ICMPv6 is an enhanced version of ICMP for IPv6 that not only performs error reporting and path diagnostics functionalities, but is extended further for other network layer functions. ICMPv6 plays a key role in:

• IPv6 router and neighbor discovery
• IPv6 stateless auto configuration
• Path MTU discovery
• Fault detection and isolation

ICMPv6 is an integral part of IPv6, and the next header field of IPv6 will be set to 58. The ICMPv6 packet has the following format:

There are different types of ICMPv6 message available for error reporting, informational, or discovery purposes. In this section, we will see how ICMPv6 can be used for fault detection and isolation, and in the forthcoming sections, we will see more applications of ICMPv6.