Designing Cisco Enterprise Networks (ENSLD) — Question 75

How is a sub-second failure of a transport link detected in a Cisco SD-WAN network?

Answer options

• A. Hellos are sent between the WAN Edge routers and the vSmart controller.
• B. BFD runs on the IPsec tunnels between WAN Edge routers.
• C. BGP is used between WAN Edge routers and the vSmart controller.
• D. Link state change messages are sent between vSmart controllers.

Correct answer: B

Explanation

The correct answer is B because Bidirectional Forwarding Detection (BFD) is specifically designed for rapid detection of link failures and operates effectively over IPsec tunnels in SD-WAN. The other options, while relevant to the network's operation, do not provide the same level of quick failure detection as BFD does.