300-420 Question 93
Select 2An enterprise network is experiencing delays in routing convergence during primary link failures. The network uses OSPF as its IGP, and the design team has been asked to implement measures to improve convergence times. Which of the following design changes can specifically enable faster convergence in this scenario?
- A
Reduce the OSPF hello and dead timers.
- B
Increase the SPF delay and hold time timers.
- C
Enable Bidirectional Forwarding Detection (BFD) for OSPF neighbors.
- D
Change the OSPF network type to broadcast on point-to-point links.
- E
Increase the OSPF priority value for all routers in the area.
Show answer and explanation
Correct answers: A, C
Explanation
Fast convergence in OSPF relies on minimizing the time it takes to detect link or neighbor failures and recalculating routes. Reducing the OSPF hello and dead timers decreases failure detection time, while enabling BFD provides an even faster, protocol-independent mechanism for failure detection. Together, these measures can significantly improve OSPF convergence times.
- A. Correct.
Reducing the OSPF hello and dead timers allows for faster detection of neighbor failures, which directly contributes to faster convergence.
- B. Incorrect.
Increasing the SPF delay and hold time timers slows down the OSPF convergence process, as it delays the recalculation of the shortest path tree.
- C. Correct.
Enabling BFD provides faster link failure detection than OSPF hello timers, allowing for quicker convergence after a failure.
- D. Incorrect.
Changing the OSPF network type to broadcast on point-to-point links has no impact on convergence times and is not relevant in this scenario.
- E. Incorrect.
Increasing the OSPF priority value is used to influence DR/BDR elections and does not directly affect convergence times.