 loss of resource (fiber cut). In the first case, events are described for conven- tional rings; in the second case, the events are for BWDM-based rings. Single- and Dual-Fiber Cuts in the SRP Ring SRP technology is capable of recovering from either a single- or dual-fiber cut. If a single fiber is cut in the SRP ring between nodes A and B, the following occurs: 1. Node B detects the fiber cut and then wraps the ring. 2. Node B sends a short message to node A on the inner ring and a long message through nodes C and D on the outer ring. 3. On receiving the short message from node B, node A wraps the ring and sends a short message to node B (this message is lost because of the fiber cut) and a long message through nodes D and C. The result of these operations is that the ring is now wrapped and all nodes are connected. (See Figure 6-13.) If a dual fiber is cut in the SRP ring between nodes A and B, the result is exactly the same as for the single-fiber cut. The following occurs: 1. Node B detects the signal failure and wraps the ring. 2. Node B then sends a short message to node A on the inner ring and a long message through nodes C and D on the outer ring. Coarse Wavelength Division Multiplexing (CWDM) Technology Figure 6-13 IPS solution to single- fiber cut. 3. Node A also detects the signal failure and wraps the ring. 4. Node A then sends a short message to node B on the outer ring and a long message through nodes D and C on the inner ring. Fiber Cut in BWDM Fiber A single-fiber cut in a fiber-optic cable car- rying BWDM signals is actually analogous to a dual-fiber cut because both the receive and transmit signals are disrupted. However, a system will recover from this situation as in the previous scenario of a single-fiber cut. (See Figure 6-14.) In this example, nodes D and E are connected to the ring via a BWDM link. If a fiber is cut on one of the BWDM links, the following occurs: 1. Node D detects the signal failure and wraps the ring. 2. Node C also detects the signal failure and wraps the ring. The resul