ICMPv6
Internet Control Message Protocol version 6 (ICMPv6) is the new implementation of the Internet Control Message Protocol (ICMP) that is part of Internet Protocol version 6 (IPv6). The ICMPv6 protocol is defined in RFC 4443.
ICMPv6 is a multipurpose protocol. It performs such things as:
- error reporting in packet processing
- diagnostic functions
- Neighbor Discovery process
- IPv6 multicast membership reporting
It also designed as a framework to use extensions for use with future implementations and changes.
Examples of extensions that have already been written for ICMPv6:
- Neighbor Discovery Protocol (NDP) - a node discovery protocol in IPv6 which replaces and enhances functions of ARP.
- Secure Neighbor Discovery Protocol (SEND) - an extension of NDP with extra security.
- Multicast Router Discovery (MRD) - allows discovery of multicast routers.
ICMPv6 messages use IPv6 packets for transportation and can include IPv6 extension headers. ICMPv6 includes some of the functionality that in IPv4 was distributed among protocols such as ICMPv4, ARP (Address Resolution Protocol), and IGMP (Internet Group Membership Protocol version 3).
ICMPv6 has simplified the communication process by eliminating obsolete messages.
ICMPv6 messages are subdivided into two classes: error messages and information messages.
Error Messages are divided into four categories:
- Destination Unreachable
- Time Exceeded
- Packet Too Big
- Parameter Problems
Information messages are divided into three groups:
- Diagnostic messages
- Neighbor Discovery messages
- Messages for the management of multicast groups.