January 07, 2013, 7:13 AM — This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter's approach.
SDN represents virtualization's evolutionary step from the server to networks. It is an emerging architecture that separates the control plane from the data plane in network switches and routers. SDN uses dynamic UDP (User Datagram Protocol) tunnels that are very similar to GRE (Generic Routing Encapsulation) tunnels, except that they can be turned on and off dynamically. SDN can be contrasted with traditional networks in which the control and data planes are jointly implemented.
TECHNOLOGIES TO WATCH IN 2013: Cisco products, more maturity for SDNs
The big advantage of SDN is that it lets you rapidly and dynamically carve up your network as you see fit. Why does that matter? Just picture today's typical programmer who thinks he's working on a development system. But unbeknownst to him, a faulty configuration has him actually working on a live production system. One simple typo could devastate the production system -- and therefore the entire business. SDN can solve this problem. The programmer can create a development system isolated in the sandbox, and then in two weeks instantly convert it to a production system.
Sounds abstract? Lets explore an analogy. When I drive my car from San Francisco to Los Angeles I take highway I-5 South -- a public road open to everyone. That represents today's network. With SDN, it's as if an engineer could quickly and inexpensively create private on-ramps, highways and exit lanes for each individual driver. And the engineer can authorize only some to get on and off. You can imagine the driving pleasure and efficiency with that type of road travel system. To do the equivalent in a traditional network would immediately become a cost-prohibitive nightmare.
What you lose: visibility