单项选择题

A. line timingB. loop timingC. internal timingD. throug……

Which timing mode is most appropriate for an ONS 15454 that has lost its BITS-1 and optical references？（）

A. line timing
B. loop timing
C. internal timing
D. through timing
E. external timing

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热门试题

单项选择题Whichisalegitimatebandwidthmatchedpair？（）

A. DS-1； E1
B. DS-1； STM-1
C. OC-3； STM-1
D. STS-1； STM-1
E. OC-192； STM-192

多项选择题WhataretwomajordifferencesbetweenMS-SPRingandSNCP？（）

A. In an MS-SPRing， all paths are protected.
B. MS-SPRing is always a high-order protection.
C. A low order circuit cannot be protected by an MS-SPRing.
D. There is no theoretical limit in the number of nodes in an SNCP ring.

单项选择题In order to avoid misconnections due to a failed node in an MS-SPRing， Alarm Indication Signals （AISs） are sent on every channel normally terminating in that node. What is the name of this process？（）

A. bridging
B. switching
C. squelching
D. nodal bypass
E. node failure insertion

单项选择题WhichtimingmodeisappropriateforanSDHNEthatisadjacenttoanSDHNEBits-1timing？（）

A. DUS
B. line timing
C. loop timing
D. internal timing
E. through timing

多项选择题WhichtwocanbetransportedinoneAU-4？（）

A. 3 E3
B. 4 E4
C. 64 E1
D. 21 E1 and 2 E3
E. 42 E1 and 2 E3