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Difficulty: MediumSeparation of Control Plane and Data Plane

A netops team is deploying a controller-based network architecture to maintain network topology intelligence centrally while retaining local packet switching on individual infrastructure nodes. Which operational behavior correctly distinguishes the responsibility of the centralized control plane from that of the local data plane?

  1. The centralized control plane constructs topology intelligence and programs forwarding tables, whereas the local data plane inspects packet headers and switches transit traffic using hardware ASICs.Answer
  2. B
    The centralized control plane performs line-rate MAC address lookups and frame encapsulation, whereas the local data plane exchanges dynamic routing protocol neighbor adjacencies to build the Routing Information Base.
  3. C
    The centralized control plane directly processes high-throughput user payload transit traffic, whereas the local data plane uses agentless SSH automation connections to update neighbor states.
  4. D
    The centralized control plane buffers out-of-profile data packets to shape transit traffic, whereas the local data plane drops control plane messages whenever link congestion occurs.

Answer

The centralized control plane constructs topology intelligence and programs forwarding tables, whereas the local data plane inspects packet headers and switches transit traffic using hardware ASICs.
The correct answer accurately distinguishes between the two operational planes. The control plane is responsible for intelligence-gathering operations such as path calculation, building the routing table (RIB), and deriving forwarding tables (FIB). The data plane is dedicated to fast, local handling of transit data packets—reading packet headers and executing switching or routing actions directly in hardware via ASICs.

Step-by-Step Solution

1
Identify the primary function of the control plane.
The control plane handles protocol intelligence, routing table computation, path selection, and table generation (such as the RIB and FIB).
Control plane operations dictate how traffic should be routed across the network network-wide.
2
Identify the primary function of the data plane.
The data plane (also known as the forwarding plane) handles direct packet handling, header inspection, MAC/FIB lookups, TTL decrements, and frame encapsulation.
Data plane tasks must occur at line rate and are handled locally by specialized hardware (ASICs/TCAM).
3
Compare the centralized SDN controller paradigm to local network node forwarding.
In SDN architectures, the controller offloads control plane logic centrally and programs the local data plane on switches/routers to execute rapid local forwarding.
Decoupling control logic from local hardware enables centralized network automation while preserving low-latency data plane forwarding performance.

Key Concept

Control Plane vs. Data Plane Functional Separation
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Topics

Separation of Control Plane and Data Plane

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