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

Chapter 9. Programmable Networks

In a sense, networks have been programmable from the beginning. BGP communities, originally outlined on two napkins drawn at a Washington DC bar by Tony Li and Yakov Rekhter, enshrined carrying complex policy within a routed control plane. While the tagging capability in many routing protocols, including OSPF, IS-IS, and EIGRP were useful for simple tasks, the ability to attach a full policy set to a single prefix added an entire range of capabilities. What else can policy-based routing and traffic engineering be considered other than programming the network? What’s different with the modern drive to make networks programmable (at press time—networking technology changes almost as quickly as the width of men’s ...