Software Defined Networking (SDN)

In this lecture, “Software-Defined Networking at the Crossroads”, Scott Shenker, University of California, Berkeley discusses SDN, it’s evolution, principals, and current state.


I’d like to solicit comments on their presumptions.  Are networks really difficult to manage?  If so it it because of the technology or because management is often an afterthought rather than an integral part of the system design?

Pay particular attention to the term “operator”.  What department or role is Dr. Shenker referring to as operator?  Is it the NOC or the Network Engineering department?

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2 Responses to Software Defined Networking (SDN)

  • Chris says:

    Re: your question: “What department or role is Dr. Shenker referring to as operator? Is it the NOC or the Network Engineering department?”, I think the question itself is biased.

    The discussion revolves around the concept of ‘abstraction’. From the perspective of abstraction, any human being that has any level of command-and-control over the network is considered an operator. Your question seems to be clinging to the (understandably) self-preserving mindset that “engineering” is on some different plane than “noc staff”, when in fact BOTH roles are ‘operators’ of the network. From the perspective of SDN, all levels of ‘operation’ are obfuscated into the various software control layers he calls out. For SDN, it doesn’t CARE if you’re a CCIE, jr NOC staff, engineer, architect, or admin… our arbitrary lines-in-the-sand delineation of responsibilities become the various control layer’s job to worry about. And once it’s defined in the SDN stack, the technical-know-how becomes relatively obfuscated as well…since the day to day ‘operation’ gets relegated to repeatable computer-instantiated transactions. (ie, no human “hands-on”)

    I’m not implying that there will no longer be any value in being a ‘network engineer’ – we’re still a ways off from this model being adopted Internet-wide…so there’s still plenty of time and plenty of places where sites will drag their feet or refuse to adopt these kind of models (for a myriad of reasons)…so traditional ‘network engineers’ will continue to be needed. However, I have to say I whole heartedly agree with the points called out in this talk. The traditional ‘networker’ role will be dissolving and replaced by software counterparts, regardless of whether you’re an ‘architect’ or a ‘noc newbie’.

    Regarding your first question, IMHO, I wouldn’t say that managing networks is ‘hard’, but rather that it’s generally not done very well. Each site and case obviously has it’s own challenges and hurdles – perhaps it’s human error, perhaps it’s platform incompatabilities, perhaps it’s lack of developer perspective…there’s a lot of reasons. A large number of which, in my experience, when you dig and get to the root-cause, are rooted around human job self-preservation issues. In countless cases I’ve worked on ‘cleaning up’ poorly-rigored environments that experience frequent outages, performance degradation, and ‘ghost-in-the-machine’ types of problems…that once human-error gets removed from the “operational” side of things, the whole environment runs and performs better. The biggest challenge comes though in what to do with all the leftover people that are no longer allowed to touch anything since they’re the ones that made the environment unstable to begin with…placing us back in the middle of the ‘human job self-preservation’ debate.

    Just my thoughts. Appreciate the discussion.

    • Craig says:

      Thanks for your comment, Chris. It certainly seems like the role of network technicians at any skill level will change with SDN. I also agree that managing networks isn’t hard, but it usually is an afterthought rather an integral part of the system design. Abstraction is key there and network design has not followed other industries in that regard. The most common approach is to provision devices based on a concrete design rather than producing an abstract design from which all devices can be provisioned in a repeatable fashion. Here again SDN will radically change the way that is being accomplished by providing the abstract constructs within the controller.