The SW SNCP protection utilizes the dual fed and selective receiving function of the cross-connections at the electrical layer to protect the line board and OCh fiber.
Trigger Conditions
The trigger conditions for the SW SNCP automatic switching are as follows:
In the case of the OptiX OSN 3800A/6800A/8800 T16 (NA)/8800 T32 (NA)/8800 T64 (NA):
- The board is offline, including the following situations: Removing or cold resetting the board.
- There is a signal failure (SF) condition. SF includes the following board-side alarms: LOF, LOS, LOC, OTU-LOF, OTU-LOM, OTU-AIS, ODU-AIS, ODU-OCI, ODU-LCK, ODU-LOFLOM, REMC-SF.
- There is a signal degraded (SD) condition. SD includes the following board-side alarms: SF-S, OTU-DEG, OTU-EXC, ODU-DEG, ODU-EXC, REMC-SD.
In the case of the OptiX OSN 1800 (NA):
- The board is offline, including the following situations: removing or cold resetting the board.
- There is a signal failure (SF) condition. SF includes the following board-side alarms: LOF, LOS, LOC, ODU-AIS, ODU-OCI, ODU-LCK, OTU-AIS, OTU-LOF.
- There is a signal degraded (SD) condition. SD includes the following board-side alarms: SF-S, ODU-DEG, ODU-EXC, OTU-DEG, OTU-EXC.
Working Principle
The SW SNCP protects inter-subnet services and requires no protocol. The SW SNCP provides protection for topologies such as ring with chain, tangent rings, intersecting rings. This ensures high flexibility in application.
Figure 1 shows the principle with the SW SNCP as an example.
Figure 1 Working principle of the SW SNCP
 : Direction of the working signal flow |
 : Direction of the protection signal flow |
NOTE: - In Figure 1, OTU 2 and 4 stand for the working OTU 1 and 3 stand for the protection OTU. They can realize dual fed and selective receiving by integrated or distributed cross grooming. Integrated cross grooming use the XCS boards to realize dual fed and selective receiving, which is not shown in Figure 1.
- The SCC board communicates with OTU through the backplane. This communication is not indicated in Figure 1.
- The FIU can be optional according to the networking requirement.
- At the transmitting end, the client services to be protected are input through the working OTU and are cross connected to the protection OTU. The working signals and the protection signals are transmitted in the working channel and in the protection channel respectively.
- At the receiving end, when the operating is normal, only the cross connection of the working OTU is enabled; that of the protection channel is disabled. When the working channel is faulty, the cross connection of the working channel at the receiving end is disabled. The cross connection of the protection channel corresponding to OTU 3 is enabled. The services are transmitted in the working channel.
- After the working channel returns to normal, the service signals can be switched back to the given OTU according to the existing configuration of restoration mode in the NMS.