Navigating Network Complexity: Next-generation Routing with SDN, Service Virtualization, and Service Chaining

Chapter 12. Virtualization and Complexity

Network services, such as stateful packet filtering, network address translation, and billing per unit of data transmitted, have traditionally been associated with appliances. If you wanted to block access to a particular application or part of the network, you would purchase an appliance called a firewall, mount it in a rack, and cable the network so traffic passing into the network would pass through the appliance. But why should packet inspection, for instance—ideally positioned as a software service to support rapid deployment of new features—be tied to an appliance, and hence to a specific physical location in the network? And why should a specific set of services, no matter how logically grouped, ...