300-420 Question 94
Select 3A company’s enterprise network uses OSPF as the routing protocol. The network design team is tasked with improving the network's convergence time in case of link failures. Which of the following design considerations would help achieve faster convergence?
- A
Decrease OSPF hello and dead intervals.
- B
Enable Bidirectional Forwarding Detection (BFD) on OSPF neighbors.
- C
Increase OSPF reference bandwidth to accommodate high-speed links.
- D
Use OSPF LSA throttling to reduce propagation delays.
- E
Enable equal-cost multipath (ECMP) routing.
Show answer and explanation
Correct answers: A, B, D
Explanation
Fast convergence in OSPF can be achieved by optimizing timers (hello and dead intervals), using mechanisms like BFD for quicker failure detection, and implementing LSA throttling to minimize update delays. These changes ensure the network can rapidly detect and respond to failures, improving overall stability and performance. However, techniques like increasing reference bandwidth or enabling ECMP focus on other aspects of network performance and do not directly affect convergence speed.
- A. Correct.
Decreasing the OSPF hello and dead intervals allows OSPF neighbors to detect link or neighbor failures more quickly, resulting in faster convergence.
- B. Correct.
Enabling BFD provides a fast mechanism to detect link failures independently of OSPF timers, thus improving convergence speed.
- C. Incorrect.
Increasing the OSPF reference bandwidth is used to better calculate link costs for high-speed links, but it does not directly impact convergence time in case of failures.
- D. Correct.
OSPF LSA throttling helps reduce the time it takes to propagate and process LSA updates, which can improve convergence during network changes.
- E. Incorrect.
Enabling ECMP provides load balancing across multiple paths but does not directly address convergence time during link failures.