Automatic switching is caused by the incorrect service configuration of ODUk SPRing protection.
Fault Type
Protection
ODUKSP_PS
OTU2_SSF
ODU2_PM_SSF
ODU1_PM_OCI
Symptom
On a
WDM ring network, the OptiX OSN 6800 V100R004C01 is used. Four OADM stations, that is, stations A, B, C, and D, are distributed anticlockwise on the network. Two NS2 boards are configured at each of the four stations and one TQS board is configured at each of stations A and C. In addition, STM-16 services are provisioned in an ODU1 channel between stations A and C. The STM-16 services are configured with ODUk SPRing protection.
The electrical-layer configuration of ODUk SPRing protection is as follows:
- Each station is configured with one ODUk SPRing protection group. The working and protection units (timeslots) of the west and east NS2 boards are mapped according to the network design: The NS2 board in slot 104 is set as the west board and the NS2 board in slot 105 is set as the east board. The first ODU1 of each board is set as the working timeslot of the board and the second ODU1 of the board is set as the protection timeslot of the board.
- At station A, the bidirectional services from the TQS board to the working timeslot of the NS2 board in slot 104 (west board) are configured. At station C, the bidirectional services from the TQS board to the working timeslot of the NS2 board in slot 105 (east board) are configured.
- Station A is set as the management node.
- The span ID for working services is set.
- The protection subnet is searched and obtained.
One day, a protection switching occurs on the current protection subnet. The original service route is station A -> station D -> station C, and the service route after the protection switching is station A -> station B -> station C.
Switching Status of station A is West Switching and Switching Status of station C is East Switching.
In the NE Explorer, click the NE. In the Function Tree, choose . In the displayed window, click Query to query the switching status of the current protection group. In the case of station A, the value of West Switching Request is SF Ring Switching - Working SF Protection SF and the value of West Remote/ Near-End Indication isNear-End. In the case of station D, the value of East Switching Request is SF Ring Switching - Working SF Protection SF and the value of East Remote/ Near-End Indication is Near-End. In the case of the other stations, the value of Switching Status is Stopped.
The SCC boards at stations A and C report the ODUKSP_PS alarm.
The NS2 board in slot 104 at station A and the NS2 board in slot 105 at station C report the OTU2_SSF and ODU2_PM_SSF alarms.
In addition, the ODU1_PM_OCI alarm is reported at stations A and C.
Cause Analysis
Use an SDH analyzer to test the NS2 board at station A. The test result shows that the services of the board are available. This indicates that the protection switching is normally implemented. On the T2000, the OCh trail from station A to station D and the OCh trail from station C to station D can be searched out and no alarm is found at the OCh layer. This indicates that the optical power is within the normal range.
Alarm analysis:
- The ODUKSP_PS alarm indicates that an APS switching occurs in the ODUk SPRing protection group.
- SSF indicates that the server-layer trail fails. The OTU2_SSF and ODU2_PM_SSF alarms indicate that the electrical-layer services are unavailable. A check shows that the cause of the alarms is that the ODU1 cross-connection between the working timeslots of the west and east NS2 boards at station D is not configured. The ODU1_PM_OCI alarm indicates that the ODU1 cross-connections between stations A and C are disconnected (that is, the services are unavailable).
- When the ODU1_PM_OCI alarm is reported, it indicates that the ODU1 cross-connections between stations A and C are disconnected (that is, the services are unavailable).
Procedure
- Manually configure the ODU1 pass through cross-connection between the working timeslots of the west and east NS2 boards at station D. Set the first ODU1 of each board as the working timeslot of the board. In this case, the services are switched back to the normal route station A -> station D -> station C because the ODUk SPRing protection is revertive.
- In the NE Explorer, click the NE. In the Function Tree, choose . In the displayed window, set Switching Status of stations B and D to Stopped and set Switching Status of stations A and C to Idle.
Result
The services at the management node (station A) are fed to three channels: the protection channel in the east direction, the protection channel in the west direction, and the working channel in the working direction (west for example). At station A (the management node), however, only the bidirectional services over the working channel in the working direction need to be manually configured. The ODUk SPRing protection group automatically generates the services to travel from the TQS boards to the protection channels.
At station C (the station where certain services are added and dropped), the unidirectional services to travel in the working direction need to be manually configured.
At station D (the pass through node of the services in the working direction), the ODU1 cross-connection between the working timeslots of the west and east NS2 boards must be manually configured.
At station B (the pass through node of the services in the protection direction), the ODU1 cross-connection between the working timeslots of the west and east NS2 boards need not be manually configured because the protection group automatically generates this cross-connection.
Reference Information
None.
