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> Chapter 15 - IPv6 > IPv6 Features > 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 is 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.

ICMPv6 Types and Codes

ICMPv6 has a number of messages that are identified by the “Type” field. Some of these types have assigned “Code” fields as well. The table below shows the different types of ICMP Types with their associated codes if there are any.

Type codes 0 − 127 are error messages and type codes 128 − 255 are for information messages.

ICMPv6 Types and Codes
Type # Type Name Code
0 Reserved 0 - no route to destination

1 - communication with destination administratively prohibited

2 - beyond scope of source address

3 - address unreachable

4 - port unreachable

5 - source address failed ingress/egress policy

6 - reject route to destination

7 - Error in Source Routing Header
1 Destination Unreachable  
2 Packet Too Big  
3 Time Exceeded 0 - hop limit exceeded in transit

1 - fragment reassembly time exceeded
4 Parameter Problem 0 - erroneous header field encountered

1 - unrecognized Next Header type encountered

2 - unrecognized IPv6 option encountered
100 Private Experimentation  
101 Private Experimentation  
102 - 126 Unassigned  
127 Reserved for expansion if ICMPv6 error messages  
128 Echo Request  
129 Echo Replay  
130 Multicast Listener Query  
131 Multicast Listener Report  
132 Multicast Listener Done  
133 Router Solicitation  
134 Router Advertisement  
135 Neighbor Solicitation  
136 Neighbor Advertisement  
137 Redirect Message  
138 Router Renumbering 0 - Router Renumbering Command

1 - Router Renumbering Result

255 - Sequence Number Reset
139 ICMP Node Information Query 0 - The Data field contains an IPv6 address which is the Subject of this Query.

1 - The Data field contains a name which is the Subject of this Query, or is empty, as in the case of a NOOP.

2 - The Data field contains an IPv4 address which is the Subject of this Query.
140 ICMP Node Information Response 0 - A successful reply. The Reply Data field may or may not be empty.

1 - The Responder refuses to supply the answer. The Reply Data field will be empty.

2 - The Qtype of the Query is unknown to the Responder. The Reply Data field will be empty.
141 Inverse Neighbor Discovery Solicitation Message  
142 Inverse Neighbor Discovery Advertisement Message  
143 Version 2 Multicast Listener Report  
144 Home Agent Address Discovery Request Message  
145 Home Agent Address Discovery Reply Message  
146 Mobile Prefix Solicitation  
147 Mobile Prefix Advertisement  
148 Certification Path Solicitation Message  
149 Certification Path Advertisement Message  
150 ICMP messages utilized by experimental mobility protocols such as Seamoby  
151 Multicast Router Advertisement  
152 Multicast Router Solicitation  
153 Multicast Router Termination  
154 FMIPv6 Messages  
155 RPL Control Message  
156 ILNPv6 Locator Update Message  
157 Duplicate Address Request  
158 Duplicate Address Confirmation  
159 − 199 Unassigned  
200 Private experimentation  
201 Private experimentation  
255 Reserved for expansion of ICMPv6 informational messages