IP for 3G - (P5)

IP MobilityThis chapter will provide an overview of IP mobility. It aims to be pretty selfcontained, and so should stand alone fairly independently of the other chapters. IP mobility is very important, because it is predicted that the vast majority of terminals will be mobile in a few years and that the vast majority of traffic will originate from IP-based applications. The challenge of ‘IP mobility’ is to deliver IP-based applications to mobile terminals/users, even though, traditionally, IP-protocols have been designed with the assumption that they are stationary...
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IP for 3G - (P5) IP for 3G: Networking Technologies for Mobile Communications Authored by Dave Wisely, Phil Eardley, Louise Burness Copyright q 2002 John Wiley & Sons, Ltd ISBNs: 0-471-48697-3 (Hardback); 0-470-84779-4 (Electronic) 5 IP Mobility5.1 Scope This chapter will provide an overview of IP mobility. It aims to be pretty self- contained, and so should stand alone fairly independently of the other chapters. IP mobility is very important, because it is predicted that the vast majority of terminals will be mobile in a few years and that the vast majority of traffic will originate from IP-based applications. The challenge of ‘IP mobility’ is to deliver IP-based applications to mobile terminals/users, even though, tradi- tionally, IP-protocols have been designed with the assumption that they are stationary. In outline, this chapter considers: † The distinction between personal and terminal mobility, and between an identifier and a locator. † For terminal mobility the distinction between macro (or global) and micro (or local) mobility. † Tunnel-based and per-host forwarding approaches to micromobility – Their key features and how they compare. † Other aspects of terminal mobility – Context (or state) transfer, paging, and security. As part of this, the chapter includes an outline of various protocols: † SIP (Session Initiation Protocol) – Its use for personal and macromobility. † Mobile IP – For macromobility. † Hierarchical mobile IPv6, regional registration, fast mobile IP for v4 and v6, cellular IP for v4 and v6, Hawaii, MER-TORA – For micro- mobility. 144 IP MOBILITY The chapter does not consider MANETs (mobile ad hoc networks): networks without a fixed infrastructure 1. In other words, the chapter concen- trates on how to cope with mobility in an IP network reminiscent of a tradi- tional cellular network – that is, a fixed network with base stations that provide wireless connections to mobile terminals. The treatment is at quite a high level; the aim is to provide an introduction to the subject, to enable the reader to understand what the key issues are, and hopefully to help an incisive analysis of future proposals. The chapter also aims to give a flavour of some of the latest thinking on this fast moving subject. Parts of Chapters 2 and 7 consider the relationship of the work of this chapter to 3G. Amongst the topics covered there are: † How does mobile IP compare with GTP? (Chapter 2) † What is the role planned for mobile IP in 3GPP and 3GPP2 networks? (Chapter 7) † How might the IP terminal micromobility protocols covered here fit into evolving 3G networks? (Chapter 7)5.2 Introduction – What is IP Mobility? This part covers a number of topics that explore what is meant by ‘IP mobi- lity’. First, two (complementary) types of mobility are distinguished: personal and terminal. Second, the different protocol layers that mobility can be solved at are looked at. Third, we discuss how the distinction between an identifier and a locator offers an insight into mobility.5.2.1 Personal and Terminal Mobility A traditional mobile network like GSM supports two types of mobility: term- inal and personal. Terminal mobility refers to a mobile device changing its point of attach- ment to the network. The aim is that during a session, a mobile terminal can move around the network without disrupting the service. This is the most obvious feature that a mobile network must support. Personal mobility refers to a user moving to a different terminal and remaining in contact. 2G networks have a form of personal mobility, because a user can remove their SIM card and put it in another terminal – so they can still receive calls, they still get billed, and their personal prefer- ences like short dialling codes still work. What mobility is widely available in the Internet today? First, portability, which is similar to terminal mobility, but there is no attempt to maintain a 1 Except tangentially in part of Section 5.6.2 about TORA. The references contain a few pointers for readers interested in this active research area. INTRODUCTION – WHAT IS IP MOBILITY? 145 continuous session. It deals with the case where the device plugs into a new network access point in between sessions. For example, a user can plug in their laptop into any network port on their home network, for example the one which happens to be nearest to where they are working. However, true terminal mobility is not currently widely available in the Internet today. Second, personal mobility, for example through a WWW portal (such as Yahoo), enables users to send and receive web-based e-mail from Internet cafes. However, this t ...