CCDE: Cisco Certified Design Expert (Written) — Question 14

What are the two preferred mechanisms for detecting Layer 2 link failures quickly? (Choose two.)

Answer options

• A. BFD
• B. fast RSVP hellos
• C. LDP keepalives
• D. loss of signal

Correct answer: A, D

Explanation

BFD (Bidirectional Forwarding Detection) provides rapid link failure detection by sending frequent hello packets, making it effective for quick identification of issues. Loss of signal indicates that a link is down, but it may not be as proactive as BFD, which actively monitors the link status, while fast RSVP hellos and LDP keepalives are not primarily designed for quick failure detection.