1. Protection Principle
Yes. 1+1 Linear Multiplex Section Protection can protect existing services after the protection group is correctly configured.
From the protection mechanism, the protection switching is mainly determined by K-byte signaling and the status of the working and protection paths. Whether a service was configured before or after the protection is established is not a prerequisite for protection.
Therefore, existing services can also be covered by the 1+1 Linear Multiplex Section Protection.
However, simply configuring 1+1 protection on two STM-4 optical ports is not sufficient. The physical paths and optical conditions should be checked first.
2. Check the STM-4 Optical Paths
Before configuring protection, first check whether the two STM-4 paths have any common points, such as:
Common board or hardware resources
Common optical path
Other possible single points of failure
The working and protection paths should be as independent as possible.
For example, on an OSN3500, the two STM-4 ports can be arranged on corresponding paired slots/ports, such as:
| Working/Protection | Example |
| STM-4 Working Path | Slot 8, Port 1 |
| STM-4 Protection Path | Slot 11, Port 1 |
The actual slot and port numbers should be determined according to the specific equipment configuration.
3. Check Optical Power and Alarms
After confirming the port arrangement, check the optical status of both STM-4 paths.
| Check Item | Requirement |
| Optical Power | Both paths should have normal optical power |
| LOS/LOF | No abnormal alarms |
| Link Stability | Both optical paths should operate normally |
| Fiber Condition | No obvious fiber or connection problems |
If any abnormal optical or hardware issue is found, resolve it before configuring protection.
This helps avoid unexpected protection switching and makes subsequent troubleshooting easier.
4. Configure 1+1 Linear Multiplex Section Protection
After confirming that both STM-4 paths are healthy and sufficiently independent, configure the 1+1 Linear Multiplex Section Protection.
The basic procedure is:
Check physical paths → Adjust ports if necessary → Check optical power → Clear existing issues → Configure 1+1 protection → Verify protection switching
5. Key Point
The important point is that existing services do not prevent 1+1 Linear Multiplex Section Protection from taking effect.
The protection mechanism is based on the status of the transmission paths and K-byte signaling, rather than whether the service was configured before the protection group.
However, the protection should not be configured directly without checking the underlying optical paths. Path independence and normal optical conditions are the key prerequisites for reliable protection.
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