Consider the two-fiber bidirectional line switched ring (2F-BLSR) shown in Figure 1. What is the total available capacity of the ring for the transmission of the working traffic from ADM 1 to ADM 2 when A communicates with B? a. When all fibers are working? b. When fibers 2 and 8 fail? c. When fiber 12 fails after fibers 2 and 8 have failed? Assume that the capacity of each fiber is OC-12/STM-4. ADM 1 ADM 2 ADM 3 1 2 A B , 6 12 ADM 6 8 ADM 5 Figure 1: 2F-BLSR ring ADM 4