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Cisco ONS 15454 DWDM Reference Manual, R8.5
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Chapter 10 Network Reference
10.6 Span Loss Verification
10.6 Span Loss Verification
Span loss measurements can be performed from the Maintenance > DWDM > WDM Span Check tab
(Figure 10-13). The CTC span check compares the far-end OSC power with the near-end OSC power. A
Span Loss Out of Range condition is raised when the measured span loss is higher than the maximum
expected span loss. It is also raised when the measured span loss is lower than the minimum expected
span loss and the difference between the minimum and maximum span loss values is greater than 1 dB.
The minimum and maximum expected span loss values are calculated by Cisco TransportPlanner for the
network and imported into CTC. However, you can manually change the minimum and expected span
loss values.
CTC span loss measurements provide a quick span loss check and are useful whenever changes to the
network occur, for example after you install equipment or repair a broken fiber. CTC span loss
measurement resolutions are:
• +/– 1.5 dB for measured span losses between 0 and 25 dB
• +/– 2.5 dB for measured span losses between 25 and 38 dB
For ONS 15454 span loss measurements with higher resolutions, an optical time domain reflectometer
(OTDR) must be used.
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