Rich Bennett and Steven Nurenberg CONTENTS 2.1 Introduction 2.2 Rapid Transition to All-IP The Network Cloud The Modern IP Network 2.4.1 The Open Systems for Interconnection Model 2.4.2 Regulation and Standards Transforming an All-IP Network to a Network Cloud 2.5.1 Network Functions Virtualization (NFV) 2.5.2 NFV Infrastructure 2.5.3 Software-Defined Networking 2.5.4 Open Network Automation Platform 2.5.5 Network Security 2.5.6 Enterprise Customer Premises Equipment 2.5.7 Network Access 2.5.8 Network Edge 2.5.9 Network Core 2.5.10 Service Platforms 2.5.11 Network Data and Measurements 2.5.12 Network Operations References This chapter provides context for and introduces topics covered in subsequent chapters. We sum- marize major factors that are driving the transformation of telecom networks, characteristics of a modern all-IP network, and briefly describe how the characteristics change as an all-IP network transforms to a Network Cloud. The brief descriptions of change include references to succeeding chapters that explore each topic in more detail. INTRODUCTION The dawn of the Internet began with industry standards groups such as the International Telecommunications Union (ITU) and government research projects, such as ARPANET, in the United States proposing designs based on loosely coupled network layers. The layered design com- bined with the ARPANET open, pragmatic approach to enhancing or extending the design proved to have many benefits including the following: integration of distributed networks without central control; reuse of layers for multiple applications; incremental evolution or substitution of technology Building the Network of the Future without disruption to other layers; and creation of a significant sized network in parallel with the development of the standards. Tremendous growth and commercialization of the network was triggered by the ubiquitous availability of the Transmission Control Protocol/Internet Protocol (TCP/IP) network stack on Windows and UNIX servers and the development of web 