A company has built an OSPF network as shown in the following figure. The links form an OSPF neighbor relationship. All devices have announced their own loopback address. On one day, the S1-R2 and S2-R1 links are faulty. Which of the following description is correct? (Area 0 is split)

Assume that the port shaping rate is 100Mbps. The input bandwidth and PIR of each service on the interface are as follows.

Then, after the first round of scheduling, what is the bandwidth allocated by the EF queue?

Which of the following is optimal for building a loop-free Layer 2 network?