Internet Control Message Protocol version 6 (ICMPv6) Parameters

Last Updated

  • 2026-06-09

Available Formats

ICMPv6 "type" Numbers

Reference

  • RFC 4443: Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification
  • RFC 9899: Extensions to the YANG Data Model for Access Control Lists (ACLs)

Note

When this registry is modified, the YANG module "iana-icmpv6-types" YANG Parameters must be updated as defined in RFC 9899.

Available Formats

Range Registration Procedures
0-127 (Error messages) IETF Review
128-255 (Informational messages) IETF Review
Type Name Reference
0 Reserved
1 Destination Unreachable RFC 4443
2 Packet Too Big RFC 4443
3 Time Exceeded RFC 4443
4 Parameter Problem RFC 4443
5-99 Unassigned
100 Private experimentation RFC 4443
101 Private experimentation RFC 4443
102-126 Unassigned
127 Reserved for expansion of ICMPv6 error messages RFC 4443
128 Echo Request RFC 4443
129 Echo Reply RFC 4443
130 Multicast Listener Query RFC 2710
131 Multicast Listener Report RFC 2710
132 Multicast Listener Done RFC 2710
133 Router Solicitation RFC 4861
134 Router Advertisement RFC 4861
135 Neighbor Solicitation RFC 4861
136 Neighbor Advertisement RFC 4861
137 Redirect Message RFC 4861
138 Router Renumbering RFC 2894
139 ICMP Node Information Query RFC 4620
140 ICMP Node Information Response RFC 4620
141 Inverse Neighbor Discovery Solicitation Message RFC 3122
142 Inverse Neighbor Discovery Advertisement Message RFC 3122
143 Version 2 Multicast Listener Report RFC 9777
144 Home Agent Address Discovery Request Message RFC 6275
145 Home Agent Address Discovery Reply Message RFC 6275
146 Mobile Prefix Solicitation RFC 6275
147 Mobile Prefix Advertisement RFC 6275
148 Certification Path Solicitation Message RFC 3971
149 Certification Path Advertisement Message RFC 3971
150 ICMP messages utilized by experimental mobility protocols such as Seamoby RFC 4065
151 Multicast Router Advertisement RFC 4286
152 Multicast Router Solicitation RFC 4286
153 Multicast Router Termination RFC 4286
154 FMIPv6 Messages RFC 5568
155 RPL Control Message RFC 6550
156 ILNPv6 Locator Update Message RFC 6743
157 Duplicate Address Request RFC 6775
158 Duplicate Address Confirmation RFC 6775
159 MPL Control Message RFC 7731
160 Extended Echo Request RFC 8335
161 Extended Echo Reply RFC 8335
162-199 Unassigned
200 Private experimentation RFC 4443
201 Private experimentation RFC 4443
202-254 Unassigned
255 Reserved for expansion of ICMPv6 informational messages RFC 4443

ICMPv6 "Code" Fields

Reference

  • RFC 4443: Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification

Note

Code field subregistries that are not explicitly documented by the specification defining the associated Type value are not individually listed here. Nevertheless, the meaning of Code field values depend upon the Type value RFC 4443, Section 2.1. Any specification wishing to define a previously unspecified Code subregistry for a given Type should note the procedures in RFC 4443, Section 6.1.

Type 0 - Reserved

Code
No registrations at this time.

Type 1 - Destination Unreachable

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4443: Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification

Available Formats

Code Name Reference
0 no route to destination
1 communication with destination administratively prohibited
2 beyond scope of source address RFC 4443
3 address unreachable
4 port unreachable
5 source address failed ingress/egress policy RFC 4443
6 reject route to destination RFC 4443
7 Error in Source Routing Header RFC 6550; RFC 6554
8 Headers too long RFC 8883
9 Error in P-Route RFC 9914

Type 2 - Packet Too Big

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4443: Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification

Available Formats

Code
0

Type 3 - Time Exceeded

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4443: Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification

Available Formats

Code Name
0 hop limit exceeded in transit
1 fragment reassembly time exceeded

Type 4 - Parameter Problem

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4443: Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification

Available Formats

Code Name Reference
0 erroneous header field encountered
1 unrecognized Next Header type encountered
2 unrecognized IPv6 option encountered
3 IPv6 First Fragment has incomplete IPv6 Header Chain RFC 7112
4 SR Upper-layer Header Error RFC 8754
5 Unrecognized Next Header type encountered by intermediate node RFC 8883
6 Extension header too big RFC 8883
7 Extension header chain too long RFC 8883
8 Too many extension headers RFC 8883
9 Too many options in extension header RFC 8883
10 Option too big RFC 8883

Type 128 - Echo Request

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4443: Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification

Available Formats

Code
0

Type 129 - Echo Reply

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4443: Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification

Available Formats

Code
0

Type 130 - Multicast Listener Query

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 2710: Multicast Listener Discovery (MLD) for IPv6

Available Formats

Code
0

Type 131 - Multicast Listener Report

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 2710: Multicast Listener Discovery (MLD) for IPv6

Available Formats

Code
0

Type 132 - Multicast Listener Done

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 2710: Multicast Listener Discovery (MLD) for IPv6

Available Formats

Code
0

Type 133 - Router Solicitation

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4861: Neighbor Discovery for IP version 6 (IPv6)

Available Formats

Code
0

Type 134 - Router Advertisement

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4861: Neighbor Discovery for IP version 6 (IPv6)

Available Formats

Code
0

Type 135 - Neighbor Solicitation

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4861: Neighbor Discovery for IP version 6 (IPv6)

Available Formats

Code
0

Type 136 - Neighbor Advertisement

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4861: Neighbor Discovery for IP version 6 (IPv6)

Available Formats

Code
0

Type 137 - Redirect Message

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 4861: Neighbor Discovery for IP version 6 (IPv6)

Available Formats

Code
0

Type 138 - Router Renumbering

Registration Procedure(s)

  • IETF Review

Reference

Available Formats

Code Name
0 Router Renumbering Command
1 Router Renumbering Result
255 Sequence Number Reset

Type 139 - ICMP Node Information Query

Registration Procedure(s)

  • Specification Required

Expert(s)

  • Unassigned

Reference

Available Formats

Code Name Reference
0 The Data field contains an IPv6 address which is the Subject of this Query. RFC 4620
1 The Data field contains a name which is the Subject of this Query, or is empty, as in the case of a NOOP. RFC 4620
2 The Data field contains an IPv4 address which is the Subject of this Query. RFC 4620

Type 140 - ICMP Node Information Response

Registration Procedure(s)

  • Specification Required

Expert(s)

  • Unassigned

Reference

Available Formats

Code Name Reference
0 A successful reply. The Reply Data field may or may not be empty. RFC 4620
1 The Responder refuses to supply the answer. The Reply Data field will be empty. RFC 4620
2 The Qtype of the Query is unknown to the Responder. The Reply Data field will be empty. RFC 4620

Type 141 - Inverse Neighbor Discovery

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 3122: Extensions to IPv6 Neighbor Discovery for Inverse Discovery Specification

Available Formats

Code
0

Type 142 - Inverse Neighbor Discovery

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 3122: Extensions to IPv6 Neighbor Discovery for Inverse Discovery Specification

Available Formats

Code
0

Type 144 - Home Agent Address Discovery

Registration Procedure(s)

  • IESG Approval

Reference

Available Formats

Code
0

Type 145 - Home Agent Address Discovery

Registration Procedure(s)

  • IESG Approval

Reference

Available Formats

Code
0

Type 146 - Mobile Prefix Solicitation

Registration Procedure(s)

  • IESG Approval

Reference

Available Formats

Code
0

Type 147 - Mobile Prefix Advertisement

Registration Procedure(s)

  • IESG Approval

Reference

Available Formats

Code
0

Type 157 - Duplicate Address Request Code Suffix

Registration Procedure(s)

  • IETF Review or IESG Approval

Reference

  • RFC 8505: Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery

Available Formats

Code Suffix Meaning Reference
0 DAR message RFC 6775
1 EDAR message with 64-bit ROVR field RFC 8505
2 EDAR message with 128-bit ROVR field RFC 8505
3 EDAR message with 192-bit ROVR field RFC 8505
4 EDAR message with 256-bit ROVR field RFC 8505
5-15 Unassigned

Type 158 - Duplicate Address Confirmation Code Suffix

Registration Procedure(s)

  • IETF Review or IESG Approval

Reference

  • RFC 8505: Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery

Available Formats

Code Suffix Meaning Reference
0 DAC message RFC 6775
1 EDAC message with 64-bit ROVR field RFC 8505
2 EDAC message with 128-bit ROVR field RFC 8505
3 EDAC message with 192-bit ROVR field RFC 8505
4 EDAC message with 256-bit ROVR field RFC 8505
5-15 Unassigned

Type 160 - Extended Echo Request

Registration Procedure(s)

  • First Come First Served

Reference

  • RFC 8335: PROBE: A Utility for Probing Interfaces

Available Formats

Code Name Reference
0 No Error RFC 8335
1-255 Unassigned

Type 161 - Extended Echo Reply

Registration Procedure(s)

  • First Come First Served

Reference

  • RFC 8335: PROBE: A Utility for Probing Interfaces

Available Formats

Code Name Reference
0 No Error RFC 8335
1 Malformed Query RFC 8335
2 No Such Interface RFC 8335
3 No Such Table Entry RFC 8335
4 Multiple Interfaces Satisfy Query RFC 8335
5-255 Unassigned

FMIPv6 Message Types (Value 154)

Registration Procedure(s)

  • RFC Required

Reference

Available Formats

Subtype Description Reference
0 Reserved RFC 5568
1 Reserved RFC 5568
2 RtSolPr RFC 5568
3 PrRtAdv RFC 5568
4 HI - Deprecated (Unavailable for Assignment) RFC 5568
5 HAck - Deprecated (Unavailable for Assignment) RFC 5568
6-255 Unassigned

IPv6 Neighbor Discovery Option Formats

Registration Procedure(s)

  • RFC Required

Reference

  • RFC 4861: Neighbor Discovery for IP version 6 (IPv6)

Note

IETF working groups with working group consensus and area director approval can request reclaimable Neighbor Discovery option type assignments from IANA. See Section 13 of RFC 4861.

Available Formats

Type Description Reference
1 Source Link-layer Address RFC 4861
2 Target Link-layer Address RFC 4861
3 Prefix Information RFC 4861
4 Redirected Header RFC 4861
5 MTU RFC 4861
6 NBMA Shortcut Limit Option RFC 2491
7 Advertisement Interval Option RFC 6275
8 Home Agent Information Option RFC 6275
9 Source Address List RFC 3122
10 Target Address List RFC 3122
11 CGA option RFC 3971
12 RSA Signature option RFC 3971
13 Timestamp option RFC 3971
14 Nonce option RFC 3971
15 Trust Anchor option RFC 3971
16 Certificate option RFC 3971
17 IP Address/Prefix Option RFC 5568
18 New Router Prefix Information Option RFC 4068
19 Link-layer Address Option RFC 5568
20 Neighbor Advertisement Acknowledgment Option RFC 5568
21 PvD ID Router Advertisement Option RFC 8801
22 Unassigned
23 MAP Option RFC 4140
24 Route Information Option RFC 4191
25 Recursive DNS Server Option RFC 5006; RFC 8106
26 RA Flags Extension Option RFC 5175
27 Handover Key Request Option RFC 5269
28 Handover Key Reply Option RFC 5269
29 Handover Assist Information Option RFC 5271
30 Mobile Node Identifier Option RFC 5271
31 DNS Search List Option RFC 8106
32 Proxy Signature (PS) RFC 6496
33 Address Registration Option RFC 6775
34 6LoWPAN Context Option RFC 6775
35 Authoritative Border Router Option RFC 6775
36 6LoWPAN Capability Indication Option (6CIO) RFC 7400
37 DHCP Captive-Portal RFC 8910
38 PREF64 option RFC 8781
39 Crypto-ID Parameters Option (CIPO) RFC 8928
40 NDP Signature Option (NDPSO) RFC 8928
41 Resource Directory Address Option RFC 9176
42 Consistent Uptime Option RFC 9685
43-137 Unassigned
138 CARD Request option RFC 4065
139 CARD Reply option RFC 4065
140-143 Unassigned
144 Encrypted DNS Option RFC 9463
145-252 Unassigned
253 RFC3692-style Experiment 1 [1] RFC 4727
254 RFC3692-style Experiment 2 [1] RFC 4727

Trust Anchor option (Type 15) Name Type field

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 3971: SEcure Neighbor Discovery (SEND)
  • RFC 6495: Subject Key Identifier (SKI) SEcure Neighbor Discovery (SEND) Name Type Fields

Available Formats

Value Description Reference
0 Reserved RFC 6495
1 DER Encoded X.501 Name RFC 3971
2 FQDN RFC 3971
3 SHA-1 Subject Key Identifier (SKI) RFC 6495
4 SHA-224 Subject Key Identifier (SKI) RFC 6495
5 SHA-256 Subject Key Identifier (SKI) RFC 6495
6 SHA-384 Subject Key Identifier (SKI) RFC 6495
7 SHA-512 Subject Key Identifier (SKI) RFC 6495
8-252 Unassigned
253-254 Reserved for Experimental Use RFC 6495
255 Reserved RFC 6495

Certificate option (Type 16) Cert Type field

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 3971: SEcure Neighbor Discovery (SEND)

Available Formats

Value Description Reference
0 Reserved
1 X.509v3 Certificate RFC 3971
2-255 Unassigned

Option-Code for Handover Assist Information Option (Type 29)

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 5271: Mobile IPv6 Fast Handovers for 3G CDMA Networks

Available Formats

Value Description Reference
0 Reserved RFC 5271
1 AN ID RFC 5271
2 Sector ID RFC 5271
3-255 Unassigned

Option-Code for Mobile Node Identifier Option (Type 30)

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 5271: Mobile IPv6 Fast Handovers for 3G CDMA Networks

Available Formats

Value Description Reference
0 Reserved RFC 5271
1 NAI RFC 5271
2 IMSI RFC 5271
3-255 Unassigned

Qtypes

Registration Procedure(s)

  • IETF Review

Reference

Available Formats

Value Description Reference
0 NOOP RFC 4620
1 Unused RFC 4620
2 Node Name RFC 4620
3 Node Addresses RFC 4620
4 IPv4 Addresses RFC 4620
5-255 Unassigned

IPv6 ND Router Advertisement Flags

Registration Procedure(s)

  • Standards Action or IESG Approval

Reference

  • RFC 5175: IPv6 Router Advertisement Flags Option

Available Formats

RA Option Bit Description Reference
0 M - Managed Address Configuration Flag RFC 4861
1 O - Other Configuration Flag RFC 4861
2 H - Mobile IPv6 Home Agent Flag RFC 3775
3 Prf - Router Selection Preferences RFC 4191
4 Prf - Router Selection Preferences RFC 4191
5 P - Neighbor Discovery Proxy Flag RFC 4389
6 S - SNAC Router Flag RFC-ietf-6man-snac-router-ra-flag-08
7-53 R - Reserved; Available for assignment RFC 5175
54-55 Private Experimentation RFC 5175

Address Registration Option Status Values

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 6775: Neighbor Discovery Optimization for IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs)
  • RFC 9010: Routing for RPL (Routing Protocol for Low-Power and Lossy Networks) Leaves

Available Formats

Value Description Reference
0 Success RFC 6775
1 Duplicate Address RFC 6775
2 Neighbor Cache Full RFC 6775
3 Moved RFC 8505
4 Removed RFC 8505
5 Validation Requested RFC 8505
6 Duplicate Source Address RFC 8505
7 Invalid Source Address RFC 8505
8 Registered Address Topologically Incorrect RFC 8505
9 6LBR Registry Saturated RFC 8505
10 Validation Failed RFC 8505
11 Registration Refresh Request RFC 9685
12 Invalid Registration RFC 9685
13-63 Unassigned RFC 9010

6LoWPAN Capability Bits

Registration Procedure(s)

  • IETF Review or IESG Approval

Reference

  • RFC 7400: 6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs)

Available Formats

Bit Description Reference
0-7 Reserved for Experimental Use RFC 7400
8 X flag: Registration for Unicast, Multicast, and Anycast Addresses Supported RFC 9685
9 AP-ND Enabled (A bit) RFC 8928
10 EDA Support (D bit) RFC 8505
11 6LR capable (L bit) RFC 8505
12 6LBR capable (B bit) RFC 8505
13 Routing Registrar (P bit) RFC 8505
14 EARO support (E bit) RFC 8505
15 GHC capable bit (G bit) RFC 7400
16 Registration for prefixes supported (F bit) RFC 9926
17-47 Unassigned

IPv6 Neighbor Discovery Prefix Information Option Flags

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 8425: IANA Considerations for IPv6 Neighbor Discovery Prefix Information Option Flags

Available Formats

PIO Option Bit Description Reference
0 L - On-link Flag RFC 4861
1 A - Autonomous Address Configuration Flag RFC 4861
2 R - Router Address Flag RFC 6275
3 P - DHCPv6-PD Preferred Flag RFC 9762
4-7 Reserved

Address Registration Option Flags

Registration Procedure(s)

  • IETF Review or IESG Approval

Reference

  • RFC 8505: Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery

Available Formats

Bit Number Description Reference
0 Unassigned
1 C-Flag RFC 9927; RFC 8928
2-3 P-Field (2 bits) RFC 9685, Section 14.1
4-5 I-Field (2 bits) RFC 8505, Section 4.1
6 R Flag RFC 8505
7 T Flag RFC 8505

Address Registration Option I-Field

Registration Procedure(s)

  • IETF Review or IESG Approval

Reference

  • RFC 8505: Registration Extensions for IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Neighbor Discovery

Available Formats

Value Meaning Reference
0 Abstract Index for Topology Selection RFC 8505
1-3 Unassigned

PvD Option Flags

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 8801: Discovering Provisioning Domain Names and Data

Available Formats

Bit Name Reference
0 H-flag RFC 8801
1 L-flag RFC 8801
2 R-flag RFC 8801
3-11 Unassigned

Crypto-Types

Registration Procedure(s)

  • Specification Required or IESG Approval

Expert(s)

  • Mohit Sethi

Reference

  • RFC 8928: Address-Protected Neighbor Discovery for Low-Power and Lossy Networks

Available Formats

Crypto-Type Value Elliptic Curve Hash Function Signature Algorithm Representation Conventions Public Key Size Signature Size Reference
0 NIST P-256 FIPS186-4 SHA-256 RFC 6234 ECDSA FIPS186-4 Weierstrass, (un)compressed, MSB/msb-order, SEC1 33/65 bytes (compressed/uncompressed) 64 bytes RFC 8928
1 Curve25519 RFC 7748 SHA-512 RFC 6234 Ed25519 RFC 8032 Edwards, compressed, LSB/lsb-order, RFC 8032 32 bytes (compressed) 64 bytes RFC 8928
2 Curve25519 RFC 7748 SHA-256 RFC 6234 ECDSA FIPS186-4 Weierstrass, (un)compressed, MSB/msb-order, draft-ietf-lwig-curve-representations-13 33/65 bytes (compressed/uncompressed) 64 bytes RFC 8928
3-255

P-Field Values

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 9685: Listener Subscription for IPv6 Neighbor Discovery Multicast and Anycast Addresses

Available Formats

Value Registered Address Type Indicator Reference
0 Registration for a Unicast Address RFC 9685
1 Registration for a Multicast Address RFC 9685
2 Registration for an Anycast Address RFC 9685
3 Registration for a Unicast Prefix RFC 9926

EDAR Message Flags

Registration Procedure(s)

  • IETF Review or IESG Approval

Reference

  • RFC 9685: Listener Subscription for IPv6 Neighbor Discovery Multicast and Anycast Addresses

Available Formats

Bit Number Meaning Reference
0-1 P-Field (2 bits) RFC 9685, Section 14.1
2-7 Unassigned

Footnote

[1]

It is only appropriate to use these values in explicitly configured experiments; they MUST NOT be shipped as defaults in implementations. See RFC 3692 for details.