An enterprise organization implements a Software-Defined Networking (SDN) architecture that decouples control plane operations to a centralized controller while maintaining distributed data plane operations on edge switches. If the Southbound API connection between an edge switch and the centralized controller fails unexpectedly, how does the switch handle existing, established data traffic?
- The switch continues forwarding established traffic streams locally using its pre-populated hardware forwarding tables.Answer
- BThe switch immediately halts all data plane forwarding because each packet lookup requires active approval from the central controller.
- CThe switch converts incoming transit data packets into ARP broadcast frames to dynamically discover new paths across the physical network.
- DThe switch punts all data plane packets directly to its local CPU to calculate new topology routes independently.
Answer
The switch continues forwarding established traffic streams locally using its pre-populated hardware forwarding tables.
In controller-based architectures with decoupled planes, the control plane programs the local data plane hardware (ASICs/TCAM) via Southbound APIs. Once forwarding tables (FIB) are established, the data plane handles packet forwarding autonomously at wire speed. Consequently, a loss of connection to the centralized controller prevents new control updates but allows existing, established data streams to continue forwarding locally without interruption.
Step-by-Step Solution
Key Concept
Decoupled Control and Data Plane Resilience