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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="std" ipr="trust200902" docName="draft-ietf-mpls-inband-pm-encapsulation-18" number="9714" consensus="true" submissionType="IETF"> submissionType="IETF" tocInclude="true" updates="" obsoletes="" symRefs="true" sortRefs="true" version="3" xml:lang="en">

  <front>
    <title abbrev="Encap for MPLS PM with AMM"> Encapsulation For AMM">Encapsulation for MPLS Performance Measurement with the Alternate-Marking Method </title> Method</title>
    <seriesInfo name="RFC" value="9714"/>
    <author fullname="Weiqiang Cheng" initials="W" surname="Cheng" role="editor">
      <organization>China Mobile</organization>
      <address>
        <postal>
         <street></street>

         <!-- Reorder these if your country does things differently -->
          <city>Beijing</city>

         <region></region>

         <code></code>
          <country>China</country>
        </postal>

       <phone></phone>
        <email>chengweiqiang@chinamobile.com</email>

       <!-- uri and facsimile elements may also be added -->
     </address>
    </author>
    <author fullname="Xiao Min" initials="X" surname="Min" role="editor">
      <organization>ZTE Corp.</organization>
      <address>
        <postal>
         <street></street>

         <!-- Reorder these if your country does things differently -->
          <city>Nanjing</city>

         <region></region>

         <code></code>
          <country>China</country>
        </postal>

       <phone></phone>
        <email>xiao.min2@zte.com.cn</email>

       <!-- uri and facsimile elements may also be added -->
     </address>
    </author>
    <author fullname="Tianran Zhou" initials="T" surname="Zhou">
      <organization>Huawei</organization>
      <address>
        <postal>
         <street></street>

         <!-- Reorder these if your country does things differently -->
         <city>Beijing</city>

         <region></region>

         <code></code>
          <country>China</country>
        </postal>

       <phone></phone>
        <phone/>
        <email>zhoutianran@huawei.com</email>

       <!-- uri and facsimile elements may also be added -->
     </address>
    </author>
    <author fullname="Jinyou Dai" initials="J" surname="Dai">
      <organization>FiberHome</organization>
      <address>
        <postal>
         <street></street>

         <!-- Reorder these if your country does things differently -->
          <city>Wuhan</city>

         <region></region>

         <code></code>
          <country>China</country>
        </postal>

       <phone></phone>
        <email>djy@fiberhome.com</email>

       <!-- uri and facsimile elements may also be added -->
     </address>
    </author>
    <author fullname="Yoav Peleg" initials="Y" surname="Peleg">
      <organization>Broadcom</organization>
      <address>
        <postal>
         <street></street>

         <!-- Reorder these if your country does things differently -->

         <city></city>

         <region></region>

         <code></code>
          <country>United States of America</country>
        </postal>

       <phone></phone>
        <email>yoav.peleg@broadcom.com</email>

       <!-- uri and facsimile elements may also be added -->
     </address>
    </author>
    <date year="2024"/>

    <area>Routing</area>
    <workgroup>MPLS Working Group</workgroup>

    <keyword>Request for Comments</keyword>
    <keyword>RFC</keyword>
    <keyword>Internet Draft</keyword>
    <keyword>I-D</keyword> year="2025" month="January"/>
    <area>RTG</area>
    <workgroup>mpls</workgroup>

<!-- [rfced] Please insert any keywords (beyond those that appear in
the title) for use on https://www.rfc-editor.org/search. -->

<keyword>example</keyword>

    <abstract>
      <t>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.</t>
    </abstract>
  </front>
  <middle>
    <section title="Introduction"> anchor="introduction">
      <name>Introduction</name>
      <t> <xref target="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. <xref target="RFC8372"/> outlines key considerations for developing a solution for MPLS flow identification, intended for
   use in performance monitoring of MPLS flows.</t>
      <t> 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.</t>
<!-- [rfced] The following is somewhat tough to parse. May we update as follows?  Otherwise, please clarify.

Original:
   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.

Perhaps:
   That means the MNA encapsulation is expected to
   provide a more advanced solution.  Once published as an RFC, it is
   agreed that this document will be made Historic.
-->

      <t> Note that in parallel to the work of this document, there is ongoing work on MPLS Network Actions (MNA) <xref target="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.</t>
    </section>
    <section title="Conventions anchor="conventions">
      <name>Conventions Used in This Document"> Document</name>
      <section title="Abbreviations">
    <t> ACL: Access anchor="abbrevs">
        <name>Abbreviations</name>
	<dl spacing="normal" newline="false">
          <dt>ACL:</dt><dd>Access Control List</t>
    <t> BoS: Bottom List</dd>
          <dt>BoS:</dt><dd>Bottom of Stack</t>
    <t> cSPL: Composite Stack</dd>
          <dt>cSPL:</dt><dd>Composite Special Purpose Label, the combination of the Extension Label (value 15) and an Extended Special Purpose Label</t>
    <t> DSCP: Differentiated Label</dd>
          <dt>DSCP:</dt><dd>Differentiated Services Code Point</t>
    <t> ECMP: Equal-Cost Multipath</t>
    <t> ELC: Entropy Point</dd>
          <dt>ECMP:</dt><dd>Equal-Cost Multipath</dd>
          <dt>ELC:</dt><dd>Entropy Label Capability</t>
    <t> ERLD: Entropy Capability</dd>
          <dt>ERLD:</dt><dd>Entropy Readable Label Depth</t>
    <t> eSPL: Extended Depth</dd>
          <dt>eSPL:</dt><dd>Extended Special Purpose Label, a special-purpose label that is placed in the label stack after the Extension Label (value 15)</t>
    <t> FL: Flow-ID Label</t>
    <t> FLC: Flow-ID 15)</dd>
          <dt>FL:</dt><dd>Flow-ID Label</dd>
          <dt>FLC:</dt><dd>Flow-ID Label Capability</t>
    <t> FLI: Flow-ID Capability</dd>
          <dt>FLI:</dt><dd>Flow-ID Label Indicator</t>
    <t> FRLD: Flow-ID Indicator</dd>
          <dt>FRLD:</dt><dd>Flow-ID Readable Label Depth</t>
    <t> IPFIX: IP Depth</dd>
          <dt>IPFIX:</dt><dd>IP Flow Information Export <xref target="RFC7011"/></t>
    <t> LSP: Label target="RFC7011"/></dd>
          <dt>LSP:</dt><dd>Label Switched Path</t>
    <t> LSR: Label Path</dd>
          <dt>LSR:</dt><dd>Label Switching Router</t>
    <t> MPLS: Multi-Protocol Router</dd>
          <dt>MPLS:</dt><dd>Multi-Protocol Label Switching</t>
    <t> NMS: Network Switching</dd>
          <dt>NMS:</dt><dd>Network Management System</t>
    <t> PHP: Penultimate System</dd>
          <dt>PHP:</dt><dd>Penultimate Hop Popping</t>
    <t> PM: Performance Measurement</t>
    <t> PW: PseudoWire</t>
    <t> SFL: Synonymous Popping</dd>
          <dt>PM:</dt><dd>Performance Measurement</dd>
          <dt>PW:</dt><dd>PseudoWire</dd>
          <dt>SFL:</dt><dd>Synonymous Flow Label</t>
    <t> SID: Segment ID</t>
    <t> SR: Segment Routing</t>
    <t> TC: Traffic Class</t>
    <t> TTL: Time to Live</t>
    <t> VC: Virtual Channel</t>
    <t> VPN: Virtual Label</dd>
          <dt>SID:</dt><dd>Segment ID</dd>
          <dt>SR:</dt><dd>Segment Routing</dd>
          <dt>TC:</dt><dd>Traffic Class</dd>
          <dt>TTL:</dt><dd>Time to Live</dd>
          <dt>VC:</dt><dd>Virtual Channel</dd>
          <dt>VPN:</dt><dd>Virtual Private Network</t>
    <t> XL: Extension Label</t> Network</dd>
          <dt>XL:</dt><dd>Extension Label</dd>
	</dl>
      </section>
      <section title="Requirements Language"> anchor="requirements">
        <name>Requirements Language</name>
        <t>
    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT",
	"RECOMMENDED", "NOT RECOMMENDED", "MAY", "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
    NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
    "<bcp14>MAY</bcp14>", and   "OPTIONAL" "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as
    described in BCP 14 BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
    when, and only when, they appear in all capitals, as shown here.</t> here.
        </t>
      </section>
    </section>
    <section title="Flow-based anchor="flow-based-pm-encapsulation">
      <name>Flow-Based PM Encapsulation in MPLS"> MPLS</name>
      <t> This document defines the Flow-based MPLS performance measurement encapsulation with alternate marking method, the Alternate-Marking Method, as shown
	in figure 1.</t> <xref target="Figure_1"/>.</t>
      <figure anchor="Figure_1" title="Flow-based anchor="Figure_1">
        <name>Flow-based PM Encapsulation in MPLS"> MPLS</name>
        <artwork align="left"><![CDATA[
 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      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ]]></artwork>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
      </figure>
      <t>
	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 <xref target="RFC9017"/>. The
	FLI is defined in this document as value TBA1. 18.
      </t>
      <t>
	The Traffic Class (TC) and Time To Live (TTL) fields of the XL and FLI MUST <bcp14>MUST</bcp14> use the same values of the label immediately
	preceding the XL. The Bottom of the Stack (BoS) bit <xref target="RFC3032"/> for the XL and FLI MUST <bcp14>MUST</bcp14> be zero. If any XL or FLI
	processed by a node has the BoS bit set, the node MUST <bcp14>MUST</bcp14> discard the packet and MAY <bcp14>MAY</bcp14> log an error.
      </t>
      <t>
	The Flow-ID Label (FL) is used as an MPLS flow identification <xref target="RFC8372"/>. Its value MUST <bcp14>MUST</bcp14> be unique within the
	administrative domain. The Flow-ID Label values MAY <bcp14>MAY</bcp14> 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. <xref target="procedures-of-flow-id-alloc"/>.
      </t>
      <t>
	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 <bcp14>MAY</bcp14> appear multiple times within a label stack. Section 3.1 <xref target="examples-for-flow-id"/> of this document provides several examples to illustrate the
	application of FL in a label stack. The TTL for the FL MUST <bcp14>MUST</bcp14> 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.
      </t>
<!-- [rfced] For readability, we have updated the sentence below.  Please let us know if updates are needed.

Original:
   To achieve the purpose
   of coloring the MPLS traffic, and to distinguish between hop-by-hop
   measurement and edge-to-edge measurement, the TC for the FL is
   defined as follows:

Current:
   To color the MPLS
   traffic and to distinguish between hop-by-hop measurement and edge-
   to-edge measurement, the TC for the FL is defined as follows:
-->

      <t>
	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 measurement, the
	TC for the FL is defined as follows:
    <list style="symbols">
      </t>
      <ul spacing="normal">
        <li>
          <t>
	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.
          </t>
        </li>
        <li>
          <t>
	D(elay) bit is used for coloring the MPLS packets for delay/jitter measurement. Setting the bit means color for delay measurement.
          </t>
        </li>
        <li>
          <t>
    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.
          </t>
    </list>
        </li>
      </ul>
      <t>
	Considering the FL is not used as a forwarding label, the repurposing of the TC for the FL is feasible and viable.
      </t>
	</t>
      <section title="Examples anchor="examples-for-flow-id">
        <name>Examples for Applying Flow-ID Label in a label stack"> Label Stack</name>
        <t> Three examples of different layouts of the Flow-ID label (4
        octets) are illustrated as follows. Note that more examples may
        exist.</t>

    <t> (1) Layout

	<section anchor="example-one">
        <name>Layout of the Flow-ID label Label when applied Applied to MPLS transport.</t> Transport</name>
        <figure anchor="Figure_2" title="Applying anchor="Figure_2">
          <name>Applying Flow-ID to MPLS transport"> Transport</name>
          <artwork align="center"><![CDATA[
+----------------------+
|          LSP         |
|         Label        |
+----------------------+ <--+
|       Extension      |    |
|         Label        |    |
+----------------------+    |--- cSPL
|     Flow-ID Label    |    |
|       Indicator      |    |
+----------------------+ <--+
|        Flow-ID       |
|         Label        |
+----------------------+
|      Application     |
|         Label        |
+----------------------+ <= Bottom of stack
|                      |
|        Payload       |
|                      |
+----------------------+
     ]]></artwork>
+----------------------+]]></artwork>
        </figure>
        <t> With penultimate hop popping (PHP, Section 3.16 of (PHP <xref target="RFC3031"/>) sectionFormat="of"
        section="3.16" target="RFC3031"/>), the top label is "popped at the
        penultimate LSR of the LSP, rather than at the LSP Egress". Since Section 4 The final bullet of
        <xref target="procedures-of-encap"/> of the present document, final bullet, document requires that "The "[t]he processing node MUST <bcp14>MUST</bcp14> 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 <xref
        target="procedures-of-encap"/> 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.</t>
        <t> 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.</t>

    <t> (2) Layout <xref
        target="flc-frld-considerations"/>.</t>
	</section>

	<section anchor="example-two">
        <name>Layout of the Flow-ID label Label when applied Applied to MPLS service.</t> Service</name>
        <figure anchor="Figure_3" title="Applying anchor="Figure_3">
          <name>Applying Flow-ID to MPLS service"> Service</name>
          <artwork align="center"><![CDATA[
+----------------------+
|          LSP         |
|         Label        |
+----------------------+
|      Application     |
|         Label        |
+----------------------+ <--+
|       Extension      |    |
|         Label        |    |
+----------------------+    |--- cSPL
|     Flow-ID Label    |    |
|       Indicator      |    |
+----------------------+ <--+
|        Flow-ID       |
|         Label        |
+----------------------+ <= Bottom of stack
|                      |
|        Payload       |
|                      |
+----------------------+
     ]]></artwork>
+----------------------+]]></artwork>
        </figure>
        <t> 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 <xref target="RFC4026"/>.</t>

    <t> (3) Layout
	</section>

	<section anchor="example-three">
        <name>Layout of the Flow-ID label Label when applied Applied to both MPLS transport Transport and MPLS service.</t> Service</name>
        <figure anchor="Figure_4" title="Applying anchor="Figure_4">
          <name>Applying Flow-ID to both MPLS transport Transport and MPLS service"> Service</name>
          <artwork align="center"><![CDATA[
+----------------------+
|          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       |
|                      |
+----------------------+
     ]]></artwork>
+----------------------+]]></artwork>
        </figure>

     <t> Note
        <t>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.</t>
	</section>
      </section>
    </section>
    <section title="Procedures anchor="procedures-of-encap">
      <name>Procedures of Encapsulation, Look-up Look-Up, and Decapsulation"> Decapsulation</name>
      <t>
    The procedures for Flow-ID label encapsulation, look-up look-up, and decapsulation are summarized as follows:
    <list style="symbols">
      </t>
      <ul spacing="normal">
        <li>
          <t>
    The MPLS ingress node <xref target="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. <xref target="flow-based-pm-encapsulation"/>.
          </t>
        </li>
        <li>
<!-- [rfced] "perform some deep labels inspection beyond the label" reads oddly.  Please review.

Original:
      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.

Perhaps:
      Note that
      while looking up the Flow-ID label, the transit node needs to
      inspect beyond the label at the top
      of the label stack used to make forwarding decisions.
-->
          <t>
    If the edge-to-edge measurement is applied, i.e., the T bit is set to 1, then only the MPLS ingress/egress node <xref target="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, referring to the Alternate-Marking method. Method. Section 6 of <xref target="I-D.ietf-ippm-alt-mark-deployment"/>
	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.
          </t>
        </li>
        <li>
          <t>
    The processing node MUST <bcp14>MUST</bcp14> 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 <bcp14>MUST</bcp14> pop the whole MPLS label stack, and this stack. This document doesn't introduce any new process to the decapsulated packet.
          </t>
    </list>
    </t>
        </li>
      </ul>
    </section>
    <section title="Procedures anchor="procedures-of-flow-id-alloc">
      <name>Procedures of Flow-ID allocation"> Allocation</name>
      <t>
    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:
    <list style="symbols">
      </t>
      <ul spacing="normal">
        <li>
          <t>
    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).
          </t>
        </li>
        <li>
          <t>
    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 <xref target="RFC7011"/>, target="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).
          </t>
    </list>
    </t>
        </li>
      </ul>
      <t>
    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 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.
      </t>
      <t>
    Whether using the two methods mentioned above or other methods to allocate Flow-ID, the NMS/controller MUST <bcp14>MUST</bcp14> ensure that every
	generated Flow-ID is unique within the administrative domain and MUST NOT <bcp14>MUST NOT</bcp14> have any value in the reserved label space
	(0-15) <xref target="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.
      </t>
    </section>
    <section title="FLC anchor="flc-frld-considerations">
      <name>FLC and FRLD Considerations"> Considerations</name>
      <t> Analogous to the Entropy Label Capability (ELC) defined in Section 5 of <xref sectionFormat="of" section="5" target="RFC6790"/> and the
  Entropy Readable Label Depth (ERLD) defined in Section 4 of <xref sectionFormat="of" section="4" target="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.</t>
      <t> The ingress node MUST <bcp14>MUST</bcp14> insert each FL at an appropriate depth, which ensures the node to which the
  FL is exposed has the FLC. The ingress node SHOULD <bcp14>SHOULD</bcp14> 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.</t>
      <t> 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 <bcp14>MAY</bcp14> allow
  the ingress node to place FL between SID labels. This means that multiple identical FLs at different depths MAY <bcp14>MAY</bcp14> be
  interleaved with SID labels. When this occurs, sophisticated network planning may be needed, which is beyond the scope of this document.</t>
    </section>
    <section title="Equal-Cost anchor="ecmp">
      <name>Equal-Cost Multipath Considerations"> Considerations</name>
      <t> Analogous to what's described in Section 5 of <xref sectionFormat="of" section="5" target="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) <xref target="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 <xref target="RFC6790"/> or add FL to all flows.</t>
    </section>
    <section title="Security Considerations"> anchor="sec-considerations">
      <name>Security Considerations</name>
      <t> As specified in Section 7.1 of <xref sectionFormat="of" section="7.1" target="RFC9341"/>, "for security reasons, the Alternate-Marking Method MUST <bcp14>MUST</bcp14> 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 <bcp14>MUST</bcp14> only be applied to controlled domains,
  otherwise domains;
  otherwise, the potential attacks discussed in Section 10 of <xref sectionFormat="of" section="10" target="RFC9341"/> may be applied to the deployed MPLS networks. </t>
      <t> As specified in Section 3, <xref target="flow-based-pm-encapsulation"/>, the value of a Flow-ID label MUST <bcp14>MUST</bcp14> 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 <bcp14>MUST NOT</bcp14> 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. </t>
      <t> To prevent packets carrying Flow-ID labels from leaking from one domain to another, domain boundary
  nodes MUST <bcp14>MUST</bcp14> deploy policies (e.g., ACL) to filter out these packets.  Specifically, at the sending edge,
  the domain boundary node MUST <bcp14>MUST</bcp14> 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 <bcp14>MUST</bcp14> 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.</t>
    </section>

    <section title="Implementation Status">
    <t>[Note to the RFC Editor - remove this section before publication, as well as remove the reference to <xref target="RFC7942"/>.</t>

    <t>This section records the status of known implementations of the protocol defined by this specification at the time
	of posting of this Internet-Draft, and is based on a proposal described in <xref target="RFC7942"/>. The description of
	implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs.
	Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore,
	no effort anchor="iana-considerations">
      <name>IANA Considerations</name>

      <t>IANA has been spent to verify assigned the information presented here that was supplied by IETF contributors. This is not
	intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are
	advised to note that other implementations may exist.</t>

    <t>According to <xref target="RFC7942"/>, "this will allow reviewers and working groups to assign due consideration to
	documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback
	that have made the implemented protocols more mature. It is up to the individual working groups to use this information
	as they see fit".</t>

    <section title="Fiberhome">
      <ul spacing="normal">
        <li>
          <t>Organization: Fiberhome Corporation.</t>
        </li>
        <li>
          <t>Implementation: Fiberhome R82*, R800*, S680*, S780* series routers are running the common-building block 'Flow-based PM Encapsulation following value in MPLS'.</t>
        </li>
        <li>
          <t>Maturity Level: Product</t>
        </li>
        <li>
          <t>Coverage: Partial, section 3 and example (2) of section 3.1.</t>
        </li>
        <li>
          <t>Version: Draft-08</t>
        </li>
        <li>
          <t>Licensing: N/A</t>
        </li>
        <li>
          <t>Implementation experience: Nothing specific.</t>
        </li>
        <li>
          <t>Contact: djy@fiberhome.com</t>
        </li>
        <li>
          <t>Last updated: December 25, 2023</t>
        </li>
      </ul>
    </section>

    <section title="Huawei Technologies">
      <ul spacing="normal">
        <li>
          <t>Organization: Huawei Technologies.</t>
        </li>
        <li>
          <t>Implementation: Huawei ATN8XX, ATN910C, ATN980B, CX600-M2, NE40E, ME60-X1X2, ME60-X3X8X16 Routers running VRPV800R021C00 or above.
		  Huawei NCE-IP Controller running V1R21C00 or above.</t>
        </li>
        <li>
          <t>Maturity Level: Product</t>
        </li>
        <li>
          <t>Coverage: Partial, section 3 and example (2) of section 3.1.</t>
        </li>
        <li>
          <t>Version: Draft-08</t>
        </li>
        <li>
          <t>Licensing: N/A</t>
        </li>
        <li>
          <t>Implementation experience: Nothing specific.</t>
        </li>
        <li>
          <t>Contact: zhoutianran@huawei.com</t>
        </li>
        <li>
          <t>Last updated: January 10, 2024</t>
        </li>
      </ul>
    </section>

    <section title="ZTE Corp">
      <ul spacing="normal">
        <li>
          <t>Organization: ZTE Corporation.</t>
        </li>
        <li>
          <t>Implementation: ZTE ZXCTN 6500-32 routers running V5.00.20 or above. ZTE ZXCTN 6170H routers running V5.00.30.20 or above. ZTE
		  ElasticNet UME Controller running V16.22.20 or above.</t>
        </li>
        <li>
          <t>Maturity Level: Product</t>
        </li>
        <li>
          <t>Coverage: Partial, section 3 and example (2) of section 3.1.</t>
        </li>
        <li>
          <t>Version: Draft-08</t>
        </li>
        <li>
          <t>Licensing: N/A</t>
        </li>
        <li>
          <t>Implementation experience: Nothing specific.</t>
        </li>
        <li>
          <t>Contact: xiao.min2@zte.com.cn</t>
        </li>
        <li>
          <t>Last updated: January 22, 2024</t>
        </li>
      </ul>
    </section>

    <section title="China Mobile">
      <t> China Mobile reported that they have conducted interconnection tests with multiple vendors according to this draft. The tests result have proven
   that the solutions from multiple vendors are mature and ready for large-scale deployment. This report was last updated on January 10, 2024.</t>
    </section>

  </section>

  <section title="IANA Considerations">
  <t> From the "Extended 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:</t>
     <texttable anchor="Table_1" title="New registry group: </t>

      <table anchor="Table_1">
        <name>New Extended Special-Purpose MPLS Label Value for Flow-ID Label Indicator">

         <ttcol align="left">Value</ttcol>

         <ttcol align="left">Description</ttcol>

         <ttcol align="left">Reference</ttcol>

         <c>TBA1 (value 18 is recommended)</c>

         <c>Flow-ID Indicator</name>
        <thead>
          <tr>
            <th align="left">Value</th>
            <th align="left">Description</th>
            <th align="left">Reference</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td align="left">18</td>
            <td align="left">Flow-ID Label Indicator (FLI)</c>

         <c>This Document</c>

     </texttable> (FLI)</td>
            <td align="left">RFC 9714</td>
          </tr>
        </tbody>
      </table>
    </section>
  </middle>
  <back>
<displayreference target="I-D.ietf-ippm-alt-mark-deployment" to="ALT-MARK"/>

    <references>
      <name>References</name>
      <references>
        <name>Normative References</name>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3031.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3032.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9017.xml"/>
      </references>
      <references>
        <name>Informative References</name>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4026.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7011.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8372.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6790.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8662.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8957.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9341.xml"/>
        <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9613.xml"/>
<!-- [I-D.ietf-ippm-alt-mark-deployment] IESG State: I-D Exists as of 10/23/2024 -->
        <xi:include href="https://datatracker.ietf.org/doc/bibxml3/draft-ietf-ippm-alt-mark-deployment.xml"/>
      </references>
    </references>

<!-- [rfced] Note the following regarding terminology:

A) The following term appears with inconsistent capitalization.  Perhaps FL can be used throughout once the abbreviated form is introduced?  This avoids the capitalization issue.

Flow-ID Label vs Flow-ID label

B) "ECMP" is only used in connection with its expanded form.  Perhaps the abbreviated form does not need to be introduced/used in this document?

Originals from

- Section 2.1:
   ECMP: Equal-Cost Multipath

- Section 7:
   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 caused by the Synonymous Flow Label
   (SFL) [RFC8957].

C) We updated the capitalization as follows for consistency with RFC 9341.  Please let us know if you disagree.

Alternate-Marking method -> Alternate-Marking Method

-->

    <section title="Acknowledgements"> anchor="acknowledgements" numbered="false">
      <name>Acknowledgements</name>
      <t> 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 <contact fullname="Loa
      Andersson"/>, <contact fullname="Tarek Saad"/>, <contact
      fullname="Stewart Bryant"/>, <contact fullname="Rakesh Gandhi"/>,
      <contact fullname="Greg Mirsky"/>, <contact fullname="Aihua Liu"/>,
      <contact fullname="Shuangping Zhan"/>, <contact fullname="Ming Ke"/>,
      <contact fullname="Wei He"/>, <contact fullname="Ximing Dong"/>,
      <contact fullname="Darren Dukes"/>, <contact fullname="Tony Li"/>,
      <contact fullname="James Guichard"/>, <contact fullname="Daniele
      Ceccarelli"/>, <contact fullname="Eric Vyncke"/>, <contact
      fullname="John Scudder"/>, <contact fullname="Gunter van de Velde, Roman Danyliw, Warren Kumari, Murray Kucherawy, Deb Cooley, Zaheduzzaman
  Sarker, and Deboraha Brungard Velde"/>,
      <contact fullname="Roman Danyliw"/>, <contact fullname="Warren
      Kumari"/>, <contact fullname="Murray Kucherawy"/>, <contact
      fullname="Deb Cooley"/>, <contact fullname="Zaheduzzaman Sarker"/>, and
      <contact fullname="Deboraha Brungard"/> for their careful review and
      very helpful comments.</t>
      <t> They also wish to acknowledge Italo Busi and Chandrasekar Ramachandran <contact fullname="Italo Busi"/> and
      <contact fullname="Chandrasekar Ramachandran"/> for their insightful
      MPLS-RT review and constructive comments.</t>
      <t> Additionally, the authors would like to thank Dhruv Dhody <contact
      fullname="Dhruv Dhody"/> for the English grammar review.</t>
    </section>
    <section title="Contributors">
  <t>Minxue Wang<br/>China Mobile<br/>Email: wangminxue@chinamobile.com</t>
  <t>Wen Ye<br/>China Mobile<br/>Email: yewen@chinamobile.com</t> anchor="contrib" numbered="false">
      <name>Contributors</name>

      <contact fullname="Minxue Wang">
      <organization>China Mobile</organization>
      <address>
        <email>wangminxue@chinamobile.com</email>
      </address>
      </contact>

      <contact fullname="Wen Ye">
      <organization>China Mobile</organization>
      <address>
        <email>yewen@chinamobile.com</email>
      </address>
      </contact>

    </section>

</middle>

<back>

    <references title="Normative References">
     <?rfc include="reference.RFC.2119"?>
     <?rfc include="reference.RFC.8174"?>
     <?rfc include="reference.RFC.3031"?>
     <?rfc include="reference.RFC.3032"?>
     <?rfc include="reference.RFC.9017"?>
    </references>

    <references title="Informative References">
     <?rfc include="reference.RFC.4026"?>
     <?rfc include="reference.RFC.7011"?>
     <?rfc include="reference.RFC.8372"?>
     <?rfc include="reference.RFC.6790"?>
     <?rfc include="reference.RFC.8662"?>
     <?rfc include="reference.RFC.8957"?>
     <?rfc include="reference.RFC.7942"?>
     <?rfc include="reference.RFC.9341"?>
     <?rfc include="reference.RFC.9613"?>
     <?rfc include="reference.I-D.ietf-ippm-alt-mark-deployment"?>
    </references>

<!-- [rfced] Please review the "Inclusive Language" portion of the online
Style Guide <https://www.rfc-editor.org/styleguide/part2/#inclusive_language>
and let us know if any changes are needed.  Updates of this nature typically
result in more precise language, which is helpful for readers.

Note that our script did not flag any words in particular, but this should
still be reviewed as a best practice.
-->

  </back>
</rfc>