The future of networks with SDN

Software Defined Networks (SDN) 

More flexibility and agility for your business

For some years, IT and network infrastructures have been moving towards greater flexibility and virtualisation with the aim of managing network and IT infrastructures efficiently.

Text: Rüdiger Sellin, 25 January 2019 (published in Netzwoche and ICT Journal)

Cloud computing and the virtualisation of resources have fundamentally changed IT. Data, storage capacity, apps, etc. in the cloud can be accessed from any terminal device - from smartphones, tablets or notebooks, as well as by business applications, such as cashier systems or M2M (Machine-to-Machine) applications. This requires a network with high elasticity to enable the provision of a flexible and agile response to changing business requirements.


An SDN-based network architecture fully satisfies these requirements. With this solution, the multitude of network components is replaced by central software applications and a few standardised hardware components. Instead of a variety of proprietary and dedicated hardware, as many functions as possible are virtualised and implemented as software. Modifications can thus be implemented quickly and easily.


Third-party providers (e.g. AWS, Azure, SAP, etc.) are integrated on a customer-specific basis, as specified via the SDN platform. Supplementary services (overlay services) are implemented easily, quickly, seamlessly and with the usual security, via the dashboard, at the click of a button.

End-to-end view

Central and transparent end-to-end management assists with the execution of customer requirements across network or geographical boundaries, with the requisite high levels of security.


Centralisation of resource and network management eases administrators’ day-to-day workload. Configurations of networks and services are coordinated instead of individual components, such as routers, switches, firewalls or access points, having to be accessed separately, as was previously the case.


Thanks to SDN, configurations “on demand” run more quickly, smoothly and free from faults, as the overall view of the network automatically takes account of the interdependence of individual systems. This extensive automation enables the roll-out of new applications and services to be significantly quicker and easier than before.


However, SDN also covers the requirements for modern resource management. Standard orchestration also takes care of the configuration and monitoring of all network elements. It uses APIs to communicate with the individual service components, which independently communicate their status or errors. This orchestration provides an end-to-end view of the network as far as network element level. Sources of error can thus be quickly identified and resolved.


Closely linked to this is the standard and transparent management of all components involved in real time. This enables customer requirements to be satisfied within minutes, instead of days or even weeks. New configurations or firmware upgrades for implementing new services for customers are also implemented promptly.

Central architectural elements

Virtualisation and optimisation of network resources enables their prompt adaptation to changing business requirements, applications or currently prevailing internet usage. This is made possible by separating the control layer from the infrastructure layer. Control and management functions across networks are concentrated in the SDN controller. The use of software enables a programmable infrastructure that is less dependent on physical devices.


SDN controllers use open standards and APIs, which permits the orchestration, control and administration of various manufacturers’ network devices. This is done on the application layer, which provides individual views of the infrastructure. Based on open platforms, it uses the scaling opportunities, performance and availability of contemporary cloud computing and storage resources. This affords new opportunities that were previously unknown. Customers can, for example, use the dashboard to configure their own infrastructure clearly and easily. Or they can order new services or locations via order management in just a few minutes, rather than taking weeks or even months.

SDN architecture with three layers

SDN architecture with three layers

Software Defined Wide Area Networks (SD-WANs) stands for an automated approach for managing corporate networks with a high degree of cost efficiency. They use programmable network elements, which use dynamic routing to remotely establish and optimise the best path for the respective application.


Based on network conditions, security and QoS (Quality of Service) requirements of the application traffic measured and the costs of the connection, the SD-WAN establishes the optimum path. SD-WANs respond proactively to real-time network conditions. Overall, the company benefits from optimised costs, greater agility and better performance.

Network function virtualisation

SDNs and SD-WANs are closely associated with network function virtualisation (NFV). Application-based network functions, such as routers, firewalls, or load balancers, etc. are thus virtualised. NFV allows the SDN controller to execute all control and management functions in the control layer. This virtualisation enables an end-to-end view across networks with efficient administration and abundant orchestration of network functions.


NFV includes cloud and virtualisation technologies to enable the rapid development of new network services with flexible scalability and automation. It also allows virtual network functions (VNFs) to be added to the SD-WAN. Virtual network services, such as virtual private networks (VPNs), firewalls, QoS or multicast can also be run in addition to the SD-WAN on the same virtual CPE platform.


NFV provides greater agility for the provision of network services with capital efficiency, as inevitable bottlenecks with manual processes become a thing of the past, thanks to automatic processes, such as with the configuration of network elements. New services can thus be provided more quickly, free from faults and as needed, which satisfies the customer’s requirement for agility and scalability.

The new SDN world

Up to now, network and service management has been somewhat complex and challenging; but that is now changing, thanks to SDN. Centralised SDN controllers conceal network complexity and smartly combine the locally available intelligence of network elements. By separating the control layer from the infrastructure layer and the orchestration on the application layer, the flexibility and agility of individual layers improves, as does the scalability of the integrated system.


NFV enables the network operator to dispense with specialised and proprietary hardware (such as switches and firewalls). Instead, the operator uses more convenient universal hardware and uses software to assign it to the respective role required. Thus, a hardware element that is a load balancer one day could be run as a firewall the next day - with the respective provision having first been made with the necessary software function from the cloud. Consequently, this reduces the network operator’s dependency on providers of specialised and/or proprietary hardware, also enabling them to use their standard hardware more universally, thus improving capacity.


Consistent service management in real time increases response capacity and network availability. Security also benefits from the splitting of network functions into straightforward units and the separation on three clearly defined layers. Finally, simplified programmability enables easier automation of network functions, thus reducing operating costs.


In future, the flexible options of SDNs will cut across national boundaries. Interconnecting various network operators’ SDN controllers will result in a seamless offer for international customers. Further developments will follow and be included in the services offered.

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