6MAN                                                              Y. Liu
Internet-Draft                                                       ZTE
Updates: 4884 (if approved)                                       Y. Liu
Intended status: Standards Track                            China Mobile
Expires: 30 March 2025                                 26 September 2024


        Extending ICMPv6 for SRv6-related Information Validation
                  draft-liu-6man-icmp-verification-06

Abstract

   This document introduces the mechanism to verify the data plane
   against the control plane and detect data plane failures in IPv6/SRv6
   networks by extending ICMPv6 messages.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 30 March 2025.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  ICMPv6 Validation Request . . . . . . . . . . . . . . . . . .   4
     2.1.  Validation Information Object . . . . . . . . . . . . . .   5
   3.  ICMPv6 Validation Reply . . . . . . . . . . . . . . . . . . .   6
   4.  ICMPv6 Validation Message Processing  . . . . . . . . . . . .   7
     4.1.  Sending a Validation Request  . . . . . . . . . . . . . .   7
     4.2.  Receiving a Validation Request  . . . . . . . . . . . . .   7
     4.3.  Sending a Validation Reply  . . . . . . . . . . . . . . .   8
       4.3.1.  Return Code . . . . . . . . . . . . . . . . . . . . .   9
     4.4.  Receiving a Validation Reply  . . . . . . . . . . . . . .   9
   5.  Updates to RFC 4884 . . . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .  10
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   An SR-MPLS SID/MPLS label can be related with various FEC
   information, e.g, VPN IP prefix [RFC4365], EVPN service information
   [RFC7432], flex algorithms[RFC9350] and etc.  Most of these
   information would be advertised via control plane protocols(e.g, IGP,
   BGP, etc).

   Procedures for simple and efficient mechanisms to verify the data
   plane against the control plane using LSP Ping in MPLS network are
   well defined in [RFC8029].  Normally, when a new feature is
   introduced and the MPLS label is associated with new information, the
   LSP Ping mechanism is still applicable by defining new FEC sub-TLV
   with the new information encoded in it.

   [RFC9489] defines procedures to detect data plane failures using LSP
   Ping in MPLS networks deploying EVPN.  Figure 1 is an unicast data
   plane connectivity check scenario provided in [RFC9489].  CE1 is
   dual-homed to PE1 and PE2, PE1 and PE2 both announced a MAC route for
   CE1 with the same C-MAC but different RDs.  On PE3, when an operator
   performs a connectivity check for the C-MAC address on PE1, the
   operator initiates an LSP Ping request with the Target FEC Stack TLV
   containing the C-MAC address, the corresponding RD and other
   necessary fields in the packet.  The egress PE will process the
   packet and perform checks for the EVPN-related information carried in
   Target FEC Stack TLV.



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                            +------------------+
                            |                  |
                            |                  |
          +----+      +-----+                  +-----+     +----+
          | CE1|------|     |                  | PE3 |-----| CE2|
          +----+\     | PE1 |   MPLS/SRv6      |     |     +----+
                 \    +-----+     Network      +-----+
                  \         |                  |
                   \  +-----+                  |
                    \ |     |                  |
                     \| PE2 |                  |
                      +-----+                  |
                            |                  |
                            +------------------+

                       <-----EVPN over MPLS/SRv6----->



                           Figure 1: EVPN Network

   For VPN/EVPN services over SRv6 as in [RFC9252], the requirements to
   detect data plane failures are similar.  Besides VPN/EVPN
   information, IPv6 addresses(mainly SRv6 SID), can be related with
   other information/functions such as flex algorithm [RFC9350]
   [RFC9502], SRv6 endpoint behaviors [RFC8986], service functions
   [I-D.ietf-spring-sr-service-programming] and so on.  Operators may
   want to validate these information as well.  But there's no such
   mechanism in IPv6/SRv6 yet.

   RFC9259 describes how the existing ICMPv6 mechanisms for ping and
   traceroute can be used in an SRv6 network for data plane connectivity
   check purpose.This document introduces the mechanism to verify the
   data plane against the control plane and detect data plane failures
   in IPv6/SRv6 networks by extending ICMPv6 messages.

   Editor's Note: Instead of extending ICMPv6 Node Information Query (or
   NI Query) and the Node Information Reply (or NI Reply) based on
   [RFC4620], this document introducing ICMPv6 Validation Request and
   ICMPv6 Validation Reply messages by defining two new types of ICMPv6
   messages taking example from [RFC8335].  The reason is that NI Query
   and NI Reply are originally defined for discovering information about
   nodes, such as names and addresses, while this document aims to
   provide an IP-related information validation mechanism, which makes
   RFC4620 not quite suitable.






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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.

2.  ICMPv6 Validation Request

   The Validation Request message is defined for ICMPv6[RFC4443].  Like
   any ICMPv6 message, the ICMPv6 Validation Request message is
   encapsulated in an IPv6 header.

   The structure of ICMPv6 Validation Request is shown in Figure 2,
   where:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Type      |     Code      |          Checksum             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Identifier          |Sequence Number|   Reserved    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       .                                                               .
       .                  ICMP Extension Structure                     .
       .                                                               .
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                      Figure 2: Validation Request

   *  Type: The value is TBD1.

   *  Code: MUST be set to 0 and MUST be ignored upon receipt.

   *  Checksum: For ICMPv6, see [RFC4443].

   *  Identifier: An Identifier to aid in matching Validation Replies to
      Validation Requests.  May be zero.

   *  Sequence Number: A Sequence Number to aid in matching Validation
      Replies to Validation Requests.  May be zero.

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






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   *  ICMP Extension Structure: The ICMP Extension Structure carries the
      information that needs to be verified.  Section 7 of [RFC4884]
      defines the ICMP Extension Structure.  As per [RFC4884], the
      Extension Structure contains one Extension Header followed by one
      or more objects.  When applied to the ICMP Validation Request
      message, the ICMP Extension Structure MUST only contain one or
      more instance of the Validation Information Objects as defined in
      section 2.1.

2.1.  Validation Information Object

   The Validation Information Object is shown in Figure 3, where:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Length                |   Class-Num   |   C-Type      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |                   // (Object payload) //                      |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                  Figure 3: Validation Information Object

   *  Length: Length of the object, measured in octets, including the
      Object Header and Object Payload.

   *  Class-Num: Validation Information Object.  The value is TBD2.

   *  Object payload: Variable-length field.  C-Type-specific data.

   *  C-Type: For this object, the C-Type is used to indicate the type
      of the information that needs to be verified.  This document only
      defines the C-Type value 0 as shown below:

                        C-Type           Object Payload
                       --------           -----------
                             0           Revsered











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   It should be noticed that this document only defines fundamental
   packet formats and processing rules, the detailed C-Type values and
   the corresponding information carried in object payload is out of the
   scope of the document and would be defined in separate documents.
   For example, [I-D.liu-bess-srv6-evpn-validation] provides solutions
   to detect data plane failures for EVPN over SRv6 leveraging the
   mechanism defined in this document.

3.  ICMPv6 Validation Reply

   The Validation Reply message is defined for ICMPv6.  Like any other
   ICMPv6 messages, the ICMP Extended Echo Reply message is encapsulated
   in an IPv6 header.  Figure 4 describes the ICMPv6 Validation Reply
   message.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Type      |     Code      |          Checksum             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           Identifier          |Sequence Number|   Reserved    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 4: Validation Reply

   ICMP fields:

   *  Type: Validation Reply.  The value is TBD3.

   *  Code: Values are

      (0) Validation passed

      (1) Malformed request received

      (2) One or more of the objects were not understood

      (3) Information mismatch

   *  Checksum: For ICMPv6, see [RFC4443].

   *  Identifier: Copied from the Identifier field of the invoking
      Validation Request packet.

   *  Sequence Number: Copied from the Sequence Number field of the
      invoking Validation Request packet.





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4.  ICMPv6 Validation Message Processing

4.1.  Sending a Validation Request

   A node that originates an ICMPv6 validation request message SHOULD
   first determine which IPv6 address/SRv6 SID needs to be verified with
   what information.  How the sender node get the information is out of
   scope of the document.

   An ICMPv6 validation request contains one or more Validation
   Information objects, depending on how the user wants to do the
   validation.  For example, an SRv6 service SID is related with an
   endpoint behavior and an IPv4 VPN prefix, if one wants to verify both
   information of the SID via one request message, an ICMPv6 validation
   request is sent with two validation information objects in it.  Or
   one may choose to send two individual ICMPv6 validation requests,
   each carries one validation information object to verify these two
   information separately.

   The target IP is the IP address/SRv6 SID to be verified and MUST be a
   unicast address.  The ICMPv6 validation request is sent with the
   target IP address/SRv6 SID set as the destination address of the IP
   header field without SRH for the SRv6 best-effort connectivity case,
   or set as the last segment with SRH.  The Source Address of the
   ICMPv6 packet MUST be a unicast address belonging to the node.

   The Hop Limit SHOULD be set to 255 to prevent transit nodes from
   processing the validation request.

4.2.  Receiving a Validation Request

   All transit nodes process the validation request message like any
   other IPv6 data packets and hence do not require any change.

   As specified in [RFC4443], if a router receives a packet with a Hop
   Limit of zero, or if a router decrements a packet's Hop Limit to
   zero, it MUST discard the packet and originate an ICMPv6 Time
   Exceeded message with Code 0 to the source of the packet.  The source
   address SHOULD be set as a local address of the router.

   The target node is a node receiving an validation request where the
   target IP of that message is locally configured as a segment or local
   interface.

   When the validation request packet arrives at the target node, and
   any of the following conditions apply, the node MUST silently discard
   the incoming message:




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   *  The node does not recognize ICMP Validation Request messages.

   *  The node has not explicitly enabled ICMP Validation functionality.

   *  The incoming ICMP Validation Request carries a Source Address that
      is not explicitly authorized for the incoming ICMP Validation
      Request type.

   *  The Source Address of the incoming message is not a unicast
      address.

   *  The Destination Address of the incoming message is not a unicast
      address.

   Otherwise, if the packet is well formed, the target node verifies the
   information encoded in the Validation Information Object against the
   corresponding local information and state.

4.3.  Sending a Validation Reply

   When a node receives an ICMPv6 Validation Request, it MUST format an
   ICMPv6 Validation Reply as follows:

   *  Copy the Source Address from the Validation Request message to the
      Destination Address of the Validation Reply.

   *  Copy the Destination Address from the Validation Request message
      to the Source Address of the Validation Reply.

   *  Set the Hop Limit to 255

   *  Set the Next Header to ICMPv6.

   *  Set the DiffServ codepoint to CS0 [RFC4594].

   *  Set the ICMP Type to Validation Reply.

   *  Copy the Identifier from the Validation Request message to the
      Validation Reply.

   *  Copy the Sequence Number from the Validation Request message to
      the Validation Reply.

   *  Set the Code field as described in Section 4.3.1

   *  Set the Checksum appropriately.

   *  Forward the ICMP Validation Reply to its destination.



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4.3.1.  Return Code

   The Code field MUST be set to 0 if all the the information encoded in
   the Validation Information Object is consistent with the the
   corresponding local information on the target node.

   The Code field MUST be set to 1 if any of the following conditions
   apply:

   *  The ICMP Request does not include an ICMP Extension Structure.

   *  The ICMP Extension Structure does not only include the Validation
      Information Object(s).

   *  The query is otherwise malformed.

   The Code field MUST be set to 2 if one or more of the objects are not
   understood by the node.

   The Code field MUST be set to 3 if the information in the Validation
   Information Object(s) is not consistent with the local information
   and validation is not passed.

4.4.  Receiving a Validation Reply

   A node should only receive a validation reply in response to a
   validation request that it sent.  Thus, on receipt of a validation
   reply, the node should parse the packet to ensure that it is well-
   formed, then attempt to match up the validation reply with a
   validation request that it had previously sent, using the Identifier
   and Sequence Number.  If no match is found, the node ignores the echo
   reply.

5.  Updates to RFC 4884

   Section 4.6 of [RFC4884] provides a list of extensible ICMP messages
   (i.e., messages that can carry the ICMP Extension Structure).  This
   document adds the ICMPv6 Validation Request message and the ICMPv6
   Validation Reply message to that list.

6.  IANA Considerations

   This document requests the following actions from IANA:

   *  Add an entry to the "ICMPv6 "type" Numbers" registry, representing
      the Validation Request.  This entry has one code 0.





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   *  Add an entry to the "ICMPv6 "type" Numbers" registry, representing
      the Validation Reply.  This entry has the following codes:

      (0) Validation passed

      (1) Malformed request received

      (2) One or more of the objects were not understood

      (3) Information mismatch

   *  Add an entry to the "ICMP Extension Object Classes and Class Sub-
      types" registry, representing the Validation Information Object
      with C-types:

      (0) Reserved

      C-Type values are assignable on a first-come-first-serve (FCFS)
      basis with a range of 0-255.

   All codes mentioned above are assigned on a First Come First Serve
   (FCFS) basis with a range of 0-255.

7.  Security Considerations

   Security considerations discussed in [RFC4443] and[RFC4884] apply to
   this document.

   To protect against unauthorized sources using validation request
   messages to obtain network information, it is RECOMMENDED that
   implementations provide a means of checking the source addresses of
   validation request messages against an access list before accepting
   the message.

   The validation mechanism SHOULD be only used in the limited domain.
   The validation request contains the control plane information,
   policies should be implemented on the edge devices of the domain to
   prevent the information from being leaked into other domains.

   In order to protect local resources, implementations SHOULD rate-
   limit incoming ICMP Request messages.


8.  Acknowledgement

   The authors would like to thank Greg Mirsky, Bruno Decraene, Matthew
   Bocci, Zafar Ali, Ali Sajassi and Jorge Rabadan for their comments
   and suggestions.



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9.  References

9.1.  Normative References

   [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>.

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

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

   [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>.

   [RFC8986]  Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
              D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
              (SRv6) Network Programming", RFC 8986,
              DOI 10.17487/RFC8986, February 2021,
              <https://www.rfc-editor.org/info/rfc8986>.

9.2.  Informative References

   [I-D.ietf-spring-sr-service-programming]
              Clad, F., Xu, X., Filsfils, C., Bernier, D., Li, C.,
              Decraene, B., Ma, S., Yadlapalli, C., Henderickx, W., and
              S. Salsano, "Service Programming with Segment Routing",
              Work in Progress, Internet-Draft, draft-ietf-spring-sr-
              service-programming-10, 23 August 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-spring-
              sr-service-programming-10>.

   [I-D.liu-bess-srv6-evpn-validation]
              Liu, Y., "Data Plane Failure Detection Mechanisms for EVPN
              over SRv6", Work in Progress, Internet-Draft, draft-liu-
              bess-srv6-evpn-validation-01, 2 August 2024,
              <https://datatracker.ietf.org/doc/html/draft-liu-bess-
              srv6-evpn-validation-01>.




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   [RFC4365]  Rosen, E., "Applicability Statement for BGP/MPLS IP
              Virtual Private Networks (VPNs)", RFC 4365,
              DOI 10.17487/RFC4365, February 2006,
              <https://www.rfc-editor.org/info/rfc4365>.

   [RFC4594]  Babiarz, J., Chan, K., and F. Baker, "Configuration
              Guidelines for DiffServ Service Classes", RFC 4594,
              DOI 10.17487/RFC4594, August 2006,
              <https://www.rfc-editor.org/info/rfc4594>.

   [RFC4620]  Crawford, M. and B. Haberman, Ed., "IPv6 Node Information
              Queries", RFC 4620, DOI 10.17487/RFC4620, August 2006,
              <https://www.rfc-editor.org/info/rfc4620>.

   [RFC5036]  Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
              "LDP Specification", RFC 5036, DOI 10.17487/RFC5036,
              October 2007, <https://www.rfc-editor.org/info/rfc5036>.

   [RFC7432]  Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
              Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
              Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
              2015, <https://www.rfc-editor.org/info/rfc7432>.

   [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>.

   [RFC8335]  Bonica, R., Thomas, R., Linkova, J., Lenart, C., and M.
              Boucadair, "PROBE: A Utility for Probing Interfaces",
              RFC 8335, DOI 10.17487/RFC8335, February 2018,
              <https://www.rfc-editor.org/info/rfc8335>.

   [RFC9252]  Dawra, G., Ed., Talaulikar, K., Ed., Raszuk, R., Decraene,
              B., Zhuang, S., and J. Rabadan, "BGP Overlay Services
              Based on Segment Routing over IPv6 (SRv6)", RFC 9252,
              DOI 10.17487/RFC9252, July 2022,
              <https://www.rfc-editor.org/info/rfc9252>.

   [RFC9350]  Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K.,
              and A. Gulko, "IGP Flexible Algorithm", RFC 9350,
              DOI 10.17487/RFC9350, February 2023,
              <https://www.rfc-editor.org/info/rfc9350>.







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   [RFC9489]  Jain, P., Sajassi, A., Salam, S., Boutros, S., and G.
              Mirsky, "Label Switched Path (LSP) Ping Mechanisms for
              EVPN and Provider Backbone Bridging EVPN (PBB-EVPN)",
              RFC 9489, DOI 10.17487/RFC9489, November 2023,
              <https://www.rfc-editor.org/info/rfc9489>.

   [RFC9502]  Britto, W., Hegde, S., Kaneriya, P., Shetty, R., Bonica,
              R., and P. Psenak, "IGP Flexible Algorithm in IP
              Networks", RFC 9502, DOI 10.17487/RFC9502, November 2023,
              <https://www.rfc-editor.org/info/rfc9502>.

Authors' Addresses

   Yao Liu
   ZTE
   Nanjing
   China
   Email: liu.yao71@zte.com.cn


   Yisong Liu
   China Mobile
   China
   Email: liuyisong@chinamobile.com



























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