What is the basic architecture used to control routing in Software Defined Networks (SDNs)?

The basic architecture used to control routing in Software Defined Networks (SDNs) is fundamentally centered around the concept of separation of the control plane and the data plane. This separation allows for more dynamic and programmable management of network resources. The correct approach leverages a centralized controller that communicates with the various network devices, managing traffic flows based on policy and network conditions.

The Virtual Router System (VRS) embodies this modern architectural approach as it enables multiple virtual routers to be instantiated on a single physical router. This functionality aligns with SDN principles by allowing programmable control over routing functions while maintaining centralized management through a single interface. It represents how SDNs can differentiate themselves from traditional networking, where routing decisions are typically distributed across individual devices without a centralized control mechanism.

In contrast, while the other options might imply some form of routing or system architecture, they do not align with the specific principles and functionalities that define the SDN environment as effectively as the Virtual Router System does. For instance, Core Routing Architecture and Distributed Processing Unit may refer to different traditional or physical routing schemas, lacking the dynamic adaptability characteristic of SDN. Node Star Design may suggest a topology format rather than an architecture for controlling routing. Thus, the emphasis on programmability and centralized control clearly distinguishes the Virtual