MPLS Working Group

Internet Engineering Task Force (IETF)                     W. Cheng, Ed.
Internet-Draft
Request for Comments: 9714                                  China Mobile
Intended status:
Category: Standards Track                                    X. Min, Ed.
Expires: 16 March 2025
ISSN: 2070-1721                                                ZTE Corp.
                                                                 T. Zhou
                                                                  Huawei
                                                                  J. Dai
                                                               FiberHome
                                                                Y. Peleg
                                                                Broadcom
                                                       12 September 2024
                                                            January 2025

   Encapsulation For for MPLS Performance Measurement with Alternate-Marking the Alternate-
                             Marking Method
               draft-ietf-mpls-inband-pm-encapsulation-18

Abstract

   This document defines the encapsulation for MPLS performance
   measurement with the Alternate-Marking method, Method, which performs flow-
   based packet loss, delay, and jitter measurements on the MPLS traffic.

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   https://www.rfc-editor.org/info/rfc9714.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
     2.1.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   3.  Flow-based  Flow-Based PM Encapsulation in MPLS . . . . . . . . . . . . .   4
     3.1.  Examples for Applying Flow-ID Label in a label stack  . .   6 Label Stack
       3.1.1.  Layout of the Flow-ID Label when Applied to MPLS
               Transport
       3.1.2.  Layout of the Flow-ID Label when Applied to MPLS
               Service
       3.1.3.  Layout of the Flow-ID Label when Applied to both MPLS
               Transport and MPLS Service
   4.  Procedures of Encapsulation, Look-up Look-Up, and Decapsulation  . . .   8
   5.  Procedures of Flow-ID allocation  . . . . . . . . . . . . . .   9 Allocation
   6.  FLC and FRLD Considerations . . . . . . . . . . . . . . . . .  10
   7.  Equal-Cost Multipath Considerations . . . . . . . . . . . . .  11
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   9.  Implementation Status . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Fiberhome . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.2.  Huawei Technologies . . . . . . . . . . . . . . . . . . .  13
     9.3.  ZTE Corp  . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.4.  China Mobile  . . . . . . . . . . . . . . . . . . . . . .  14
   10.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   12. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  14
   13.
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     13.1.
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  15
     13.2.
     10.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Acknowledgements
   Contributors
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   [RFC9341] describes a performance measurement method, which can be
   used to measure packet loss, delay, and jitter on data traffic.
   Since this method is based on marking consecutive batches of packets,
   it is referred to as the Alternate-Marking Method.  [RFC8372]
   outlines key considerations for developing a solution for MPLS flow
   identification, intended for use in performance monitoring of MPLS
   flows.

   This document defines the encapsulation for MPLS performance
   measurement with the Alternate-Marking method, Method, which performs flow-
   based packet loss, delay, and jitter measurements on the MPLS
   traffic.  The encapsulation defined in this document supports
   performance monitoring at the intermediate nodes and MPLS flow
   identification at both transport and service layers.

   Note that in parallel to the work of this document, there is ongoing
   work on MPLS Network Actions (MNA) [RFC9613].  The MPLS performance
   measurement with the Alternate-Marking method Method can also be achieved by
   MNA encapsulation.  In addition, MNA will provide a broader use case use-case
   applicability.  That means the MNA encapsulation is expected to
   provide a more advanced solution, when published as an RFC and it is
   agreed that this document will be made Historic at that time.

2.  Conventions Used in This Document

2.1.  Abbreviations

   ACL:  Access Control List

   BoS:  Bottom of Stack

   cSPL:  Composite Special Purpose Label, the combination of the
      Extension Label (value 15) and an Extended Special Purpose Label

   DSCP:  Differentiated Services Code Point

   ECMP:  Equal-Cost Multipath

   ELC:  Entropy Label Capability

   ERLD:  Entropy Readable Label Depth

   eSPL:  Extended Special Purpose Label, a special-purpose label that
      is placed in the label stack after the Extension Label (value 15)

   FL:  Flow-ID Label

   FLC:  Flow-ID Label Capability

   FLI:  Flow-ID Label Indicator

   FRLD:  Flow-ID Readable Label Depth

   IPFIX:  IP Flow Information Export [RFC7011]

   LSP:  Label Switched Path

   LSR:  Label Switching Router

   MPLS:  Multi-Protocol Label Switching

   NMS:  Network Management System

   PHP:  Penultimate Hop Popping

   PM:  Performance Measurement

   PW:  PseudoWire

   SFL:  Synonymous Flow Label

   SID:  Segment ID

   SR:  Segment Routing

   TC:  Traffic Class

   TTL:  Time to Live

   VC:  Virtual Channel

   VPN:  Virtual Private Network

   XL:  Extension Label

2.2.  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.

3.  Flow-based  Flow-Based PM Encapsulation in MPLS

   This document defines the Flow-based MPLS performance measurement
   encapsulation with alternate marking method, the Alternate-Marking Method, as shown in figure
   Figure 1.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Extension Label (15)         |  TC |S|      TTL      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flow-ID Label Indicator (TBA1) (18)      |  TC |S|      TTL      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Flow-ID Label             |L|D|T|S|      TTL      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 1: Flow-based PM Encapsulation in MPLS

   The Flow-ID Label Indicator (FLI) is an Extended Special Purpose
   Label (eSPL), which is combined with the Extension Label (XL, value
   15) to form a Composite Special Purpose Label (cSPL), as defined in
   [RFC9017].  The FLI is defined in this document as value TBA1. 18.

   The Traffic Class (TC) and Time To Live (TTL) fields of the XL and
   FLI MUST use the same values of the label immediately preceding the
   XL.  The Bottom of the Stack (BoS) bit [RFC3032] for the XL and FLI
   MUST be zero.  If any XL or FLI processed by a node has the BoS bit
   set, the node MUST discard the packet and MAY log an error.

   The Flow-ID Label (FL) is used as an MPLS flow identification
   [RFC8372].  Its value MUST be unique within the administrative
   domain.  The Flow-ID Label values MAY be allocated by an external NMS
   or controller based on the measurement object instances (such as LSP
   or PW).  There is a one-to-one mapping between a Flow-ID and a flow.
   The specific method on how to allocate the Flow-ID Label values is
   described in Section 5.

   The FL, preceded by a cSPL, can be placed either at the bottom or in
   the middle, but not at the top, of the MPLS label stack, and it MAY
   appear multiple times within a label stack.  Section 3.1 of this
   document provides several examples to illustrate the application of
   FL in a label stack.  The TTL for the FL MUST be zero to ensure that
   it is not used inadvertently for forwarding.  The BoS bit for the FL
   depends on whether the FL is placed at the bottom of the MPLS label
   stack, i.e., the BoS bit for the FL is set only when the FL is placed
   at the bottom of the MPLS label stack.

   Besides the flow identification, a color-marking field is also
   necessary for the Alternate-Marking method. Method.  To achieve the purpose
   of coloring color the MPLS traffic,
   traffic and to distinguish between hop-by-hop measurement and edge-to-edge edge-
   to-edge measurement, the TC for the FL is defined as follows:

   *  L(oss) bit is used for coloring the MPLS packets for loss
      measurement.  Setting the bit means color 1 1, and unsetting the bit
      means color 0.

   *  D(elay) bit is used for coloring the MPLS packets for delay/jitter
      measurement.  Setting the bit means color for delay measurement.

   *  T(ype) bit is used to indicate the measurement type.  When the T
      bit is set to 1, that means edge-to-edge performance measurement.
      When the T bit is set to 0, that means hop-by-hop performance
      measurement.

   Considering the FL is not used as a forwarding label, the repurposing
   of the TC for the FL is feasible and viable.

3.1.  Examples for Applying Flow-ID Label in a label stack Label Stack

   Three examples of different layouts of the Flow-ID label (4 octets)
   are illustrated as follows.  Note that more examples may exist.

   (1)

3.1.1.  Layout of the Flow-ID label Label when applied Applied to MPLS transport. Transport

                +----------------------+
                |          LSP         |
                |         Label        |
                +----------------------+ <--+
                |       Extension      |    |
                |         Label        |    |
                +----------------------+    |--- cSPL
                |     Flow-ID Label    |    |
                |       Indicator      |    |
                +----------------------+ <--+
                |        Flow-ID       |
                |         Label        |
                +----------------------+
                |      Application     |
                |         Label        |
                +----------------------+ <= Bottom of stack
                |                      |
                |        Payload       |
                |                      |
                +----------------------+

                Figure 2: Applying Flow-ID to MPLS transport Transport

   With penultimate hop popping (PHP, (PHP Section 3.16 of [RFC3031]) [RFC3031]), the top
   label is "popped at the penultimate LSR of the LSP, rather than at
   the LSP Egress".  Since  The final bullet of Section 4 of the present document, final
   bullet,
   document requires that "The "[t]he processing node MUST pop the XL, FLI FLI,
   and FL from the MPLS label stack when it needs to pop the preceding
   forwarding label", this which implies that the penultimate Label Switching
   Router (LSR) needs to follow the requirement of Section 4 in order to
   support this specification.  If this is done, the egress LSR would be is
   excluded from the performance measurement.  Therefore, when this
   specification is in use use, PHP should be disabled, unless the
   penultimate LSR is known to have the necessary support, support and unless
   it's acceptable to exclude the egress LSR.

   Also note that in other examples of applying Flow-ID to MPLS
   transport, one LSP label can be substituted by multiple SID labels in
   the case of using SR Policy, and the combination of cSPL and Flow-ID
   label can be placed between SID labels, as specified in Section 6.

   (2)

3.1.2.  Layout of the Flow-ID label Label when applied Applied to MPLS service. Service

                +----------------------+
                |          LSP         |
                |         Label        |
                +----------------------+
                |      Application     |
                |         Label        |
                +----------------------+ <--+
                |       Extension      |    |
                |         Label        |    |
                +----------------------+    |--- cSPL
                |     Flow-ID Label    |    |
                |       Indicator      |    |
                +----------------------+ <--+
                |        Flow-ID       |
                |         Label        |
                +----------------------+ <= Bottom of stack
                |                      |
                |        Payload       |
                |                      |
                +----------------------+

                 Figure 3: Applying Flow-ID to MPLS service Service

   Note that in this case, the application label can be an MPLS PW
   label, MPLS Ethernet VPN label label, or MPLS IP VPN label, and it is also
   called a VC label as defined in [RFC4026].

   (3)

3.1.3.  Layout of the Flow-ID label Label when applied Applied to both MPLS transport Transport
        and MPLS service. Service

                +----------------------+
                |          LSP         |
                |         Label        |
                +----------------------+ <--+
                |       Extension      |    |
                |         Label        |    |
                +----------------------+    |--- cSPL
                |     Flow-ID Label    |    |
                |       Indicator      |    |
                +----------------------+ <--+
                |        Flow-ID       |
                |         Label        |
                +----------------------+
                |      Application     |
                |         Label        |
                +----------------------+ <--+
                |       Extension      |    |
                |         Label        |    |
                +----------------------+    |--- cSPL
                |     Flow-ID Label    |    |
                |       Indicator      |    |
                +----------------------+ <--+
                |        Flow-ID       |
                |         Label        |
                +----------------------+ <= Bottom of stack
                |                      |
                |        Payload       |
                |                      |
                +----------------------+

     Figure 4: Applying Flow-ID to both MPLS transport Transport and MPLS service Service

   Note that for this example, the two Flow-ID Label values appearing in
   a label stack must be different.  In other words, the Flow-ID label
   applied to the MPLS transport and the Flow-ID label applied to the
   MPLS service must be different.  Also, note that the two Flow-ID
   label values are independent of each other.  For example, two packets
   can belong to the same VPN flow but different LSP flows, or two
   packets can belong to different VPN flows but the same LSP flow.

4.  Procedures of Encapsulation, Look-up Look-Up, and Decapsulation

   The procedures for Flow-ID label encapsulation, look-up look-up, and
   decapsulation are summarized as follows:

   *  The MPLS ingress node [RFC3031] inserts the XL, FLI FLI, and FL into
      the MPLS label stack.  At the same time, the ingress node sets the
      Flow-ID Label value, the two color-marking bits bits, and the T bit, as
      defined in Section 3.

   *  If the edge-to-edge measurement is applied, i.e., the T bit is set to
      1, then only the MPLS ingress/egress node [RFC3031] is the
      processing node, otherwise node; otherwise, all the MPLS nodes along the LSP are
      the processing nodes.  The processing node looks up the FL with
      the help of the XL and FLI, and exports the collected data, such data (such
      as the Flow-ID, block counters counters, and timestamps, timestamps) to an external NMS/
      controller,
      NMS/controller, referring to the Alternate-Marking method. Method.
      Section 6 of [I-D.ietf-ippm-alt-mark-deployment] [ALT-MARK] describes protocols for collected data export, and
      export; the details on how to export the collected data are
      outside the scope of this document.  Note that while looking up
      the Flow-ID label, the transit node needs to perform some deep
      labels inspection beyond the label (at the top of the label stack)
      used to make forwarding decisions.

   *  The processing node MUST pop the XL, FLI FLI, and FL from the MPLS
      label stack when it needs to pop the preceding forwarding label.
      The egress node MUST pop the whole MPLS label stack, and this stack.  This
      document doesn't introduce any new process to the decapsulated
      packet.

5.  Procedures of Flow-ID allocation Allocation

   There are at least two ways of allocating Flow-ID.  One way is to
   allocate Flow-ID by a manual trigger from the network operator, and
   the other way is to allocate Flow-ID by an automatic trigger from the
   ingress node.  Details are as follows:

   *  In the case of a manual trigger, the network operator would manually input
      inputs the characteristics (e.g. (e.g., IP five tuples and IP DSCP) of
      the measured flow, flow; then the NMS/controller would generate generates one or two
      Flow-IDs based on the input from the network operator, operator and provision
      provisions the ingress node with the characteristics of the
      measured flow and the corresponding allocated Flow-ID(s).

   *  In the case of an automatic trigger, the ingress node would
      identify identifies
      the flow entering the measured path, export path and exports the
      characteristics of the identified flow to the NMS/controller by
      IPFIX [RFC7011], [RFC7011]; then the NMS/controller would generate generates one or two
      Flow-IDs based on the characteristics exported from the ingress
      node,
      node and provision provisions the ingress node with the characteristics of
      the identified flow and the corresponding allocated Flow-ID(s).

   The policy pre-configured preconfigured at the NMS/controller decides whether one
   Flow-ID or two Flow-IDs would be are generated.  If the performance
   measurement on the MPLS service is enabled, then one Flow-ID applied
   to the MPLS service would be is generated.  If the performance measurement on
   the MPLS transport is enabled, then one Flow-ID applied to the MPLS
   transport would be is generated.  If both of them are enabled, then two Flow-IDs Flow-
   IDs are respectively applied to the MPLS service and the MPLS
   transport would be are generated.  In this case, a transit node needs to look
   up both of the two Flow-IDs by default.  However, this behaviour behavior can
   be changed through configuration, such as by setting it to look up
   only the Flow-ID applied to the MPLS transport.

   Whether using the two methods mentioned above or other methods to
   allocate Flow-ID, the NMS/controller MUST ensure that every generated
   Flow-ID is unique within the administrative domain and MUST NOT have
   any value in the reserved label space (0-15) [RFC3032].
   Specifically, the statement of "Flow-ID is unique" means that the
   values of Flow-ID are distinct and non-redundant for any flow at any
   given time within an administrative domain, such that no two flows
   share the same Flow-ID.  This uniqueness ensures that each flow can
   be individually identified, tracked, and differentiated from others
   for accurate performance monitoring and management.

6.  FLC and FRLD Considerations

   Analogous to the Entropy Label Capability (ELC) defined in Section 5
   of [RFC6790] and the Entropy Readable Label Depth (ERLD) defined in
   Section 4 of [RFC8662], the Flow-ID Label Capability (FLC) and the
   Flow-ID Readable Label Depth (FRLD) are defined in this document.
   Both FLC and FRLD have similar semantics with the ELC and ERLD to a
   router, except that the Flow-ID is used in its flow identification
   function while the Entropy is used in its load-balancing function.

   The ingress node MUST insert each FL at an appropriate depth, which
   ensures the node to which the FL is exposed has the FLC.  The ingress
   node SHOULD insert each FL within an appropriate FRLD, which is the
   minimum FRLD of all the on-path nodes that need to read and use the
   FL in question.  How the ingress node knows the FLC and FRLD of all
   the on-path nodes is outside the scope of this document.

   When the SR paths are used for transport, the label stack grows as
   the number of on-path segments increases.  If the number of on-path
   segments is high, that may become a challenge for the FL to be placed
   within an appropriate FRLD.  To overcome this potential challenge, an
   implementation MAY allow the ingress node to place FL between SID
   labels.  This means that multiple identical FLs at different depths
   MAY be interleaved with SID labels.  When this occurs, sophisticated
   network planning may be needed, which is beyond the scope of this
   document.

7.  Equal-Cost Multipath Considerations

   Analogous to what's described in Section 5 of [RFC8957], under
   conditions of Equal-Cost Multipath (ECMP), the introduction of the FL
   may lead to the same problem as that is caused by the Synonymous Flow
   Label (SFL) [RFC8957].  The two solutions proposed for SFL would also apply
   here.  Specifically, adding FL to an existing flow may cause that
   flow to take a different path.  If the operator expects to resolve
   this problem, they can choose to apply entropy labels [RFC6790] or
   add FL to all flows.

8.  Security Considerations

   As specified in Section 7.1 of [RFC9341], "for security reasons, the
   Alternate-Marking Method MUST only be applied to controlled domains".
   That domains."
   This requirement applies when the MPLS performance measurement with
   Alternate-Marking Method is taken into account, which means the MPLS
   encapsulation and related procedures defined in this document MUST
   only be applied to controlled domains, otherwise domains; otherwise, the potential
   attacks discussed in Section 10 of [RFC9341] may be applied to the
   deployed MPLS networks.

   As specified in Section 3, the value of a Flow-ID label MUST be
   unique within the administrative domain.  In other words, the
   administrative domain is the scope of a Flow-ID label.  The method
   for achieving multi-domain performance measurement with the same
   Flow-ID label is outside the scope of this document.  The Flow-ID
   label MUST NOT be signaled and distributed outside the administrative
   domain.  Improper configuration that allows the Flow-ID label to be
   passed from one administrative domain to another would result in
   Flow-ID conflicts.

   To prevent packets carrying Flow-ID labels from leaking from one
   domain to another, domain boundary nodes MUST deploy policies (e.g.,
   ACL) to filter out these packets.  Specifically, at the sending edge,
   the domain boundary node MUST filter out the packets that carry the
   Flow-ID Label Indicator and are sent to other domains.  At the
   receiving edge, the domain boundary node MUST drop the packets that
   carry the Flow-ID Label Indicator and are from other domains.  Note
   that packet leakage is neither breaching privacy nor can be a source of DoS.

10.

9.  IANA Considerations

   From

   IANA has assigned the following value in the "Extended Special-Purpose Special-
   Purpose MPLS Label Values" registry in within the "Special-Purpose
   Multiprotocol Label Switching (MPLS) Label Values"
   namespace, a new value for the Flow-ID Label Indicator is requested
   from IANA as follows:

     +================================+=================+===========+ registry group:

           +=======+===============================+===========+
           | Value | Description                   | Reference |
     +================================+=================+===========+
           +=======+===============================+===========+
           | TBA1 (value 18 is recommended)    | Flow-ID Label   | This      |
     |                                | Indicator (FLI) | Document RFC 9714  |
     +--------------------------------+-----------------+-----------+
           +-------+-------------------------------+-----------+

              Table 1: New Extended Special-Purpose MPLS Label
                     Value for Flow-ID Label Indicator

13.

10.  References

13.1.

10.1.  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>.

   [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
              Label Switching Architecture", RFC 3031,
              DOI 10.17487/RFC3031, January 2001,
              <https://www.rfc-editor.org/info/rfc3031>.

   [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
              Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
              Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
              <https://www.rfc-editor.org/info/rfc3032>.

   [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>.

   [RFC9017]  Andersson, L., Kompella, K., and A. Farrel, "Special-
              Purpose Label Terminology", RFC 9017,
              DOI 10.17487/RFC9017, April 2021,
              <https://www.rfc-editor.org/info/rfc9017>.

13.2.

10.2.  Informative References

   [I-D.ietf-ippm-alt-mark-deployment]

   [ALT-MARK] Fioccola, G., Keyi, Z., Zhu, K., Graf, T., Nilo, M., and L. Zhang,
              "Alternate Marking Deployment Framework", Work in
              Progress, Internet-Draft, draft-ietf-ippm-alt-mark-
              deployment-01, 3 July
              deployment-02, 9 October 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-ippm-
              alt-mark-deployment-01>.
              alt-mark-deployment-02>.

   [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
              Private Network (VPN) Terminology", RFC 4026,
              DOI 10.17487/RFC4026, March 2005,
              <https://www.rfc-editor.org/info/rfc4026>.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, DOI 10.17487/RFC6790, November 2012,
              <https://www.rfc-editor.org/info/rfc6790>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/info/rfc7011>.

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,
              <https://www.rfc-editor.org/info/rfc7942>.

   [RFC8372]  Bryant, S., Pignataro, C., Chen, M., Li, Z., and G.
              Mirsky, "MPLS Flow Identification Considerations",
              RFC 8372, DOI 10.17487/RFC8372, May 2018,
              <https://www.rfc-editor.org/info/rfc8372>.

   [RFC8662]  Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
              Shakir, R., and J. Tantsura, "Entropy Label for Source
              Packet Routing in Networking (SPRING) Tunnels", RFC 8662,
              DOI 10.17487/RFC8662, December 2019,
              <https://www.rfc-editor.org/info/rfc8662>.

   [RFC8957]  Bryant, S., Chen, M., Swallow, G., Sivabalan, S., and G.
              Mirsky, "Synonymous Flow Label Framework", RFC 8957,
              DOI 10.17487/RFC8957, January 2021,
              <https://www.rfc-editor.org/info/rfc8957>.

   [RFC9341]  Fioccola, G., Ed., Cociglio, M., Mirsky, G., Mizrahi, T.,
              and T. Zhou, "Alternate-Marking Method", RFC 9341,
              DOI 10.17487/RFC9341, December 2022,
              <https://www.rfc-editor.org/info/rfc9341>.

   [RFC9613]  Bocci, M., Ed., Bryant, S., and J. Drake, "Requirements
              for Solutions that Support MPLS Network Actions (MNAs)",
              RFC 9613, DOI 10.17487/RFC9613, August 2024,
              <https://www.rfc-editor.org/info/rfc9613>.

11.

Acknowledgements

   The authors would like to acknowledge Loa Andersson, Tarek Saad, Stewart Bryant,
   Rakesh Gandhi, Greg Mirsky, Aihua Liu, Shuangping Zhan, Ming Ke, Wei
   He, Ximing Dong, Darren Dukes, Tony Li, James Guichard, Daniele
   Ceccarelli, Eric Vyncke, John Scudder, Gunter van de Velde, Roman
   Danyliw, Warren Kumari, Murray Kucherawy, Deb Cooley, Zaheduzzaman
   Sarker, and Deboraha Brungard for their careful review and very
   helpful comments.

   They also wish to acknowledge Italo Busi and Chandrasekar Ramachandran for
   their insightful MPLS-RT review and constructive comments.

   Additionally, the authors would like to thank Dhruv Dhody for the English grammar
   review.

12.

Contributors

   Minxue Wang
   China Mobile
   Email: wangminxue@chinamobile.com

   Wen Ye
   China Mobile
   Email: yewen@chinamobile.com

Authors' Addresses

   Weiqiang Cheng (editor)
   China Mobile
   Beijing
   China
   Email: chengweiqiang@chinamobile.com

   Xiao Min (editor)
   ZTE Corp.
   Nanjing
   China
   Email: xiao.min2@zte.com.cn

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

   Jinyou Dai
   FiberHome
   Wuhan
   China
   Email: djy@fiberhome.com

   Yoav Peleg
   Broadcom
   United States of America
   Email: yoav.peleg@broadcom.com