Federating virtualised network controllers

Integration: An infrastructure for enabling efficient data sharing across incompatible applications that evolve independently in a coordinated manner to serve the needs of the enterprise and its stakeholders.”
John G. Schmidt, and David Lyle
, in their book “Lean Integration: An Integration Factory Approach to Business Agility.”

Another of Tom Nolle’s insightful blogs has helped to describe a question that I’ve had for some time in relation to SDN (Software Defined Networking) – that of how SDN controllers would federate in a complex or multi-domain network. He breaks this federation down as follows:

  • The concept of having a single, master SDN controller to establish end-to-end services through a network would seem to have challenges in scaling for larger networks
  • The next alternative is to break these virtualised networks into zones to be administered by different SDN controllers
  • But the challenge with this “zoned” model comes when federating across administrative boundaries such as between CSPs.

Tom uses the term, “functional federation” to describe the hand-off between zones with minimal adjacent zone knowledge, such as how BGP exchanges addressing between Autonomous Systems. He then uses the term “structural federation” to describe an alternative method where SDN control is hierarchical to overcome issues seen in complex networks (eg transit networks) and or complex traffic engineering scenarios.

Given that the locations, topologies and capabilities of the controllers will develop hand-in-glove with service management, network management and “protect the king” security in virtualised networks, the ramifications of how controller federation plays out could have a significant impact on how the OSS and BSS topologies of the future might look.

I can’t help but think that the B/OSS processing load of the future will be highly distributed across commoditised server/storage platforms. But watch this space in terms of how the controller federation models develop and how B/OSS intertwines with it.


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