单项选择题
A. LO-PATH circuits
B. HO-PATH circuits
C. 1：1 protection circuits
D. 1：N protection circuits
E. LO-TUNNEL tunnel circuits
单项选择题 WhatisthecorrectrelativeswitchingpriorityinanMS-SPRingring（highertolower）？（）
单项选择题 WhatprotocolenablesEthernetoverSONET/SDHencapsulationinteroperabilitybetweentheG-seriesandML-seriesEthernetcards？（）
单项选择题 You are provisioning an E-1 circuit on an ONS 15454 MS-SPRing configuration and XC-VXL-10G card. Each VC-12 connection must also terminate via the VC-3 matrix. How many VC-3 ports remain after this circuit is created， assuming no other circuits？（）