TABLE OF CONTENTS Most networking protocols require some channel for the exchange of network meta-data, and IPv6 is no exception. The Internet Control Message Protocol for IPv6 (ICMPv6) is built largely on ICMP as used with IPv4. Unlike ICMP for IPv4, ICMPv6 provides a more complete set of tools for the exchange of meta-information about the Internet layer among nodes. This chapter outlines how ICMPv6 works and how it is used.
IP nodes need a special protocol to exchange messages that pertain to IP-related conditions. The Internet Control Message Protocol (ICMP) defines a set of messages and requests used to report error and informational conditions, as well as for use with diagnostic functions. ICMPv6 is based on ICMP but adds new messages to support IPv6. The specification for ICMPv6 was first published in 1995 in RFC 1885, Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification, and updated in 1998 with RFC 2463.
Originally, ICMPv6 incorporated IPv6 multicast group management functions provided in IPv4 by the Internet Group Management Protocol (IGMP), but these functions are now performed by the Multicast Listener Discovery (MLD) mechanism discussed in Chapter 10. This chapter focuses on ICMPv6 message definitions, requests and responses, and how ICMPv6 is used.
ICMPv6 represents a fundamentally changed protocol from ICMP. Not only is MLD implemented completely as a subprotocol of ICMPv6, but so is Neighbor Discovery (Chapter 13); many of the other features made possible with IPv6, including stateless...
