LSR_WILL_DIE Alarm of the WDM OTU Board Caused by Bookham Laser

By | August 15, 2014

Abstract:

The 10G optical transponder unit (OTU) boards that are delivered before August 2011 use the Bookham laser on the WDM (OptiX BWS 1600G, BWS 1600S, Metro 6100,OptiX OSN 8800,OSN6800)side. After the boards have worked for one and half a year, the LSR_WILL_DIE alarm was reported on the WDM side for 0.43% of boards, and the alarm was not cleared. When the alarm was generated, services were not interrupted.

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[Problem Description]
Trigger conditions:
The LSR_WILL_DIE alarm is not triggered by external conditions. When the boards work properly, the LSR_WILL_DIE alarm is reported for 0.43% of boards.
Fault symptom:
After the boards have worked for one and half a year, the LSR_WILL_DIE alarm is reported on the WDM side for some boards, and the alarm is not cleared. When the alarm is generated, services are not interrupted. However, the laser life cycle is increased to 100% within two months.

In this case, mode hopping may occur (the wavelength is shifted to adjacent wavelength or other ITU wavelengths). As a result, downstream services are interrupted. Therefore, the alarm must be cleared.
Identification method:
Install the latest patch of SmartKit NSE2700 V002R006C00 or later, start the SmartKit NSE2700, click Statistics Items, click Module special StatisticItem, and select 10G module age, as shown in the following figure. The SmartKit NSE2700 earlier than V002R006C00 does not provide the 10G module age option. In the generated 10G module life cycle statistical report, you need only to view the information about the OTU boards with TL5000BCJ Bookham lasers whose life cycle is greater than 70%.

The following table describes the mapping between the module software and the modules that support life cycle inspection and laser upgrade.

As shown in the following module life cycle statistics report, for the board with the bar code 030JDC1089000177, the type of the WDM-side module is SSX2T2DR, the laser vendor is Bookham, the laser type is TL5000BCJ, and the life cycle is 77%. The LSR_WILL_DIE alarm may be reported for this module. You need to upgrade its laser software to V1.7.23 by following the Bookham Laser Software Upgrade Guide. For the board with the bar code 030ETB10A4000002, the module type is SSX2T2TM, and the module software version is 150T01. The life cycle of this module cannot be directly queried. You need to upgrade the module to V160T03 by following the description in section 3.5 in the Bookham Laser Software Upgrade Guide, and then query the life cycle of the module.

[Root Cause]
Some Bookham lasers report the LSR_WILL_DIE alarm after they have worked for one and half a year due to the defect of the laser software.
[Impact and Risks]
When the Bookham laser reports the LSR_WILL_DIE alarm, the board performance is not affected and services are not interrupted. However, when the laser life cycle is increased to 100%, mode hopping may occur (the wavelength is shifted to adjacent wavelength or other ITU wavelengths), which causes service interruption.

Solutions:
If the board has reported the LSR_WILL_DIE alarm or the queried life cycle of the board is greater than 70%, upgrade the laser software to V1.7.23 by following the Bookham Laser Software Upgrade Guide. Services are interrupted for less than 10 minutes during upgrade. It takes about 15 minutes to upgrade a board.

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