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Chapter 1
Introduction
Recently, Internet access has been revolutionized by mobile broadband. However, mobile Internet access is not a new technologyāit has been available since the beginning of the 2000s, but only during the past last few years has the growth of mobile usage of the Internet exploded. This explosion is due to the increased data speeds that have brought mobile Internet access speeds close to those of fixed broadband access, and the prices dropping to affordable and competitive ranges. In addition, the exploding usage is due in very large part to the introduction of the smartphone.
At the same time, and partly as a result, the Internet is facing its biggest change and its biggest challenge since its introduction. This is the transition to the new version of the Internet Protocol (IP)āIP version 6. The old versionāIP version 4 (IPv4)āhas been in use since 1983 when the ARPANET transitioned from Network Control Program (NCP) to the Internet Protocol. Now, the exhaustion of readily available Internet Protocol version 4 (IPv4) addresses at the beginning of 2011 puts the growth of the whole Internet at risk.
The ongoing transition of the Internet to the new version of IP will, obviously, have implications for mobile networks as well. We have written this book to look at these important two topics togetherāmobile broadband access to the Internet, and the transition to Internet Protocol version 6 (IPv6). In Chapter 1, we start with an overview of the Internet technologies, and the background and implications of the transition to IPv6 to the Internet. Chapter 2 explains the basics of the Third Generation Partnership Project (3GPP) specified mobile broadband technologies, and Chapter 3 examines the IPv6 technology, giving a good understanding of how IPv6 works. Chapter 4 goes through how IPv6 is intended to work in the 3GPP mobile broadband networks. Chapter 5 concentrates on giving an understanding of different transition strategies that can be used in 3GPP networks. Chapter 6 gives a forward-looking view by the authors of some areas relevant to the future of IPv6 in 3GPP networks.
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.
1.1 Introduction to Internet and the Internet Protocol
The Internet and the Internet Protocol creation were originally funded by theDefense 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)āa United Nations (UN) organization discussing matters that concern the governance of the Internet, both technical and non-technicalāwas 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 blockāthe Internet Protocol. For the interested reader, at the end of the chapter there are additional reading materials for more information about the fascinating history of the Internet.
1.2 Internet Principles
Today the Internet is used for file transfer, email, voice, video, gaming, and many, many other applications. We have become dependent on the Internet starting from, the world economy, via businesses big and small, to the normal people who trust the Internet either to keep them connected to the artery of the economic world, or to keep up relationships with their loved ones. It is surprising how big and important the Internet has become in such a short time. However, the versatility of the Internet is not accidental. The reasons lie in the design of the Internet.
In the heart of the design of the Internet and the technology that powers it has certain principles. These principles have ensured that the Internet and the Internet technologies enable the current usage of the Internet, which is way beyond the usage and expectations envisioned by anybody at the dawn of the Internet. Let's look at the main principles:
- packet switched networking;
- the end-to-end principle;
- layered architecture;
- Postel's robustness principle; and
- creative anarchy.
Packet Switched Networking
This first principle is very widely used in modern communication networks. However, traditionally, the voice centric networks, such as the Public Switched Telephony Network (PSTN), were based on a different technological principleācircuit switched networking. In circuit switched networking connections or calls are switched through the network by reserving a circuit from the caller to the callee. Each connection has its own circuit, and the same resource is reserved for the call regardless how much traffic is transferred through that circuit. For instance, a voice call uses exactly the same resources within the network whether the participants speak or are silent.
In contrast, the modern data networks are built based on Packet Switched (PS) networking. In packet switched networking, the sent data is divided into smaller packets that travel independently to their destinations, each transmitted through a route that seems best for a given packet at a given moment. In the Internet, the packets can travel different routes even to the same destination, can get out of order at transit, and even get completely lost, never arriving to their destination.
End-to-End Principle
The end-to-end principle is one of the most important principles of the Internet and of the Internet technology. It states that the network should not interfere with or alter traffic on layers that are above the network layer. Sometimes this principle is also known as āIntelligent endpointsādump networkā principle, but that name does not do justice to the concept. Basically, what the principle states is that the network should not make any assumptions about any particular service or characteristic of the data in transit. The network must concentrate on moving the data from its source to its destination. It is up to the end points to understand the traffic and its use. This principle allows the Internet to be used for many different services and applications. Even applications and services can be supported that were at the time of the design of the Internet either technically unfeasible, completely impossible, or even unimaginable. Thus, the principle enables us to create new services without changing the network. Only the end points have to be changed to support the new service or application.
Layered Architecture
The layered architecture principle is closely linked to the end-to-end principle. The layered architecture principle states that there are different protocol layers that talk to each other on the same level. Figure 1.1 shows the principle in a drawing. The main idea behind the principle is that each layer does its workāno more and no less. This strict separation allows the layers to be independent of each other, and make sure that layers can be changed without changing other layers. The Open System Interconnect (OSI) [1] model defines seven layers. The Internet model, however, only defines five. The Internet technologies range from the layer three (network layer) upwards.
Robustness Principle
The Postel's robustness principle, also known as Postel's law, has gotten its name from its inventorāJon Postel. Jon Postel was one of the Internet pioneers who has had an enormous effect on the Internet and its design through his contribution in engineering and governance. The principle is quoted as āBe liberal in what you accept, and conservative in what you send.ā [2] This principle means that the sender should be very conservative and strictly cohere with the standard, whereas the receiver should be able to receive even input that does not strictly conform to the standard. This is a very important principle for interpretability, and when making future extensions and improvements to the technologies.
Creative Anarchy
The final principle, creative anarchy, is something that seems to be at odds with proper telecommunications networking. However, this means that anyone (from a single individual to large enterprises or operators) can create and distribute new services and applications. This principle can be perhaps seen more as a symptom of the other principles, but comprehending it is still important to understand the Internet and its technologies. Without the creative anarchy principle, the Googles, Facebooks, and the like of this world would never have seen the light of day!
1.3 The Internet Protocol
The most important building block in the Internet is the Internet Protocol. IP is the networking protocol that ensures that packets travel from the source through the network and reach the right destination. Currently two versions of the Internet Protocol exist: IPv4 [3] and IPv6 [4]. At the time of writing, IPv4 is much more widely spread and used. IPv6 is a newer, upcoming protocol version which the world is transitioning towards. As you may have realised from this book's title and the number of pages we have been able to write, this transition is not quite straightforward. However, despite a few differences, the functionality of the two IP versions is very similar and in parts, the same. Therefore, the overview that this chapter gives to IP is applicable to the both versions.
The Internet Protocol has two parts: the header and the payload. The header consists of fixed length binary fields that show, among other information, where the packet has come from (source address), where it is going to (destination address), and what is in the payloadāor better put, what is the upper layer protocol. The payload can be the transport layer protocol, and the protocols and data above it, or even an IP packet. The IPv4 and IPv6 headers are depicted in Figure 1.2.
IP provides an unreliable packet delivery service. Basically the main part of the service is addressingāthe capability to tell where a packet should be delivered. In addition to the packet delivery, IP also performs other tasks. For instance it includes a Time To Live (TTL) field, which provides the mechanism to make sure that packets are removed from the network if they do not reach their destination due to, for instance, a loop in the network. Practically, this is achieved by decrementing the TTL at every hop in the network. When the TTL reaches zero the packet is discarded. There is also a simple per packet prioritization mechanism (Type of Service or Quality of Service). Everything needed for the communication, such as reliable transport, packet ordering, and identification of applications, is provided by upper layer protocols such as Transport Control Protocol (TCP) [5].
The nodes of an IP network are connected to the network via a network connection or an interface. A node can have one or more interfaces connected at a given time to the same, or different networks. Each interface has to have a unique I...
