Examkin

Question

Difficulty: MediumComparing Traditional Networks with Controller-Based Networking

Following an infrastructure audit, a network administrator discovers that Quality of Service (QoS) class maps and policy configurations differ significantly across 50 access switches because they were configured individually via manual CLI commands. Which capability of a controller-based network architecture directly addresses and resolves this operational challenge?

  1. The centralized network controller abstracts device configurations into enterprise intent policies and provisions managed devices consistently using Southbound APIs.Answer
  2. B
    Each access switch uses Northbound APIs to autonomously pull policy scripts from the controller and run Ansible playbooks locally.
  3. C
    The central controller uses HTTP POST requests to retrieve switch telemetry and HTTP GET requests to modify switch QoS policy tables.
  4. D
    The controller centralizes data plane forwarding for all access switches, buffering out-of-profile QoS packets directly on the controller hardware.

Answer

The central network controller maintains an intent-based policy model and deploys consistent configuration settings across network elements using Southbound APIs.
In traditional networks, each device is managed individually using distributed control and management planes (typically via CLI or SNMP), leading to configuration drift over time. In a controller-based architecture, the network administrator specifies high-level business intent on a centralized controller. The controller then translates this intent into specific device configurations and pushes them downstream using Southbound APIs (such as NETCONF, RESTCONF, or OpenFlow), ensuring complete consistency across all network elements.

Step-by-Step Solution

1
Identify the core operational problem in the scenario
Manual, per-device CLI configuration leads to configuration drift and inconsistent policies across multiple switches.
Traditional networking relies on distributed management where each device is logged into and configured independently.
2
Analyze how controller-based SDN models handle management and configuration distribution
The controller centralizes management and control logic, allowing administrators to express business intent centrally.
Centralization removes the need for individual CLI configuration on each node.
3
Determine the role of APIs in enforcing consistent network policies
Southbound APIs (e.g., NETCONF, RESTCONF) allow the controller to communicate down to the switches to enforce uniform policy.
Southbound protocols interface between the SDN controller's control plane/management layer and the physical data plane devices.

Key Concept

Centralized abstraction and policy enforcement via Southbound APIs in SDN architecture vs. distributed per-device CLI management in traditional networking.
Rate this question

Topics

Comparing Traditional Networks with Controller-Based Networking

More questions from this topic