IT teams don't want to implement an SDN just for the sake of changing the network. What they want to do is solve one or more problems and/or find new ways to add value to the business. "If I were to go to a business unit manager and say that I need $3 million to implement OpenFlow and that will allow me to centralize the control plane of my network, they would kick me out of their office," says an infrastructure portfolio architect for a multinational professional services organization.
In other words, it only makes sense to implement SDN if it results in a measurable and significant improvement of the IT infrastructure and operations. "If I go to management with a plan to implement SDN and reduce the number of network administrators from 20 to 10 and to reduce provisioning time from two weeks to four days, they will at least listen to me," the infrastructure architect says.
Those anticipated improvements are reflected in the most common benefits IT will use to sell SDN to business partners: a more efficient and flexible network that improves delivery speed, cited by two-thirds of respondents planning to have SDN or that have it. Only half cite hardware cost savings, reflecting the uncertainty of SDN to deliver cheaper networking.
No Easy Cost Savings
It's not at all clear that cost savings anticipated with a controller-based SDN model will appear. Where IT teams anticipate those cost savings, it's in large part because dumbed-down switches will be cheaper than conventional switches. But given the current state of the market, the deployment of SDN won't result in dumber switches and routers for at least the next two years. That follows in part because it will take a new generation of merchant silicon to build fully functional, highly scalable OpenFlow-enabled devices.
And even if fully functional OpenFlow devices were available, the vast majority of IT organizations would adopt them over time and most likely would implement them only in part of their infrastructure. That's because IT organizations seldom swap out one infrastructure for another in a single move, particularly with a new technology.
It's also possible that the cost savings of commodity switches will be eaten up by the costs of centralized controllers. In fact, when we asked survey respondents to anticipate the impact of SDN on switch and router markets in 2015, the second-highest response was that costs would simply shift to controllers and software.
In addition, some IT organizations are likely to adopt SDN in a hybrid model, in which some control plane functionality is centralized and the remaining functionality remains distributed within switches. Depending upon how much control functionality is centralized, this scenario may not result in switches with significantly less functionality; in fact, this scenario may result in switches that require additional functionality to handle new applications written for an SDN-enabled network.