This section describes the application of the intra-board 1+1 protection.
The intra-board 1+1 protection realized by the OLP or DCP and that realized by dual fed and selective receiving OTU share the same application. The latter is taken for example.
As shown in Figure 1, station A and station B form a ring network in project T. Both A and B are OADM stations. The Intra-board 1+1 protection is adopted between the two stations. Each station is configured with an OTU board (with the dual-fed signal selection function).
 : Direction of the working signal flow |
 : Direction of the protection signal flow |
See Figure 1.
The OTU in station A sends signals to station B by the working route and the protection route at the same time. When signals reach station B, only the signals in the working route are sent to the client-side equipment by the OTU.
Similarly, the OTU in station B sends signals to station A by two routes at the same time. In station A, only the signals in the working route are sent to the client-side equipment.
| : Direction of the working signal flow |
: Direction of the protection signal flow |
See Figure 2.
When the working route between A and B is faulty, the receive OTU board chooses the protection route and sends the protection signals to the client side.