Software-Defined Networking (SDN): An Overview

Most of us have heard of traditional networks by now, which have a hardware-based infrastructure and work by using devices like routers and switches. But with the introduction of Software-Defined Networking (SDN), the game of networking has completely changed. 

 

SDN is a software-based architecture that enables network managers to operate the network, modify configuration settings, supply resources, and expand network capacity—all from a centralized user interface and without the need for additional hardware. It is a better and more secure option when it comes to networking. 

 

So, let us look at this overview of SDN and learn about the following related topics:

 

• Software-Defined Networking: Definition, types, and working.

• Importance of SDN

• Advantages and disadvantages of SDN

 

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Software-Defined Networking: Definition

 

As previously stated, Software-Defined Networking (SDN) is a software-based networking method in which Application Programming Interfaces (APIs) are incorporated to connect with fundamental hardware infrastructure and guide network traffic. This method streamlines the administration of infrastructure, which may be tailored to a single company or partitioned to be shared by multiple. 

 

What are the components of SDN?

 

There are mainly 3 components of Software-Defined Networking according to this blog by IBM:

 

1. Applications that send network information or requests for particular resource availability or allocation.

2. SDN controllers connect with applications to identify where data packets should be routed. Within SDN, controllers serve as load balancers.

3. Networking devices that take instructions from controllers on how to route packets.

 

Along with these components, a programmable networking protocol called OpenFlow is used in SDN. The Open Networking Foundation (ONF) contributed to the standardization of the OpenFlow protocol as well as other open-source SDN technologies. To ensure appropriate network traffic flow, these components collaborate to build SDN ecosystems.

 

Other than that, Network Virtualization plays a huge role in SDN. The terms “Virtual Network” and “SDN” are sometimes used interchangeably. These two ideas are quite different, but they complement each other effectively.

 

While network virtualization enables organizations to segment different virtual networks within a single physical network or connects devices on different physical networks to form a single virtual network, software-defined networking enables a new method of controlling data packet routing through a centralized server.

 

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Software-Defined Networking: Types

 

There are mainly 4 types of SDN, all of which are given below:

 

1. Open SDN:

 

It uses open protocols that control both the physical and virtual devices which are responsible for routing the data packets. 

 

2. API SDN:

 

It uses programming interfaces by integrating APIs for controlling the data that is sent and received by a device.

 

3. Overlay Model SDN:

 

It builds a virtual network on top of current hardware, offering tunnels with connections to data centers, and then assigns devices to each channel and distributes bandwidth in each channel.

 

4. Hybrid Model SDN:

 

This approach mixes SDN and conventional networking, allowing the best protocol for each kind of traffic to be assigned. Hybrid SDN is frequently utilized as an SDN phase-in technique.

 

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Software-Defined Networking: Working

 

Now that we know the definition and types of SDN, it is crucial to understand how SDN works. We have gathered some information from VMware, and these are stated as follows:

 

• In software-defined networking, the software is first disconnected from the hardware, and the SDN reallocates the control plan to determine where the traffic should be sent in the software.

• The data plan moves the traffic in the hardware. This enables network administrators who utilize SDN to program and administer the whole network from a single point of control rather than device by device.

• Data is moved via the network by physical or virtual networking devices. Virtual switches, which can be incorporated in either software or hardware, can take over the tasks of physical switches and combine their operations into a single, intelligent switch in some instances. The switch verifies the authenticity of both the data packets and their virtual machine destinations before forwarding them.

 

Importance of SDN

 

After learning all about SDN, the one question that comes to our minds is, “Why is SDN important?”. Software-defined Networking is important due to the following reasons:

 

1. Greater Speed and Flexibility:

 

As hardware needs to be manually controlled, it can be quite hard to program each vendor-specific device. But, in the case of software, developers may easily regulate the flow of network traffic by developing an open standard software-based controller. 

 

Network managers can also pick more flexible networking equipment since they can use a single protocol to connect with any number of hardware devices via a central controller.

 

 

2. Customizable Infrastructure:

 

Administrators using a software-defined network can create network services and assign virtual resources to alter the network infrastructure in real-time from a centralized place. 

 

This enables network managers to optimize data flow over the network and prioritize applications that demand higher availability.

 

 

3. Better Security:

 

Compared to traditional networking, SDN delivers more secured services by providing transparency and visibility into the whole network. With the growth of internet-connected smart devices, SDN provides apparent benefits over conventional networking. 

 

Operators can build discrete zones for devices that require varying degrees of protection, or they can quarantine compromised devices immediately so that they do not contaminate the rest of the network.

 

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Advantages and Disadvantages of SDN:

 

The following are the advantages of Software-Defined Networking:

 

1. SDN enables data to be readily moved between distant sites, which is essential for cloud services. Many of today's services and applications, particularly those using the cloud, would be impossible to run without SDN.

2. SDN enables the rapid movement of workloads across a network. For example, by splitting a virtual network into pieces using a technology known as network functions virtualization (NFV), telecom companies can transfer client services to less expensive servers or even the customer's own servers. Service providers can utilise a virtual network architecture to move workloads from private to public cloud infrastructures as needed, and to immediately launch new client services.

3. SDN also makes it very easy for any network to flex and expand by allowing network managers to add and delete virtual computers, whether on-premises or in the cloud.

4. Because of the efficiency and precision provided by SDN, it can facilitate new trends and technologies such as edge computing and the Internet of Things, which need transmitting data rapidly and easily across remote sites.

 

(Related blog: Types of virtualization)

 

Like advantages, there are some risks that come along with software-defined networks. 

1. SDN may benefit a business in a variety of ways, including increased agility and control, simplified management and setup, and enhanced security. The controller is crucial to the operation of a secure network. 

2. It is centralised and hence has the potential for a single point of failure. This possible risk can be addressed by adding network-wide controller redundancy with automated fail-over. This may be expensive, but it is no different than adding redundancy to other parts of the network to maintain business continuity.

3. A software-defined wide area network, or SD-WAN, can benefit both network operators and businesses. An SD-WAN is designed programmatically and enables centralised administration for any cloud, on-premises, or hybrid network topology in a wide area network. SD-WAN is appealing since it will enable many forms of connection, such as SDN, virtual private networks, MPLS, and others.

 

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Conclusion

 

SDN is a revolutionizing technology that has overpowered the architectural barriers of traditional networking. SDN does not replace traditional networking equipment and is only applicable to switches via automation. It  just reshapes the architecture to provide centralised management with many degrees of automation throughout the network. 

 

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In this article, we have learned about the definition and types of Software-defined networking along with its working. We have also discussed the importance of SDN, its advantages as well as disadvantages.