There are numerous impediments to the adoption of software-defined networking, one of the major ones being cultural. In this case, the culture is one in which the network staff avoids the use of automation tools. This culture is based on the premise of: "Don't use anything that can break the network faster than I can fix it using the manual methods I know and currently use." SDN won't be successful in these environments until the network teams become comfortable with the use of automated network configuration tools.
Another form of cultural barrier is organizational inertia. As Network World writer Jim Duffy points out in Enterprises Hesitant on SDNs, the risk of change is causing organizations to proceed slowly. It is difficult to assess the impact of changing the fundamental network technology when the organization is running many applications, each of which needs to be validated.
A rule of thumb regarding technology improvements is that any new technology must provide ten times (10X) the benefits of the current technology to make the adoption of the new technology viable. Frankly, most enterprises don't see a 10X benefit from SDN over what they are already doing.
What about application agility? Many enterprises don't need to have new applications deployed any faster than what they are doing now. The current deployment process provides time for them to understand the application, create deployment plans, and understand how to diagnose problems when they occur. These organizations will need to develop new processes to rapidly deploy new applications and they are not prepared to spend the time to do this development.
A lot of planning will be required for an organization to migrate from an existing to new infrastructure. As an example, I worked with a customer who wanted to understand SDN and whether its recent investment in one type of network technology was now outdated. The plans that the company had developed over the past five years had it buying another round of non-SDN equipment. Its vendor was pushing the company to buy into the first generation of SDN-capable products.
Our approach was to look at its business processes to identify where SDN would be beneficial. Application agility wasn't a factor because its application deployment process hadn't changed. The business had over 75% virtual servers, but its existing processes wouldn't benefit from an SDN approach. The eventual conclusion, after reviewing the benefits of SDN, was that it wasn't quite the right time to switch to SDN. The company could wait for a second generation of SDN hardware, start learning more about SDN, and plan for a lab environment in which hands-on experience with some non-critical applications could be gained.
To read more aboout use cases, go to the full article on No Jitter.