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Introduction to Software Defined Networking

Subhra Priyadarshini Biswal and Sanjeev Patel*

Department of Computer Science and Engineering, National Institute of Technology Rourkela, Odisha, India

Abstract

In recent years, we have seen the rapid growth of software-defined networking (SDN) in development and production. In traditional networking systems, fixed dedicated network devices, such as switches, routers are used to control the network traffic. However, nonprogrammable feature, poor network security and performance drawback have created new challenges for future Internet-based information and communication system. The complexity in traditional networking makes the system difficult to reconfigure the network to counter faults, load, and error. To overcome these issues, SDN is taking control over the traditional manually configured network to make proper utilization of physical network infrastructure. The aggregation of separate control plane and data plane allows network virtualization and dynamically programmable network configuration to improve the performance. The control plane is responsible for routing the data packet from source to destination. Similarly, the data plane is used for forwarding the packets that is also known as the forwarding plane. It is constructed on centralized network topologies that enable resource management. As a result, the network operator or service provider can manage and directly control their resources and network despite knowing any hardware technologies. It gives high flexibility, automation, service integration functionalities to accommodate innovative network designs. The SDN controller regulates the flow of control over the switches/routers to deploy intelligent networks. The open architecture of SDN broadly includes the infrastructure layer, control layer, and application layer. In this chapter, we focus on the architecture along with the advantage of using SDN networking over traditional networking systems.

Keywords: Software-defined networking, SDN architecture, open flow, NFV, centralized controller, network operating systems

1.1 Introduction

In traditional networking system, the communication between devices by transferring packets was possible by the help of various distributed and transport control protocols present inside switches and routers. This is widely used and adopted by many industries and companies in all over the world. But the architecture used in traditional network generates huge difficulties in maintaining and managing the whole network infrastructures. Nowadays, as the growth of technology is rapidly increasing, it may lead to the rise of data communication or transmission in the network. As a result, the number of devices connected to the network will also increase. It may require proper maintenance as the networking devices are maintained manually by human, which may lead to various configuration errors. This problem arises due to the nonprogrammable features of traditional networking. Due to the huge network infrastructure, it is very difficult to add, manage, and maintain the network properly. It is time consuming and less flexible. With the increase in the number of devices, the operational and management cost will also increase. As most of the things in traditional networking are done manually, it is very difficult to make changes in the existing network. It is very difficult to virtualize the entire network. Further, we can say traditional networking is hardware based as it contains fixed function network devices. It is more rigid and very difficult to customize the network.

Moreover, the traditional networking shown in Figure 1.1, the network operator has to set up some low-level commands in each separate network for maintaining the desired network policies. To enforce the desired vendor-specific policies in such dynamic environment is highly challenging. Due to the complexity in configuration, it is very difficult to handle the dynamic changes in load, as well as faults and errors. The communication between different network nodes, like switches, routers, etc., is more complex. In addition, most of the networks give less flexibility as both the data plane and control plane are integrated inside the networking devices. As a result, it is very difficult to change or adjust the forwarding policy by changing the configuration of devices. The control plane is responsible for configuration of different nodes, and it determines the path to route the packet or frame. Similarly, the data plane is responsible for forwarding the packets or frame from one interface to other [1]. Security is one of the biggest challenges in this network. As it has the vendor-specific environment, the network became less capable of protecting data.

Figure 1.1 Traditional networking.

Software-defined networking (SDN) is a type of application-centric and software-based network design concept, which uses different technologies to manage the network. The concept of SDN was first introduced in 2009 at Stanford University, United States [2]. Here, the network operator can target on various network applications, such as security, data traffic, policies, etc., in more flexible way [49]. It also allows the network operator and administrators to maintain the desired bandwidth in the network. As a result, the issues related to complex network configuration will minimize. However, instead of using costly hardware and firmware, it provides an open-source logically centralized network system. It also provides a centralized open flow controller in multivendor environment, which is used as a control point in SDN strategically [48]. The OpenFlow provides interface to the networking devices like switch [40]. As a result, it facilitates the network administrator to abstract configuration of various physical or virtual network devices. Moreover, each networking devices contain flow tables and the controller's job is to update and insert the forwarding rules for the traffic flows in the network.

The separation of both control plane and data planes with centralize network intelligence allows dynamic programmability instead of static manual operation. It fulfills the requirement of virtualization, dynamic scaling, automation, multitenancy, performance optimization, service integration, openness, etc. The benefits of SDN in different scenarios also include different enterprises and cloud data center. In traditional network, each networking device directs the network traffic. But in case of SDN infrastructure, the automated programmable interface determines and route the network traffic. The SDN controller helps to automate the whole network management, which reduces the complexity for the end users. The network administrator can change the network wide infrastructure with a centralized console. It mainly converts the hardware intensive traditional network to fully virtualized and programmable network, which fulfill the need of scalability, agility, and visibility of the network [32]. Due to these many advantages, various industries and enterprises may get support in the field for development and innovations of application services [31]. It helps to improve user security and reliability of the network. In SDN, the deployment of the network is simplified. It provides programmable network services to the user with proper network control. Unlike traditional network, it overcomes the issues related to managing individual networking devices.

The most looked for and promising features of SDN networks are related with:

• providing centralized control policies, which gives a global view of network configuration and activity as various nodes has different functionalities;
• capability to dynamically program all features and configuration of network resources conveniently over automated SDN services instead of static manual operation;
• independent of physical infrastructure as the network administrator can dynamically modify the network traffic flow to meet the changes;
• implement open standard, which simplifies the network design and operations.

The main objective and contribution of this book chapter are outlined as follows:

• To give insight related to this new emerging SDN-based networking along with its challenges and future scopes.
• The aim of this chapter is to elaborate the differences between NFV and SDN.
• To discuss the applications of SDN in IT, challenges, and future direction of the research.
• Our main contribution for this chapter is to present the snapshot of the SDN deployments, its architectures and how it will be efficient in IT industries along with various opportunities.

The rest of this chapter are organized as follows. Section 1.2 starts by explaining different terminologies related to SDN network. Then, the SDN architecture with different layers has been explained properly. Additionally, we have identified and broadly explained each layer's specifications, objectives, and functionalities. In section 1.3, the role of network operating system in SDN infrastructure has been presented. Then the discussion with regard to the differences between Network Function Virtualization (NFV) and SDN is done in Section 1.4. Next, we look at how NFV has been incorporated in SDN-based Internet of Things (IoT) systems in section 1.5. Likewise, then various challenges, future research, and applications of SDN are discussed in section 1.6 and 1.7....