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Making Networks Cool Again through Network Softwarization

Computer networks are complex and can be very difficult to manage. In a typical network, one can find many kinds of equipment, ranging from forwarding elements such as routers and switches to middleboxes, which are equipments that perform a wide range of networking tasks, such as firewalls, network address translators (NATs), load balancers, intrusion detection/prevention systems, etc.

For the past few decades, network operators have been relying on a handful of equipment vendors that provide proprietary and vertically integrated hardware running complex, closed and proprietary control software. The software implements network protocols that undergo years of standardization and interoperability testing. Because of the lack of network programmability and flexible management interfaces, network administrators typically configure individual network devices adapting tedious and error-prone manual configuration methods.

This mode of operation has slowed innovation, increased complexity, and inflated both the capital and operational costs of running a network.

The recent trend toward Network Softwarization is driving an unprecedented techno-economic shift in the Telecom and ICT (Information and Communication Technologies) industries. By separating the hardware on which network functions/services run and the software that realizes and controls the network functions/services, Software-Defined Networking (SDN) and Network Function Virtualization (NFV) are creating an open ecosystem that drastically reduces the cost of building networks and changes the way operators manage their networks.

SDN and NFV paradigms enable the design, deployment and management of networking services with much lower costs and higher flexibility than traditional networks. In particular, they are contributing to the deployment of 5G infrastructures, from high data rate fixed-mobile services to the Internet of Things. As a result, new value chains and service models are emerging, creating novel business models and significant socio-economic impact.

SDN and NFV are two sides of the same trend toward network softwarization. SDN involves three principles: separation of the control logic (control plane) from packet forwarding (data plane), centralization of the control logic and programmability of the data plane through well
defined control plane-data plane interfaces.

Unlike traditional networks where control is distributed and embedded into network devices (switches and routers), SDN logically centralizes the control plane in one entity called the SDN controller. The SDN controller runs on a single or cluster of servers, has a global view of the network, and translates high level operational policies into switch/flow level traffic management decisions. This separation allows employing much simpler forwarding hardware (generic switching equipment that is built using cheap merchant silicon) that provides much faster packet forwarding. OpenFlow is the standard communications interface defined between the control and forwarding planes of an SDN. This programmability enables a great
flexibility in network management, and leads to faster innovation in network traffic engineering, security and efficiency.

On the other hand, NFV softwarizes network functions (NFs) such as load balancers, firewalls and intrusion detection systems that were previously provided by special-purpose, generally closed and proprietary hardware. NFs will now be implemented by software that could run on virtual machines running on commodity hardware. They also can be provisioned
as virtual NFs (VNFs) in a cloud service to leverage the economies of scale provided by cloud computing, and consequently, reducing network capital and operational expenditures.

While either SDN or NFV can be used by itself, the two technologies are complementary and there is big synergy in combining both of them. However, the new features brought by either SDN or NFV are also the source of new security challenges, and the combination of both technologies may increase the impact of the related security threats. For NFV and SDN
to achieve widespread adoption by the industry, security remains a top concern and has been a hurdle to the adoption of network softwarization. Based on recent surveys, security is one of the biggest concerns impacting the broad adoption of SDN and NFV.

Another exciting research question in network softwarization is How to leverage the centralized control in SDN to advance traffic routing, which is arguably the most fundamental networking task. For decades, innovation in routing did not get a fair attention from the industry for various historical, financial and practical reasons. However, the unprecedented growth in network traffic and application requirements witnessed by today’s networks is driving a huge need for automation. Network operators are paying attention to innovative routing and traffic engineering solutions. We argue that the combination of network sofwarization and the recent breakthroughs in machine learning techniques offer an ideal framework for network automation. For example, thanks to new powerful deep learning techniques, operators are able to model very complex networks and find patterns in large amounts of network data, which offers great opportunities toward automation of network control.


Feamster, Nick, Jennifer Rexford, and Ellen Zegura. “The road to SDN.” Queue 11.12 (2013): 20.

Harvey Freeman and Raouf Boutaba. Networking industry transformation through softwarization. IEEE Communications Magazine, August 2016.

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