ICMPv6

This new version of the ICMP protocol is used for RS and RA and for NS and NA, which means it will be finding the MAC addresses for IPv6 neighbors and redirecting the host to the best router or default gateway.

ICMPv6 is not implemented as separate L3 protocol, but, it is an integrated part of IPv6 and is carried in an extension header, within the next header field of the IPv6 header.

By default, IPv6 is prevented from doing fragmentation through an ICMPv6 process called the MTU path:

ICMPv6 types

Let's refer to the following table of ICMPv6 types and their descriptions:

...

ICMPv6 type	Description
1	Destination unreachable
128	Echo request
129	Echo reply
133	Router solicitation