A. signal fail, signal degrade, manual switchB. signal ……

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

A. Switch times would exceed 50 ms for an OC-3 BLSR ring.
B. An equal amount of working and protect bandwidth is required.
C. DCC bandwidth is not large enough to handle K1/K2 processing.
D. There is not enough bandwidth in an OC-3 ring to justify BLSR protection.

多项选择题What are two characteristics of dual-ring interconnect in SONET networks? （）(Choose two.)

A. It protects signals against node failures between rings.
B. It protects signals against node failure within a single ring.
C. It allows for traffic to be preempted when a ring switch occurs.
D. Traffic can be dropped and continued at interconnecting nodes.
E. It protects preemptible traffic from being dropped when a ring switch occurs.

单项选择题What protocol enables Ethernet over SONET SDH encapsulation interoperability between the G-series and ML-series Ethernet cards?（）

A.LEX
B.HDLC
C.GFP-F
D.PPP/BCP

单项选择题Click the Exhibit button. In the DCN connection shown in the exhibit, all non-GNE nodes are located on different subnets from the GNE. There are no static routes or external OSPF on any elements. CTC Workstation and GNE have Cisco Router as their default gateway. Can the CTC workstation see the entire SONET network?（）

A. Yes, but only if OSPF is enabled around the ring.
B. Yes, because the GNE will only serve as a proxy-ARP for elements on the same subnet.
C. Yes, but only if the router's address is entered as a static route in the non-GNE elements.
D. Yes, because the GNE will serve as a proxy-ARP for all elements, regardless of their subnets.

多项选择题Which three timing modes are supported on the ONS 15454 shelf? （）(Choose three.)

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