 much faster decline in unit cost, more in-line with what is needed to keep up with the evolution of deployed technology Required unit cost evolution to handle traffic growth Impact of technology on unit cost FIGURE 1.1 Cost evolution. Building the Network of the Future growth in traffic. A second problem with the current way of network design and implementation is that in the face of rampant traffic growth, network planners deploy more capacity than what is needed (since it could take several months to enhance deployed capacity, beyond simple plug add-ons), thus creating a low utilization rate. We need to transition from a hardware-centric network design methodology to one that is soft- ware centric. Wherever possible, the hardware deployed ought to be one that is standardized and commoditized (cloud hardware, for example) and can be independently upgraded SO as to benefit from technology advances as and when they occur. The network function capability ought to be largely implemented in software running on the commodity hardware. The hardware is shared among several network functions, SO that we get maximum utilization. Network capacity upgrades occur in a fluid manner, with continuous deployment of new hardware resources and network func- tion software as and when needed. In addition, the implementation of software-defined networking (SDN) would provide three key benefits: (1) separation of the control plane from the data plane allowing greater operational flexibility; (2) software control of the physical layer enabling real- time capacity provisioning; and (3) global centralized SDN control with advanced and efficient algorithms coupled with real-time network data allowing much better multilayer network resource optimization on routing, traffic engineering, service provisioning, failure restoration, etc. This new network design methodology (depicted in Figure 1.2) has a much lower cost structure in both capital outlays and ongoing operating expenses, greater flexibility to react to traffic surges and failures,