The concept of Software Defined Networking (SDN) is about taking the routing control away from the individual network elements, and putting it in the hands of a centralized control layer - for example Nevion VideoIPath orchestration and SDN control system.
SDN has been around in the IT industry for several years, and its adoption is increasing – particularly in data-centres. SDN as a concept is also both vendor neutral and supported by industry standards, like Netconf/Yang, OpenConfig or Openflow.
With SDN, the orchestration and SDN control software holds a complete view of the available equipment, the network infrastructure and the services (media flows) – not just those currently in place, but also those that are planned. Thanks to this, it can make intelligent decisions on routing and controlling flows far more efficiently than is often possible with automatic routing. It can also provide the explicit routing capability that broadcasters expect and need.
The communication between the orchestration and SDN control software and the network elements (IP switches and routers) can be done in a variety of ways including OpenFlow® (an open standard that is supported by an increasing number of IP switches), NETCONF (Network Configuration Protocol - RFC 6241) or other interfaces. While SDN may appear more complex at first glance, it also offers many advantages.
SDN guarantees a much higher level of performance when compared to automatic routing. As the orchestration and SDN control software has all the required information about how sources and destinations are interconnected and the processing power to make the switching decisions fast, it can meet the clean switching speed requirements of studios.
The orchestration and SDN control software is also in control of every media flow, which means it is much more aware of, and much better at dealing with, existing and even planned (scheduled productions) bandwidth requirements.
The orchestration and control software knows all about the network topology and how to control the routing, which means it can easily create path diversity to protect failures.
Unlike automated routing, SDN can, with the right orchestration and control software, easily handle any network architecture, whether star, dual-star (pseudo spine-leaf) or true leaf spine – without compromise.
The orchestration and control software has full control of which destination can receive which multicast, thereby reducing the security risk substantially.
The default behaviour of an automatically routed network is to allow all traffic, unless it is specifically instructed to block it. In contrast, an SDN-controlled network works in the exact opposite way: it blocks all traffic, unless specifically instructed to allow it. Since the number of pieces of equipment that could connect to a media flow in a network is potentially infinite, blocking equipment is a complex, time-consuming and never-ending task, whereas allowing valid equipment is a fairly contained exercise.
There is no need for drivers for every piece of equipment, as the control is done in the network. That means that new equipment can be brought into the production set-up easily and cost-effectively.
Despite the clear advantages of a SDN routing approach over automatic routing, there continues to be passionate debate about which option is the best. Many leading names in this industry will actively champion automatic routing as the approach of choice, but there is a good reason behind this: many of their products have automatic routing built into them, and so there is a vested interest to promote a technology they have spent lots of money on, and which they believe provides a unique selling point.
Nevion, on the other hand, has no such vested interest. The Nevion VideoIPath software can handle both automated routing (e.g. IGMP/PIM) and SDN, but the benefits of SDN make it the control of choice for the creation of truly flexible, scalable and high-performance IP media networks.