The optical amplifier reports the IN_PWR_HIGH alarm because of optical power reflection.
Symptom
A metropolitan area ring network composed of the OptiX Metro 6040 bears single wavelengths. After the local commissioning of all sites, if you shut down all the optical amplifiers such as the OPU and OBU, the IN_PWR_HIGH alarm is reported. In this case, if you power on some of the amplifiers, the optical power of the network is restored.
Cause Analysis
This problem is caused by optical refection of the amplifiers.
The sites of the network are OADM sites. That is, services pass through between the MI and MO optical interfaces on the MR2 boards of all the sites. If the pass-through wavelengths of the network are not blocked, optical power reflection of the amplifiers occur.
Procedure
- To solve this problem, the pass-through wavelengths between the MI and MO optical interfaces on the MR2 boards of the network must be blocked. If a wavelength bearing no services passes through the MR2 boards of all the sites, this wavelength must also be blocked. You can also add a electrically variable optical attenuator to the link between the MI and MO optical interfaces of each site, and set the attenuation of each electrically variable optical attenuator to the maximum value until more pass-through wavelengths are loaded.
- This method is used to avoid repeated amplification of noise.
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