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？（）
A. 92 B. 93 C. 94 D. 95 E. 96
单项选择题 Whatisthedifferencebetween1+1and1：1protectionswitching？（）
单项选择题 WithR4.0，howmanytotalDCC-RtunnelconnectionscaneachONS15454supportusingtheTCC+card？（）
单项选择题 WhichtimingmodeismostappropriateforanONS15454thathaslostitsBITS-1andopticalreferences？（）
