Cutting Through the Hype: What SDN Really Means

SDN provides the deterministic and scalable performance so critical to the professional broadcast community.
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As broadcasting moves into an environment increasingly driven by IT/IP architectures, Software Defined Networking (SDN) has become one of the most overused phrases in the past year. This is due in part because it is correctly seen as an important technology related to IP, but also because some broadcast equipment vendors are intent on imposing their own variations of the technology. SDN, however, is a clearly defined concept that is already widely used in the telco world. It's all about the abstraction and centralization of the network control plane outside the network itself.

Benefits in the Broadcast Realm
The ability to leverage the capabilities and favorable price points of the much larger IT industry by adopting IP-related standards is appealing. The cost of deterministic, high-bandwidth packet switching and high data rate physical network interfaces are being driven down by data centers and other key high-volume IT applications. Like it or not, more and more media interfaces are evolving to IP. As this happens the mandate for a switching and control layer that can handle this reality becomes all the more important—and that's where SDN comes into play.

In the early days of packet-based networks, the control and packet-forwarding functions of a router or switch were typically executed by a microprocessor, resulting in non-deterministic packet processing paths and times. As technology capabilities have evolved, larger routers and switches have largely separated the forwarding plane and the control plane, allowing for much more deterministic and scalable performance. The SDN journey is the next stage of this evolution, with the control and data planes decoupled, and control plane centralized. As a result, enterprises, carriers and now broadcasters, can gain unprecedented automation and network control, enabling them to build highly scalable, flexible and deterministic networks that can readily adapt to the most stringent business needs—for example the very low latency and ultra-high reliability required by broadcasters.

Delving deeper, SDN solutions now provided in the IT space are enabling simpler network switching elements to be controlled centrally for the required connectivity. Off-the-shelf switching elements provide extremely low cost switching and under an SDN control layer can form highly effective networks. Network equipment manufacturers are providing SDN capabilities on key product ranges to ensure they don't miss out on the action. SDN systems can also now control switching of the core optical layer, as well as packet switching around the edges of the network.

SDN at Play on Campuses
Broadcasters make use of telco networks for many aspects of their long-distance signal transport, e.g. contribution, primary distribution, distribution, etc. Since telcos have led the way in the adaptation of SDN technology, indirectly SDN has been part of broadcasters' extended networks for years—even if that capability has not, until now, been readily available to them.

Today, however, much of broadcasting's focus is in the campus/studio environment and SDN has an important role to play here.

In many ways, broadcast connectivity control over the past few decades in the campus/ studio environment has been quite "SDN-like" in that typically a central control system defines explicit routing of a video feed from one location to another. In that set up, there is absolute deterministic routing behavior, delivering what is inherently expected and desired. In addition to the cost benefit, the convergence and unification of real-time media delivery with non-real time file transfers means a single connectivity solution can handle both types of data. This kind of synergy is critical in today's increasingly IP-centric professional broadcast environment.

Wider Area Broadcasting and Remote Production
The requirements for wider area real-time media connectivity are increasing, particularly driven by the rising interest in remote production. For remote production, the ideal requirement is to have all of your studio and/or campus capabilities over a long distance. Most studio benefits and capabilities can now be realized in a wider area network. For example, location-to-location connectivity can be realized via one of more central hubs with low latency and transparent IP connectivity under the lid.

With the help of SDN technology, the management and control of a complete network becomes seamless, delivering the flexibility and cost effectiveness of IP, while maintaining the deterministic performance expected by the broadcast industry.

All this is only possible, however, if a standards-based approach is used. Vendor-specific solutions only end up locking broadcasters into specific and often costly technologies.

Vendor Neutrality and Control Functionality
Nevion, for example, is taking a standards-based approach to SDN—with its VideoIPath network management system at the core of the solution.

VideoIPath is now a fully-featured, technology-agnostic control system, capable of controlling both media edge and network connectivity. The system can provide full connectivity orchestration, both in the traditional broadcast space (SDI routers) and in the modern IP network. The platform is now integrated with many manufacturers of high- performance Ethernet switches, including Cisco and Juniper, as well as with Nevion's own eMerge media switch product range.

VideoIPath allows the underlying technology base to be migrated while the user interface remains constant and familiar. This allows the system to facilitate the transition from traditional SDI routers to an IP-based solution with no visible change in the user control experience.

As happens all too frequently in the new technology space, some manufacturers have moved ahead with proprietary "SDN" solutions that do not adhere to standards or provide a future roadmap to a compatible world. It's essential that both media interfaces and control layers are standards compliant to allow for full interworking. Otherwise, the true benefits of IP cannot be realized.

VideoIPath also integrates with OpenFlow, a key SDN technology. OpenFlow is the standardized protocol used to control the flow of data through a network by direct communication with the forwarding plane of the network elements.

Technology-Agnostic User Experience
With the ever-increasing complexity of the digital packetized world, it becomes essential to avoid challenging end users with the underlying technology and complexity of service provisioning. VideoIPath was designed with this in mind, providing a simple, non-technical interface for controlling end-to-end connectivity. So users deal with concepts that make sense to their business (connect studio 1 to studio 2), rather than having to handle the intricacies of the underlying network (network router ports, media gateway settings, etc.)

A Continuing Evolution
SDN provides the deterministic and scalable performance so critical to the professional broadcast community. Even more, SDN has the potential to provide more flexibility, lower costs and a future-proof route to a broadcast world where real-time and non real-time content/media converge. SDN technology is providing the means to transition to IP, through technology-agnostic solutions such as Nevion's VideoIPath media management platform, including soft-reconfigurable media edge adaption. Systems such as these provide a fully open, standards-compliant way of navigating this new world with confidence.

Andy Rayner is vice president engineering at Nevion.  


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