While we are seeing a big hype going #SDN way still technical community does not seems to be totally comfortable with SDN. Tom Nolle summarized those missing links in his blog According to him some of the key missing links are 1. Lack of standards for full device control 2. Service control software is missing 3. Multivendor network control a barrier to adoption 4. Managing control traffic in centralized networks 5. Boundary functions are needed