



Internet Area Working Group                                    B. Fenner
Internet-Draft                                                 R. Thomas
Intended status: Standards Track                         Arista Networks
Expires: 8 February 2026                                   7 August 2025


  Adding Extensions to ICMP Errors for Originating Node Identification
               draft-ietf-intarea-extended-icmp-nodeid-03

Abstract

   RFC5837 describes a mechanism for Extending ICMP for Interface and
   Next-Hop Identification, which allows providing additional
   information in an ICMP error that helps identify interfaces
   participating in the path.  This is especially useful in environments
   where a given interface may not have a unique IP address to respond
   to, e.g., a traceroute.

   This document introduces a similar ICMP extension for Node
   Identification.  It allows providing a unique IP address and/or a
   textual name for the node, in the case where each node may not have a
   unique IP address (e.g., a deployment in which all interfaces have
   IPv6 addresses and all nexthops are IPv6 nexthops, even for IPv4
   routes).

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at
   https://fenner.github.io/icmp-node-id/draft-ietf-intarea-extended-
   icmp-nodeid.html.  Status information for this document may be found
   at https://datatracker.ietf.org/doc/draft-ietf-intarea-extended-icmp-
   nodeid/.

   Discussion of this document takes place on the Internet Area Working
   Group Working Group mailing list (mailto:int-area@ietf.org), which is
   archived at https://mailarchive.ietf.org/arch/browse/int-area/.
   Subscribe at https://www.ietf.org/mailman/listinfo/int-area/.

   Source for this draft and an issue tracker can be found at
   https://github.com/fenner/icmp-node-id.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.




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Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Node Identification Object  . . . . . . . . . . . . . . . . .   4
     3.1.  C-Type Meaning in a Node Identification Object  . . . . .   5
       3.1.1.  Behavior when additional bits are reserved  . . . . .   6
     3.2.  IP Address Sub-Object . . . . . . . . . . . . . . . . . .   6
     3.3.  Name Sub-Object . . . . . . . . . . . . . . . . . . . . .   7
   4.  Addition of Node Identification Object by Intermediate
           Nodes . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A.  Change history . . . . . . . . . . . . . . . . . . .  11
     A.1.  Changes since
           draft-fenner-intarea-extended-icmp-hostid-00  . . . . . .  11
     A.2.  Changes since
           draft-fenner-intarea-extended-icmp-hostid-01  . . . . . .  11




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     A.3.  Changes since
           draft-fenner-intarea-extended-icmp-hostid-02  . . . . . .  11
     A.4.  Changes since
           draft-ietf-intarea-extended-icmp-nodeid-00  . . . . . . .  11
     A.5.  Changes since
           draft-ietf-intarea-extended-icmp-nodeid-01  . . . . . . .  11
     A.6.  Changes since
           draft-ietf-intarea-extended-icmp-nodeid-02  . . . . . . .  12
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   In addition to adding incoming interface information to a traceroute
   using the mechanisms described in [RFC5837], a network operator may
   be interested in adding information to unambiguously identify nodes
   themselves.  For example, [I-D.chroboczek-intarea-v4-via-v6]
   describes a scenario in which individual nodes do not have unique
   IPv4 addresses to use to reply to an IPv4 traceroute, so additional
   information is needed.  Another scenario is described in
   [I-D.equinox-v6ops-icmpext-xlat-v6only-source]: when an IPv6-only
   node runs the customer-side translator (CLAT, [RFC6877]), traceroute
   to an IPv4 destination can not represent intermediate IPv6-only
   routers.

   The goal of this specification is to have a mechanism to provide
   additional useful information about the identification of a node
   sending an ICMP error, which depends on the actual context and scope
   of the message being delivered.  To this end, it is RECOMMENDED to
   use a combination of IP Address and Name sub-objects (including
   combinations where one of the sub-objects is not used) that is unique
   and meaningful in the actual context and scope.  It is explicitly
   permitted to use an IP address that may have only local meaning
   (e.g., ULA [RFC4193]), since that information can then be provided to
   the operator of the domain who can then determine the local meaning.

   This document defines an ICMP extension that fills that void.

2.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   ICMPv4 is used to refer to Internet Control Message Protocol (ICMP)
   specified in [RFC0792].



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   ICMPv6 is used to refer to Internet Control Message Protocol (ICMPv6)
   for the Internet Protocol Version 6 (IPv6) specified in [RFC4443].

   ICMP is used to refer to both ICMPv4 and ICMPv6.

3.  Node Identification Object

   This section defines the Node Identification Object, an ICMP
   Extension Object with a Class-Num (Object Class Value) of 5 (see
   Section 6).

   Similar to Section 4 of [RFC5837], this object can be appended to the
   following messages:

   *  ICMPv4 Time Exceeded

   *  ICMPv4 Destination Unreachable

   *  ICMPv4 Parameter Problem

   *  ICMPv6 Time Exceeded

   *  ICMPv6 Destination Unreachable

   For reasons described in [RFC4884], this extension cannot be appended
   to any of the currently defined ICMPv4 or ICMPv6 messages other than
   those listed above.

   The extension defined herein MAY be appended to any of the above
   listed messages and SHOULD be appended whenever required to identify
   the node and when local policy or security considerations do not
   supersede this requirement.  See Section 5 for suggested
   configuration regarding including these messages.

   Similarly to the Interface Identification Object defined in
   [RFC5837], there are two different pieces of information that can
   appear in a Node Identification Object:

   1.  An IP Address Sub-Object MAY be included, containing an address
       of sufficient scope to identify the node within the domain.  The
       IP Address Sub-Object is defined in Section 3.2 of this memo.

   2.  A Name Sub-Object MAY be included, as specified in Section 3.3,
       containing up to 63 octets of the YANG sys:hostname ([RFC7317])
       or another appropriate name uniquely identifying the node.






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3.1.  C-Type Meaning in a Node Identification Object

   The C-Type contains a bitmask describing what information is included
   in this Node Identification Object (Figure 1).  The fields in this
   bitmask are chosen so that the IPAddr and name bits overlap with the
   same bits as defined in [RFC5837], so that an implementation that
   supports exactly these bits can reuse packet generation and parsing
   code.

   Bit     0       1       2       3       4       5       6       7
       +-------+-------+-------+-------+-------+-------+-------+-------+
       |               Unassigned              | IPAddr|  Name |  Un2  |
       +-------+-------+-------+-------+-------+-------+-------+-------+

            Figure 1: C-Type for the Node Identification Object

   The following are bit-field definitions for C-Type:

   *  Unassigned (bits 0-4): These bits are reserved for future use and
      MUST be set to 0 on transmit and ignored on receipt.

   *  IP Addr (bit 5) : When set, an IP Address Sub-Object is present.
      When clear, an IP Address Sub-Object is not present.  The IP
      Address Sub-Object is described in Section 3.2 of this memo.

   *  Name (bit 6): When set, a Name Sub-Object is included.  When
      clear, it is not included.  The Name Sub-Object is described in
      Section 3.3 of this memo.

   *  Un2 (bit 7): This bit is reserved for future use and MUST be set
      to 0 on transmit and ignored on receipt.

   The information included does not self-identify, so this
   specification defines a specific ordering for sending the information
   that must be followed.

   If bit 5 (IP Address) is set, an IP Address Sub-Object MUST be sent
   first.  If bit 6 (Name) is set, a Name Sub-Object MUST be sent next.
   The information order is thus: IP Address Sub-Object, Name Sub-
   Object.  Any or all pieces of information may be present or absent,
   as indicated by the C-Type.  Any data that follows these optional
   pieces of information MUST be ignored.

   It is valid (though pointless until additional bits are assigned by
   IANA) to receive a Node Identification Object where bits 5 and 6 are
   both 0; this MUST NOT generate a warning or error.  A packet with
   such a Node Identification Object SHOULD be treated as though it
   contains no Node Identification Object.



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3.1.1.  Behavior when additional bits are reserved

   Bit values SHOULD be assigned from left to right in the diagram
   above, i.e., starting at zero.  The sub-objects associated with each
   new bit MUST be placed in the packet after the sub-objects defined in
   this memo.  For example, if bit 0 is assigned to the Fooblewomp, a
   packet with bits 0 and 5 set MUST contain the IP Address Sub-Object,
   followed by the Fooblewomp sub-object.

   If a bit is set that a receiver does not support, followed by a bit
   that the receiver does support, the receiver MUST ignore all of the
   additional data, since the length of the unsupported data is unknown.

3.2.  IP Address Sub-Object

   If the Node Identification Object identifies the node by address, the
   Object Payload contains an address sufficient to identify the node
   within the appropriate scope - global or as otherwise configured - as
   depicted in Figure 2.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              AFI              |            Reserved           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Address...

                      Figure 2: IP Address Sub-Object

   Payload fields are defined as follows:

   *  Address Family Identifier (AFI): This 16-bit field identifies the
      type of address represented by the Address field.  Values for this
      field represent a subset of values found in the IANA registry of
      Address Family Numbers (available from
      [IANA.address-family-numbers]).  Valid values are as follows:

      -  1: 32-bit IPv4 address

      -  2: 128-bit IPv6 address.

   *  Reserved: This field MUST be set to 0 and ignored upon receipt.

   *  Address: This variable-length field represents an address of
      appropriate scope (global, if none other defined) that can be used
      to identify the node.  The length of this field is derived from
      the AFI (i.e., 32 bits if the AFI field is set to 1, and 128 bits
      if the AFI is set to 2).



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3.3.  Name Sub-Object

   Figure 3 depicts the Name Sub-Object:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Length    |                Node Name . . .                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 3: Name Sub-Object

   The Name Sub-Object MUST have a length that is a multiple of 4 octets
   and MUST NOT exceed 64 octets.  If the length field exceeds 64
   octets, the receiver MUST ignore the sub-object.

   The Length field represents the length of the Name Sub-Object,
   including the length, the node name, and any padding, in octets.  The
   maximum valid length is 64 octets.  The length is constrained to
   ensure there is space for the start of the original packet and
   additional information.

   The second field contains the human-readable node name.  The node
   name SHOULD be the YANG sys:hostname [RFC7317], if less than 64
   octets, or the first 63 octets of the sys:hostname, if the
   sys:hostname is longer.  The node name MAY be some other human-
   meaningful name of the node.  The node name MUST be padded with ASCII
   NUL characters if the object would not otherwise terminate on a
   4-octet boundary.  An example of truncation of a 66-octet node name,
   beginning "HelpMyAscii" and ending "Homestar" would be encoded as
   follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       64      |       H       |       e       |       l       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       p       |       M       |       y       |       A       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            . . . .                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       o       |       m       |       e       |       s       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The node name MUST be represented in the UTF-8 charset [RFC3629]
   using the Default Language [RFC2277].





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4.  Addition of Node Identification Object by Intermediate Nodes

   An IP/ICMP translator MAY use this extension when translating an ICMP
   message listed above to include the pre-translation source address of
   a packet.  When doing so, it MUST include the IP Address Sub-Object.
   If an ICMP Extension Structure is already present in the packet being
   translated, this Extension Object is appended to the existing ICMP
   Extension Structure and the checksum is updated.  If an ICMP
   Extension Structure is not present in the packet being translated,
   one is added using the rules of [RFC4884].  Further details of this
   mode of operation are outside the scope of this memo.

5.  Security Considerations

   A node name may reveal sensitive information, especially when it
   encodes semantic information.  It may not be desirable to allow this
   information to be sent to an arbitrary receiver.  The addition of
   this information to the ICMP responses listed in Section 3 is
   configurable, and SHOULD be disabled by default, with the exception
   of IP/ICMP translators [RFC7915].  Those translators SHOULD add the
   Node Identification Extension Object with the IP Address Sub-Object,
   as described in [I-D.equinox-v6ops-icmpext-xlat-v6only-source].  An
   implementation may determine what objects may be appended to a given
   message based on the destination IP address of the ICMP message that
   will contain the objects.  Access control lists (ACLs) may be used to
   filter the destinations to which this information may be
   communicated.

   This document does not specify an authentication mechanism for the
   extension that it defines.  Application developers should be aware
   that ICMP messages and their contents are easily spoofed.

6.  IANA Considerations

   This IANA has allocated the ICMP Extension Object Class value 5 to
   the extension described above.

      +=============+============================+=================+
      | Class Value | Class Name                 | Reference       |
      +=============+============================+=================+
      | 5           | Node Identification Object | [This document] |
      +-------------+----------------------------+-----------------+

                                 Table 1

   The corresponding Class Sub-types Registry is as follows:





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         +================+==========================+===========+
         | C-Type (Value) | Description              | Reference |
         +================+==========================+===========+
         | 0-4            | Unassigned - allocatable | [This     |
         |                | with Standards Action    | document] |
         +----------------+--------------------------+-----------+
         | 5              | IP Address Sub-object    | [This     |
         |                | included                 | document] |
         +----------------+--------------------------+-----------+
         | 6              | Name Sub-object included | [This     |
         |                |                          | document] |
         +----------------+--------------------------+-----------+
         | 7              | Unassigned - allocatable | [This     |
         |                | with Standards Action    | document] |
         +----------------+--------------------------+-----------+

                                  Table 2

   As mentioned in Section 3.1.1, IANA is requested to assign additional
   bits starting at zero.

7.  References

7.1.  Normative References

   [IANA.address-family-numbers]
              IANA, "Address Family Numbers",
              <https://www.iana.org/assignments/address-family-numbers>.

   [RFC0792]  Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981,
              <https://www.rfc-editor.org/rfc/rfc792>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC2277]  Alvestrand, H., "IETF Policy on Character Sets and
              Languages", BCP 18, RFC 2277, DOI 10.17487/RFC2277,
              January 1998, <https://www.rfc-editor.org/rfc/rfc2277>.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <https://www.rfc-editor.org/rfc/rfc3629>.






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   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", STD 89,
              RFC 4443, DOI 10.17487/RFC4443, March 2006,
              <https://www.rfc-editor.org/rfc/rfc4443>.

   [RFC4884]  Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
              "Extended ICMP to Support Multi-Part Messages", RFC 4884,
              DOI 10.17487/RFC4884, April 2007,
              <https://www.rfc-editor.org/rfc/rfc4884>.

   [RFC5837]  Atlas, A., Ed., Bonica, R., Ed., Pignataro, C., Ed., Shen,
              N., and JR. Rivers, "Extending ICMP for Interface and
              Next-Hop Identification", RFC 5837, DOI 10.17487/RFC5837,
              April 2010, <https://www.rfc-editor.org/rfc/rfc5837>.

   [RFC7317]  Bierman, A. and M. Bjorklund, "A YANG Data Model for
              System Management", RFC 7317, DOI 10.17487/RFC7317, August
              2014, <https://www.rfc-editor.org/rfc/rfc7317>.

   [RFC7915]  Bao, C., Li, X., Baker, F., Anderson, T., and F. Gont,
              "IP/ICMP Translation Algorithm", RFC 7915,
              DOI 10.17487/RFC7915, June 2016,
              <https://www.rfc-editor.org/rfc/rfc7915>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

7.2.  Informative References

   [I-D.chroboczek-intarea-v4-via-v6]
              Chroboczek, J., Kumari, W., and T. Høiland-Jørgensen,
              "IPv4 routes with an IPv6 next hop", Work in Progress,
              Internet-Draft, draft-chroboczek-intarea-v4-via-v6-03, 20
              January 2025, <https://datatracker.ietf.org/doc/html/
              draft-chroboczek-intarea-v4-via-v6-03>.

   [I-D.equinox-v6ops-icmpext-xlat-v6only-source]
              Lamparter, D. and J. Linkova, "Using Dummy IPv4 Address
              and Node Identification Extensions for IP/ICMP translators
              (XLATs)", Work in Progress, Internet-Draft, draft-equinox-
              v6ops-icmpext-xlat-v6only-source-02, 21 March 2025,
              <https://datatracker.ietf.org/doc/html/draft-equinox-
              v6ops-icmpext-xlat-v6only-source-02>.






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   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,
              <https://www.rfc-editor.org/rfc/rfc4193>.

   [RFC6877]  Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
              Combination of Stateful and Stateless Translation",
              RFC 6877, DOI 10.17487/RFC6877, April 2013,
              <https://www.rfc-editor.org/rfc/rfc6877>.

Appendix A.  Change history

   This section is to be removed before publishing as an RFC.

A.1.  Changes since draft-fenner-intarea-extended-icmp-hostid-00

   *  Instead of having two different messages with the same Class Value
      and different CType values, we copy the bitmap implementation from
      [RFC5837].  The re-use of bit positions means that packet parsing
      and generation code can be largely reused from existing [RFC5837]
      code.

A.2.  Changes since draft-fenner-intarea-extended-icmp-hostid-01

   *  Fixed several copy-pasta errors that still referred to interface
      names instead of node name.

A.3.  Changes since draft-fenner-intarea-extended-icmp-hostid-02

   *  Renamed to draft-ietf-intarea-extended-icmp-nodeid-00 to reflect
      adoption by WG

A.4.  Changes since draft-ietf-intarea-extended-icmp-nodeid-00

   *  Several edits suggested by Med Boucadair

   *  Added Section 4 to address the needs of XLAT

   *  Changed title to "Adding Extensions to ICMP Errors for Originating
      Node Identification"

A.5.  Changes since draft-ietf-intarea-extended-icmp-nodeid-01

   *  Added the request to assign bits starting at 0 to the IANA
      Considerations

   *  Updated IANA Considerations wording based on RFC8126





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   *  Shortened sub-object names to "IP Address" and "Name", eliminating
      "Node".

A.6.  Changes since draft-ietf-intarea-extended-icmp-nodeid-02

   *  Added table to reflect Object Class assignment to IANA
      Considerations

   *  Use SVG for packet figures

   *  Add example of an encoded, truncated node name

   *  Be explicit on treatment of a packet with no bits set

   *  Clarified "defaults to off" in security considerations

   *  Clarified use of IP address and names

Acknowledgments

   This document derives text heavily from [RFC5837], since the
   underlying mechanism is identical, and only the semantics of the
   message differs.  Thanks are therefore due to that document's
   authors: Alia K.  Atlas, Ronald P.  Bonica, Carlos Pignataro, Naiming
   Shen, and JR.  Rivers.

   Further thanks are due to the following who have provided valuable
   contributions to this document: Med Boucadair, Jen Linkova, David
   Lamparter, and Luigi Iannone.

Authors' Addresses

   Bill Fenner
   Arista Networks
   5453 Great America Parkway
   Santa Clara, California 95054
   United States of America
   Email: fenner@fenron.com


   Reji Thomas
   Arista Networks
   Global Tech Park
   Bangalore 560103
   Karnataka
   India
   Email: reji.thomas@arista.com




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