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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."'"
OpenFlow is basically a way to turn a packet network into a rather dumb virtual circuit network. It works something like Tymnet, circa 1971. In Tymnet, all the virtual circuits were set up by a "supervisor" computer, which told each node where each flow was supposed to be forwarded. The supervisor also handled authentication, but data packets didn't have to pass through the supervisor once the connection was set up. That's what OpenFlow does, mostly. The first packet of each new "flow" (IP/port/IP/port set, usually) is sent to Master Control, which decides whether that flow will be allowed. Master Control can also choose to monitor the flow. The implications are obvious.
DOCSIS 3, the cable modem traffic control architecture, can potentially do most of the same things, and offers better control over bandwidth. DOCSIS 3 tends to be run more to control users than to maximize throughput, but that's a marketing issue. (If your cable connection is throttling something, the commands to do it were probably sent to a DOCSIS node.) There's good QoS and fair queuing stuff in DOCSIS 3, but it's not always used intelligently. DOCSIS is less intrusive than OpenFlow; the nodes are sent rules to enforce, but there's no need to get permission of Master Control for every new flow.
The rest of "software defined networking" seems to involve adding another layer of indirection to Ethernet addresses so they can be moved around within the data center. ("There is no problem in computer science that cannot be solved by adding another layer of indirection.") That's a reasonable network management tool, but it's not exactly a profound concept.