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.