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Ultra-Long-Haul Interconnection Fails Due to Inconsistent Board Models in TDM and HYB Versions on the OSN 3500

Publication Date:  2019-04-15 Views:  106 Downloads:  0

Issue Description

When two OSN 3500 devices are interconnected using SF16E+OBU+DCU, the 200 km ultra-long haul link needs to be provisioned. After the interconnection is complete, the receive optical power meets the requirement. However, SF16E boards at both ends report the BEFFEC_EXC alarm. The signal flow is as follows.

Alarm Information


Handling Process

1. Check the receive optical power of the SF16E boards at both ends. The power values are -15 dBm and -17 dBm respectively, which meet the receive sensitivity requirement (-28 dBm).

2. Use fibers and optical attenuators to perform self-loops on the SF16E boards at both ends. The BEFFEC_EXC alarm is cleared.

3. Apply an 80-km module at the receive end of DCU. The dispersion tolerance of the SF16E board is 2400ps/nm (120 km after conversion).

4. According to the signal flow SF16E(OUT)-DCU(IN)-DCU(OUT)-SF16E(IN), use a fiber to perform a loopback test. The BEFFEC_EXC alarm is cleared.

5. Perform loopback tests on the OBU1 and BPA boards respectively according to step 4. The BEFFEC_EXC alarm is cleared.

6. Add an optical attenuator (from 2 dBm to 5 dBm) to the OBU1(OUT) port at the transmit end. The alarm persists on the SF16E board and bit errors are accumulated on the performance query interface (not non-linear effect).

7. Obtain the barcode from the customer feedback on the live network. It is suspected that the board does not match. The customer reports the barcode of the board is SSN1SF16E in the PDM system. Check the two OSN 3500 NE versions of the customer. The NE versions are V200R013 and V100R010. The board is supported since V200R012C00.

In conclusion, the SF16E board is not supported by the OSN 3500 V100R010. In this version, the logical board is manually added as the SF16 board. As a result, the interconnection fails.

Root Cause

The SF16E board is supported since the V200R012C00. The board cannot be used in the TDM version.


Delete the SF16 logical board from the NMS and remove the SF16E physical board. Delete the NE database data of the V100R010 version and upgrade the version to the V200R013 version. Re-insert the SF16E board and add the logical board (SF16E). The alarm is cleared and services are provisioned.


The SDH long-haul interconnection scenario is widely accepted by customers. The interconnection depends on the optical cable quality. The model of the optical amplifier board varies according to the attenuation. For details, see the long-haul interconnection guide. This fault analysis describes how to troubleshoot the long-haul interconnection failure. The cause lies in the SF16E board, which is supported only since V200R012C00.