nies to deploy and manage these boxes. Many also tried adding new management platforms that provided a "single pane of glass" management interface. However, because new func- tions were being created in isolation, the customer was left with multiple "single pane of glass" management interfaces. As enterprise IT continuously deployed additional middle boxes, the rules to manage traffic between the network elements became SO complex that it often required highly skilled networking professional to plan and test a small change in network design. In addition to the middle-box and management issues, growing network demand due to the change in business environment has also been contributing to an increase in network complexity. Whether a business is expanding or consolidating, it requires the capabilities to run demanding applications like streaming data, email, and video content. IT managers are looking for a network service that is fast, versatile, and can carry mission-critical traffic without any downtime. The adop- tion of cloud services and the need for user-mobility requires significant change in traditional net- work design. From service-provider perspective, one needed a broader approach-a software-centric model for all networking needs. New virtual network appliances that met the requirements associated with software-based cloud services could also be used to address use-cases associated with CPE deploy- ment. One can create a software-centric model for CPE devices that will provide managed service providers and their customers with an opportunity to evolve the enterprise networks to be more flexible, responsive, and future proof. This is depicted in Figure 10.1. In this new software-centric model approach, the network becomes a collection of virtual net- work services. The services can be instantiated on-demand at the customer premise, within network nodes, or within the customer datacenter as needed. This also allows the possibility of creating a dynamic policy control environment where different policies or