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Changing the playing field for data centre networks with SDN

By Stu Benington, vice president of cloud and SDN business unit, Coriant

The evolving connectivity needs of both businesses and consumers are piling the pressure on service providers on a daily basis. Traditional business models are being exposed as outdated, while the limitations of traditional static transport architectures are being challenged.

The difficulties facing providers include the ever-increasing demand for network capacity to cope with the multitude of bandwidth-intensive end-user applications. Other headaches troubling providers include increasingly unpredictable traffic patterns and usage spikes and, most importantly, the transformational architecture shift toward a cloud-centric networking environment.

To meet these challenges, service providers in both developed and emerging markets are turning to one of the industry’s most promising technologies – software-defined networking (SDN). While still in a formative stage from an implementation perspective in the wide-area network (compared to server and storage virtualisation in the data center), SDN will play a critical role in enabling service providers to create a more efficient, agile and scalable transport infrastructure capable of meeting the demands of cloud-centric connectivity.

Indeed, while service providers have been exploring these concepts for a number of years, 2014 is shaping up as the year of glory for SDN as more operators make the move from research and lab trials to field trials and implementation in their networks. Indeed, analyst firm IDC bullishly estimates that SDN will be a $3.7 billion market by 2016.

But what separates SDN from other technologies that promised to transform the way we do business but ultimately failed?

On-demand elasticity for a new networked world

As end users become more cloud-centric and traffic patterns become increasingly unpredictable, service-provider networks need to mirror the on-demand flexibility, scalability, and programmability of data center compute and storage resources.

The end goal is not just to make the network more efficient, however. Rather, it is to fundamentally change the network paradigm and create an application-centric service delivery model that is capable of on-demand agility, flexible performance parameters and seamless scalability. This requirement is compounded by the emergence of technologies such as network functions virtualisation (NFV) that enable applications and network appliances to be distributed closer to the end user and leverage commercial off-the-shelf hardware.

SDN implementation provides service providers with an opportunity to innovate while fully leveraging the value of their existing assets, including network resources, networking expertise and investments in the network brand.

Enabling service transformation

Many businesses are already preparing for SDN by deploying Ethernet fabrics and bolstering the robustness and flexibility of their networks. As service providers transform existing network resources and architectures, there are a number of key network attributes that need to be addressed:


The fastest way to introduce and change services is to make the network more programmable – in other words, make it fully adaptable to the changing needs of end users, network operators, and the applications themselves. Software-defined programmability and the automation of network resources will enable service providers to unlock new service revenue opportunities (e.g., transport as a service, bandwidth-on-demand, scheduled bandwidth, etc.), adapt to real time network changes (e.g., virtual machine migration), reduce overall network complexity, and more efficiently use network resources at the lowest cost.

End-to-end multilayer integration

As end-user services and applications increasingly move to private and public cloud networks, it becomes increasingly important to provide agile and efficient integration of compute and storage resources across multiple geographies, such as access, metro and core, and protocol layers like wavelength, Optical Transport Network, Ethernet and IP/MPLS. SDN can play an important role in harmonising capabilities across this broad range of resources and enabling a true end-to-end global view of the network.


Packet optical transport infrastructure networks are multi-vendor and multi-technology by nature. They therefore depend on standards-based protocols to enable interoperability at the physical layer, yet the majority of current networks are built on 20-year-old legacy technology, which are often closed off and restrictive.

SDN enables an unparalleled ability to administer multi-vendor networks and architectures with an open and collaborative software-based development process, focused on end-user applications and optimised for enhanced-network programmability. An open SDN environment has huge potential for both users and operators. It can drive innovation at an unprecedented pace by enabling simple introduction of new functions and applications written by network vendors, third-party developers and even the operators themselves.


The ability to foster innovation in the areas discussed above is perhaps the most lucrative opportunity for an SDN-enabled network. As a further example, it’s possible to write abstracted applications for the network and apply them in a way that’s detached from specific vendors, protocols, or geographic environments. These abstracted applications can be specific to use cases such as dynamic congestion management, carrier applications like mobile video management, technologies including weather management for microwave links, and many more.

Developing app-centric service creation

SDN promises the integration of network resources to create what can be described as a unified network operating system or controller infrastructure. This has the potential to enable optimal connectivity for end-user applications across multiple layers, domains, vendors, and technologies.

In addition to the high degree of programmability and automation, the SDN-enabled network is application-centric. Not every application has the same set of requirements or priorities, and neither are they billable in the same way nor equally profitable to the service provider. Aligning network resources to serve the performance requirements of specific applications and services translates into direct financial benefit for service providers. In this sense, the operator has the ability to ‘monetise’ network properties such as differentiated resiliency or lack of latency.

SDN by the numbers

SDN has the potential to deliver significant cost and time saving benefits for businesses. These business advantages include:

  •  Automation of program controls and functions, reducing human error and increasing efficiency
  •  Rapid availability of new products and services
  •  Decreased times for dimensioning and provisioning resources for applications
  •  Reduced complexity of provisioning and configuring diverse resources
  •  Decreased capex and opex by enabling customers to quickly customise required connection parameters, while operators distribute loads to the most appropriate resources with greater efficiency
  •  Minimised vendor lock-in and forced upgrade cycles

It is important to note that while SDN is already proving its worth to organisations that run very large networks, it should not be viewed as something to adopt for its own sake. In time, it may well be seen as the first step in a more foundational shift in IT: the creation of the software-defined data center. As more individual hardware functions are transitioned to software, the natural progression is to eventually virtualise the entire data center.

Nevertheless, organisations must ensure adopt the right infrastructure elements early, and begin to implement virtualisation and SDN as soon they are able to. Those that have prepared themselves invariably realise the benefits sooner and gain a competitive advantage over their competitors.


Media Partners