300-420 Question 140
Select 2An enterprise is deploying Cisco SD-Access to simplify network management and improve security. As part of the architecture, they need to understand the role of the underlay and overlay within the SD-Access fabric. Which of the following accurately describes the purpose of the underlay and overlay in SD-Access?
- A
The underlay provides IP reachability and connectivity between fabric nodes.
- B
The overlay is responsible for enabling virtual networks and policy enforcement.
- C
The underlay operates based on VXLAN tunnels for traffic encapsulation.
- D
The overlay is used for automating the configuration of physical network devices.
- E
The underlay is responsible for transporting user traffic within the fabric.
Show answer and explanation
Correct answers: A, B
Explanation
In Cisco SD-Access, the underlay provides the foundational physical infrastructure with basic IP reachability between nodes. The overlay builds on the underlay, creating virtual networks using VXLAN tunnels for segmentation and policy enforcement. Understanding the distinction between these layers is critical for designing and deploying SD-Access solutions correctly.
- A. Correct.
Correct: The underlay is the physical network infrastructure that provides basic IP connectivity and reachability between fabric nodes. It enables the overlay to function.
- B. Correct.
Correct: The overlay creates virtualized networks over the underlay and supports advanced features like segmentation and policy application.
- C. Incorrect.
Incorrect: VXLAN tunnels are part of the overlay, not the underlay, as they enable the creation of virtual networks.
- D. Incorrect.
Incorrect: Automation of physical devices is a function of Cisco DNA Center, not specifically the overlay in the SD-Access architecture.
- E. Incorrect.
Incorrect: The underlay does not transport user traffic directly; instead, the overlay handles user traffic through encapsulated tunnels.