Read routing, switching and management access.
Centralised configuration and automation
Automation asks software to perform a defined task instead of repeating every step manually. It is useful for collecting facts, checking compliance and applying repeatable changes. A mistake can also spread quickly, so validate inputs, review the intended change and start with a small lab.
A traditional device-by-device workflow can be automated too. A controller-based architecture gives a central place to express policy and coordinate supported devices. The data plane forwards packets; the control plane decides how forwarding should work. Where those functions live depends on the architecture.
Underlay, overlay and interfaces
The underlay is the network providing basic transport. An overlay builds logical connectivity over it, often using encapsulation. A fabric is a coordinated networking system combining devices and control. If the underlay cannot carry the overlay packets, the overlay cannot fix the missing transport path by itself.
A northbound API connects higher-level applications to controller services. Southbound interfaces connect the controller to managed infrastructure. These are architectural directions, not physical compass directions. A controller is not automatically in the path of every user packet. Check the actual design.
Practical exercise
Before automating configuration changes, propose a first automation task that only reads information.
Show the answer and explanation
Collect interface names, operational state and software versions, then compare them with an inventory. Reading facts is a useful first step before permitting changes.
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Technical references checked on 25 October 2026. These are original teaching explanations, not official Cisco course material. See how content and lab validation are described.
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