📖 What is Software Defined Networking (SDN)?
Software Defined Networking (SDN) is a network architecture approach that decouples the control plane from the data plane. This allows network administrators to manage network traffic centrally via software rather than configuring individual hardware devices, increasing agility in large environments.
"The 'Control Plane' makes the decisions about where traffic goes, while the 'Data Plane' is responsible for actually moving the packets."
📚 Certification: Certified Information Systems Security Professional (CISSP)
🔑 What are the Key Concepts of Software Defined Networking (SDN)?
- ▸ The Control Plane acts as the brain, making routing decisions centrally, while the Data Plane executes those decisions by moving packets across the network.
- ▸ Northbound APIs allow the controller to communicate with applications and orchestration tools, while Southbound APIs, like OpenFlow, communicate with the physical hardware.
- ▸ SDN enables micro-segmentation, allowing administrators to define granular security policies for individual workloads regardless of their physical location in the network infrastructure.
- ▸ Centralized orchestration reduces manual configuration errors and allows for rapid, automated network changes across the entire environment from a single management console.
- ▸ The SDN controller represents a single point of failure and a high-value target, requiring robust high-availability configurations and strict access controls.
🎯 How does Software Defined Networking (SDN) appear on the CISSP Exam?
You may be asked to identify the architecture that allows a network administrator to change traffic flow patterns across multiple switches simultaneously without accessing each device individually.
A scenario might describe a need for granular security policies that follow a virtual machine as it migrates across hosts; identify SDN-enabled micro-segmentation as the solution.
Expect questions about the security risks associated with centralized control, specifically focusing on the impact of a compromised SDN controller on the entire network fabric.
❓ Frequently Asked Questions
What is the difference between SDN and Network Function Virtualization (NFV)?
SDN focuses on separating the control and data planes to manage traffic flow, whereas NFV replaces dedicated hardware appliances, such as firewalls or load balancers, with software running on virtual machines.
How does SDN facilitate a Zero Trust architecture?
SDN enables micro-segmentation, allowing the network to be divided into small, isolated zones. This ensures traffic is strictly controlled between workloads, effectively preventing lateral movement by attackers.
What happens to the data plane if the SDN controller becomes unavailable?
Depending on the implementation, the data plane may continue to forward traffic based on the last known instructions or cached flows, but no new routing decisions can be made.