The Protection Switching Times Out Severely

The protection switching time is out severely in the event of wavelength protection between the SCS boards of the OptiX Metro 6100 because of the wrong test method.

Product

OptiX OSN6800

OptiX OSN8800

Fault Type

Protection

Symptom

In the test of inter-board wavelength protection of the SCS board, the test result is severely beyond the standard. The minimum switching time is over 1000 ms and the maximum switching time even reaches up to 3000 ms. The standard switching time should be less than 50 ms. As a result, the test result is far from the required switching time.

The test meter used on site is the ANT-20SE.

The test procedure is as follows:

1. Perform a hard loopback between the IN and OUT optical interfaces of the LQS board by using a fiber, and connect the TI1 and RO1 optical interfaces of the SCS board to the test instrument.
2. Configure inter-board wavelength protection by using the T2000.
3. After completing the configuration, test the inter-board wavelength protection by using the tester. No alarm is found and the optical path is normal.
4. Disconnect the fibers on the client-side optical receiving interfaces of the active and standby LQS boards. The protection switching can be completed but times out severely.

Cause Analysis

The trigger condition of the wavelength protection switching is an anomaly of service receiving on the WDM side. Hence, the correct test moth is to remove the fiber on the WDM side of the LQS board. During the test, however, the client-side receive fiber of the LQS board is removed. Hence, the switching process is as follows:

• Remove the client-side receiving fiber of the LQS board.
• The LQS board shuts down the WDM-side laser according to the ALS function in about 2 seconds.
• The system detects that there is no optical input on the WDM-side optical interface of the LQS board. Hence, the board reports the SF event.
• The protection group switches over to the protection path.

Hence, the actual test time includes the switching time and the time taken for the ALS to close the laser. As a result, the switching times out severely.

Procedure

1. The test method is changed to perform by disconnecting the WDM-side fiber, the switching time is normal.
2. The test is past after the test method is changed to perform by disconnecting the WDM-side fiber.

Reference Information

None.

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