Optix Metro1000 Dual-Fiber Unidirectional Multiplexing Segment Protection Ring

On a two-fiber unidirectional multiplexed segment protection ring, one of the bi-directional STM-N lines is the working line and the other is the protection line. As shown in Figure 1, the services on the two-fiber unidirectional multiplexed segment protection ring use split routing. Before the protection inversion, the service signal flow from NE A to NE C is NE A→NE B→NE C, and the service signal flow from NE A to NE C is NE C→NE D→NE A. The protection inversion is not a protection route.

Under normal conditions, the service is transmitted on the working line. When the line is interrupted somewhere and the working line is unavailable, the service is inverted from the working line in the direction of fault to the protection line in the other direction at both ends of the fault point to realize protection inversion. The application of two-fiber unidirectional multiplexing segment protection ring is shown in Figure 1. After protection inversion, the service signal flow from NE A to NE C is NE A→NE D→NE C→NE B→NE C; the service signal flow from NE A to NE C remains unchanged, and still is NE C→NE D→NE A.

Fig. 1 Dual-fiber unidirectional multiplexing segment protection ring

Optix Metro1000 Dual-Fiber Two-Way Multiplexing Segment Protection Ring

On the two-fiber bidirectional multiplexing segment protection ring, the first half of the VC-4 of each STM-N line is the working channel, and the second half of the VC-4 is the protection channel. As shown in Figure 2, the services on the two-fiber bidirectional multiplexing segment protection ring use consistent routing. Before the protection inversion, the service signal flow from NE A to NE C is NE A→NE B→NE C, and the service signal flow from NE C to NE A is NE C→NE B→NE A. The protection inverted is the same as the protection inverted, and the protection inverted is the same as the protection inverted.

Under normal conditions, the service is transmitted on the working channel, and the service flows in the opposite direction on the two fibers. When the line is interrupted somewhere and the working channel is unavailable, the service is inverted from the working channel of the fiber in the direction of fault to the protection channel of the fiber in the other direction at both ends of the fault point to realize protection inversion. The application of two-fiber bidirectional multiplexing segment protection ring is shown in Figure 2. After protection inversion, the service signal flow from NE A to NE C is NE A→NE D→NE C→NE B→NE C; and the service signal flow from NE C to NE A is NE C→NE B→NE C→NE D→NE A.

Fig. 2 Dual-fiber bidirectional multiplexing segment protection ring

Protocol standards followed by the ring multiplexing segment protection

• ITU-T Recommendation G.841 Types and characteristics of SDH network protection architectures
• ITU-T Recommendation G.842 Cooperation of the SDH network protection structure