There’s a lot of talk about SDN giving control to applications over the network’s behaviour. I’m not too sure I buy a lot of it.
Necessary clarification: when I’m using term “application” in this blog post, I mean the applications that need network connectivity services to deliver their data to their users, rather than the specialised applications, designed for sole purpose of controlling data traffic flows.
Network transport services in my mind are somewhat similar to the physical world transport services: they are built to shift a lot of stuff, on a fairly regular schedule. In the physical world, while we theoretically can buy/rent and drive our own trucks, when it comes to regular service, we do that relatively rarely.
Instead, we rent services of specialised transport companies, which offer us a selection of transport services, with associated SLGs, at well-defined price points. They take care of making sure that our goods are handled accordingly; and that other necessary services, such as air and sea, are aligned seamlessly to deliver on the promise, when needed. They also take care of capacity planning and management (and a whole raft of other things), so that we don’t have to.
Sure enough, we are not always happy with the service we receive from these companies, but in my opinion this doesn’t necessarily means that we should be starting our own.
On the other hand, where I think we can (and should) improve things, is the process of provisioning of those transport services from those specialists, and this is where I think the value of SDN lays. Quantum in my mind is an example of things going in the right direction – provide a connectivity service brokerage, with a standardised front-end, and flexible, plugin-based back-end.
The magic behind curtains? I’m not particularly fussed about how it’s done, so long as the network delivered on its SLG promise. The last thing I want to worry about when thinking about my container full of goods on its way to customers are the things like the oil level in some truck’s engine or an incident somewhere on some highway somewhere.