tworks. We wish the reader interesting reading moments, and we hope that this book provides help to the reader, whether a student, operator, network vendor, application developer, or handset manufacturer, to learn about and navigate through the IPv6 transition in the 3GPP network ecosystem. Deploying IPv6 in 3GPP Networks: Evolving Mobile Broadband from 2G to LTE and Beyond, First Edition. Jouni Korhonen, Teemu Savolainen and Jonne Soininen. C 2013 John Wiley & Sons, Ltd. Published 2013 by John Wiley & Sons, Ltd. Deploying IPv6 in 3GPP Networks Introduction to Internet and the Internet Protocol The Internet and the Internet Protocol creation were originally funded by the Defense Advanced Research Agency (DARPA) in the United States. Yet, today the Internet has become the global network of the whole world connecting all continents, virtually all of the countries, and already has significantly over two billion users. This path from a relatively small research project to the global information superhighway has been both fascinating and relatively quick. The DARPA project was started at the very end of the 1960s, the current version of the Internet Protocol was introduced in the early 1980s, and the first commercial Internet access providers came online in the end of 1980s or early 1990s depending on country and region. As late as 2006, one of the main topics of the Internet Governance Forum (IGF) - a United Nations (UN) organization discussing matters that concern the governance of the Internet, both technical and non-technical - was to connect the unconnected, that is how to get Internet access to the developing countries. Since that day, most of the developing countries have at least Internet access in the bigger cities, usually through mobile networks. The Internet has very quickly encompassed our lives, regardless where we live. This chapter concentrates on explaining what are the guiding principles that led and enabled this evolution, and to describe what is the Internet's most important building block - the In