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The Wavelength Lockout of the WMU on the OptiX OSN 6800 Depends on the Logical Fiber Connection

Publication Date:  2012-07-25 Views:  37 Downloads:  3
Issue Description

The OptiX OSN 6800 is configured with the WMU. Wavelength lockout is performed for the OTU. After a period of time when the OTU is configured on the WMU, the WMU reports the WAVE_LEN_OVER alarm. OTU monitoring is deleted from the WMU, and hard reset is performed on the OTU. On the second day, the drift of the wavelength of the OTU is still serious.

NE version: V100R004C02B01j(5.51.04.24) 
Alarm Information
WAVE_LEN_OVER
Handling Process
1.       Delete the OTU monitoring configuration of the WMU. Run :cfg-scramble-search to start wavelength lockout manually. On the MCA, it is found that the wavelength drift occurs on the OTUs in two directions.

2.       Query the tube core temperature of the two OTUs, that is, query the central frequency by running :optp:1,1,83,1,ff,3d,1,1,0;. The information "#9-1660:szhw [1660-Renhe][][2009-09-19 10:48:00+08:00]>" is returned.

:optp:2,1,83,1,ff,3d,1,1,0;
Optp cmd : ff3d                                                                   
01 01 00 00 00 09 c6

The last two bits of the tube core temperature of the OTU are in direct proportion to the wavelength.

3.       Set the tube core temperature manually. Set the central frequency of the OTU to an offset. Not that the offset should be a small value. The WMU can lock only the offset within ±10 GHz.

:optp:2,1,83,1,ff,3c,1,1,0,00,00,0a,16;

4. Start wavelength search once manually after querying the wavelength through the MCA.

5. After one minute, use the MCA to query the central wavelength. The query result shows that the offset is larger. It indicates that the offset becomes larger after the adjustment.

6. Run :log-query:1,"bb10.log"; to query the black box of the board. (Note that you must initialize the black box before running the command. Otherwise, there are too many records to be viewed.)

7. Check whether the adjustment is valid based on the records in the black box. Start adjustment for several times manually. View the black box of the OTU. If there is no record in the black box, it indicates that the adjustment occurs on other OTUs. If there are multiple adjustment records about the OTU, but the wavelength drift in the WMU performance is still large, it is possible that the wavelength detected by the WMU is not transmitted by the OTU.

8. The preceding operations determine that the WMU can be adjusted. The offset, however, becomes larger after the adjustment.

9. Check the physical fiber connection. The check result shows that the physical fiber connection is proper. Compare the physical fiber connection diagram with the logical fiber connection. The result shows that the logical fiber connection is improper. Re-configure the logical fiber connection, and the WMU lockout is normal.

When the WMU is not configured, the WMU can adjust the central wavelength of the OTU. Why?

The wavelength is adjusted according to the logical fiber connection. When the WMU is not configured, the adjustment is performed according to the logical fiber connection. When the WMU is configured with wavelength monitoring, but the configuration is inconsistent with the logical fiber connection, the OTU is adjusted incorrectly. Pay attention to this point during maintenance. 
Root Cause

1.       The OTU fault causes the drift of the wavelength.

2.       The WMU fails. As a result, wavelength information cannot be detected correctly, or wavelength adjustment information cannot be reported to the SCC correctly.

3.       The fiber connection error causes incorrect adjustment.

 
Suggestions
In the R004C02 version, the WMU wavelength lockout has two modes, namely, depending on the logical fiber and board monitoring (which does not depends on the logical fiber). When the WMU is not configured, the wavelength is adjusted according to the logical fiber connection. When the WMU is configured with wavelength monitoring, but the configuration is inconsistent with the logical fiber connection, the OTU is adjusted incorrectly. Pay attention to this point during maintenance.

END