These capabilities are enacted through one or more SDN controllers, which also serve as platforms on which controller applications can run. The applications themselves are the ultimate vehicles for SDN value. With the entire network as their resource, these applications can do things like streamline provisioning by making intelligent, top-down decisions based on controller input. For example, users can steer traffic to network monitoring points. What would have been a distributed configuration problem can now be solved from a single administrative touch point, reducing effort and the risk of downtime due to misconfiguration.
The role of big data
To be truly dynamic, SDN applications must be responsive to the world in which they exist. Minimally, there will need to be feedback loops to ensure the desired behavior is actually occurring after a change is made. Beyond that, it seems inevitable that the triggers for network changes will evolve from manual intervention to state-driven changes.
The natural progression from manual to automated will pass first through network analytics. For example, can current traffic conditions be used to drive path optimizations in the network? Can locality be used to intelligently pair users with content that is cached in close proximity?
Once you accept that analytics can play a meaningful role, you need to consider where that role should begin and end. What are the sources of information that can potentially be used? How many endpoints should be considered? What is the impact of virtualization on the number of endpoints? How much state information is distributed across these network and non-network entities? How is that state information collected, stored, and correlated?
The natural conclusion of this line of thinking is that analytics as we know it today will just scratch the surface. Ultimately, the promise of SDN will be inherently tied to the information that surrounds the network and drives the decisions that make SDN applications interesting. With more and more endpoints driving increasing traffic to a growing number of users, that adds up to big data.
When SDN and big data collide
There are a number of practical implications of moving to a dynamic IT infrastructure with hooks into multiple data sources. Here is a handful of the questions we'll need to consider: