New IT Navigation: SDN shifts from technology-driven to application-driven

The energy of digital technologies represented by cloud computing, big data, mobility and the Internet of Things is constantly being released. Driven by these emerging digital technologies, the original value chain is being broken and reshaped. The digital business models that continue to emerge in the new ecosystem are breaking the original rules of the game and creating new experiences for users.

As business model innovation represented by cloud computing, big data, social commerce and mobile technology continues to evolve, the demand for underlying network infrastructure is also growing. For operators, to seize these emerging opportunities, they need to restructure their networks internally to achieve the evolution of technical architecture and optimize internal efficiency. For enterprises, all innovative businesses are more or less restricted by or dependent on the underlying network infrastructure. In order to better meet the development of current businesses, changes at the network level are also in full swing. Network innovation based on SDN/NFV is developing rapidly and has become the main direction of current network innovation.

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SDN is a new type of network architecture. It builds an open and programmable network architecture by decoupling network control and forwarding. In 2011, the Open Network Foundation (ONF) was born, and the first Open Network Summit (ONS) was successfully held, and SDN developed rapidly. First, Google released the first SDN large-scale application case B4, and then various manufacturers launched their own controllers, and then standardization organizations successively launched OpenDaylight and ONOS open source controllers; at the same time, in the process of practice, the chip manufacturer Barefoot based on the SDN concept and the programming language P4 appeared one after another, allowing the entire software-defined network concept to flourish.

In actual implementation, the concept of SDN to separate forwarding and control has a great value in control based on business segmentation compared to traditional networks. However, in the actual network environment, it is difficult to fully achieve the ideal effect due to the rigidification and closedness of traditional network equipment. The emergence of a large number of applications based on SDN technology has also promoted the development of the network element layer towards standardization and definability. The demand for white-box equipment and NFV has emerged rapidly, especially in the construction of operator network reconstruction, NFV has become the core content of network element layer optimization.

In the process of technological evolution, a large number of SDN-based network models have emerged. However, after actually using SDN-related technologies to build specific networks, SDN is still far from meeting users' expectations for network disruption. What exactly caused this situation? The author believes that there are mainly two reasons:

• In the early stages, manufacturers focused more on the implementation of technical models and the improvement of infrastructure brought about by technological innovation, but did not pay enough attention to improving the actual user experience;
• The network based on SDN technology is just an IAAS platform, but lacks SDN-based application APP. Only by building appropriate applications on this platform can the value of SDN be maximized, that is, SDN needs to gradually shift from technology-driven to application-driven.

1. SDN gradually shifts from technology-driven to application-driven

The author believes that there are three reasons why SDN has shifted from being technology-driven to being application-driven.

(1) The application environment itself has changed

The difficulty of traditional networks to meet the requirements. The emergence of technologies such as cloud computing, big data, mobility, and the Internet of Things has made it difficult for traditional networks to meet current needs. This is the fundamental reason why SDN can develop rapidly. First, the emergence of cloud computing has made tenant-based resource allocation a basic requirement of IT. Traditional networks lack elasticity, scalability, and definability. The above resource allocation is very complex, time-consuming, and labor-intensive. Therefore, a method of quickly elastically expanding and allocating network resources is needed; secondly, with the emergence of a large number of mobile applications, the contradiction between application migration and location-based security technology has further intensified, requiring new security technologies; in the face of rapid changes in enterprise needs, operators also need to reconstruct rigid networks to adapt to the needs of agile deployment under the new situation.

(2) The time has come to promote the cycle of technology and application

In the IT industry, technology and applications are often the dual driving forces for development. First, there is a technological breakthrough, then a breakthrough in applications based on technology, and so on, which drives the entire IT industry forward continuously. For SDN, the early stages have already gone through the technology-driven stage of theoretical formation, practical model verification, and technology upgrading. Subsequent sustainable development requires continuous innovation based on applications in various scenarios. Only by finding the core value in each scenario can SDN achieve major breakthroughs in various industries.

(3) Users have a clearer understanding of SDN technology

User demand will gradually dominate its development. In the early stages of SDN development, users were more in the process of trying and exploring the technology. After the development in recent years, especially the gradual implementation of application models, many users have a deeper understanding of SDN. They will also do more thinking and business-based innovation in combination with their own business, and ultimately reflect the greater value of SDN in various scenarios.

2. Characteristics of application-driven SDN networks

Application-driven SDN networks should have at least the following four characteristics.

(1) Scenario-based

Different scenarios have different demands in network construction, and their business requirements vary greatly. In the combination of applications and technologies, scenario-based segmentation solutions will inevitably emerge. For example, the core requirement of the data center is "cloud-to-network elasticity and definability". At this time, the SDN network needs to have the ability to connect with multiple cloud platforms Openstack and Cloudstack, and can be easily defined by the cloud; secondly, it must be able to be easily expanded at the network level, such as single DC multiple Fabrics, single DC multiple Borders, and multiple DC elastic expansion; even in the wide area network, industry networks and DCI are more likely to achieve business visualization and intelligent scheduling through SDN, while in the branch interconnection scenario, they hope to achieve differentiated services through SDN, reduce wide area line costs, and ensure the quality of key business services. A single network model cannot meet various needs, so the scenario-based solution segmentation is the inevitable result of application-driven SDN development.

(2) Automation

The initial prototype of SDN came from a centralized control optimization solution proposed by Casado and his mentor Professor McKeown in the process of solving large-scale equipment management. It can be said that SDN has the gene of automation in its bones. Because SDN realizes the decoupling of the control layer and the forwarding layer, it objectively reduces the complexity of the forwarding layer equipment and maintains the relative consistency of the forwarding layer. Realizing the automation of equipment online is an inevitable development of SDN.

(3) Openness

After SDN realizes centralized control, it simplifies the management of devices. However, its greater value lies in providing an IaaS platform, where users can easily control massive network devices through the controller. This requires providing a large number of open interfaces on the controller to be called by upper-layer cloud OS, management system, business system and other applications. It can be said that if SDN loses its openness, its ultimate value will be greatly reduced.

(4) Flexibility

After the SDN network is centrally controlled, the expansion of the network itself becomes simpler and the network itself becomes more flexible. At the same time, for users and terminals accessing the network, since the control points are no longer scattered on each device, the movable location and range are expanded, and the entire network has a greater range of service consistency, making the entire operation and maintenance simpler.

Conclusion

SDN has gone through a cycle from technology to exploration of applicable scenarios. Now we need to return to the essence of the entire business, that is, to drive SDN further forward by customer needs and customer applications. After the combination of technology and application has achieved a breakthrough in value for customers, SDN will inevitably usher in greater development.