300-440 Question 44
Single answerAn enterprise network is using Bidirectional Forwarding Detection (BFD) to monitor the health of a critical OSPF routing path. The network engineer notices that BFD sessions frequently fail, causing OSPF to reconverge unnecessarily. Upon inspection, the engineer identifies that the timers configured for BFD are very aggressive. What is the most likely solution to stabilize the BFD sessions while maintaining fast failure detection?
- A
Increase the BFD detection multiplier value.
- B
Decrease the BFD hello interval.
- C
Disable BFD for OSPF and use default OSPF dead interval settings.
- D
Configure BFD to operate in asynchronous mode instead of demand mode.
Show answer and explanation
Correct answer: A
Explanation
BFD uses a combination of hello intervals and a detection multiplier to determine a session failure. If the timers are too aggressive (low hello intervals and low detection multiplier), minor delays or packet loss can cause unnecessary session failures. By increasing the detection multiplier, the router waits for more consecutive missed packets before declaring the session down, improving stability while still maintaining fast failure detection.
- A. Correct.
Increasing the BFD detection multiplier value allows the router to tolerate more missed BFD packets before declaring the session down, thereby reducing unnecessary session failures.
- B. Incorrect.
Decreasing the BFD hello interval makes the timers even more aggressive, which could exacerbate the problem and lead to more frequent BFD session failures.
- C. Incorrect.
Disabling BFD for OSPF would reduce the speed of failure detection and is not a suitable solution when fast failure detection is required.
- D. Incorrect.
BFD asynchronous mode is the default operational mode and does not address the issue of aggressive timers causing session failures.