bold, show the values of span loss thresholds configured. |
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