多项选择题
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 A customer would like to create a 1：1 protection group with a DS3Ni-12 card. Where should it be placed in the chassis？（）
单项选择题 A customer has 20 E1s to add between far-end nodes in an SNCP ring. What type of circuit would you recommend？（）
单项选择题 Click the Exhibit button. As shown in the exhibit， a customer has several interconnected core rings. They want to create several irtual rings？utilizing their STM-64 backbone （nodes 1， 2， 3， and 4）. What do you recommend？ （）