200-301 Question 470
Select 3You are working in an enterprise network that has recently migrated to a software-defined architecture using controllers. During a troubleshooting session, you need to explain the roles of overlay, underlay, and fabric within the network. Which of the following statements correctly describe these components?
- A
The underlay provides the physical connectivity and routing for the network.
- B
The overlay is responsible for creating virtual networks on top of the physical network.
- C
The fabric is another term for the physical topology of the network underlay.
- D
The overlay uses tunneling protocols like VXLAN to connect devices logically.
- E
The underlay dynamically creates virtual networks without requiring overlay protocols.
Show answer and explanation
Correct answers: A, B, D
Explanation
In a controller-based, software-defined architecture, the underlay provides the physical infrastructure while the overlay creates virtualized networks using tunneling protocols like VXLAN. The fabric represents the logical structure of the network. Understanding these roles is critical for managing and troubleshooting SDN environments.
- A. Correct.
Correct. The underlay refers to the physical infrastructure, including devices like routers and switches, that form the foundation of the network.
- B. Correct.
Correct. The overlay operates above the underlay, allowing for the creation of virtualized or logical networks that abstract the physical topology.
- C. Incorrect.
Incorrect. The fabric describes the end-to-end logical structure of the network, which can encompass both the overlay and underlay, not just the physical topology.
- D. Correct.
Correct. The overlay uses protocols like VXLAN, GRE, or MPLS to create logical tunnels over the physical network for traffic segmentation and virtualization.
- E. Incorrect.
Incorrect. The underlay does not create virtual networks; it provides the physical connectivity over which the overlay operates.