300-415 Question 131
Single answerAn enterprise is deploying a Cisco SD-WAN solution across its global branches. The WAN Edge devices at two remote sites are connected to the underlay network via MPLS and Internet links. However, these devices are not able to establish an overlay tunnel with each other. Upon investigation, you discover that the MPLS provider is not advertising the public IP addresses of the WAN Edge devices. What is the most appropriate solution to resolve this issue while maintaining overlay connectivity?
- A
Implement a NAT device at each site to translate private IP addresses to public IPs for the WAN Edge devices.
- B
Enable BGP on the MPLS underlay network to ensure public IP addresses are advertised.
- C
Configure static routes on the MPLS network to route traffic between public IP addresses of the WAN Edge devices.
- D
Deploy a vBond orchestrator to facilitate the secure exchange of IP addresses between WAN Edge devices.
Show answer and explanation
Correct answer: A
Explanation
In Cisco SD-WAN, overlay tunnels are established between WAN Edge devices using public IP addresses. When the underlay network (e.g., MPLS) does not support public IP routing, deploying a NAT device ensures private IP addresses are translated to public IPs, enabling the overlay connectivity. Other options, such as modifying underlay routing protocols or deploying vBond, do not address the specific issue of public IP reachability.
- A. Correct.
This is the correct answer. NAT ensures that private IP addresses used by the WAN Edge devices are translated into public IPs, allowing the devices to establish overlay tunnels over the MPLS underlay.
- B. Incorrect.
While BGP can advertise routes, this does not resolve the issue of the MPLS network not supporting public IPs for overlay connectivity.
- C. Incorrect.
Static routes on the MPLS network would not resolve the issue of public IP address reachability, as MPLS underlays are not designed for direct public IP address routing.
- D. Incorrect.
The vBond orchestrator facilitates overlay control and secure connectivity management, but it does not resolve issues with public IP address reachability in the underlay.