单项选择题
A. Slot 2 and Slot 4
B. Slot 4 and Slot 6
C. Slots 5 or 13 only
D. Slot 16 and Slot 17
单项选择题 Click the Exhibit button. Which type of protection is shown in the exhibit?（）
单项选择题 You are provisioning a DS-1 circuit on an ONS 15454 UPSR configuration and XC-10G card. How many total VT ports are used within the VT matrix at the source node?（）
单项选择题 What is the correct relative switching priority in a BLSR ring (higher to lower)?（）