Software Defined Networking | SDN

Summary

Software-Defined Networking (SDN) separates the control plane from the data plane, providing greater flexibility and cost-efficiency compared to traditional networks. In traditional networks, routers handle both routing decisions and packet forwarding. In SDN, a central controller manages routing and network configurations, allowing for dynamic real-time adjustments based on application needs. While SDN offers benefits like easier management and scalability, it also requires robust security to prevent network breaches if applications are compromised.

Takeaways

• 😀 SDN separates the control plane (network management) from the data plane (data forwarding), allowing more flexibility in network management.
• 😀 Traditional networks use routers that handle both routing decisions and data forwarding, often relying on proprietary hardware and vendor-specific software.
• 😀 SDN switches only handle data forwarding, making them more cost-effective as they require less expensive hardware compared to traditional routers.
• 😀 The control plane in SDN is managed by a centralized controller that makes routing decisions and updates the flow tables on SDN switches.
• 😀 Communication between the SDN controller and switches happens through southbound APIs like OpenFlow, which allow updates to the flow tables.
• 😀 SDN controllers also offer northbound APIs that allow applications to communicate directly with the controller, enabling real-time network configuration based on business needs.
• 😀 Applications in SDN can dynamically instruct the controller to prioritize traffic types, such as giving video streaming priority over other services like VoIP.
• 😀 Developers can create network applications that can reconfigure the network infrastructure without needing to understand the complexities of the physical network.
• 😀 Since SDN controllers can run on virtual machines, there is no need for expensive proprietary hardware to manage the network control layer.
• 😀 Security is a key consideration in SDN: if an application or controller is compromised, attackers could gain access to and manipulate the entire network, requiring strong security measures across all layers.

Q & A

What is Software Defined Networking (SDN)?

Software Defined Networking (SDN) is a network architecture that separates the control plane (which decides the path for data) from the data plane (which forwards the data). This enables centralized control and flexible management of network traffic, allowing for more efficient network configurations.

How does SDN differ from traditional networking?

In traditional networking, routers handle both control and data plane functions within the same hardware, using proprietary technologies. In SDN, the control and data planes are separated. The control plane is managed by a central controller, while switches only handle data forwarding, often running on cheaper, more flexible hardware.

What are the two main functions performed by traditional routers?

Traditional routers perform two main functions: 1) Deciding the best path for data to travel using routing protocols like OSPF, which updates the routing table. This is managed by the control plane. 2) Forwarding the actual data packets to their destination based on the routing information, which is managed by the data plane.

What is the role of the controller in SDN?

The controller in SDN manages the control plane. It is responsible for determining the best route for data and updating the flow table in SDN switches. It communicates with switches using southbound APIs like OpenFlow and provides a northbound API for applications to interact with the network.

What are southbound and northbound APIs in SDN?

Southbound APIs are used by the SDN controller to communicate with and configure switches, while northbound APIs allow applications to communicate with the controller, sending network configuration instructions based on business requirements.

How can SDN benefit application traffic management?

In SDN, applications can dynamically send instructions to the controller to prioritize specific types of traffic, such as video streaming. This allows businesses to optimize network resources in real-time based on application needs, improving network performance for critical tasks.

How does SDN provide abstraction for applications?

SDN abstracts the underlying network complexity for applications by allowing them to interact with the controller. The applications do not need to understand the physical network infrastructure; they simply send high-level instructions to the controller, which takes care of the network configurations.

Can SDN controllers run on any hardware?

Yes, SDN controllers can run on virtual machines, which means there is no need for proprietary hardware. This flexibility allows developers to deploy and manage SDN controllers on any suitable hardware or virtual environment.

What security risks should be considered when implementing SDN?

One security concern with SDN is that if the operating system running the application is compromised, a bad actor could potentially gain access to the entire network. Therefore, it is critical to implement strong security controls on applications, controllers, and the physical network infrastructure to prevent such breaches.

What are the main advantages of using SDN?

The main advantages of SDN include increased flexibility, centralized control, cost reduction due to the use of less expensive hardware, dynamic and real-time network management, and the ability for applications to directly interact with and configure the network.