单项选择题
A.line timing
B.loop timing
C.internal timing
D.through timing
E.external timing
单项选择题 You are provisioning a DS-1 circuit on an ONS 15454 2F-BLSR with a XC-10G card. Each VT1.5 connection must also terminate via the STS matrix. On the originating circuit node, how many STS ports are now available for VT1.5 circuits?（）
单项选择题 A customer has 2 DS1s to add between adjacent nodes in a UPSR ring. What type of circuit should you recommend?（）
单项选择题 Click the Exhibit button. Given the information shown in the exhibit, when creating 2 DS1 circuits, how many STS ports are used on the VT1.5 matrix at Node 1 as VT circuits and how many are used after using VT tunnels?（）