Control-Plane Centralization: Controller-Based vs Traditional Networks

200-301 By islever Editorial Last updated

Describe controller-based, software defined architecture (overlay, underlay, and fabric)

Short answer

D Controller-based networks centralize control-plane functions in a controller, while traditional networks distribute control-plane functions across devices.

Question

What is the difference between controller-based networks and traditional networks as they relate to control-plane and/or data-plane functions?
  1. Controller-based networks centralize all important data-plane functions, and traditional networks distribute data-plane functions.
  2. Traditional networks centralize all important control-plane functions, and controller-based networks distribute control-plane functions.
  3. Traditional networks centralize all important data-plane functions, and controller-based networks distribute data-plane functions.
  4. Controller-based networks centralize all important control-plane functions, and traditional networks distribute control-plane functions. Correct Answer

Key Takeaways

The defining SDN shift is control-plane centralization: logic moves from per-device to a controller; the data plane stays distributed in the forwarding devices.

In traditional (distributed) networks, each device runs its own control plane (routing, STP) locally. In controller-based/SDN networks, the control plane is centralized in a controller that manages the data plane of all devices via southbound APIs.

Common mistake: Picking A/B/C: those mix up which plane is centralized. It is the CONTROL plane that controller-based networks centralize, not the data plane.

Expert Analysis

Why the Answer Is Correct

D is correct. Controller-based (SDN) networks centralize control-plane functions in a controller, whereas traditional networks distribute those control-plane decisions (routing, STP) across the individual devices.

Why the Other Options Are Wrong

A, B, and C misassign or invert the planes. The centralized element in controller-based networking is the control plane, not the data plane.

Community Comment Notes

The vote is D (100). The top comment spells out that traditional networks distribute control-plane functions across devices while controller-based networks centralize them.

Official Reference

https://learningnetwork.cisco.com/s/ccna-exam-topics

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Community Votes

D
100%

100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

  1. exiledwl 👍 5 Answered D
    D. Controller-based networks centralize all important control-plane functions, and traditional networks distribute control-plane functions. In traditional networks, control-plane functions (such as routing decisions) are distributed across network devices like routers. In controller-based (software-defined) networks, these functions are centralized in a controller, which manages and controls the network devices.
  2. dimo475 👍 1
    It is D please CORRECT
  3. 3040636 👍 1
    D pleASE CORRECT

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