Quality of Service and performance characterization of IPv6 relative to IPv4

CHAPTER II: THEORETICAL CONCEPTS AND TERMINOLOGY

II.1 INTRODUCTION

This chapter provides terminology used and presents a brief description of theoretical concepts related to IP. This chapter provides also different versions of IP and an explanation of features, benefits of IPv6 and comparison of versions of IP. The purpose of this chapter is to provide readers of this book guidance on the evolution of IP.

II.2 TERMINOLOGY

II.2.1 Internet

The Internet, or simply the Net, is the publicly accessible worldwide system of interconnected computer networks that transmit data by packet switching using a standardized Internet Protocol (IP).^2(*)

In other word the Internet is a massive network of networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known as protocols.^3(*)

As of January 2006, over 1 billion people use the Internet according to Internet World Stats^4(*)

II.2.2 WWW

The World Wide Web ("WWW" or simply the "'Web") is a global information space which people can read-from and write-to via a large number of different Internet-connected devices.^5(*)

The term WWW is often mistakenly used as a synonym for the Internet itself, but the Web is actually something that is available over the Internet, just like e-mail and many other Internet services.

II.2.3 Types of Nodes

The following terms are used in this study:

· Node: A device that implements IP. A node can be a host, router, a Personal Digital Assistant (PDA) or a cell phone.

· Host: Any node that is not a router, it can be a personal computer, a PDA or a cell phone.

· Router: A router is a node with two or more network (physical or virtual) interfaces, capable of forwarding packets between the interfaces.

· IPv4-only node: A host or router that implements only IPv4. An IPv4-only node does not understand IPv6. The installed base of IPv4 hosts and routers existing before the transition begins are IPv4-only nodes. Nodes that do not support IPv6.

· IPv6/IPv4 node: A host or router that implements both IPv4 and IPv6.

· IPv6-only node: A host or router that implements IPv6, and does not implement IPv4. A node that will replace IPv4-only node.

II.2.4 Techniques Used in the Transition

· The term «dual-stack» refers to TCP/IP capable devices providing support for both IPv4 and IPv6. It is important to understand that having a device being able to communicate over both IPv4 or IPv6 does not necessarily mean that all applications operating within this device are capable of utilizing both IPv4 and IPv6. The term «Dual-stack routing» refers to a network that is dual IP, that is to say all routers must be able to route both IPv4 and IPv6.

· The term «tunneling» refers to a means to encapsulate one version of IP in another so the packets can be sent over a backbone that does not support the encapsulated IP version. For example, when two isolated IPv6 networks need to communicate over an IPv4 network, dual-stack routers at the network edges can be used to set up a tunnel which encapsulates the IPv6 packets within IPv4, allowing the IPv6 systems to communicate without having to upgrade the IPv4 network infrastructure that exists between the networks.

These are not expected to be the only tools available for transition mechanisms. Additional transition mechanism (such as Automatic tunneling, Pv4 multicast tunneling, IPv4-compatible IPv6 addresses) are available but this study is focused on these techniques mechanism of transition stated above.

* ² http://en.wikipedia.org/wiki/Internet (April 04, 2006)

* ³ http://www.webopedia.com/TERM/W/World_Wide_Web.html (April 04, 2006)

* ⁴ http://www.Internetworldstats.com/stats.htm (April 05, 2006)

* ⁵ http://en.wikipedia.org/wiki/Www (April 05, 2006)