path: root/doc/rfc/rfc9041.txt

Internet Engineering Task Force (IETF)                      L. Andersson
Request for Comments: 9041                      Bronze Dragon Consulting
Updates: 8029, 8611                                              M. Chen
Category: Standards Track                            Huawei Technologies
ISSN: 2070-1721                                             C. Pignataro
                                                           Cisco Systems
                                                                 T. Saad
                                                        Juniper Networks
                                                               July 2021


   Updating the MPLS Label Switched Paths (LSPs) Ping Parameters IANA
                                Registry

Abstract

   This document updates RFCs 8029 and 8611, both of which define IANA
   registries for MPLS Label Switched Path (LSP) Ping.  In particular,
   the registration procedure "Private Use" (previously known as "Vendor
   Private Use") has been changed to "First Come First Served" for the
   TLV and sub-TLV registries.

   It also updates the description of the procedures for the responses
   sent when an unknown or erroneous code point is found.  The updates
   are to clarify and align this namespace with recent developments,
   e.g., aligning terminology with RFC 8126 instead of the now obsoleted
   RFC 5226 (both titled "Guidelines for Writing an IANA Considerations
   Section in RFCs").

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9041.

Copyright Notice

   Copyright (c) 2021 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 and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
     1.1.  Requirements Language
     1.2.  Terminology
       1.2.1.  Terminology Used in This Document
       1.2.2.  Abbreviations
   2.  Updating the Message Types, Reply Modes, and Return Codes
           Registries
   3.  Updating the TLV and Sub-TLV Registries
     3.1.  General Principles for the LSP Ping TLV and Sub-TLV
           Registries
       3.1.1.  Unrecognized Experimental Use TLVs and Sub-TLVs
     3.2.  Common Registration Procedures for TLVs and Sub-TLVs
     3.3.  Changes to the LSP Ping Registries
       3.3.1.  Changes Common to the TLV and Sub-TLV Registries
   4.  Updates to Related RFCs
     4.1.  Updates to RFC 8029
     4.2.  Updates to RFC 8611
   5.  Security Considerations
   6.  IANA Considerations
     6.1.  Updates by IANA to the Message Types, Reply Modes, and
           Return Codes Registries
       6.1.1.  Updates to the Message Types Registry
       6.1.2.  Updates to the Reply Modes Registry
       6.1.3.  Updates to the Return Codes Registry
     6.2.  Updates to the TLV and Sub-TLV Registries
       6.2.1.  Updates to the TLVs Registry
       6.2.2.  Updates to the Registry for Sub-TLVs for TLV Types 1,
               16, and 21
       6.2.3.  Updates to the Registry for Sub-TLVs for TLV Type 6
       6.2.4.  Updates to the Registry for Sub-TLVs for TLV Type 11
       6.2.5.  Updates to the Registry for Sub-TLVs for TLV Type 20
       6.2.6.  Updates to the Registry for Sub-TLVs for TLV Type 23
       6.2.7.  Updates to the Registry for Sub-TLVs for TLV Type 27
   7.  References
     7.1.  Normative References
     7.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   There were a number of reasons to start the work that has led to this
   document, e.g.,

   *  When the LSP Ping registry was created, it was incorrectly assumed
      that code points allocated by Experimental RFCs would be
      "experimental" code points; a code point made available in a
      public IANA registry is not limited by the type of RFC that made
      the allocation: it is available for use in any type of document.

   *  The number of "experimental" code points was also too large as
      compared to what is normally allocated for "Experimental Use".

   *  The words "mandatory" and "optional" are used differently in
      [RFC8029] than in other RFCs.  For example, [RFC8029] talks about
      mandatory TLVs to indicate that it is mandatory to take a certain
      action if the TLV is found in a message but is not recognized.
      Other RFCs use "mandatory TLV" to indicate a TLV that must be
      present in a message.

   Over time, there have been attempts to administratively update some
   of the registries, but it was soon decided that an RFC was needed.
   Other, often minor, potential updates were found, e.g., reserving the
   value 0 (zero) in registries where that is possible.

   [RFC8029] contains updates to the "Multiprotocol Label Switching
   (MPLS) Label Switched Paths (LSPs) Ping Parameters" IANA namespace
   [IANA-LSP-PING].

   [RFC8611] created LSP Ping IANA registries that match [RFC8126].
   This document further clarifies the entries in those registries and
   makes the definitions more precise.

   This document updates [RFC8029] and [RFC8611] by updating two groups
   of registries as follows:

   First, the "Message Types" [IANA-MT], "Reply Modes" [IANA-RM], and
   "Return Codes" [IANA-RC] registries are updated.  The changes to
   these registries are minor.

   Second, this document updates the TLV and sub-TLV registries listed
   below:

   *  "TLVs", [IANA-TLV-reg]

   *  "Sub-TLVs for TLV Types 1, 16, and 21", [IANA-Sub-1-16-21]

   *  "Sub-TLVs for TLV Type 6", [IANA-Sub-6]

   *  "Sub-TLVs for TLV Type 11", [IANA-Sub-11]

   *  "Sub-TLVs for TLV Type 20", [IANA-Sub-20]

   *  "Sub-TLVs for TLV Type 23", [IANA-Sub-23]

   *  "Sub-TLVs for TLV Type 27", [IANA-Sub-27]

   It should be noted that [RFC8029] was published before [RFC8126] and
   uses outdated terminology for some registration procedures, e.g.,
   "Vendor Private Use".  [RFC8611] was published after [RFC8126] and
   uses its recommended terminology, e.g., "Private Use".  However, now
   both "Vendor Private Use" and "Private Use" have been removed and
   replaced with "First Come First Served" (FCFS) code points.

   One reason to change from code points allocated by Vendor Private Use
   or Private Use is that such code points are allowed in production
   networks.  Theoretically, it is possible that two vendors might use
   the same code point value with different meanings.  If such a code is
   ever deployed in the same network, this could cause protocol issues
   that would be hard to debug.

   With FCFS code points, this will not happen.  Vendors that have
   existing code using Vendor Private Use or Private Use code points
   should register those code points as FCFS code points as soon as this
   document is published as an RFC.

   The "Sub-TLVs for TLV Type 9" subregistry is not updated.

   Third, according to [RFC8029], some code points (TLVs and sub-TLVs)
   are called "mandatory" or "optional".  Contrary to how other RFCs use
   these words, indicating that it is mandatory or optional to include
   the code points in a message, [RFC8029] uses these words to indicate
   that an action might or might not be mandatory.  This document
   updates [RFC8029] to drop the words "mandatory" and "optional", and
   the text is changed to focus on what should be done.

1.1.  Requirements Language

   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.

1.2.  Terminology

   This section lists terms that are used when discussing the hierarchy
   of IANA registries (Section 1.2.1), and abbreviations used in IANA
   registries are updated in this document (Section 1.2.2).

1.2.1.  Terminology Used in This Document

   Terms related to IANA registries are used as follows in this
   document:

   Namespace
      A namespace is a top-level registry.  An example could be
      "Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs)
      Ping Parameters" [IANA-LSP-PING].  A namespace is most often a
      container for registries that hold code points that share some
      affinity.

   Registry
      An IANA registry holds code points and lists the registration
      procedures and allocation for these code points.  One example
      would be the "TLVs" registry [IANA-TLV-reg].

   Subregistry
      A subregistry is used when a code point, or a set of code points
      allocated in a single registry, needs "sub-code-points" scoped by
      the code point or the set of code points.  An example of a
      subregistry that holds code points for more than one TLV is
      "Sub-TLVs for TLV Types 1, 16, and 21" [IANA-Sub-1-16-21].

1.2.2.  Abbreviations

   This section lists abbreviations used in the unchanged part of the
   registries updated by this document.  These abbreviations were
   originally expanded in the document defining the registries.  They
   are listed here following the requirement to expand any abbreviation
   that is not well known.  All these abbreviations are from the "Return
   Codes" registry [IANA-RC].

   BFD:      Bidirectional Forwarding Detection

   DDMAP:    Downstream Detailed Mapping

   FEC:      Forwarding Equivalence Class

   OAM:      Operation, Administration, and Maintenance

   PM:       Performance Monitoring

   RSC:      Return Subcode

2.  Updating the Message Types, Reply Modes, and Return Codes Registries

   The following changes have been made to the "Message Types"
   [IANA-MT], "Reply Modes" [IANA-RM], and "Return Codes" [IANA-RC]
   registries.

   *  In the listing of assigned code points, the term "Vendor Private
      Use" is changed to "Private Use" for the 252-255 range.  The
      registration procedures have been updated to reflect this.

   *  The registration procedure "Specification Required" is changed to
      "RFC Required" and the note "Experimental RFC needed" is removed
      for the 192-247 range.

   *  A small set of four code points (248-251) for Experimental Use is
      added by reducing the "RFC Required" range.  The registration
      procedures have been updated to reflect this.

   *  A note "Reserved, not to be assigned" has been added for the
      registration procedures of the "Private Use" and "Experimental
      Use" ranges.

   *  In the lists that capture the assignment status, the fields that
      are reserved, i.e., 0 (zero), Private Use, and Experimental Use,
      are clearly marked as such.

      -  Note that in the "Return Codes" registry [IANA-RC], the code
         point "0" has already been assigned.  This assignment is not
         changed, and in this registry, the code point "0" continues to
         be assigned as "No Return Code".

   The new registration procedures, the registry layouts, and the new
   assignments for these registries are found in Section 6.1.

3.  Updating the TLV and Sub-TLV Registries

3.1.  General Principles for the LSP Ping TLV and Sub-TLV Registries

   The following principles apply to the processing of any TLV from any
   of the LSP Ping TLV and sub-TLV IANA registries.

   *  All TLVs and sub-TLVs with a type in the range 0-32767 require a
      response if they are not recognized.

   *  All TLVs and sub-TLVs in the range 32768-65535 can be silently
      dropped if they are not recognized.  Alternatively, the receiver
      may step over the unrecognized TLV or send an error message.

   Each of the blocks has code point spaces with the following
   registration procedures:

   *  Standards Action

   *  RFC Required

   *  Experimental Use

   *  First Come First Served (FCFS)

   The exact definitions of these procedures are found in [RFC8126].

3.1.1.  Unrecognized Experimental Use TLVs and Sub-TLVs

   Unrecognized TLVs and sub-TLVs in the Experimental Use and FCFS
   ranges are handled as any other unrecognized TLV or sub-TLV.

   *  If the unrecognized TLV or sub-TLV is from the Experimental Use
      range (31740-31743) or from the FCFS range (31744-32767), a Return
      Code of 2 ("One or more of the TLVs was not understood") must be
      sent in the echo response.

   *  If a TLV or sub-TLV from the Experimental Use range (64508-64511)
      or from the FCFS range (64512-65535) is unrecognized, then the
      receiver can silently drop the TLV.  Alternatively, the receiver
      may step over the unrecognized TLV or send an error message.

   The IETF does not prescribe how recognized or unrecognized
   Experimental Use and Private Use TLVs and sub-TLVs are handled in
   experimental or private networks; that is up to the agency running
   the experimental or the private network.  The statement above
   describes how standards-compliant implementations must treat the
   unrecognized TLVs and sub-TLVs from these ranges.

3.2.  Common Registration Procedures for TLVs and Sub-TLVs

   This section describes the new registration procedures for the TLV
   and sub-TLV registries.

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

             Table 1: TLV and Sub-TLV Registration Procedures

3.3.  Changes to the LSP Ping Registries

   This section lists the changes to each MPLS LSP Ping TLV and sub-TLV
   registry.  Sections 6.2.1 to 6.2.7 describe how the new versions of
   the IANA registries should look, together with the registration
   procedures for each registry.

   The new registration procedure descriptions and the new assignments
   for these registries are used to model the changed MPLS LSP Ping
   registries; see Section 6.

3.3.1.  Changes Common to the TLV and Sub-TLV Registries

   The following changes are made to the TLV and sub-TLV registries.

   *  The registration procedures "First Come First Served" (FCFS) and
      "Experimental Use" have been added to the table of registration
      procedures.

   *  Two small sets of code points (four code points each) for
      Experimental Use have been created.  The first set is for the
      range that requires a response if the TLV or sub-TLV is not
      recognized; the second set is for the range where the TLV or sub-
      TLV may be silently dropped if not recognized.  The code points
      for Experimental Use have been taken from the ranges previously
      called "Specification Required" and "RFC Required" [RFC8029].

   *  The registration procedure "Specification Required" has been
      changed to "RFC Required", and the note "Experimental RFC needed"
      has been removed.

   *  In the listing of assignments, the term "Vendor Private Use" has
      been changed to "First Come First Served" (FCFS).

   *  In the listing of assignments, the range for "Experimental Use"
      has been added.

   *  A note saying "Not to be assigned" has been added for the
      registration procedure "Experimental Use".

   *  In the list that captures assignment status, the fields that are
      reserved, i.e., 0 (zero) and Experimental Use, have been clearly
      marked.

4.  Updates to Related RFCs

   Some referenced RFCs use the concept "mandatory TLVs" and "mandatory
   sub-TLVs" to indicate that, if a TLV or sub-TLV of the range 0-32767
   in a message is not understood, an error message needs to be sent in
   response.

   The same RFCs use "optional TLVs" and "optional sub-TLVs" to mean
   TLVs or sub-TLVs that can be silently ignored if not recognized.

   Since other RFCs use "mandatory TLVs" and "mandatory sub-TLVs" to
   indicate TLVs and sub-TLVs that must be present in a message, we want
   to discontinue the use of "mandatory" to indicate TLVs and sub-TLVs
   that require an error message in response if not understood.  The
   changes to the RFCs below align with this practice.

4.1.  Updates to RFC 8029

   "Mandatory" and "optional" are used to indicate whether a response is
   needed if a TLV or sub-TLV is not understood in Section 3 of
   "Detecting Multiprotocol Label Switched (MPLS) Data-Plane Failures"
   [RFC8611].

   The text in those two paragraphs is now updated to the following:

   |  TLV and sub-TLV types less than 32768 (i.e., with the high-order
   |  bit equal to 0) are TLVs and sub-TLVs that MUST either be
   |  supported by an implementation or result in a Return Code of 2
   |  ("One or more of the TLVs was not understood") being sent in the
   |  echo response.
   |  
   |  An implementation that does not understand or support a received
   |  TLV or sub-TLV with a type greater than or equal to 32768 (i.e.,
   |  with the high-order bit equal to 1) SHOULD ignore and step over
   |  the TLV or sub-TLV; however, an implementation MAY send an echo
   |  response with a Return Code of 2 ("One or more of the TLVs was not
   |  understood") as it would have done if the high-order bit had been
   |  clear.

   In Section 3.8 of [RFC8029], "mandatory" is used in the same way.
   The first two paragraphs of this section are now updated to read as
   follows:

   |  The following TLV is a TLV that MAY be included in an echo reply
   |  to inform the sender of an echo request that includes TLV or sub-
   |  TLV Types less than 32768 (i.e., with the high-order bit equal to
   |  0) that are either not supported by the implementation or parsed
   |  and found to be in error.
   |  
   |  The Value field uses sub-TLVs to encode the received TLVs and sub-
   |  TLVs that were not understood.

4.2.  Updates to RFC 8611

   Section 13.4.1 of "Label Switched Path (LSP) Ping and Traceroute
   Multipath Support for Link Aggregation Group (LAG) Interfaces"
   [RFC8611] defines "Sub-TLVs for TLV Type 6" [IANA-Sub-6].

   The "Sub-TLVs for TLV Type 6" registry has been updated to align with
   changes defined in this document.

   Section 13.4.1 of [RFC8611] is now updated as follows:

   |  Section 13.4.1 Sub-TLVs for TLV Type 6

   IANA has created a new subregistry, "Sub-TLVs for TLV Type 6",
   [IANA-Sub-6] under the "TLVs" registry [IANA-TLV-reg] of the
   "Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs)
   Ping Parameters" namespace [lsp-ping-Namespace].

   The "Sub-TLVs for TLV Type 6" subregistry is now updated to align
   with changes defined in this document.

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

          Table 2: Sub-TLVs for TLV Type 6 Registration Procedures

5.  Security Considerations

   This document updates IANA registries.  It also updates terminology
   used to define, and clarifies the terminology related to, the code
   points in the registries.  The document does not change how the code
   points in the registries are used.  This should not create any new
   threats.

   However, the updated terminology and the clarifications improve
   security because it makes it more likely that implementations will be
   consistent and harder to attack.

6.  IANA Considerations

   IANA has updated the "Multiprotocol Label Switching (MPLS) Label
   Switched Paths (LSPs) Ping Parameters" namespace [IANA-LSP-PING] as
   described in this document.

   See Section 1.2.1 of "Terminology Used in This Document" to see how
   "namespace", "registry", and "subregistry" are used in this document.

   In other parts of this document, the commonality of the changes to
   the LSP Ping registries has been the focus.  For the IANA
   Considerations, each changed registry has been described in its own
   right.

   The following registries and subregistries have been changed:

   *  "Message Types", [IANA-MT]

   *  "Reply Modes", [IANA-RM]

   *  "Return Codes", [IANA-RC]

   *  "TLVs", [IANA-TLV-reg]

   *  "Sub-TLVs for TLV Types 1, 16, and 21", [IANA-Sub-1-16-21]

   *  "Sub-TLVs for TLV Type 6", [IANA-Sub-6]

   *  "Sub-TLVs for TLV Type 11", [IANA-Sub-11]

   *  "Sub-TLVs for TLV Type 20", [IANA-Sub-20]

   *  "Sub-TLVs for TLV Type 23", [IANA-Sub-23]

   *  "Sub-TLVs for TLV Type 27", [IANA-Sub-27]

   This document has been listed as an additional reference for each of
   the registries described in Sections 6.1 and 6.2.

6.1.  Updates by IANA to the Message Types, Reply Modes, and Return
      Codes Registries

   This section details the updated registration procedures and
   allocations for the "Message Types", "Reply Modes", and "Return
   Codes" registries.

6.1.1.  Updates to the Message Types Registry

   These are the changes to the "Message Types" registry specified in
   this document:

   *  Code Point 0 (zero) has been marked Reserved.

   *  The registration procedure "Specification Required" has been
      changed to "RFC Required", and the comment "Experimental RFC
      needed" has been removed.

   *  Four code points have been taken from what was previously
      "Specification Required" to form a set of code points for
      "Experimental Use".

   The registration procedures after the changes listed above for the
   "Message Types" registry are shown in the table below:

   +=========+=========================+==============================+
   | Range   | Registration Procedures | Note                         |
   +=========+=========================+==============================+
   | 0-191   | Standards Action        |                              |
   +---------+-------------------------+------------------------------+
   | 192-247 | RFC Required            |                              |
   +---------+-------------------------+------------------------------+
   | 248-251 | Experimental Use        | Reserved, not to be assigned |
   +---------+-------------------------+------------------------------+
   | 252-255 | Private Use             | Reserved, not to be assigned |
   +---------+-------------------------+------------------------------+

              Table 3: Message Types Registration Procedures

   The updated assignments for the "Message Types" registry appear as
   follows:

        +=========+===============================+===============+
        | Value   | Meaning                       | Reference     |
        +=========+===============================+===============+
        | 0       | Reserved                      | This document |
        +---------+-------------------------------+---------------+
        | 1       | MPLS Echo Request             | [RFC8029]     |
        +---------+-------------------------------+---------------+
        | 2       | MPLS Echo Reply               | [RFC8029]     |
        +---------+-------------------------------+---------------+
        | 3       | MPLS Proxy Ping Request       | [RFC7555]     |
        +---------+-------------------------------+---------------+
        | 4       | MPLS Proxy Ping Reply         | [RFC7555]     |
        +---------+-------------------------------+---------------+
        | 5       | MPLS Relayed Echo Reply       | [RFC7743]     |
        +---------+-------------------------------+---------------+
        | 6-247   | Unassigned                    |               |
        +---------+-------------------------------+---------------+
        | 248-251 | Reserved for Experimental Use | This document |
        +---------+-------------------------------+---------------+
        | 252-255 | Reserved for Private Use      | [RFC8029]     |
        +---------+-------------------------------+---------------+

            Table 4: Assignments for the Message Types Registry

6.1.2.  Updates to the Reply Modes Registry

   These are the changes to the "Reply Modes" registry specified in this
   document:

   *  Code Point 0 (zero) has been marked Reserved.

   *  The registration procedure "Specification Required" has been
      changed to "RFC Required", and the comment "Experimental RFC
      needed" has been removed.

   *  Four code points have been taken from what was previously
      "Specification Required" to form a set of code points for
      "Experimental Use".

   The registration procedures after the changes for the "Reply Modes"
   registry are shown in the table below:

   +=========+=========================+==============================+
   | Range   | Registration Procedures | Note                         |
   +=========+=========================+==============================+
   | 0-191   | Standards Action        |                              |
   +---------+-------------------------+------------------------------+
   | 192-247 | RFC Required            |                              |
   +---------+-------------------------+------------------------------+
   | 248-251 | Experimental Use        | Reserved, not to be assigned |
   +---------+-------------------------+------------------------------+
   | 252-255 | Private Use             | Reserved, not to be assigned |
   +---------+-------------------------+------------------------------+

               Table 5: Reply Modes Registration Procedures

   The updated assignments for the "Reply Modes" registry are as
   follows:

      +=========+===================================+===============+
      | Value   | Meaning                           | Reference     |
      +=========+===================================+===============+
      | 0       | Reserved                          | This document |
      +---------+-----------------------------------+---------------+
      | 1       | Do not reply                      | [RFC8029]     |
      +---------+-----------------------------------+---------------+
      | 2       | Reply via an IPv4/IPv6 UDP packet | [RFC8029]     |
      +---------+-----------------------------------+---------------+
      | 3       | Reply via an IPv4/IPv6 UDP packet | [RFC8029]     |
      |         | with Router Alert                 |               |
      +---------+-----------------------------------+---------------+
      | 4       | Reply via application-level       | [RFC8029]     |
      |         | control channel                   |               |
      +---------+-----------------------------------+---------------+
      | 5       | Reply via Specified Path          | [RFC7110]     |
      +---------+-----------------------------------+---------------+
      | 6-247   | Unassigned                        |               |
      +---------+-----------------------------------+---------------+
      | 248-251 | Reserved for Experimental Use     | This document |
      +---------+-----------------------------------+---------------+
      | 252-255 | Reserved for Private Use          | [RFC8029]     |
      +---------+-----------------------------------+---------------+

             Table 6: Assignments for the Reply Modes Registry

6.1.3.  Updates to the Return Codes Registry

   These are the changes to the "Return Codes" registry specified in
   this document:

   *  The registration procedure "Specification Required" has been
      changed to "RFC Required", and the comment "Experimental RFC
      needed" has been removed.

   *  Four code points have been taken from what was previously
      "Specification Required" to form a set of code points for
      "Experimental Use".

   The registration procedures after the changes for the "Return Codes"
   registry are shown in the table below:

   +=========+=========================+==============================+
   | Range   | Registration Procedures | Note                         |
   +=========+=========================+==============================+
   | 0-191   | Standards Action        |                              |
   +---------+-------------------------+------------------------------+
   | 192-247 | RFC Required            |                              |
   +---------+-------------------------+------------------------------+
   | 248-251 | Experimental Use        | Reserved, not to be assigned |
   +---------+-------------------------+------------------------------+
   | 252-255 | Private Use             | Reserved, not to be assigned |
   +---------+-------------------------+------------------------------+

              Table 7: Return Codes Registration Procedures

   The updated assignments for the "Return Codes" registry are as
   follows:

    +=========+=========================================+=============+
    | Value   | Meaning                                 | Reference   |
    +=========+=========================================+=============+
    | 0       | No Return Code                          | [RFC8029]   |
    +---------+-----------------------------------------+-------------+
    | 1       | Malformed echo request received         | [RFC8029]   |
    +---------+-----------------------------------------+-------------+
    | 2       | One or more of the TLVs was not         | [RFC8029]   |
    |         | understood                              |             |
    +---------+-----------------------------------------+-------------+
    | 3       | Replying router is an egress for the    | [RFC8029]   |
    |         | FEC at stack-depth <RSC>                |             |
    +---------+-----------------------------------------+-------------+
    | 4       | Replying router has no mapping for the  | [RFC8029]   |
    |         | FEC at stack-depth <RSC>                |             |
    +---------+-----------------------------------------+-------------+
    | 5       | Downstream Mapping Mismatch (See [1])   | [RFC8029]   |
    +---------+-----------------------------------------+-------------+
    | 6       | Upstream Interface Index Unknown (See   | [RFC8029]   |
    |         | [1])                                    |             |
    +---------+-----------------------------------------+-------------+
    | 7       | Reserved                                | [RFC8029]   |
    +---------+-----------------------------------------+-------------+
    | 8       | Label switched at stack-depth <RSC>     | [RFC8029]   |
    +---------+-----------------------------------------+-------------+
    | 9       | Label switched but no MPLS forwarding   | [RFC8029]   |
    |         | at stack-depth <RSC>                    |             |
    +---------+-----------------------------------------+-------------+
    | 10      | Mapping for this FEC is not the given   | [RFC8029]   |
    |         | label at stack-depth <RSC>              |             |
    +---------+-----------------------------------------+-------------+
    | 11      | No label entry at stack-depth <RSC>     | [RFC8029]   |
    +---------+-----------------------------------------+-------------+
    | 12      | Protocol not associated with interface  | [RFC8029]   |
    |         | at FEC stack-depth <RSC>                |             |
    +---------+-----------------------------------------+-------------+
    | 13      | Premature termination of ping due to    | [RFC8029]   |
    |         | label stack shrinking to a single label |             |
    +---------+-----------------------------------------+-------------+
    | 14      | See DDMAP TLV for meaning of Return     | [RFC8029]   |
    |         | Code and Return Subcode (See [2])       |             |
    +---------+-----------------------------------------+-------------+
    | 15      | Label switched with FEC change          | [RFC8029]   |
    +---------+-----------------------------------------+-------------+
    | 16      | Proxy Ping not authorized               | [RFC7555]   |
    +---------+-----------------------------------------+-------------+
    | 17      | Proxy Ping parameters need to be        | [RFC7555]   |
    |         | modified                                |             |
    +---------+-----------------------------------------+-------------+
    | 18      | MPLS Echo Request could not be sent     | [RFC7555]   |
    +---------+-----------------------------------------+-------------+
    | 19      | Replying router has FEC mapping for     | [RFC7555]   |
    |         | topmost FEC                             |             |
    +---------+-----------------------------------------+-------------+
    | 20      | One or more TLVs not returned due to    | [RFC7743]   |
    |         | MTU size                                |             |
    +---------+-----------------------------------------+-------------+
    | 21      | OAM Problem/Unsupported BFD Version     | [RFC7759]   |
    +---------+-----------------------------------------+-------------+
    | 22      | OAM Problem/Unsupported BFD             | [RFC7759]   |
    |         | Encapsulation format                    |             |
    +---------+-----------------------------------------+-------------+
    | 23      | OAM Problem/Unsupported BFD             | [RFC7759]   |
    |         | Authentication Type                     |             |
    +---------+-----------------------------------------+-------------+
    | 24      | OAM Problem/Mismatch of BFD             | [RFC7759]   |
    |         | Authentication Key ID                   |             |
    +---------+-----------------------------------------+-------------+
    | 25      | OAM Problem/Unsupported Timestamp       | [RFC7759]   |
    |         | Format                                  |             |
    +---------+-----------------------------------------+-------------+
    | 26      | OAM Problem/Unsupported Delay Mode      | [RFC7759]   |
    +---------+-----------------------------------------+-------------+
    | 27      | OAM Problem/Unsupported Loss Mode       | [RFC7759]   |
    +---------+-----------------------------------------+-------------+
    | 28      | OAM Problem/Delay variation unsupported | [RFC7759]   |
    +---------+-----------------------------------------+-------------+
    | 29      | OAM Problem/Dyadic mode unsupported     | [RFC7759]   |
    +---------+-----------------------------------------+-------------+
    | 30      | OAM Problem/Loopback mode unsupported   | [RFC7759]   |
    +---------+-----------------------------------------+-------------+
    | 31      | OAM Problem/Combined mode unsupported   | [RFC7759]   |
    +---------+-----------------------------------------+-------------+
    | 32      | OAM Problem/Fault management signaling  | [RFC7759]   |
    |         | unsupported                             |             |
    +---------+-----------------------------------------+-------------+
    | 33      | OAM Problem/Unable to create fault      | [RFC7759]   |
    |         | management association                  |             |
    +---------+-----------------------------------------+-------------+
    | 34      | OAM Problem/PM Configuration Error      | [RFC7759]   |
    +---------+-----------------------------------------+-------------+
    | 35      | Mapping for this FEC is not associated  | [RFC8287],  |
    |         | with the incoming interface             | Section 7.4 |
    +---------+-----------------------------------------+-------------+
    | 36-247  | Unassigned                              |             |
    +---------+-----------------------------------------+-------------+
    | 248-251 | Reserved for Experimental Use           | This        |
    |         |                                         | document    |
    +---------+-----------------------------------------+-------------+
    | 252-255 | Reserved for Private Use                | [RFC8029]   |
    +---------+-----------------------------------------+-------------+

             Table 8: Assignments for the Return Codes Registry

   Note 1:  Notes [1] and [2] for code points 5, 6, and 14 point to
      footnotes in the "Multiprotocol Label Switching (MPLS) Label
      Switched Paths (LSPs) Ping Parameters" namespace.  The footnotes
      are not changed by this document.

   Note 2:  <RSC> stands for "Return Subcode" and is explained in
      Section 3.1 of [RFC8029].

6.2.  Updates to the TLV and Sub-TLV Registries

   The updates to the TLV and the sub-TLV registries are mostly the
   same; however, the "Sub-TLVs for TLV Type 9" [IANA-Sub-9] registry
   has not been updated.

   Note that when a field in an assignment table says "EQ", it means
   that there is no change from the existing field in the "Multiprotocol
   Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters"
   namespace [IANA-LSP-PING].

6.2.1.  Updates to the TLVs Registry

   This section describes the new registration procedures and the
   assignments for the "TLVs" registry [IANA-TLV-reg] that are based on
   them.

   The registration procedures have been changed, as follows, for the
   "TLVs" registry.

   *  The "Specification Required" registration procedure has been
      changed to "RFC Required".  The comment "Experimental RFC
      Required" has been removed.  Note that when a field in an
      assignment table says "EQ", it means that there is no change from
      the existing field in the "Multiprotocol Label Switching (MPLS)
      Label Switched Paths (LSPs) Ping Parameters" namespace
      [IANA-LSP-PING].

   *  [RFC8611] was published after [RFC8126] and uses the new
      terminology, e.g., "Private Use".  The code points registration
      procedure "Private Use" has been replaced by the "First Come First
      Served" code point registration procedure.

   *  Two small sets, four code points each, have been created for
      Experimental Use.

   *  Code points that are reserved are clearly marked as such.

   *  The assignments have been updated to match the new registration
      procedures.

   *  The notes related to the registration procedures have been changed
      to reflect whether or not a response is required if a TLV is not
      recognized.

   The registration procedures for the "TLVs" registry [IANA-TLV-reg]
   after the changes listed above are shown in the table below:

   +=============+==============+=====================================+
   | Range       | Registration | Note                                |
   |             | Procedures   |                                     |
   +=============+==============+=====================================+
   | 0-16383     | Standards    | This range is for TLVs that require |
   |             | Action       | an error message if not recognized. |
   |             |              | This document, Section 3.1          |
   +-------------+--------------+-------------------------------------+
   | 16384-31739 | RFC Required | This range is for TLVs that require |
   |             |              | an error message if not recognized. |
   |             |              | This document, Section 3.1          |
   +-------------+--------------+-------------------------------------+
   | 31740-31743 | Reserved for | Not to be assigned.  This range is  |
   |             | Experimental | for TLVs that require an error      |
   |             | Use          | message if not recognized.  This    |
   |             |              | document, Section 3.1               |
   +-------------+--------------+-------------------------------------+
   | 31744-32767 | FCFS         | This range is for TLVs that require |
   |             |              | an error message if not recognized. |
   |             |              | This document, 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 | Reserved for | Not to be assigned.  This range is  |
   |             | Experimental | for TLVs that can be silently       |
   |             | Use          | dropped if not recognized.          |
   +-------------+--------------+-------------------------------------+
   | 64512-65535 | FCFS         | This range is for TLVs that can be  |
   |             |              | silently dropped if not recognized. |
   +-------------+--------------+-------------------------------------+

                  Table 9: TLVs Registration Procedures

   The updated assignments for this registry appear as follows:

   Note that when a field in an assignment table says "EQ", it means
   that there was no change from the existing field in the
   "Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs)
   Ping Parameters" namespace [IANA-LSP-PING].

    +=============+==============+===========+=======================+
    | Type        | TLV Name     | Reference | Sub-TLV Registry      |
    +=============+==============+===========+=======================+
    | 0           | Reserved     | This      |                       |
    |             |              | document  |                       |
    +-------------+--------------+-----------+-----------------------+
    | 1-7         | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 8           | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 9-16        | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 17-19       | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 20-27       | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 28-31739    | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 31740-31743 | Reserved for | This      | Not to be assigned.   |
    |             | Experimental | document  | This range is for     |
    |             | Use          |           | TLVs that require an  |
    |             |              |           | error message if not  |
    |             |              |           | recognized.  This     |
    |             |              |           | document, Section 3.1 |
    +-------------+--------------+-----------+-----------------------+
    | 31744-32767 | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 32768-32770 | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 32771-64507 | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 64508-64511 | Reserved for | This      | Not to be assigned.   |
    |             | Experimental | document  | This range is for     |
    |             | Use          |           | TLVs that can be      |
    |             |              |           | silently dropped if   |
    |             |              |           | not recognized.       |
    +-------------+--------------+-----------+-----------------------+
    | 64512-65535 | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+

                        Table 10: TLV Assignments

6.2.2.  Updates to the Registry for Sub-TLVs for TLV Types 1, 16, and 21

   This section describes the new registration procedures and the
   assignments for the "Sub-TLVs for TLV Types 1, 16, and 21"
   [IANA-Sub-1-16-21] subregistry that are based on them.

   *  The "Specification Required" registration procedure has been
      changed to "RFC Required", and the comment "Experimental RFC
      Required" has been removed.

   *  The code points registration procedure "Vendor Private Use" has
      been removed and replaced with "First Come First Served"
      procedure.

   *  Two small sets, four code points each, have been created for
      Experimental Use.

   *  Code points that are reserved are clearly marked as such.

   *  The assignments have been updated to match the new registration
      procedures.

   *  The notes related to the registration procedures have been changed
      to reflect whether or not a response is required if a sub-TLV is
      not recognized.

   The registration procedures for the "Sub-TLVs for TLV Types 1, 16,
   and 21" [IANA-Sub-1-16-21] subregistry appear as follows after the
   changes listed above:

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

        Table 11: Registration Procedures for Sub-TLVs for TLV Types
                               1, 16, and 21

    +=============+==============+===========+=======================+
    | Sub-Type    | Sub-TLV Name | Reference | Comment               |
    +=============+==============+===========+=======================+
    | 0           | Reserved     | This      |                       |
    |             |              | document  |                       |
    +-------------+--------------+-----------+-----------------------+
    | 1-4         | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 5           | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 6-8         | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 9           | EQ           | EQ        | DEPRECATED            |
    +-------------+--------------+-----------+-----------------------+
    | 10-20       | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 21          | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 22-37       | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 38          | PeerAdj SID  | [draft-   | TEMPORARY -           |
    |             | Sub-TLV      | ietf-     | registered            |
    |             |              | mpls-sr-  | 2021-05-11, expires   |
    |             |              | epe-oam-  | 2022-05-11            |
    |             |              | 03]       |                       |
    +-------------+--------------+-----------+-----------------------+
    | 39          | PeerNode SID | [draft-   | TEMPORARY -           |
    |             | Sub-TLV      | ietf-     | registered            |
    |             |              | mpls-sr-  | 2021-05-11, expires   |
    |             |              | epe-oam-  | 2022-05-11            |
    |             |              | 03]       |                       |
    +-------------+--------------+-----------+-----------------------+
    | 40          | PeerSet SID  | [draft-   | TEMPORARY -           |
    |             | Sub-TLV      | ietf-     | registered            |
    |             |              | mpls-sr-  | 2021-05-11, expires   |
    |             |              | epe-oam-  | 2022-05-11            |
    |             |              | 03]       |                       |
    +-------------+--------------+-----------+-----------------------+
    | 41-31739    | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 31740-31743 | Reserved for | This      | Not to be assigned.   |
    |             | Experimental | document  | This range is for     |
    |             | Use          |           | sub-TLVs that require |
    |             |              |           | an error message if   |
    |             |              |           | not recognized.  This |
    |             |              |           | document, Section 3.1 |
    +-------------+--------------+-----------+-----------------------+
    | 31744-64507 | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 64508-64511 | Reserved for | This      | Not to be assigned.   |
    |             | Experimental | document  | This range is for     |
    |             | Use          |           | sub-TLVs that can be  |
    |             |              |           | silently dropped if   |
    |             |              |           | not recognized.       |
    +-------------+--------------+-----------+-----------------------+
    | 64512-65535 | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+

           Table 12: Sub-TLV for TLVs 1, 16, and 21 Assignments

6.2.3.  Updates to the Registry for Sub-TLVs for TLV Type 6

   This section describes the new registration procedures and the
   assignments for the "Sub-TLVs for TLV Type 6" [IANA-Sub-6]
   subregistry that are based on them.

   *  [RFC8611] was published after [RFC8126] and uses the new
      terminology, e.g., "Private Use".  The code points registration
      procedure "Private Use" has been replaced by the "First Come First
      Served" code point registration procedure.

   *  Two small sets, four code points each, have been created for
      Experimental Use.

   *  Code points that are reserved are clearly marked as such.

   *  The assignments have been updated to match the new registration
      procedures.

   *  The notes related to the registration procedures have been changed
      to reflect whether or not a response is required if a sub-TLV is
      not recognized.

   The registration procedures for the "Sub-TLVs for TLV Type 6"
   [IANA-Sub-6] subregistry after the changes listed above are shown in
   the table below:

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

       Table 13: Registration Procedures for Sub-TLVs for TLV Type 6

    +=============+==============+===========+=======================+
    | Sub-Type    | Sub-TLV Name | Reference | Comment               |
    +=============+==============+===========+=======================+
    | 0           | Reserved     | This      |                       |
    |             |              | document, |                       |
    |             |              | [RFC8611] |                       |
    +-------------+--------------+-----------+-----------------------+
    | 1-2         | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 3-31739     | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 31740-31743 | Reserved for | This      | Not to be assigned.   |
    |             | Experimental | document  | This range is for     |
    |             | Use          |           | sub-TLVs that require |
    |             |              |           | an error message if   |
    |             |              |           | not recognized.  This |
    |             |              |           | document, Section 3.1 |
    +-------------+--------------+-----------+-----------------------+
    | 31744-64507 | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 64508-64511 | Reserved for | This      | Not to be assigned.   |
    |             | Experimental | document  | This range is for     |
    |             | Use          |           | sub-TLVs that can be  |
    |             |              |           | silently dropped if   |
    |             |              |           | not recognized.       |
    +-------------+--------------+-----------+-----------------------+
    | 64512-65535 | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+

              Table 14: Sub-TLVs for TLV Type 6 Assignments

6.2.4.  Updates to the Registry for Sub-TLVs for TLV Type 11

   This section describes the new registration procedures and the
   assignments for the "Sub-TLVs for TLV Type 11" [IANA-Sub-11]
   subregistry that are based on them.

   *  The "Specification Required" registration procedure has been
      changed to "RFC Required", and the comment "Experimental RFC
      Required" has been removed.

   *  The code points registration procedure "Vendor Private Use" has
      been removed and replaced with "First Come First Served" code
      points.

   *  Two small sets, four code points each, have been created for
      Experimental Use.

   *  Code points that are reserved are clearly marked as such.

   *  The assignments have been updated to match the new registration
      procedures.

   *  The notes related to the registration procedures have been changed
      to reflect whether or not a response is required if a sub-TLV is
      not recognized.

   The registration procedures for the "Sub-TLVs for TLV Type 11"
   [IANA-Sub-11] subregistry after the changes listed above are shown in
   the table below:

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

       Table 15: Registration Procedures for Sub-TLVs for TLV Type 11

    +=============+==============+===========+=======================+
    | Sub-Type    | Sub-TLV Name | Reference | Comment               |
    +=============+==============+===========+=======================+
    | 0           | Reserved     | This      |                       |
    |             |              | document  |                       |
    +-------------+--------------+-----------+-----------------------+
    | 1-4         | EQ           | EQ        | EQ                    |
    +-------------+--------------+-----------+-----------------------+
    | 5-31739     | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 31740-31743 | Reserved for | This      | Not to be assigned.   |
    |             | Experimental | document  | This range is for     |
    |             | Use          |           | sub-TLVs that require |
    |             |              |           | an error message if   |
    |             |              |           | not recognized.  This |
    |             |              |           | document, Section 3.1 |
    +-------------+--------------+-----------+-----------------------+
    | 31744-64507 | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+
    | 64508-64511 | Reserved for | This      | Not to be assigned.   |
    |             | Experimental | document  | This range is for     |
    |             | Use          |           | sub-TLVs that can be  |
    |             |              |           | silently dropped if   |
    |             |              |           | not recognized.       |
    +-------------+--------------+-----------+-----------------------+
    | 64512-65535 | Unassigned   |           |                       |
    +-------------+--------------+-----------+-----------------------+

              Table 16: Sub-TLVs for TLV Type 11 Assignments

6.2.5.  Updates to the Registry for Sub-TLVs for TLV Type 20

   This section describes the new registration procedures and the
   assignments for the "Sub-TLVs for TLV Type 20" [IANA-Sub-20]
   subregistry that are based on them.

   *  The "Specification Required" registration procedure has been
      changed to "RFC Required", and the comment "Experimental RFC
      Required" has been removed.

   *  The code points registration procedure "Vendor Private Use" has
      been removed and replaced with "First Come First Served" code
      points.

   *  Two small sets, four code points each, have been created for
      Experimental Use.

   *  Code points that are reserved are clearly marked as such.

   *  The assignments have been updated to match the new registration
      procedures.

   *  The notes related to the registration procedures have been changed
      to reflect whether or not a response is required if a sub-TLV is
      not recognized.

   The registration procedures for the "Sub-TLVs for TLV Type 20"
   [IANA-Sub-20] subregistry after the changes listed above are shown in
   the table below:

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

       Table 17: Registration Procedures for Sub-TLVs for TLV Type 20

    +=============+==============+===========+========================+
    | Sub-Type    | Sub-TLV Name | Reference | Comment                |
    +=============+==============+===========+========================+
    | 0           | Reserved     | This      |                        |
    |             |              | document  |                        |
    +-------------+--------------+-----------+------------------------+
    | 1-5         | EQ           | EQ        | EQ                     |
    +-------------+--------------+-----------+------------------------+
    | 6-31739     | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 31740-31743 | Reserved for | This      | Not to be assigned.    |
    |             | Experimental | document  | This range is for sub- |
    |             | Use          |           | TLVs that require an   |
    |             |              |           | error message if not   |
    |             |              |           | recognized.  This      |
    |             |              |           | document, Section 3.1] |
    +-------------+--------------+-----------+------------------------+
    | 31744-64507 | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 64508-64511 | Reserved for | This      | Not to be assigned.    |
    |             | Experimental | document  | This range is for sub- |
    |             | Use          |           | TLVs that can be       |
    |             |              |           | silently dropped if    |
    |             |              |           | not recognized.        |
    +-------------+--------------+-----------+------------------------+
    | 64512-65535 | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+

               Table 18: Sub-TLVs for TLV Type 20 Assignments

6.2.6.  Updates to the Registry for Sub-TLVs for TLV Type 23

   This section describes the new registration procedures and the
   assignments for the "Sub-TLVs for TLV Type 23" [IANA-Sub-23]
   subregistry that are based on them.

   *  The "Specification Required" registration procedure has been
      changed to "RFC Required", and the comment "Experimental RFC
      Required" has been removed.

   *  The code points registration procedure "Vendor Private Use" has
      been removed and replaced with "First Come First Served" code
      points.

   *  Two small sets, four code points each, have been created for
      Experimental Use.

   *  Code points that are reserved are clearly marked as such.

   *  The assignments have been updated to match the new registration
      procedures.

   *  The notes related to the registration procedures have been changed
      to reflect whether or not a response is required if a sub-TLV is
      not recognized.

   The registration procedures for the "Sub-TLVs for TLV Type 23"
   [IANA-Sub-23] subregistry after the changes listed above are shown in
   the table below:

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

       Table 19: Registration Procedures for Sub-TLVs for TLV Type 23

    +=============+==============+===========+========================+
    | Sub-Type    | Sub-TLV Name | Reference | Comment                |
    +=============+==============+===========+========================+
    | 0           | Reserved     | [RFC7555] |                        |
    +-------------+--------------+-----------+------------------------+
    | 1           | EQ           | EQ        | EQ                     |
    +-------------+--------------+-----------+------------------------+
    | 2-31739     | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 31740-31743 | Reserved for | This      | Not to be assigned.    |
    |             | Experimental | document  | This range is for sub- |
    |             | Use          |           | TLVs that require an   |
    |             |              |           | error message if not   |
    |             |              |           | recognized.  This      |
    |             |              |           | document, Section 3.1] |
    +-------------+--------------+-----------+------------------------+
    | 31744-64507 | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 64508-64511 | Reserved for | This      | Not to be assigned.    |
    |             | Experimental | document  | This range is for sub- |
    |             | Use          |           | TLVs that can be       |
    |             |              |           | silently dropped if    |
    |             |              |           | not recognized.        |
    +-------------+--------------+-----------+------------------------+
    | 64512-65535 | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+

               Table 20: Sub-TLVs for TLV Type 23 Assignments

6.2.7.  Updates to the Registry for Sub-TLVs for TLV Type 27

   This section describes the new registration procedures and the
   assignments for the "Sub-TLVs for TLV Type 27" [IANA-Sub-27]
   subregistry that are based on them.

   *  The "Specification Required" registration procedure has been
      changed to "RFC Required", and the comment "Experimental RFC
      Required" has been removed.

   *  The code points registration procedure "Vendor Private Use" has
      been removed and replaced with "First Come First Served" code
      points.

   *  Two small sets, four code points each, have been created for
      Experimental Use.

   *  Code points that are reserved are clearly marked as such.

   *  The assignments have been updated to match the new registration
      procedures.

   *  The notes related to the registration procedures have been changed
      to reflect whether or not a response is required if a sub-TLV is
      not recognized.

   The registration procedures for the "Sub-TLVs for TLV Type 27"
   [IANA-Sub-27] subregistry after the changes listed above are shown in
   the table below:

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

       Table 21: Registration Procedures for Sub-TLVs for TLV Type 27

    +=============+==============+===========+========================+
    | Sub-Type    | Sub-TLV Name | Reference | Comment                |
    +=============+==============+===========+========================+
    | 0           | Reserved     | [RFC7759] |                        |
    +-------------+--------------+-----------+------------------------+
    | 1-99        | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 100-104     | EQ           | EQ        | EQ                     |
    +-------------+--------------+-----------+------------------------+
    | 105-199     | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 200-202     | EQ           | EQ        | EQ                     |
    +-------------+--------------+-----------+------------------------+
    | 203-299     | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 300         | EQ           | EQ        | EQ                     |
    +-------------+--------------+-----------+------------------------+
    | 301-399     | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 400         | EQ           | EQ        | EQ                     |
    +-------------+--------------+-----------+------------------------+
    | 401-31739   | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 31740-31743 | Reserved for | This      | Not to be assigned.    |
    |             | Experimental | document  | This range is for sub- |
    |             | Use          |           | TLVs that require an   |
    |             |              |           | error message if not   |
    |             |              |           | recognized.  This      |
    |             |              |           | document, Section 3.1] |
    +-------------+--------------+-----------+------------------------+
    | 31744-64507 | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+
    | 64508-64511 | Reserved for | This      | Not to be assigned.    |
    |             | Experimental | document  | This range is for sub- |
    |             | Use          |           | TLVs that can be       |
    |             |              |           | silently dropped if    |
    |             |              |           | not recognized.        |
    +-------------+--------------+-----------+------------------------+
    | 64512-65535 | Unassigned   |           |                        |
    +-------------+--------------+-----------+------------------------+

               Table 22: Sub-TLVs for TLV Type 27 Assignments

7.  References

7.1.  Normative References

   [IANA-LSP-PING]
              IANA, "Multiprotocol Label Switching (MPLS) Label Switched
              Paths (LSPs) Ping Parameters",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters>.

   [IANA-MT]  IANA, "Message Types", <https://www.iana.org/assignments/
              mpls-lsp-ping-parameters/>.

   [IANA-RC]  IANA, "Return Codes", <https://www.iana.org/assignments/
              mpls-lsp-ping-parameters/>.

   [IANA-RM]  IANA, "Reply Modes", <https://www.iana.org/assignments/
              mpls-lsp-ping-parameters/>.

   [IANA-Sub-1-16-21]
              IANA, "Sub-TLVs for TLV Types 1, 16, and 21",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters/>.

   [IANA-Sub-11]
              IANA, "Sub-TLVs for TLV Type 11",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters/>.

   [IANA-Sub-20]
              IANA, "Sub-TLVs for TLV Type 20",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters/>.

   [IANA-Sub-23]
              IANA, "Sub-TLVs for TLV Type 23",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters/>.

   [IANA-Sub-27]
              IANA, "Sub-TLVs for TLV Type 27",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters/>.

   [IANA-Sub-6]
              IANA, "Sub-TLVs for TLV Type 6",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters/>.

   [IANA-TLV-reg]
              IANA, "TLVs", <https://www.iana.org/assignments/mpls-lsp-
              ping-parameters/>.

   [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>.

   [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>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [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>.

   [RFC8611]  Akiya, N., Swallow, G., Litkowski, S., Decraene, B.,
              Drake, J., and M. Chen, "Label Switched Path (LSP) Ping
              and Traceroute Multipath Support for Link Aggregation
              Group (LAG) Interfaces", RFC 8611, DOI 10.17487/RFC8611,
              June 2019, <https://www.rfc-editor.org/info/rfc8611>.

7.2.  Informative References

   [IANA-Sub-9]
              IANA, "Sub-TLVs for TLV Type 9",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters/>.

   [lsp-ping-Namespace]
              IANA, "Multiprotocol Label Switching (MPLS) Label Switched
              Paths (LSPs) Ping Parameters",
              <https://www.iana.org/assignments/mpls-lsp-ping-
              parameters/>.

   [RFC7110]  Chen, M., Cao, W., Ning, S., Jounay, F., and S. Delord,
              "Return Path Specified Label Switched Path (LSP) Ping",
              RFC 7110, DOI 10.17487/RFC7110, January 2014,
              <https://www.rfc-editor.org/info/rfc7110>.

   [RFC7555]  Swallow, G., Lim, V., and S. Aldrin, "Proxy MPLS Echo
              Request", RFC 7555, DOI 10.17487/RFC7555, June 2015,
              <https://www.rfc-editor.org/info/rfc7555>.

   [RFC7743]  Luo, J., Ed., Jin, L., Ed., Nadeau, T., Ed., and G.
              Swallow, Ed., "Relayed Echo Reply Mechanism for Label
              Switched Path (LSP) Ping", RFC 7743, DOI 10.17487/RFC7743,
              January 2016, <https://www.rfc-editor.org/info/rfc7743>.

   [RFC7759]  Bellagamba, E., Mirsky, G., Andersson, L., Skoldstrom, P.,
              Ward, D., and J. Drake, "Configuration of Proactive
              Operations, Administration, and Maintenance (OAM)
              Functions for MPLS-Based Transport Networks Using Label
              Switched Path (LSP) Ping", RFC 7759, DOI 10.17487/RFC7759,
              February 2016, <https://www.rfc-editor.org/info/rfc7759>.

   [RFC8287]  Kumar, N., Ed., Pignataro, C., Ed., Swallow, G., Akiya,
              N., Kini, S., and M. Chen, "Label Switched Path (LSP)
              Ping/Traceroute for Segment Routing (SR) IGP-Prefix and
              IGP-Adjacency Segment Identifiers (SIDs) with MPLS Data
              Planes", RFC 8287, DOI 10.17487/RFC8287, December 2017,
              <https://www.rfc-editor.org/info/rfc8287>.

Acknowledgements

   The authors wish to thank Adrian Farrel, who both made very useful
   comments and agreed to serve as the Document Shepherd.

   The authors also wish to thank Michelle Cotton and Amanda Baber, who
   very patiently worked with us to determine how our registries could
   and should be updated.

   The authors thank Donald Eastlake 3rd and Tom Petch for their careful
   and detailed review.

Authors' Addresses

   Loa Andersson
   Bronze Dragon Consulting

   Email: loa@pi.nu


   Mach(Guoyi) Chen
   Huawei Technologies

   Email: mach.chen@huawei.com


   Carlos Pignataro
   Cisco Systems

   Email: cpignata@cisco.com


   Tarek Saad
   Juniper Networks

   Email: tsaad@juniper.net