SDN's biggest threat is all us people talking about it!!
In a recent article titled something along the lines of "Which SDN protocol should I use?", I found myself totally confused... Not the same kind of confused as entering a turnstile in the southern hemisphere (did you know they spin the other way down there). No, I found myself wondering if any of us can agree what SDN is.
A common comparison that has me scratching my big, shiny head is OpenFlow versus VXLAN or NVGRE. This is like comparing a Transformer (the shapeshifting robot, not the power supply) and a family sedan. What do I mean? Well, if you squint your eye's really hard and look at them from a long way away, then yes, there a small realtionship (both have wheels), but they do such very different things.
VXLAN and NVGRE are encapsulation protocols. They don't provide "programmable flow instantiation", which is what OpenFlow does, and that is SDN. If we are to label VXLAN and NVGRE as SDN, then we must also accept that older encapsulation protocols are SDN, too. For example, 802.1q VLAN tagging, GRE, etc. It pains me to even make this suggestion.
Lets say I put the Oxford English Dictionary down for a moment, while I climb off my high horse, and we do loosen the SDN term to include non-OpenFlow programmable flow instantiation (I prefer to call this simply "Programmable Networking"), then this still doesn't include encapsulation protocols for there is no programmable element to them.
May I humbly suggest that dynamic routing protocols are closer to SDN than encapsulation protocols? At least dynamic routing procotols do alter flow in packet forwarding devices!
That said, I would then have to add Advanced ADC’s to the mix as they evaluate real-time state (performance/security/app experience) and use this to make constant, flow-altering decisions. This example is even closer to SDN than dynamic routing... its just not using OpenFlow.
I'm all for abanoning the SDN acronym altogether. Its broad uses are far too ambigious, and with ambiguity comes confusion, followed shortly by fear and uncertainty.
That's it. I'm taking a stand. SDN has been struck from my autocorrect!!