300-415 Question 29
Single answerA company has deployed Cisco SD-WAN with multiple WAN Edge devices across geographically dispersed branch locations. During a network outage, one of the WAN Edge devices loses connectivity to all its transport circuits. However, the device continues to forward traffic between its local LAN segments. What is the most likely reason for this behavior?
- A
The WAN Edge device is operating in TLOC extension mode.
- B
The WAN Edge device is leveraging local forwarding enabled by the data plane.
- C
The WAN Edge device is using another WAN Edge device for transport redundancy.
- D
The WAN Edge device has fallback to its local OMP (Overlay Management Protocol) configuration.
Show answer and explanation
Correct answer: B
Explanation
In Cisco SD-WAN, the data plane on a WAN Edge device is capable of performing local traffic forwarding even when there is no connectivity to the transport circuits. This ensures that local LAN-to-LAN communication within a branch location is not interrupted during a transport outage, maintaining limited functionality.
- A. Incorrect.
TLOC extension mode allows a WAN Edge to use another device's transport circuits, but this does not explain why the device is forwarding traffic between its local LAN segments during a complete transport outage.
- B. Correct.
Local forwarding enabled by the data plane ensures that the WAN Edge device can continue to route traffic within its local LAN even when all transport circuits are down. This is the correct explanation for the behavior described.
- C. Incorrect.
Transport redundancy using another WAN Edge device typically requires functional transport circuits on at least one device, which is not the case in this scenario.
- D. Incorrect.
Fallback to a local OMP configuration is not a valid feature in Cisco SD-WAN. OMP is used for overlay routing and requires functional transport circuits to communicate with vSmart controllers.