The OptiX OSN equipment fails to interconnect with the SONET equipment. Check the relevant information. It is found that all the optical interface boards must be of the N2 series and that the pass-through services must be configured at the 3xAU-3 level. Otherwise, the interconnection fails.
Product

OptiX OSN 2500
Fault Type

Equipment_Interconnection_Fault
Symptom

On the STM-16 MSP ring comprising the OptiX OSN 2500, two stations are added with the N2SLQ1 boards, on which one STM-1 optical port is added to support the interconnection between the OptiX OSN 2500 and the SONET equipment. The pass-through services on the MSP ring are configured at the VC-4 level. Connect the analyzer to the OptiX OSN 2500 and the SONET equipment. It is found that the analyzer shows normal test results. Interconnect the OptiX OSN 2500 and the SONET equipment, perform the test again, and then find that the corresponding ports of the equipment on both the sides report AIS and that the services are unavailable.
Cause Analysis

The analysis result shows that the OptiX OSN 2500 and the SONET equipment are normal. Hence, the fault may exist in the interconnection. In this case, check whether the overheads of the OptiX OSN 2500 and the SONET equipment are consistent, whether the OptiX OSN 2500 and the SONET equipment has any restrictions on interconnection, or whether any special configurations are required.
Procedure

Check the relevant information. It is found that the SDH service configuration is correct, that the N2-series boards are auto-adaptive in interconnecting with the SONET equipment, and that the overheads such as the S1 byte are transparently transmitted.
Check other SDH boards. It is found that the N2-series optical interface boards are only used for interconnection and that the boards on the line side are N1-series optical interface boards. Then, it is confirmed that all the optical interface boards should be of the N2 series.
Replace the in-service N1-series optical interface boards with N2-series optical interface boards (including the N2SL16 and N2SLQ1). Configure the pass-through services on the entire MSP ring at the VC-4 level. The services, however, are still unavailable.
Refer to the deployment guide. It is found that the 3xAU-3 services are added to the N2-series optical interface boards. Note that the pass-through services must be configured at the 3xAU-3 level, not at the VC-4 level, in the case of interconnection with the SONET equipment.
When the pass-through services on the entire transmission link are configured at the 3xAU-3 level, the services are normal and the interconnection between the OptiX OSN equipment and the SONET equipment is successful.
Reference Information

The N2-series optical interface boards on the OptiX OSN equipment can interconnect with the SONET equipment only when the following conditions are met:
All the line boards must work with N2-series optical interface boards (for example the N2SL64, N2SL16, and N2SLQ1 boards), instead of the Q2SL16 and Q2SL4 boards.
The pass-through services must be configured at the 3xAU-3 level, not at the VC-4 level.