Hello, everyone!
This post will tell you one issue for Analysis of the Downloading Process with One SCC on the OptiX OSN 3500.
Problem description:
One day, a customer used the interrupt downloading mode when changing the SCC. The services are intermittently interrupted for 16 seconds. The customer requested that a downloading test with one SCC on the OptiX OSN 3500 be performed in the lab environment.
TU_AIS. The version of the T2000 is V2R 6C 03. The version of the OptiX OSN 3500 is 5.21.13 .47.
Handling procedure:
Inform the customer that the service interruption duration is long for the OptiX OSN 3500 of 5.0 when the T2000 uses the interrupt downloading mode. The following conclusion is drawn from the downloading test.
During the downloading process of the OptiX OSN 3500, if the normal mode is used, the SDH service interruption duration is unpredictable. The SDH service is downloaded after the protection such as ring multiplexing section and linear multiplexing section. The SDH service is downloaded and checked packet by packet. Each packet contains 200 cross-connections (estimated value for reference only). After the last packet is downloaded and verified, the SDH service is recovered. After several attempts, it is found that the interruption duration for the SDH service ranges from more than ten seconds to several minutes. The T2000 downloading sequence is random. In theory, changing the downloading mode of the OptiX OSN 3500 to non-interrupt mode can avoid impact on the SDH service. That is, when the non-interrupt mode is used to download services, the SDH service interruption duration is no longer than 50 ms.
To ensure no impact on the service, the following conditions must be met:
The versions of the NE and service board must match.
The service configuration of the T2000 must be consistent with the current configuration of the NE.
No protection group on the NE can be in switching state.
No anomaly, such as reset and fiber disconnection, occurs on the NE during the downloading.
Risks of operation failure are high during downloading of the T2000. The purpose of the solution of recovering services through downloading by the T2000 is to rectify faults. This solution is mostly used when the SCC needs to be replaced. It is recommended that the SCC work in active/standby mode to efficiently reduce the frequency of downloading and greatly lower the risks in downloading by the T2000.
Root cause:
NA.
Solution:
Analysis of the downloading process is as follows:
1. During NE initialization of the downloading process, the SCC data is cleared and the SCC enters into the installation state. At this time, no configuration is delivered to boards. The services are not interrupted.
2. Create an MSP ring protection group after creating boards and dynamic port. Then, deliver the check command. At this time, configuration is delivered to the board. Service interruption starts.
3. The SDH service is downloaded packet by packet. The T2000 delivers each packet of 200 cross-connections to the OptiX OSN 3500. Each packet is verified after being downloaded. The next packet is downloaded when the verification of the previous packet is successful. As the verification of each packet is successful, the involved SDH service starts to be recovered. After all the packets of the SDH service are downloaded, the SDH service is completely recovered.
4. The downloading sequence of cross-connections is random. The T2000 code does not ensure that cross-connections with lower IDs are delivered first.
That's all, I welcome everyone to leave a message and exchange in the comment area!
Thank you！
