300-420 Question 3
Single answerAn enterprise network consists of multiple branch offices connected to a central data center through an MPLS service provider. The company plans to implement a failover mechanism between the MPLS network and a new VPN over the internet to ensure high availability. Which routing solution should you implement to prioritize MPLS connectivity while automatically switching to VPN in case of a failure?
- A
Configure static routes with a lower administrative distance for MPLS and higher administrative distance for VPN.
- B
Implement BGP with route reflectors to dynamically advertise MPLS and VPN routes.
- C
Use OSPF with MPLS routes assigned to Area 0 and VPN routes assigned to a stub area.
- D
Configure EIGRP with MPLS routes having a higher feasible distance compared to VPN routes.
Show answer and explanation
Correct answer: A
Explanation
Static routes with different administrative distances provide a simple and effective way to implement failover between MPLS and VPN. The primary route (MPLS) is chosen based on its lower administrative distance, and the backup route (VPN) is used only if the primary route fails. This ensures high availability without requiring complex configurations.
- A. Correct.
This is the correct option. By using static routes with a lower administrative distance for MPLS and higher administrative distance for VPN, MPLS will be preferred by default while VPN will act as a failover path if MPLS fails.
- B. Incorrect.
While BGP allows dynamic route advertisement, it does not inherently prioritize one path over another without additional configuration like local preference or AS-path manipulation, making it less straightforward for this scenario.
- C. Incorrect.
OSPF's area designations do not prioritize routes between different areas in this manner. It would not be a suitable solution for implementing failover between MPLS and VPN.
- D. Incorrect.
In EIGRP, the feasible distance does not control primary and backup route selection. Administrative distance would need to be adjusted for proper prioritization, which is not mentioned here.