TABLE OF CONTENTS This chapter focuses on the description of Internet protocol version 6 (IPv6). We introduced basic IPv6 concepts in Chapter 1, and we have alluded to in the chapters that followed the advantages and motivations for considering IPv6 in the VoIP context. The discussion is based on IETF RFC 2460 [DEE199801]. There is an extensive body of technical research literature on this topic (as documented in Appendix B of Chapter 1) and only the most basic concepts are covered in this chapter.
IP version 6 (IPv6) is a new version of the Internet protocol, designed as the successor to IP version 4 (IPv4) described in RFC 791. The changes from IPv4 to IPv6 fall primarily into the following categories:
Expanded addressing capabilities IPv6 increases the IP address size from 32 bits to 128 bits, to support more levels of addressing hierarchy, a much greater number of addressable nodes, and simpler auto-configuration of addresses. The scalability of multicast routing is improved by adding a "scope" field to multicast addresses; and a new type of address, called an anycast address is defined and used to send a packet to any one of a group of nodes.
Header format simplification Some IPv4 header fields have been dropped or made optional, to reduce the common-case processing cost of packet handling and to limit the bandwidth cost of the IPv6 header.
Improved support for extensions and options Changes in the way IP header options are encoded allows for more efficient...
