



MPLS Working Group                                                X. Min
Internet-Draft                                                 ZTE Corp.
Intended status: Standards Track                               G. Mirsky
Expires: 26 March 2026                                          Ericsson
                                                            L. Andersson
                                                Bronze Dragon Consulting
                                                       22 September 2025


        LSP Ping/Traceroute for Enabled In-situ OAM Capabilities
              draft-xiao-mpls-lsp-ping-ioam-conf-state-07

Abstract

   This document describes the application of the mechanism of
   discovering In-situ OAM (IOAM) capabilities, described in RFC 9359
   "Echo Request/Reply for Enabled In Situ OAM (IOAM) Capabilities", in
   MPLS networks.  The MPLS Node IOAM Information Query functionality
   uses the MPLS echo request/reply messages, allowing the IOAM
   encapsulating node to discover the enabled IOAM capabilities of each
   IOAM transit and IOAM decapsulating node.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 26 March 2026.

Copyright Notice

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

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights



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   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
   3.  IOAM Capabilities Query TLV . . . . . . . . . . . . . . . . .   3
     3.1.  Examples of the IOAM Capabilities Query . . . . . . . . .   4
   4.  IOAM Capabilities Response TLV  . . . . . . . . . . . . . . .   4
     4.1.  IOAM Capabilities Sub-TLVs  . . . . . . . . . . . . . . .   5
     4.2.  Examples of IOAM Capabilities Response TLV  . . . . . . .   6
   5.  Return Code Field Processing  . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  TLV assigments  . . . . . . . . . . . . . . . . . . . . .   9
     6.2.  New Sub-TLV registry  . . . . . . . . . . . . . . . . . .   9
     6.3.  Return Code assignment  . . . . . . . . . . . . . . . . .  11
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   MPLS encapsulation for In-situ OAM (IOAM) data is defined in
   [I-D.ietf-mpls-mna-ioam], which utilizes MPLS Network Actions (MNA)
   techniques ([I-D.ietf-mpls-mna-fwk]) to carry IOAM data fields
   ([RFC9197], [RFC9326]) in MPLS packets.

   As specified in [RFC9359], the echo request/reply can be used by the
   IOAM encapsulating node to discover the enabled IOAM capabilities at
   IOAM transit and decapsulating nodes.

   [RFC8029] defines a probe message called "MPLS echo request", and a
   response message called "MPLS echo reply" for returning the result of
   the probe.

   This document describes the MPLS Node IOAM Information Query
   functionality, which uses the MPLS echo request/reply messages,
   allowing the IOAM encapsulating node to discover the enabled IOAM
   capabilities of each IOAM transit and IOAM decapsulating node.






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   [RFC8029] specifies "ping" and "traceroute" modes.  In "ping" mode,
   the ingress LSR sends a single MPLS echo request with the TTL in the
   outermost label set to 255.  The MPLS echo request is intended to
   reach the end of the path and only the egress LSR is expected to
   respond with the MPLS echo reply.  In "traceroute" mode, the ingress
   LSR transmits a sequence of MPLS echo requests with the TTL value
   being set in successive probe packets to 1, 2, and so on.  Using TTL
   expiration as the exception mechanism, each LSR is expected to
   respond by transmitting an MPLS echo reply.

   In an MPLS network, the ingress LSR may also act as the IOAM
   encapsulating node.  In such a case, a transit LSR acts as the IOAM
   transit node, and the egress LSR acts as the IOAM decapsulating node.
   Usually, the trace option of IOAM data is needed, the IOAM
   encapsulating node requires to query the enabled IOAM capabilities of
   each IOAM transit and decapsulating node, then the "traceroute" mode
   can be used.  In case that only the edge to edge option of IOAM data
   is needed, the IOAM encapsulating node requires to query the enabled
   IOAM Capabilities of only the IOAM decapsulating node, then the
   "ping" mode can be used.

   The mechanism specified in this document applies to both point-to-
   point (P2P) MPLS LSP and point-to-multipoint (P2MP) MPLS LSP.

2.  Conventions Used in This Document

   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.

3.  IOAM Capabilities Query TLV

   The IOAM Capabilities Query TLV presented in Figure 1 is carried as a
   TLV of the MPLS Echo Request message:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  IOAM Capa. Query Type (TBA1) |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     .                                                               .
     .                  List of IOAM Namespace-IDs                   .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 1: IOAM Capabilities Query TLV



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   Type: Indicates the IOAM Capabilities Query TLV.  The value is TBA1.

   Length: The length of the TLV's Value field in octets.

   The Value field is a List of IOAM Namespace-IDs, which is also called
   IOAM Capabilities Query Container Payload in Section 3.1 of
   [RFC9359].

3.1.  Examples of the IOAM Capabilities Query

   The format of an IOAM Capabilities Query can vary from deployment to
   deployment.

   In a deployment where only the default Namespace-ID is used, the IOAM
   Capabilities Query is depicted as the following:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  IOAM Capa. Query Type (TBA1) |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          |          Zero-padded          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 2: IOAM Capabilities Query of the Default IOAM Namespace

   In a deployment where two Namespace-IDs (Namespace-ID1 and Namespace-
   ID2) are used, the IOAM Capabilities Query is depicted as the
   following:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  IOAM Capa. Query Type (TBA1) |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID1         |         Namespace-ID2         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 3: IOAM Capabilities Query of the Two IOAM Namespaces

4.  IOAM Capabilities Response TLV

   The IOAM Capabilities Response TLV presented in Figure 4 is carried
   as a TLV of the MPLS Echo Reply message:







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      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |IOAM Capa. Response Type (TBA2)|            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     .                                                               .
     .               List of IOAM Capabilities Sub-TLVs              .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 4: IOAM Capabilities Response TLV

   Type: Indicates the IOAM Capabilities Response TLV.  The value is
   TBA2.

   Length: The length of the TLV's Value field in octets.

   The Value field is a List of IOAM Capabilities Objects, which is also
   called IOAM Capabilities Response Container Payload in Section 3.2 of
   [RFC9359].  Each IOAM Capabilities Object is encoded in a sub-TLV
   format.

4.1.  IOAM Capabilities Sub-TLVs

   All IOAM Capabilities sub-TLVs (aka Objects) are encapsulated in an
   IOAM Capabilities Response TLV of an MPLS Echo Reply message.

   Each IOAM Capabilities sub-TLV has the following format:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |      IOAM Capa. Sub-type      |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     .                                                               .
     .                IOAM Capabilities Object Payload               .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 5: IOAM Capabilities Sub-TLV

   Sub-type: Indicates the IOAM Capabilities sub-TLVs.  The values are
   listed as the following:








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      Value         Sub-type Name
      -----         -----------
      1             IOAM Pre-allocated Tracing Capabilities Object
      2             IOAM Proof of Transit Capabilities Object
      3             IOAM Edge-to-Edge Capabilities Object
      4             IOAM DEX Capabilities Object
      5             IOAM End-of-Domain Object

   Length: The length of the sub-TLV's Value field in octets.

   The Value field of the IOAM Capabilities sub-TLV is the IOAM
   Capabilities Object Payload, which is defined in Sections 3.2.1,
   3.2.3, 3.2.4, 3.2.5, and 3.2.6 of [RFC9359].

4.2.  Examples of IOAM Capabilities Response TLV

   The format of an IOAM Capabilities Response can vary from deployment
   to deployment.

   In a deployment where only the default Namespace-ID is used, the IOAM
   Pre-allocated Tracing Capabilities and IOAM Proof of Transit
   Capabilities are enabled at an IOAM transit node, if that IOAM
   transit node received an MPLS echo request containing IOAM
   Capabilities Query TLV, then the IOAM Capabilities Response TLV
   contained in an MPLS echo reply is depicted as the following:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |IOAM Capa. Response Type (TBA2)|            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (1)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IOAM-Trace-Type                 |  Reserved   |W|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          |          Ingress_MTU          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Ingress_if_id (short or wide format)         ......          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (2)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          | IOAM-POT-Type |SoP| Reserved  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 6: Example 1 of IOAM Capabilities Response TLV






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   In a deployment where two Namespace-IDs (Namespace-ID1 and Namespace-
   ID2) are used, for both Namespace-ID1 and Namespace-ID2 the IOAM Pre-
   allocated Tracing Capabilities and IOAM Proof of Transit Capabilities
   are enabled at an IOAM transit node, if that IOAM transit node
   received an MPLS echo request containing IOAM Capabilities Query TLV,
   then the IOAM Capabilities Response TLV contained in an MPLS echo
   reply is depicted as the following:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |IOAM Capa. Response Type (TBA2)|            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (1)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IOAM-Trace-Type                 |  Reserved   |W|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID1         |          Ingress_MTU          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Ingress_if_id (short or wide format)         ......          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (2)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID1         | IOAM-POT-Type |SoP| Reserved  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (1)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IOAM-Trace-Type                 |  Reserved   |W|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID2         |          Ingress_MTU          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Ingress_if_id (short or wide format)         ......          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (2)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID2         | IOAM-POT-Type |SoP| Reserved  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 7: Example 2 of IOAM Capabilities Response TLV

   Note that multiple sub-TLVs with the same sub-type may be present in
   an IOAM Capabilities Response TLV, as long as the Namespace-IDs in
   these sub-TLVs are all different.

   In a deployment where only the default Namespace-ID is used, the IOAM
   Pre-allocated Tracing Capabilities, IOAM Proof of Transit
   Capabilities and IOAM Edge-to-Edge Capabilities are enabled at the
   IOAM decapsulating node, if that IOAM decapsulating node received an



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   MPLS echo request containing IOAM Capabilities Query TLV, then the
   IOAM Capabilities Response TLV contained in an MPLS echo reply is
   depicted as the following:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |IOAM Capa. Response Type (TBA2)|            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (1)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IOAM-Trace-Type                 |  Reserved   |W|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          |          Ingress_MTU          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Ingress_if_id (short or wide format)         ......          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (2)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          | IOAM-POT-Type |SoP| Reserved  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IOAM Capa. Sub-type (3)    |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Namespace-ID          |         IOAM-E2E-Type         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |TSF|         Reserved          |           Reserved            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 8: Example 3 of IOAM Capabilities Response TLV

5.  Return Code Field Processing

   The Return Code field in the MPLS echo reply MUST be set to (TBA3) No
   Matched Namespace-ID if any of the following conditions apply:

   *  The IOAM Capabilities Query TLV does not include any Namespace-ID.

   *  None of the contained list of IOAM Namespace-IDs is recognized.

   *  None of the contained list of IOAM Namespace-IDs is enabled.

6.  IANA Considerations

   This document does request that IANA assigns two new TLVs, and new
   sub-TLV registry for one of the new TLVs, 5 sub-TLVs to initially
   populate this registry and a new return code (TBA3).





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6.1.  TLV assigments

   IANA is requested to assign two new TLVs (TBA1 and TBA2) from the
   "TLV" registry in the "Multiprotocol Label Switching (MPLS) Label
   Switched Paths (LSPs) Ping Parameters" registry group.  The TLVs'
   values should be assigned from the range of TLVs that require an
   error message if the TLV is not recognized.  If possible the two
   lowest free values should be used for these TLVs.

   +======+=========================+===============+==================+
   | Type | TLV Name                | Reference     | Sub-TLV Registry |
   +======+=========================+===============+==================+
   | TBA1 | IOAM Capabilities Query | This          | No Sub-TLVs      |
   |      |                         | document      |                  |
   +------+-------------------------+---------------+------------------+
   | TBA2 | IOAM Capabilities       | This          | Table 3          |
   |      | Response                | document      |                  |
   +------+-------------------------+---------------+------------------+

                             Table 1: New TLVs

6.2.  New Sub-TLV registry

   A new sub-TLV registry should be created for the TLV TBA2 created in
   Section 6.1.

   The registration procedures for this sub-TLV registry shall be:
























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   +=============+==============+=====================================+
   | Range       | Registration | Note                                |
   |             | Procedure    |                                     |
   +=============+==============+=====================================+
   | 0-16383     | Standards    | This range is for TLVs that require |
   |             | Action       | an error message if not recognized. |
   |             |              | [[RFC9041], Section 3.1]            |
   +-------------+--------------+-------------------------------------+
   | 16384-31739 | RFC Required | This range is for TLVs that require |
   |             |              | an error message if not recognized. |
   |             |              | [[RFC9041], Section 3.1]            |
   +-------------+--------------+-------------------------------------+
   | 31740-31743 | Experimental | Reserved, not to be assigned.  This |
   |             | Use          | range is for TLVs that require an   |
   |             |              | error message if not recognized.    |
   |             |              | [[RFC9041], Section 3.1]            |
   +-------------+--------------+-------------------------------------+
   | 31744-32767 | First Come   | This range is for TLVs that require |
   |             | First Served | an error message if not recognized. |
   |             |              | [[RFC9041], Section 3.1]            |
   +-------------+--------------+-------------------------------------+
   | 32768-49161 | Standards    | This range is for TLVs that can be  |
   |             | Action       | silently dropped if not recognized. |
   +-------------+--------------+-------------------------------------+
   | 49162-64507 | RFC Required | This range is for TLVs that can be  |
   |             |              | silently dropped if not recognized. |
   +-------------+--------------+-------------------------------------+
   | 64508-64511 | Experimental | Reserved, not to be assigned.  This |
   |             | Use          | range is for TLVs that can be       |
   |             |              | silently dropped if not recognized. |
   +-------------+--------------+-------------------------------------+
   | 64512-65535 | First Come   | This range is for TLVs that can be  |
   |             | First Served | silently dropped if not recognized. |
   +-------------+--------------+-------------------------------------+

                 Table 2: Sub-TLV Registration Procedures

   This sub-TLV registry should initially be populated with the
   following values.












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    +==========+============================+===============+=========+
    | Sub-Type | Sub-TLV name               | Reference     | Comment |
    +==========+============================+===============+=========+
    | 0        | Reserved                   | This document |         |
    +----------+----------------------------+---------------+---------+
    | 1        | IOAM Pre-allocated Tracing | This document |         |
    |          | Capabilities Object        |               |         |
    +----------+----------------------------+---------------+---------+
    | 2        | IOAM Proof of Transit      | This document |         |
    |          | Capabilities Object        |               |         |
    +----------+----------------------------+---------------+---------+
    | 3        | IOAM Edge-to-Edge          | This document |         |
    |          | Capabilities Object        |               |         |
    +----------+----------------------------+---------------+---------+
    | 4        | IOAM DEX Capabilities      | This document |         |
    |          | Object                     |               |         |
    +----------+----------------------------+---------------+---------+
    | 5        | IOAM End-of-Domain Object  | This document |         |
    +----------+----------------------------+---------------+---------+

                 Table 3: New Sub-TLV Registry for TLV TBA2

6.3.  Return Code assignment

   IANA is requested to assign a new Return Code from the "Return Code"
   registry in the "Multiprotocol Label Switching (MPLS) Label Switched
   Paths (LSPs) Ping Parameters" registry group as follows:

            +=======+=========================+===============+
            | Value | Meaning                 | Reference     |
            +=======+=========================+===============+
            | TBA3  | No Matched Namespace-ID | This document |
            +-------+-------------------------+---------------+

                          Table 4: New Return Code

7.  Security Considerations

   Security issues discussed in [RFC8029] and [RFC9359] apply to this
   document.

   This document recommends that the network operators establish
   policies that restrict access to MPLS Node IOAM Information Query
   functionality.  In order to enforce these policies, nodes that
   support MPLS Node IOAM Information Query functionality SHOULD support
   the following configuration options:





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   *  Enable/disable MPLS Node IOAM Information Query functionality.  By
      default, MPLS Node IOAM Information Query functionality is
      disabled.

   *  Define enabled Namespace-IDs.  By default, all Namespace-IDs
      except the default one (i.e., Namespace-ID 0x0000) are disabled.

   While applying the MPLS Node IOAM Information Query to P2MP MPLS LSP,
   since a single MPLS echo request may trigger multiple echo replies,
   there are scaling concerns and some mitigation measures, e.g.,
   containing the Echo Jitter TLV in the MPLS echo request, as being
   specified in [RFC6425], MAY be applied.

8.  Acknowledgements

   The authors would like to acknowledge Tarek Saad for his comments on
   the idea of using LSP Ping for MPLS IOAM Capabilities Discovery.

9.  References

9.1.  Normative References

   [I-D.ietf-mpls-mna-ioam]
              Gandhi, R., Mirsky, G., Li, T., Song, H., and B. Wen,
              "Supporting In Situ Operations, Administration and
              Maintenance Using MPLS Network Actions", Work in Progress,
              Internet-Draft, draft-ietf-mpls-mna-ioam-03, 30 May 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-mpls-
              mna-ioam-03>.

   [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/info/rfc2119>.

   [RFC6425]  Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
              Yasukawa, S., and T. Nadeau, "Detecting Data-Plane
              Failures in Point-to-Multipoint MPLS - Extensions to LSP
              Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011,
              <https://www.rfc-editor.org/info/rfc6425>.

   [RFC8029]  Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
              Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
              Switched (MPLS) Data-Plane Failures", RFC 8029,
              DOI 10.17487/RFC8029, March 2017,
              <https://www.rfc-editor.org/info/rfc8029>.





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   [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/info/rfc8174>.

   [RFC9041]  Andersson, L., Chen, M., Pignataro, C., and T. Saad,
              "Updating the MPLS Label Switched Paths (LSPs) Ping
              Parameters IANA Registry", RFC 9041, DOI 10.17487/RFC9041,
              July 2021, <https://www.rfc-editor.org/info/rfc9041>.

   [RFC9359]  Min, X., Mirsky, G., and L. Bo, "Echo Request/Reply for
              Enabled In Situ OAM (IOAM) Capabilities", RFC 9359,
              DOI 10.17487/RFC9359, April 2023,
              <https://www.rfc-editor.org/info/rfc9359>.

9.2.  Informative References

   [I-D.ietf-mpls-mna-fwk]
              Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS
              Network Actions (MNA) Framework", Work in Progress,
              Internet-Draft, draft-ietf-mpls-mna-fwk-15, 27 December
              2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
              mpls-mna-fwk-15>.

   [RFC9197]  Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi,
              Ed., "Data Fields for In Situ Operations, Administration,
              and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197,
              May 2022, <https://www.rfc-editor.org/info/rfc9197>.

   [RFC9326]  Song, H., Gafni, B., Brockners, F., Bhandari, S., and T.
              Mizrahi, "In Situ Operations, Administration, and
              Maintenance (IOAM) Direct Exporting", RFC 9326,
              DOI 10.17487/RFC9326, November 2022,
              <https://www.rfc-editor.org/info/rfc9326>.

Authors' Addresses

   Xiao Min
   ZTE Corp.
   Nanjing
   China
   Phone: +86 18061680168
   Email: xiao.min2@zte.com.cn


   Greg Mirsky
   Ericsson
   United States of America
   Email: gregimirsky@gmail.com



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   Loa Andersson
   Bronze Dragon Consulting
   Sweden
   Email: loa@pi.nu















































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