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Inventor of OpenFlow SDN Admits Most SDN Today Is Hype
darthcamaro writes "Every networking vendor today is talking about Software Defined Networking (SDN). The basic idea is that the control of the underlying networking hardware is abstracted by software. Martin Casado helped to come up with the whole topic with his 2005 Stanford thesis (PDF). Eight years later after selling his startup Nicira to VMware for $1.2 Billion, Casado sees the term SDN meaning everything and nothing to all people. From the article: '"I actually don't know what SDN means anymore, to be honest," Casado said. Casado noted that the term SDN was coined in 2009 and at the time it did mean something fairly specific. "Now it is just being used as a general term for networking, like all networking is SDN," Casado said. "SDN is now just an umbrella term for, cool stuff in networking."'"
Certainly not all of them; but I'm pretty sure that the box they are all plugged in to is, pretty much, using a software layer to abstract the ugly details of dumping traffic between them over a really, really, fat internal bus of some flavor.
And, in many cases, a single fiber is(thanks to software) being sliced up into a bunch of little VLANs to create a logical topology that (while it is ultimately constrained by the physical one) is substantially different than the physical topology, especially once you count aggregated port groups, redundant links, and so on.
'SDN' doesn't mean jack in part because everything except your 20 year old 10Mb hub is already doing some amount of software trickery(even dumb switches keep track of which MAC(s) are on which port, and anything with 'managed' in the title can do quite a bit more), with varying levels of ASIC vs. general-purpose-CPU and varying levels of correlation between the logical topology and the physical topology.
There just isn't a nice bright line(at least in terms of real-world use cases, obviously a VM chattering to itself over a loopback interface is 'software' and a passive ethernet tap is 'hardware') between what is 'software defined' and what isn't. They all obviously depend on hardware to execute the software; but the amount of additional logical complexity slopes up surprisingly smoothly.