SDN

What is Software Defined Networking (SDN) ?

SDN is an architecture that divides the control plane from the data plane to give networks additional flexibility and programmability. Users can react fast to changes thanks to software-defined networks in cloud computing. Network performance and monitoring are enhanced thanks to SDN management, which also increases network configuration efficiency.

Directly programmable network control is made possible for applications and network services by software-defined networking (SDN). To develop a more manageable and flexible network infrastructure, software-defined network architecture decouples the network control and forwarding operations from the actual hardware, such as switches and routers.

The OpenFlow protocol, which was eventually produced through a research partnership between Stanford University and the University of California at Berkeley in the 2008 period, is where SDN's roots may be found.

SDN Architecture

SDN Broadly Consists of Three Layers :

Infrastructure Layer :

The numerous networking devices that make up the infrastructure layer create the underlying network that carries out network traffic forwarding. In the data center, it could be a group of network switches and routers. This layer would be the physical one over which the control layer would establish network virtualization (where SDN controllers would sit and manage the underlying physical network).

Control Layer :

The control layer is the region of the control plane where clever logic for SDN controllers to control network infrastructure would be found. Each network vendor is focusing on developing its SDN controller and framework products in this area. A lot of business logic is implemented in the controller for this layer to retrieve and retain many types of network information, including state data, topology details, statistics details, and more. SDN controllers must contain control logic for real-world network use-cases including switching, routing, L2 and L3 VPNs, firewall security rules, DNS, DHCP, and clustering because they are used to manage networks.

Application Layer :

Utilizing all available network information regarding network topology, network state, network statistics, etc., the application layer is an open region where as many creative applications as possible can be created. Applications for network automation, network setup and management, network monitoring, network troubleshooting, network policy, and network security are just a few examples of the many different sports that can be created. For actual enterprise and data center networks, these SDN applications can offer a variety of end-to-end solutions. Vendors of networks are developing their suite of SDN apps.

Why SDN is Important ?

• The network connectivity for sales, customer support, internal communications, and document sharing is improved by software-defined networking (SDN).
• SDN enables businesses to create network services and infrastructure that are unique to them by utilizing hardware and software from several manufacturers.
• SDN, network function virtualization, and white boxes are all combined in a virtual network.
• The deployment of new apps, services, and business models is accelerated by SDN.

Working on Software-Defined Networking (SDN)

SDN decouples the software from the hardware, much like any other virtualized technology. SDN keeps the hardware-based data plane for carrying out actual traffic forwarding while moving the control plane, which decides where to send traffic, to software. This makes it possible for network managers who work with software-defined networking to program and manage the entire network through a single interface rather than device by device.

A Typical SDN Architecture Consists of 3 Components, Each of Which may be Situated in a Separate Physical Location :

• Applications that transmit information about the network as a whole or requests for resources.
• Controllers choose the best route for a data packet based on the information from applications.
• Networking devices that receive instructions from the controller on how to move data.

Data is moved through the network by physical or virtual networking devices. Virtual switches may take over the duties of physical switches and combine their tasks into a single, intelligent switch. They can be incorporated into either the software or the hardware.

The switch advances the data packets after verifying the integrity of both their virtual machine destinations and themselves.

How is SDN Different from Traditional Networking ?

SDN is different from traditional networking in that it is primarily software-based as opposed to hardware-based, as is the case with traditional networking. Given that SDN is software-based, it is more adaptable and versatile, allowing users to manage resources virtually throughout the entire control plane. Switches, routers, and other physical infrastructure are used in traditional networks to establish connections and manage the network.

There are 3 most important differences between traditional networking and SDN :

• Using application programming interfaces, the SDN controller's northbound interface interacts with applications (APIs). As a result, network programming can be done directly by application developers. Contrary to this, protocols are used in traditional networking.
• A software-based network called SDN enables users to choose network paths, proactively set up network services, and manage resource allocation at the virtual level through the control plane. While conventional networking needs physical equipment (such as switches and routers) to operate and make connections.
• Traditional networking is less able than SDN to connect with all networked devices. SDN enables administrators to govern traffic flow from a centralized user interface and allows resources to be provisioned from a single location with a more thorough evaluation. Users have more control over their network capabilities thanks to the network's complete virtualization. The control plane, however, is housed in a switch or router in traditional networking, which is particularly problematic. To control traffic, the administrators cannot readily access it.

Different Models of SDN

Switch-based SDN

The switch-based architecture served as the foundation for the original SDN concept. The network switches' behavior is determined by a system called OpenFlow that the switches use to handle packets. As a result, there is a single point of control for managing how the switches handle network traffic. Switches and controllers that support compatible OpenFlow versions can both be used with the model. Both virtual and physical OpenFlow-enabled switches are available to businesses.

The switch-based model's requirement for purchasing switching fabric, which may force enterprises to update their hardware or firmware, is a drawback.

Additionally, not every switch and router supports OpenFlow. Other switches might stop operating at a line rate once the system is started, which doesn't assist bring down the cost of switches.

Hybrid SDN

In a single environment, the hybrid SDN model mixes two or more networking technologies. While traditional networking protocols regulate the other traffic flows on the network, a network manager, for example, can configure the SDN control plane to manage a set of specialized traffic flows. Multiple locations and workers are connected with hybrid SDN using a range of networking protocols, including VPN, Ethernet, and MPLS, among others. By utilizing the most recent SDN technology to satisfy the needs of each location, a hybrid SDN solution offers flexibility.

A drawback of a hybrid method is that it might be challenging to diagnose due to the complicated network it creates. Network administrators and IT workers must get familiar with a variety of systems, which may necessitate hiring more staff or allocating business training time. In addition, because of the upfront costs involved in launching the network, the hybrid SDN architecture may be challenging to implement. Consequently, mid-to-large-sized businesses are more likely to benefit from hybrid SDN.

SDN Overlay

To run numerous virtual network (VN) topologies on top of existing infrastructure, the SDN overlay model tunnels through the physical network. Depending on the type of overlay, this enables a VN to be a layer 2 or layer 3 network and a physical network to be a layer 2 or layer 3 network. Layer 2 and layer 3 networks don't need to modify or be configured to sustain the network's virtualization because virtualization occurs at the network's edge. The overlay also makes the most use of network resources by channelizing bandwidth and assigning each channel to a specific device or service.

Advantages of Software-Defined Networking (SDN)

Following are the benefits or advantages of SDN :

• It makes it possible to manage networking devices centrally.
• It facilitates the automation of networking hardware and benefits end users.
• Compared to traditional networking, it offers flexibility, scalability, and efficiency.
• SDN provides real-time visibility into the operation of your network. You can improve your network's efficiency and performance thanks to this visibility.
• Scaling-up is automated via SDN (and scaling down). Engineers can operationally normalize traffic across a large space quickly and seamlessly because of this capability and the added visibility it delivers.
• For large, complicated networks that demand high uptime, SDN is a fantastic alternative. It enables engineers to instantly reroute networks.
• It is commonly utilized by search engines with enormous databases and social networking sites like Facebook, Twitter, and Google Plus (Google, Yahoo, Ask, etc.)