B.3 The 6bone

A.1 Introduction

This appendix is an overview of IPv4, IPv6, ICMPv4, and ICMPv6. This material provides additional background that may be helpful in understanding the discussion of TCP and UDP in Chapter 2. Some features of IP and ICMP are also used in some of the later chapters: IP options (Chapter 27), along with the ping and traceroute programs (Chapter 28), for example.