300-415 Question 30
Single answerA company has deployed Cisco SD-WAN and configured multiple WAN Edge devices at branch sites. During a routine network audit, it was discovered that traffic between two branch locations is not being forwarded, despite both WAN Edge devices being online and reachable. Which data plane issue could cause this problem?
- A
IPSec tunnels between the WAN Edge devices are not established.
- B
Control plane connectivity to the vSmart controller is down.
- C
There is a mismatch in data plane MTU settings between the WAN Edge devices.
- D
The OMP (Overlay Management Protocol) routes are not advertised between the WAN Edge devices.
Show answer and explanation
Correct answer: A
Explanation
In the Cisco SD-WAN architecture, the data plane relies on IPSec tunnels between WAN Edge devices to securely forward user traffic. If these tunnels are not established, traffic cannot traverse between devices, even if the control plane is functioning correctly. This makes the establishment of IPSec tunnels critical to the data plane operation.
- A. Correct.
Correct: IPSec tunnels are a fundamental part of the data plane in Cisco SD-WAN. If these are not established, data cannot be forwarded between WAN Edge devices.
- B. Incorrect.
Incorrect: Control plane connectivity to the vSmart controller affects the exchange of policies and routes but does not directly result in data plane forwarding issues as long as the data plane tunnels are already established.
- C. Incorrect.
Incorrect: While MTU mismatches could theoretically cause packet drops, they do not prevent data plane forwarding entirely unless the fragmentation handling is misconfigured.
- D. Incorrect.
Incorrect: OMP operates at the control plane level and is responsible for route advertisement. A failure in OMP may prevent route learning, but the question specifies that both WAN Edge devices are online and reachable.