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)?（）

单项选择题 Why is an OC-3 2F-BLSR not feasible?（）