The Paradigm Shift: Software Defined Networks, Software Driven Networks and OpenFlow

In a recent blog entry, Harry Quackenboss from Layerz NGN makes some interesting and apropos points regarding the present and evolving world of Software Defined Networks and Software Driven Networks (both use the SDN acronym for now) and OpenFlow. The issue is there are many problems that can be solved with these technologies, and in some cases, the same problems can be solved using more than one technology, which brings to mind the proverbial “you can skin a cat in different ways” situation. Let me spell things out a bit, which hopefully can clarify things by explaining why SDN (and Software Driven Networks) represent a critical paradigm shift in the software application and network technology industries. First, it might be controversial to say this, but there are really no use cases in this space that I can think of or that have been discussed recently that cannot be solved using existing mechanisms versus Software Driven Networks (SDrN), and in a subset of those cases, Software Defined Networks (SDN). Of course with that in mind, please also remember that given enough thrust just about any pig can be made to fly! What is, however, important about SDrN is HOW it solves (or proposes to solve) these problems and how quickly it can solve them in terms of real operational and application development time. Take the basic premise of OpenFlow itself: on its surface (at least for now) it amounts to what is really just static routes/forwarding entries. We already know how to manipulate/provision/interact with those constructs in existing devices today using interfaces such as CLI, XMLConf, SNMP, etc.  Why don't we just use those things and call it a day? Simple. Where things differ is how applications interact with those components today versus how you need to interact with them -- especially in a hyper-virtualized environment that not only needs to be brought up quickly, but also needs to change frequently. These environments also contain orders of magnitude more components than a traditional non-virtualized environment. What is important is what network devices and service points provide to the applications and at what rate of speed you can interact with them.