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Multicast On-path Telemetry using IOAM
draft-ietf-mboned-multicast-telemetry-08

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This is an older version of an Internet-Draft whose latest revision state is "Active".
Authors Haoyu Song , Mike McBride , Greg Mirsky , Gyan Mishra , Hitoshi Asaeda , Tianran Zhou
Last updated 2023-12-04 (Latest revision 2023-10-06)
Replaces draft-song-multicast-telemetry
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draft-ietf-mboned-multicast-telemetry-08
MBONED                                                           H. Song
Internet-Draft                                                M. McBride
Intended status: Standards Track                  Futurewei Technologies
Expires: 8 April 2024                                          G. Mirsky
                                                                Ericsson
                                                               G. Mishra
                                                            Verizon Inc.
                                                               H. Asaeda
                                                                    NICT
                                                                 T. Zhou
                                                     Huawei Technologies
                                                          6 October 2023

                 Multicast On-path Telemetry using IOAM
                draft-ietf-mboned-multicast-telemetry-08

Abstract

   This document specifies the requirements of on-path telemetry for
   multicast traffic using In-situ OAM.  While In-situ OAM is
   advantageous for multicast traffic telemetry, some unique challenges
   are present.  This document provides the solutions based on the In-
   situ OAM trace option and direct export option to support the
   telemetry data correlation and the multicast tree reconstruction
   without incurring data redundancy.

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.

Status of This Memo

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

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

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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 8 April 2024.

Copyright Notice

   Copyright (c) 2023 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements for Multicast Traffic Telemetry  . . . . . . . .   4
   3.  Issues of Existing Techniques . . . . . . . . . . . . . . . .   4
   4.  Modifications to Existing Solutions . . . . . . . . . . . . .   5
     4.1.  Per-hop postcard using IOAM DEX . . . . . . . . . . . . .   5
     4.2.  Per-section postcard for IOAM Trace . . . . . . . . . . .   8
   5.  Application Considerations for Multicast Protocols  . . . . .   9
     5.1.  Mtrace verson 2 . . . . . . . . . . . . . . . . . . . . .   9
     5.2.  Application in PIM  . . . . . . . . . . . . . . . . . . .   9
     5.3.  Application of MVPN X-PMSI Tunnel Encapsulation
           Attribute . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.4.  Application in BIER . . . . . . . . . . . . . . . . . . .  10
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

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1.  Introduction

   Multicast has many use cases.  For example, it can be used by
   residential broadband customers across operator networks, private
   MPLS customers, and internal customers within corporate intranet.
   Multicast provides real time interactive online meetings or podcasts,
   IPTV, and financial markets real-time data, which all have a reliance
   on UDP's unreliable transport.  End-to-end QOS, therefore, should be
   a critical component of multicast deployment in order to provide a
   good end user experience.  In multicast real-time media streaming,
   loss of a single packet containing a reference frame can result in
   the inability of thousands of receivers to decode a whole sequence of
   packets called Group-of-Picture, introducing black picture for
   periods of a few seconds.  Unexpected long delay in propagation of a
   packet in such real-time media streaming may equally result in the
   packet not being received and create the same results.  Multicast
   packet drops and delay can therefore severely affect the application
   performance and user experience.

   It is important to monitor the performance of the multicast traffic.
   New on-path telemetry techniques such as In-situ OAM (IOAM)
   [RFC9197], IOAM Direct Export (DEX) [RFC9326] IOAM Marking-based
   Postcard (PBT-M) [I-D.song-ippm-postcard-based-telemetry], and Hybrid
   Two-Step (HTS) [I-D.ietf-ippm-hybrid-two-step] are useful and
   complementary to the existing active OAM performance monitoring
   methods (e.g., ICMP ping [RFC0792]), provide promising means to
   directly monitor the network experience of multicast traffic.
   However, multicast traffic has some unique characteristics which pose
   some challenges on applying such techniques in an efficient way.

   The IP multicast packet data for a particular (S, G) state is
   identical from one branch to another on its way to multiple
   receivers.  When adding IOAM trace data to multicast packets, each
   replicated packet would keep the telemetry data for its entire
   forwarding path.  Since the replicated packets all share common path
   segments, redundant data will be collected for the same original
   multicast packet.  Such redundancy consumes extra network bandwidth
   unnecessarily.  For a large multicast tree, such redundancy is
   considerable.  Alternatively, it could be more efficient to collect
   the telemetry data using solutions such as IOAM DEX to eliminate the
   data redundancy.  However, IOAM DEX lacks a branch identifier, making
   telemetry data correlation and multicast-tree reconstruction
   difficult.

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   This draft provides two solutions to the IOAM data redundancy problem
   based on the IOAM standards.  The requirements for multicast traffic
   telemetry are discussed along with the issues of the existing on-path
   telemetry techniques.  We propose modifications to make these
   techniques adapt to multicast in order for the original multicast
   tree to be correctly reconstructed while eliminating redundant data.

2.  Requirements for Multicast Traffic Telemetry

   Multicast traffic is forwarded through a multicast tree.  With PIM
   and P2MP, the forwarding tree is established and maintained by the
   multicast routing protocol.  With BIER, no state is created in the
   network to establish a forwarding tree; instead, a bier header
   provides the necessary information for each packet to know the egress
   points.  Multicast packets are only replicated at each tree branch
   fork node for efficiency.

   There are several requirements for multicast traffic telemetry, a few
   of which are:

   *  Reconstruct and visualize the multicast tree through data plane
      monitoring.

   *  Gather the multicast packet delay and jitter performance on each
      path.

   *  Find the multicast packet drop location and reason.

   *  Gather the VPN state and tunnel information in case of P2MP
      multicast.

   In order to meet these requirements, we need the ability to directly
   monitor the multicast traffic and derive data from the multicast
   packets.  The conventional OAM mechanisms, such as multicast ping
   [RFC6450] and trace [RFC8487], are not sufficient to meet these
   requirements.

3.  Issues of Existing Techniques

   On-path Telemetry techniques that directly retrieve data from
   multicast traffic's live network experience are ideal for addressing
   the aforementioned requirements.  The representative techniques
   include In-situ OAM (IOAM) Trace option [RFC9197], IOAM Direct Export
   (DEX) option [RFC9326], and PBT-M
   [I-D.song-ippm-postcard-based-telemetry].  However, unlike unicast,
   multicast poses some unique challenges to applying these techniques.

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   Multicast packets are replicated at each branch fork node in the
   corresponding multicast tree.  Therefore, there are multiple copies
   of the original multicast packet in the network.

   If the IOAM trace option is used for on-path data collection, the
   partial trace data will also be replicated into the packet copy for
   each branch.  The end result is that, at the multicast tree leaves,
   each copy of the multicast packet has a complete trace.  Most of the
   data (except data from the last leaf branch) appear in multiple
   copies while only one copy is sufficient.  Data redundancy introduces
   unnecessary header overhead, wastes network bandwidth, and
   complicates the data processing.  The larger the multicast tree, or
   the longer the multicast path, the more severe the redundancy problem
   becomes.

   The postcard-based solutions (e.g., IOAM DEX), can be used to
   eliminate such data redundancy, because each node on the tree only
   sends a postcard covering local data.  However, they cannot track and
   correlate the tree branches properly due to the lack of branching
   information, so they can bring confusion about the multicast tree
   topology.  For example, in a multicast tree, Node A has two branches,
   one to Node B and the other to node C; further, Node B leads to Node
   D and Node C leads to Node E.  When applying postcard-based methods,
   one cannot tell whether or not Node D(E) is the next hop of Node B(C)
   from the received postcards alone, unless one correlates the
   exporting nodes with knowledge about the tree collected by other
   means (e.g., mtrace).  Such correlation is undesirable because it
   introduces extra work and complexity.

   The fundamental reason for this problem is that there is not an
   identifier (either implicit or explicit) to correlate the data on
   each branch.

4.  Modifications to Existing Solutions

   We provide two solutions to address the above issues.  One is based
   on IOAM DEX and requires an extension to the instruction header of
   the IOAM DEX Option.  The second solution combines the IOAM trace
   option and postcards for redundancy removal.

4.1.  Per-hop postcard using IOAM DEX

   One way to mitigate the postcard-based telemetry's tree tracking
   weakness is to augment it with a branch identifier field.  Note that
   this works for the IOAM DEX option but not for PBT-M because the IOAM
   DEX option has an instruction header which can be used to hold the
   branch identifier.  To make the branch identifier globally unique,
   the branch fork node ID plus an index is used.  For example, Node A

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   has two branches: one to Node B and the other to Node C.  Node A will
   use [A, 0] as the branch identifier for the branch to B, and [A, 1]
   for the branch to C.  The identifier is carried with the multicast
   packet until the next branch fork node.  Each node MUST export the
   branch identifier in the received IOAM DEX header in the postcards it
   sends.  The branch identifier, along with the other fields such as
   flow ID and sequence number, is sufficient for the data collector to
   reconstruct the topology of the multicast tree.

   Figure 1 shows an example of this solution.  "P" stands for the
   postcard packet.  The square brackets contains the branch identifier.
   The curly brace contains the telemetry data about a specific node.

   P:[A,0]{A}  P:[A,0]{B} P:[B,1]{D}  P:[B,0]{C}   P:[B,0]{E}
        ^            ^          ^        ^           ^
        :            :          :        :           :
        :            :          :        :           :
        :            :          :      +-:-+       +-:-+
        :            :          :      |   |       |   |
        :            :      +---:----->| C |------>| E |-...
      +-:-+        +-:-+    |   :      |   |       |   |
      |   |        |   |----+   :      +---+       +---+
      | A |------->| B |        :
      |   |        |   |--+   +-:-+
      +---+        +---+  |   |   |
                          +-->| D |--...
                              |   |
                              +---+

                         Figure 1: Per-hop Postcard

   Each branch fork node needs to generate a unique branch identifier
   (i.e., branch ID) for each branch in its multicast tree instance and
   include it in the IOAM DEX option header.  The branch ID remains
   unchanged until the next branch fork node.  The branch ID contains
   two parts: the branch fork node ID and an interface index.

   Conforming to the node ID specification in IOAM [RFC9197], the node
   ID is a 3-octet unsigned integer.  The interface index is a two-octet
   unsigned integer.  As shown in Figure 2, the branch ID consumes 8
   octets in total.  The three unused octets MUST be set to 0.

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                 node_id                       |     unused    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Interface Index         |           unused              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 2: Multicast Branch ID format

   Figure 3 shows that the branch ID is carried as an optional field
   after the flow ID and sequence number optional fields in the IOAM DEX
   option header.  Two bits "N" and "I" (i.e., the third and fourth bits
   in the Extension-Flags field) are reserved to indicate the presence
   of the optional branch ID field.  "N" stands for the Node ID and "I"
   stands for the interface index.  If "N" and "I" are both set to 1,
   the optional multicast branch ID field is present; otherwise it is
   absent.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |        Namespace-ID           |     Flags     |F|S|N|I|E-Flags|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |               IOAM-Trace-Type                 |   Reserved    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                         Flow ID (optional)                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Sequence Number  (Optional)               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                         Multicast Branch ID                   |
    |                            (optional)                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 3: Carry Branch ID in IOAM DEX option header

   Once a node gets the branch ID information from the upstream, it MUST
   carry this information in its telemetry data export postcards, so the
   original multicast tree can be correctly reconstructed based on the
   postcards.

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4.2.  Per-section postcard for IOAM Trace

   The second solution is a combination of the IOAM trace option and the
   postcard-based telemetry.  To avoid data redundancy, at each branch
   fork node, the trace data accumulated up to this node is exported by
   a postcard before the packet is replicated.  In this solution, each
   branch also needs to maintain some identifier to help correlate the
   postcards for each tree section.  The natural way to accomplish this
   is to simply carry the branch fork node's data (including its ID) in
   the trace of each branch.  This is also necessary because each
   replicated multicast packet can have different telemetry data
   pertaining to this particular copy (e.g., node delay, egress
   timestamp, and egress interface).  As a consequence, the local data
   exported by each branch fork node can only contain partial data
   (e.g., ingress interface and ingress timestamp).

   Figure 4 shows an example in a segment of a multicast tree.  Node B
   and D are two branch fork nodes and they will export a postcard
   covering the trace data for the previous section.  The end node of
   each path will also need to export the data of the last section as a
   postcard.

                P:{A,B'}            P:{B1,C,D'}
                   ^                     ^
                   :                     :
                   :                     :
                   :                     :    {D1}
                   :                     :    +--...
                   :        +---+      +---+  |
                   :   {B1} |   |{B1,C}|   |--+ {D2}
                   :    +-->| C |----->| D |-----...
       +---+     +---+  |   |   |      |   |--+
       |   | {A} |   |--+   +---+      +---+  |
       | A |---->| B |                        +--...
       |   |     |   |--+   +---+             {D3}
       +---+     +---+  |   |   |{B2,E}
                        +-->| E |--...
                       {B2} |   |
                            +---+

                       Figure 4: Per-section Postcard

   There is no need to modify the IOAM trace option header format as
   specified in [RFC9197].  We just need to configure the branch fork
   nodes to export the postcards and refresh the IOAM header and data
   (e.g., clear the node data list and reset the Remaining Length
   field).

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5.  Application Considerations for Multicast Protocols

5.1.  Mtrace verson 2

   Mtrace version 2 (Mtrace2) [RFC8487] is a protocol that allows the
   tracing of an IP multicast routing path.  Mtrace2 provides additional
   information such as the packet rates and losses, as well as other
   diagnostic information.  Unlike unicast traceroute, Mtrace2 traces
   the path that the tree building messages follow from receiver to
   source.  It is usually initiated from an Mtrace2 client by sending an
   Mtrace2 Query to a Last-Hop Router (LHR) or to a Rendezvous Point
   (RP).  The LHR/RP turns the Query packet into an Mtrace2 Request,
   appends a Standard Response Block containing its interface addresses
   and packet statistics to the Request packet, and forwards the packet
   towards the source/RP.  In a similar fashion, each router along the
   path to the source/RP appends a Standard Response Block to the end of
   the Request packet and forwards it to its upstream router.  When the
   First-Hop Router (FHR) receives the Request packet, it appends its
   own Standard Response Block, turns the Request packet into a Reply,
   and unicasts the Reply back to the Mtrace2 client.

   New on-path telemetry techniques will enhance Mtrace2, and other
   existing OAM solutions, with more granular and realtime network
   status data through direct measurements.  There are various multicast
   protocols that are used to forward the multicast data.  Each will
   require their own unique on-path telemetry solution.  Mtrace2 doesn't
   integrate with IOAM directly, but network management systems may use
   Mtrace2 to learn about routers of interest.

5.2.  Application in PIM

   PIM-SM [RFC7761] is the most widely used multicast routing protocol
   deployed today.  PIM-SSM, however, is the preferred method due to its
   simplicity and removal of network source discovery complexity.  With
   PIM, control plane state is established in the network in order to
   forward multicast UDP data packets.  PIM utilizes network based
   source discovery.  PIM-SSM, however, utilizes application based
   source discovery.  IP Multicast packets fall within the range of
   224.0.0.0 through 239.255.255.255.  The telemetry solution will need
   to work within this IPv4 address range and provide telemetry data for
   this UDP traffic.

   A proposed solution for encapsulating the telemetry instruction
   header and metadata in IPv6 packets is described in
   [I-D.ietf-ippm-ioam-ipv6-options].

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5.3.  Application of MVPN X-PMSI Tunnel Encapsulation Attribute

   IOAM, and the recommendations of this document, are equally
   applicable to multicast MPLS forwarded packets.  Multipoint Label
   Distribution Protocol (mLDP), P2MP RSVP-TE, Ingress Replication (IR)
   and PIM MDT SAFI with GRE Transport are all commonly used within a
   Multicast VPN (MVPN) environment utilizing MVPN procedures such as
   Multicast in MPLS/BGP IP VPNs [RFC6513] and BGP Encoding and
   Procedures for Multicast in MPLS/BGP IP VPNs [RFC6514].  MLDP LDP
   Extension for P2MP and MP2MP LSPs [RFC6388] provides extensions to
   LDP to establish point-to-multipoint (P2MP) and multipoint-to-
   multipoint (MP2MP) label switched paths (LSPs) in MPLS networks.
   P2MP RSVP-TE provides extensions to RSVP-TE RSVP-TE for P2MP LSPs
   [RFC4875] to establish traffic-engineered P2MP LSPs in MPLS networks.
   Also used is Ingress Replication Tunnels in Multicast VPNs [RFC7988]
   which uses unicast replication from parent node to child node over a
   MPLS Unicast Tunnel.  PIM MDT SAFI Multicast in BGP/MPLS IP VPNs
   [RFC6037]utilizes PIM-SSM, PIM-SM or PIM-BIDIR control plane with GRE
   transport data plane in the core for X-PMSI P-Tree using MVPN
   procedures.  SR Replication Segment for Multi-point Service Delivery
   [I-D.ietf-spring-sr-replication-segment] utilizes replication
   segments for P2MP multicast service delivery in Segment Routing SR-
   MPLS networks.  The telemetry solution will need to be able to follow
   these P2MP and MP2MP paths.  The telemetry instruction header and
   data should be encapsulated into MPLS packets on P2MP and MP2MP
   paths.  A corresponding proposal is described in
   [I-D.song-mpls-extension-header].

5.4.  Application in BIER

   BIER [RFC8279] adds a new header to multicast packets and allows the
   multicast packets to be forwarded according to the header only.  By
   eliminating the requirement of maintaining per multicast group state,
   BIER is more scalable than the traditional multicast solutions.

   OAM Requirements for BIER [I-D.ietf-bier-oam-requirements] lists many
   of the requirements for OAM at the BIER layer which will help in the
   forming of on-path telemetry requirements as well.

   Depending on how the BIER header is encapsulated into packets with
   different transport protocols, the method to encapsulate the
   telemetry instruction header and metadata also varies.  It is also
   possible to make the instruction header and metadata a part of the
   BIER header itself, such as in a TLV.

   BIER-TE [RFC9262] contains multicast tree information in the packet
   header.  It would therefore be possible to directly deduce the tree,
   that a packet traversed, when correlating received IOAM information.

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6.  Security Considerations

   The schemes discussed in this document share the same security
   considerations for the IOAM trace option [RFC9197] and the IOAM DEX
   option [RFC9326].  In particular, since multicast has a built-in
   nature for packet amplification, the possible amplification risk for
   the DEX-based scheme is greater than the case of unicast.  Hence,
   stricter mechanisms for protections need to be applied.  In addition
   to selecting packets to enable DEX and limiting the exported traffic
   rate, we can also allows only a subset of the nodes in a multicast
   tree to process the option and export the data (e.g., only the
   branching nodes in the multicast tree are configured to process the
   option).

7.  IANA Considerations

   The document requests two new extension flag registrations in the
   "IOAM DEX Extension-Flags" registry, as described in Section 4.1.

   Bit 2 "Multicast Branching Node ID [RFC XXXX] [RFC Editor: please
   replace with the RFC number of the current document]".

   Bit 3 "Multicast Branching Interface Index [RFC XXXX] [RFC Editor:
   please replace with the RFC number of the current document]".

8.  Acknowledgments

   The authors would like to thank Frank Brockners, Nils Warnke, Jake
   Holland, Dino Farinacci, Henrik Nydell, and Toerless Eckert for their
   comments and suggestions.

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>.

   [RFC4875]  Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
              Yasukawa, Ed., "Extensions to Resource Reservation
              Protocol - Traffic Engineering (RSVP-TE) for Point-to-
              Multipoint TE Label Switched Paths (LSPs)", RFC 4875,
              DOI 10.17487/RFC4875, May 2007,
              <https://www.rfc-editor.org/info/rfc4875>.

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   [RFC6388]  Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B.
              Thomas, "Label Distribution Protocol Extensions for Point-
              to-Multipoint and Multipoint-to-Multipoint Label Switched
              Paths", RFC 6388, DOI 10.17487/RFC6388, November 2011,
              <https://www.rfc-editor.org/info/rfc6388>.

   [RFC6513]  Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
              BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February
              2012, <https://www.rfc-editor.org/info/rfc6513>.

   [RFC6514]  Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
              Encodings and Procedures for Multicast in MPLS/BGP IP
              VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
              <https://www.rfc-editor.org/info/rfc6514>.

   [RFC7761]  Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
              Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
              Multicast - Sparse Mode (PIM-SM): Protocol Specification
              (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
              2016, <https://www.rfc-editor.org/info/rfc7761>.

   [RFC7988]  Rosen, E., Ed., Subramanian, K., and Z. Zhang, "Ingress
              Replication Tunnels in Multicast VPN", RFC 7988,
              DOI 10.17487/RFC7988, October 2016,
              <https://www.rfc-editor.org/info/rfc7988>.

   [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>.

   [RFC8279]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
              Explicit Replication (BIER)", RFC 8279,
              DOI 10.17487/RFC8279, November 2017,
              <https://www.rfc-editor.org/info/rfc8279>.

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

   [RFC9262]  Eckert, T., Ed., Menth, M., and G. Cauchie, "Tree
              Engineering for Bit Index Explicit Replication (BIER-TE)",
              RFC 9262, DOI 10.17487/RFC9262, October 2022,
              <https://www.rfc-editor.org/info/rfc9262>.

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

9.2.  Informative References

   [I-D.ietf-bier-oam-requirements]
              Mirsky, G., Nainar, N. K., Chen, M., and S. Pallagatti,
              "Operations, Administration and Maintenance (OAM)
              Requirements for Bit Index Explicit Replication (BIER)
              Layer", Work in Progress, Internet-Draft, draft-ietf-bier-
              oam-requirements-13, 10 August 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bier-
              oam-requirements-13>.

   [I-D.ietf-ippm-hybrid-two-step]
              Mirsky, G., Lingqiang, W., Zhui, G., Song, H., and P.
              Thubert, "Hybrid Two-Step Performance Measurement Method",
              Work in Progress, Internet-Draft, draft-ietf-ippm-hybrid-
              two-step-00, 4 October 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-ippm-
              hybrid-two-step-00>.

   [I-D.ietf-ippm-ioam-ipv6-options]
              Bhandari, S. and F. Brockners, "In-situ OAM IPv6 Options",
              Work in Progress, Internet-Draft, draft-ietf-ippm-ioam-
              ipv6-options-12, 7 May 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-ippm-
              ioam-ipv6-options-12>.

   [I-D.ietf-spring-sr-replication-segment]
              Voyer, D., Filsfils, C., Parekh, R., Bidgoli, H., and Z.
              J. Zhang, "SR Replication segment for Multi-point Service
              Delivery", Work in Progress, Internet-Draft, draft-ietf-
              spring-sr-replication-segment-19, 28 August 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-spring-
              sr-replication-segment-19>.

   [I-D.song-ippm-postcard-based-telemetry]
              Song, H., Mirsky, G., Zhou, T., Li, Z., Graf, T., Mishra,
              G. S., Shin, J., and K. Lee, "On-Path Telemetry using
              Packet Marking to Trigger Dedicated OAM Packets", Work in
              Progress, Internet-Draft, draft-song-ippm-postcard-based-
              telemetry-16, 2 June 2023,
              <https://datatracker.ietf.org/doc/html/draft-song-ippm-
              postcard-based-telemetry-16>.

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   [I-D.song-mpls-extension-header]
              Song, H., Zhou, T., Andersson, L., Zhang, Z. J., and R.
              Gandhi, "MPLS Network Actions using Post-Stack Extension
              Headers", Work in Progress, Internet-Draft, draft-song-
              mpls-extension-header-12, 14 April 2023,
              <https://datatracker.ietf.org/doc/html/draft-song-mpls-
              extension-header-12>.

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

   [RFC6037]  Rosen, E., Ed., Cai, Y., Ed., and IJ. Wijnands, "Cisco
              Systems' Solution for Multicast in BGP/MPLS IP VPNs",
              RFC 6037, DOI 10.17487/RFC6037, October 2010,
              <https://www.rfc-editor.org/info/rfc6037>.

   [RFC6450]  Venaas, S., "Multicast Ping Protocol", RFC 6450,
              DOI 10.17487/RFC6450, December 2011,
              <https://www.rfc-editor.org/info/rfc6450>.

   [RFC8487]  Asaeda, H., Meyer, K., and W. Lee, Ed., "Mtrace Version 2:
              Traceroute Facility for IP Multicast", RFC 8487,
              DOI 10.17487/RFC8487, October 2018,
              <https://www.rfc-editor.org/info/rfc8487>.

Authors' Addresses

   Haoyu Song
   Futurewei Technologies
   2330 Central Expressway
   Santa Clara,
   United States of America
   Email: hsong@futurewei.com

   Mike McBride
   Futurewei Technologies
   2330 Central Expressway
   Santa Clara,
   United States of America
   Email: mmcbride@futurewei.com

   Greg Mirsky
   Ericsson
   Email: gregimirsky@gmail.com

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   Gyan Mishra
   Verizon Inc.
   Email: gyan.s.mishra@verizon.com

   Hitoshi Asaeda
   National Institute of Information and Communications Technology
   Japan
   Email: asaeda@nict.go.jp

   Tianran Zhou
   Huawei Technologies
   Beijing
   China
   Email: zhoutianran@huawei.com

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