Comparison of Traditional Networks and Controller-Based Networks

A.

Most traditional devices use a distributed architecture, in which each control plane is resided in a networking device.

Therefore they need to communicate with each other via messages to work correctly.

In contrast to distributed architecture, centralized (or controller-based) architectures centralizes the control of networking devices into one device, called SDN controller.

The correct answer is A. Only controller-based networks decouple the control plane and the data plane.

Traditional networks use a distributed control plane architecture, which means that each network device has its own control plane. Control plane functionality includes routing protocols, neighbor discovery, and path selection. Data plane functionality is responsible for forwarding packets. In traditional networks, the control and data planes are tightly coupled, meaning that the control plane and data plane run on the same device.

Controller-based networks, on the other hand, use a centralized control plane architecture. The control plane is abstracted from the data plane and is located on a central controller device. The controller communicates with network devices through a southbound API to manage and configure them. The data plane, responsible for forwarding packets, remains on the network devices themselves.

Option B is incorrect because both traditional and controller-based networks can abstract policies from device configurations. This is achieved through the use of policy-based networking, which defines policies that govern how traffic is handled across the network.

Option C is incorrect because both traditional and controller-based networks can support centralized management. In traditional networks, centralized management is achieved through tools like SNMP and RADIUS. In controller-based networks, centralized management is achieved through the central controller.

Option D is incorrect because only controller-based networks offer a centralized control plane. In traditional networks, the control plane is distributed across network devices.