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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902"
     docName="draft-ietf-mpls-sfl-framework-11" category="std"> number="8957" obsoletes=""
     updates="" submissionType="IETF" category="std" consensus="true"
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  <front>
    <title abbrev="MPLS FL">Synonymous Flow Label Framework</title>
    <seriesInfo name="RFC" value="8957"/>
    <author initials="S." surname="Bryant" fullname="Stewart Bryant">
      <organization>Futurewei Technologies Inc</organization> Inc.</organization>
      <address>
        <email>sb@stewartbryant.com</email>
      </address>
    </author>

    <author initials="M." surname="Chen" fullname="Mach fullname="Mach(Guoyi) Chen">
      <organization>Huawei</organization>
      <address>
        <email>mach.chen@huawei.com</email>
      </address>
    </author>
    <author initials="G." surname="Swallow" fullname="George Swallow">
      <organization>Southend Technical Center</organization>
      <address>
        <email>swallow.ietf@gmail.com</email>
      </address>
    </author>
    <author initials="S." surname="Sivabalan" fullname="Siva Sivabalan">
      <organization>Ciena Corporation</organization>
      <address>
        <email>ssivabal@ciena.com</email>
      </address>
    </author>
    <author initials="G." surname="Mirsky" fullname="Gregory Mirsky">
      <organization>ZTE Corp.</organization>
      <address>
        <email>gregimirsky@gmail.com</email>
      </address>
    </author>
    <date year="2020" month="October" day="02"/> year="2021" month="January"/>
    <workgroup>MPLS Working Group</workgroup>

    <abstract>
      <t>RFC 8372 (MPLS ("MPLS Flow Identification Considerations) Considerations") describes the
      requirement for introducing flow identities within the MPLS
      architecture.  This document describes a method of accomplishing this by
      using a technique called
Synonymous "Synonymous Flow Labels Labels" in which labels which that
      mimic the behaviour behavior of other labels provide the identification service.
      These identifiers can be used to trigger per-flow operations on the
      packet at the receiving label switching router.</t>
    </abstract>
  </front>
  <middle>
    <section anchor="introduction" title="Introduction"> numbered="true" toc="default">
      <name>Introduction</name>
      <t><xref target="RFC8372"/> (MPLS target="RFC8372" format="default"/> ("MPLS Flow Identification Considerations)
      Considerations") describes the requirement for introducing
flow identities within the MPLS architecture.
This document describes a method of providing the required identification by using a
technique called Synonymous "Synonymous Flow Labels (SFL) (SFLs)" in
which labels which that mimic the behaviour behavior of other MPLS labels provide the
identification service.  These identifiers can be used to trigger
per-flow operations on the packet at the receiving label switching
router.</t>
    </section>
    <section anchor="requirements-language" title="Requirements Language">

<t>The numbered="true" toc="default">
      <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 anchor="SFL" title="Synonymous numbered="true" toc="default">
      <name>Synonymous Flow Labels"> Labels</name>
      <t>An SFL is defined to be a label that causes exactly the same
behaviour
behavior at the egress Label Edge Router (LER) as the label it
replaces, except that it also causes one or more additional actions that have
been previously agreed between the peer LERs to be executed
on the packet.  There are many possible additional actions actions, such as
the measurement of
measuring the number of received packets in a flow,
triggering an IP Flow Information Export (IPFIX) <xref target="RFC7011"/> target="RFC7011"
format="default"/> capture, triggering other types of Deep Packet
Inspection, deep packet
inspection, or identification of identifying the packet source.  In, for  For example, in
a Performance Monitoring (PM) application, the agreed action could be
the
recording of the receipt of the packet by incrementing a packet
counter.  This is a natural action in many MPLS implementations, and
where supported supported, this permits the implementation of high quality high-quality
packet loss measurement without any change to the packet forwarding packet-forwarding
system.</t>
      <t>To illustrate the use of this technology, we start by  considering
the case where there is an “application” <tt>application</tt> label in the MPLS label stack.
As a first example, let us consider a
pseudowire (PW) <xref target="RFC3985"/> target="RFC3985" format="default"/> on which it is desired to make
packet loss measurements. Two labels, synonymous with the PW labels, are obtained
from the egress terminating provider edge (T-PE). By alternating
between these SFLs and using them in place of the PW label, the PW
packets may be batched for counting without any impact on the PW
forwarding behavior <xref target="RFC8321"/> target="RFC8321" format="default"/> (note that
strictly only one SFL is needed in
this application, but that is an optimization that is a matter for
the implementor). The method of obtaining these additional
labels is outside the scope of this text, text; however,
one control protocol that provides a method of obtaining SFLs  is described in
<xref target="I-D.bryant-mpls-sfl-control"/>.</t>

<t>Now target="I-D.bryant-mpls-sfl-control" format="default"/>.</t>
      <t>Next, consider an MPLS application that is multi-point multipoint to point point, such as
a VPN.  Here  Here, it is necessary to identify a packet batch from a
specific source.  This is achieved by making the SFLs source
specific, so that batches from one source are marked differently from
batches from another source.  The sources all operate independently
and asynchronously from each other, independently coordinating with
the destination.  Each ingress LER is thus able to establish its own SFL
to identify the sub-flow subflow and thus enable PM per flow.</t>

<t>Finally
      <t>Finally, we need to consider the case where there is no MPLS
application label such as occurs when sending IP over an LSP, i.e. a Label Switched Path
(LSP), i.e., there is a single label in the MPLS label stack.  In
this case case, introducing an SFL that was synonymous with the LSP label
would introduce network-wide forwarding state.  This would not be
acceptable for scaling reasons.  We therefore Therefore, we have no choice but to
introduce an additional label.  Where penultimate hop popping (PHP)
is in use, the semantics of this additional label can be similar to
the LSP label.  Where PHP is not in use, the semantics are similar to
an MPLS explicit Explicit NULL <xref target="RFC3032"/>. target="RFC3032" format="default"/>.  In both of
these cases cases, the label has the additional semantics of the SFL.</t>
      <t>Note that to achieve the goals set out above, SFLs need to be
allocated from the platform label table.</t>
    </section>
    <section anchor="user-service-traffic-in-the-data-plane" title="User numbered="true" toc="default">
      <name>User Service Traffic in the Data Plane"> Plane</name>
      <t>As noted in <xref target="SFL"/> target="SFL" format="default"/>, it is necessary to
      consider two cases:</t>

<t><list style="numbers">
  <t>Application
      <ol spacing="normal" type="1">
	<li>Application label is present</t>
  <t>Single label stack</t>
</list></t> present</li>
        <li>Single-label stack</li>
      </ol>
      <section anchor="ALP" title="Application numbered="true" toc="default">
        <name>Application Label Present"> Present</name>
        <t><xref target="Figure1"/> target="Figure1" format="default"/> shows the case in which
	both an LSP label and an application
label are present in the MPLS label stack.  Traffic with no SFL
function present runs over the “normal” <tt>normal</tt> stack, and SFL-enabled flows
run over the SFL stack with the SFL used to indicate the packet
batch.</t>
        <figure title="Use anchor="Figure1">
          <name>Use of Synonymous Labels In A Two Label in a Two-Label MPLS Label Stack" anchor="Figure1"><artwork><![CDATA[ Stack</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
 +-----------------+          +-----------------+
 |      LSP        |          |      LSP        |
 |     Label       |          |     Label       |
 |  (May be PHPed) |          |  (May be PHPed) |
 +-----------------+          +-----------------+
 |                 |          |                 |
 |  Application    |          | Synonymous Flow |
 |     Label       |          |     Label       |
 +-----------------+ <= BoS   +-----------------+ <= Bottom of stack Stack
 |                 |          |                 |
 |   Payload       |          |   Payload       |
 |                 |          |                 |
 +-----------------+          +-----------------+

"Normal" Label Stack         Label Stack with SFL
]]></artwork></figure>
]]></artwork>
        </figure>
        <t>At the egress LER LER, the LSP label is popped (if present).
Then Then, the
	SFL is processed executing both the synonymous function and the
	corresponding application function.</t>
        <section anchor="TTLandTC" title="Setting numbered="true" toc="default">
          <name>Setting TTL and the Traffic Class Bits"> Bits</name>
          <t>The TTL and the Traffic Class bits <xref target="RFC5462"/> target="RFC5462"
	  format="default"/> in the SFL label stack entry (LSE) would
normally be set to the same value as would have been set in the label
that the SFL is synonymous with.  However, it is recognized that that, if there
is an application need need, these fields in the SFL Label Stack Entry (LSE) MAY LSE
<bcp14>MAY</bcp14> be set these to some other value.  An
example would be where it was desired to cause the SFL to trigger an
action in the TTL expiry exception path as part of the label action.</t>
        </section>
      </section>
      <section anchor="SLS" title="Single Label Stack"> numbered="true" toc="default">
        <name>Single-Label Stack</name>
        <t><xref target="Figure2"/> target="Figure2" format="default"/> shows the case in which
	only an LSP label is present in the
MPLS label stack.  Traffic with no SFL function present runs over the
“normal” stack
"normal" stack, and SFL-enabled flows run over the SFL stack with the
SFL used to indicate the packet batch.  However  However, in this case case, it is
necessary for the ingress Label Edge Router (LER) to first push the SFL and
	then to push the LSP label.</t>
        <figure title="Use anchor="Figure2">
          <name>Use of Synonymous Labels In A Single Label in a Single-Label MPLS Label Stack" anchor="Figure2"><artwork><![CDATA[ Stack</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
                              +-----------------+
                              |      LSP        |
                              |     Label       |
                              |  (May be PHPed) |
 +-----------------+          +-----------------+
 |      LSP        |          |                 | <= Synonymous with
 |     Label       |          | Synonymous Flow |    Explicit NULL
 |  (May be PHPed) |          |     Label       |
 +-----------------+ <= BoS   +-----------------+ <= Bottom of stack Stack
 |                 |          |                 |
 |   Payload       |          |   Payload       |
 |                 |          |                 |
 +-----------------+          +-----------------+

"Normal" Label Stack         Label Stack with SFL
]]></artwork></figure>
]]></artwork>
        </figure>
        <t>At the receiving Label Switching Router (LSR) (LSR), it is necessary to
	consider two cases:</t>

<t><list style="numbers">
  <t>Where
        <ol spacing="normal" type="1">
	  <li>Where the LSP label is still present</t>
  <t>Where present</li>
          <li>Where the LSP label is penultimate hop popped</t>
</list></t> popped</li>
        </ol>
        <t>If the LSP label is present, it is processed exactly as it would
        normally processed be processed, and then it is popped.  This reveals the SFL,
        which, in the case of the measurements defined in <xref target="RFC6374"/> measurements,
        target="RFC6374" format="default"/>, is simply counted and then
        discarded.  In this respect respect, the processing of the SFL is synonymous
        with an MPLS Explicit NULL.  As the SFL is the bottom of stack, the IP
        packet that follows is processed as normal.</t>
        <t>If the LSP label is not present due to PHP action in the upstream
LSR, two almost equivalent processing actions can take place.  Either
the
The SFL can be treated either 1) as an LSP label that was not PHPed and the
additional associated SFL action is taken when the label is
processed.  Alternatively, it can be treated
processed or 2) as an MPLS Explicit NULL with
associated SFL actions.  From the perspective of the measurement
system described in this document document, the behaviour behavior of the two approaches is
indistinguishable and thus
indistinguishable; thus, either may be implemented.</t>
        <section anchor="setting-ttl-and-the-traffic-class-bits" title="Setting numbered="true" toc="default">
          <name>Setting TTL and the Traffic Class Bits"> Bits</name>
          <t>The TTL and the Traffic Class considerations described in <xref target="TTLandTC"/>
	  target="TTLandTC" format="default"/> apply.</t>
        </section>
      </section>
      <section anchor="aggregation-of-sfl-actions" title="Aggregation numbered="true" toc="default">
        <name>Aggregation of SFL Actions"> Actions</name>
        <t>There are cases where it is desirable to aggregate an SFL action
against a number of labels.  For labels, for example, where it is desirable to
have one counter record the number of packets received over a group
of application labels, labels or where the number of labels used by a single
application is large, large and the resultant increase in the number of
allocated labels needed to support the SFL actions may
becomes
become too large to be viable.  In these circumstances circumstances, it would be
necessary to introduce an additional label in the stack to act as an
aggregate instruction.  This is not strictly a synonymous action in
that the SFL is not replacing an existing label, label but is somewhat
similar to the single label single-label case shown in <xref target="SLS"/>, target="SLS" format="default"/>, and the same
signalling, management
signaling, management, and configuration tools would be applicable.</t>
        <figure title="Aggregate anchor="Figure3">
          <name>Aggregate SFL Actions" anchor="Figure3"><artwork><![CDATA[ Actions</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
                              +-----------------+
                              |      LSP        |
                              |     Label       |
                              |  (May be PHPed) |
 +-----------------+          +-----------------+
 |      LSP        |          |                 |
 |     Label       |          |   Aggregate     |
 |  (May be PHPed) |          |      SFL        |
 +-----------------+          +-----------------+
 |                 |          |                 |
 |  Application    |          |  Application    |
 |     Label       |          |     Label       |
 +-----------------+ <=BoS    +-----------------+ <= Bottom of stack Stack
 |                 |          |                 |
 |   Payload       |          |   Payload       |
 |                 |          |                 |
 +-----------------+          +-----------------+

"Normal" Label Stack         Label Stack with SFL
]]></artwork></figure>
]]></artwork>
        </figure>
        <t>The Aggregate aggregate SFL is shown in the label stack depicted in <xref target="Figure3"/>
	target="Figure3" format="default"/> as
preceding the application label, however label; however, the choice of position
before,
before or after, after the application label will be application specific.
In the case described in <xref target="ALP"/>, target="ALP" format="default"/>, by definition definition, the SFL has the
full application context.  In this case case, the positioning will depend
on whether the SFL action needs the full context of the application
to perform its action and whether the complexity of the application
will be increased by finding an SFL following the application label.</t>
      </section>
    </section>
    <section anchor="equal-cost-multipath-considerations" title="Equal Cost numbered="true" toc="default">
      <name>Equal-Cost Multipath Considerations"> Considerations</name>
      <t>The introduction of an SFL to an existing flow may cause that flow to take
a different path through the network under conditions of Equal Cost
Multi-path Equal-Cost
Multipath (ECMP).  This  This, in turn turn, may invalidate certain uses of
the SFL SFL, such as performance measurement applications.  Where this is
a problem problem, there are two solutions worthy of consideration:</t>

<t><list style="numbers">
  <t>The
      <ol spacing="normal" type="1">
	<li>The operator MAY <bcp14>MAY</bcp14> elect to always run with the SFL
	in place in the MPLS label stack.</t>
  <t>The stack.</li>
        <li>The operator can elect to use entropy labels <xref target="RFC6790"/> Entropy Labels target="RFC6790"
	format="default"/> in a network that fully supports
	this type of ECMP. If this approach is adopted, the intervening MPLS
	network MUST NOT <bcp14>MUST NOT</bcp14> load balance on any packet field other
	than the entropy label. Note that this is stricter than the text in Section 4.3 of
	<xref target="RFC6790"/>.</t>
</list></t> target="RFC6790" sectionFormat="of" section="4.3"/>.</li>
      </ol>
    </section>
    <section anchor="privacy" title="Privacy Considerations"> numbered="true" toc="default">
      <name>Privacy Considerations</name>
      <t>IETF concerns on pervasive monitoring are described in <xref target="RFC7258"/>.
      target="RFC7258" format="default"/>.  The inclusion of originating
      and/or flow information in a packet provides more identity information
      and hence potentially degrades the privacy of the communication to an
      attacker in a position to observe the added identifier.  Whilst the
      inclusion of the additional granularity does allow greater insight into
      the flow
characteristics characteristics, it does not specifically identify which node
      originated the packet unless the attacker can inspect the network at the
      point of ingress, ingress or inspection of inspect the control protocol packets.  This privacy
      threat may be mitigated by encrypting the control protocol packets, packets by
      regularly changing the synonymous labels or by concurrently using a
      number of such labels, including the use of a combination of those
      methods.  Minimizing the scope of the identity indication can be useful
      in minimizing the observability of the flow characteristics. Whenever
      IPFIX or other
DPI deep packet inspection (DPI) technique is used, their relavent
      relevant privacy considerations apply.</t>
    </section>
    <section anchor="security-considerations" title="Security Considerations"> numbered="true" toc="default">
      <name>Security Considerations</name>
      <t>There are
no new security issues associated with the MPLS data plane.  Any
control protocol used to request SFLs will need to ensure the
legitimacy of the request, i.e. i.e., that the requesting node is authorized
to make that SFL request by the network operator.</t>
    </section>
    <section anchor="iana-considerations" title="IANA Considerations"> numbered="true" toc="default">
      <name>IANA Considerations</name>
      <t>This draft makes document has no IANA requests.</t> actions.</t>
    </section>
  </middle>
  <back>

<displayreference target="I-D.bryant-mpls-sfl-control" to="MPLS-SFL-CONTROL"/>

    <references>
      <name>References</name>
      <references>
        <name>Normative References</name>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5462.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3032.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6790.xml"/>
      </references>
      <references>
        <name>Informative References</name>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3985.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8372.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6374.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7258.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8321.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7011.xml"/>

        <xi:include href="https://datatracker.ietf.org/doc/bibxml3/reference.I-D.bryant-mpls-sfl-control.xml"/>
      </references>
    </references>
    <section anchor="contributing-authors" title="Contributing Authors">

<figure><artwork><![CDATA[
Zhenbin Li
Huawei
Email: lizhenbin@huawei.com
]]></artwork></figure> numbered="false" toc="default">
      <name>Contributors</name>
<contact fullname="Zhenbin Li">
  <organization>Huawei</organization>
  <address>
    <postal/>
  <email>lizhenbin@huawei.com</email>
  </address>
</contact>
    </section>

  </middle>

  <back>

    <references title='Normative References'>

<reference  anchor="RFC5462" target='https://www.rfc-editor.org/info/rfc5462'>
<front>
<title>Multiprotocol Label Switching (MPLS) Label Stack Entry: &quot;EXP&quot; Field Renamed to &quot;Traffic Class&quot; Field</title>
<author initials='L.' surname='Andersson' fullname='L. Andersson'><organization /></author>
<author initials='R.' surname='Asati' fullname='R. Asati'><organization /></author>
<date year='2009' month='February' />
<abstract><t>The early Multiprotocol Label Switching (MPLS) documents defined the form of the MPLS label stack entry.  This includes a three-bit field called the &quot;EXP field&quot;.  The exact use of this field was not defined by these documents, except to state that it was to be &quot;reserved for experimental use&quot;.</t><t>Although the intended use of the EXP field was as a &quot;Class of Service&quot; (CoS) field, it was not named a CoS field by these early documents because the use of such a CoS field was not considered to be sufficiently defined.  Today a number of standards documents define its usage as a CoS field.</t><t>To avoid misunderstanding about how this field may be used, it has become increasingly necessary to rename this field.  This document changes the name of the field to the &quot;Traffic Class field&quot; (&quot;TC field&quot;).  In doing so, it also updates documents that define the current use of the EXP field.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='5462'/>
<seriesInfo name='DOI' value='10.17487/RFC5462'/>
</reference>

<reference  anchor="RFC2119" target='https://www.rfc-editor.org/info/rfc2119'>
<front>
<title>Key words for use in RFCs to Indicate Requirement Levels</title>
<author initials='S.' surname='Bradner' fullname='S. Bradner'><organization /></author>
<date year='1997' month='March' />
<abstract><t>In many standards track documents several words are used to signify the requirements in the specification.  These words are often capitalized. This document defines these words as they should be interpreted in IETF documents.  This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t></abstract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='2119'/>
<seriesInfo name='DOI' value='10.17487/RFC2119'/>
</reference>

<reference  anchor="RFC8174" target='https://www.rfc-editor.org/info/rfc8174'>
<front>
<title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title>
<author initials='B.' surname='Leiba' fullname='B. Leiba'><organization /></author>
<date year='2017' month='May' />
<abstract><t>RFC 2119 specifies common key words that may be used in protocol  specifications.  This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the  defined special meanings.</t></abstract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='8174'/>
<seriesInfo name='DOI' value='10.17487/RFC8174'/>
</reference>

<reference  anchor="RFC3032" target='https://www.rfc-editor.org/info/rfc3032'>
<front>
<title>MPLS Label Stack Encoding</title>
<author initials='E.' surname='Rosen' fullname='E. Rosen'><organization /></author>
<author initials='D.' surname='Tappan' fullname='D. Tappan'><organization /></author>
<author initials='G.' surname='Fedorkow' fullname='G. Fedorkow'><organization /></author>
<author initials='Y.' surname='Rekhter' fullname='Y. Rekhter'><organization /></author>
<author initials='D.' surname='Farinacci' fullname='D. Farinacci'><organization /></author>
<author initials='T.' surname='Li' fullname='T. Li'><organization /></author>
<author initials='A.' surname='Conta' fullname='A. Conta'><organization /></author>
<date year='2001' month='January' />
<abstract><t>This document specifies the encoding to be used by an LSR in order to transmit labeled packets on Point-to-Point Protocol (PPP) data links, on LAN data links, and possibly on other data links as well.  This document also specifies rules and procedures for processing the various fields of the label stack encoding.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='3032'/>
<seriesInfo name='DOI' value='10.17487/RFC3032'/>
</reference>

<reference  anchor="RFC6790" target='https://www.rfc-editor.org/info/rfc6790'>
<front>
<title>The Use of Entropy Labels in MPLS Forwarding</title>
<author initials='K.' surname='Kompella' fullname='K. Kompella'><organization /></author>
<author initials='J.' surname='Drake' fullname='J. Drake'><organization /></author>
<author initials='S.' surname='Amante' fullname='S. Amante'><organization /></author>
<author initials='W.' surname='Henderickx' fullname='W. Henderickx'><organization /></author>
<author initials='L.' surname='Yong' fullname='L. Yong'><organization /></author>
<date year='2012' month='November' />
<abstract><t>Load balancing is a powerful tool for engineering traffic across a network.  This memo suggests ways of improving load balancing across MPLS networks using the concept of &quot;entropy labels&quot;.  It defines the concept, describes why entropy labels are useful, enumerates properties of entropy labels that allow maximal benefit, and shows how they can be signaled and used for various applications.  This document updates RFCs 3031, 3107, 3209, and 5036.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='6790'/>
<seriesInfo name='DOI' value='10.17487/RFC6790'/>
</reference>

    </references>

    <references title='Informative References'>

<reference  anchor="RFC3985" target='https://www.rfc-editor.org/info/rfc3985'>
<front>
<title>Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture</title>
<author initials='S.' surname='Bryant' fullname='S. Bryant' role='editor'><organization /></author>
<author initials='P.' surname='Pate' fullname='P. Pate' role='editor'><organization /></author>
<date year='2005' month='March' />
<abstract><t>This document describes an architecture for Pseudo Wire Emulation Edge-to-Edge (PWE3).  It discusses the emulation of services such as Frame Relay, ATM, Ethernet, TDM, and SONET/SDH over packet switched networks (PSNs) using IP or MPLS.  It presents the architectural framework for pseudo wires (PWs), defines terminology, and specifies the various protocol elements and their functions.  This memo provides information for the Internet community.</t></abstract>
</front>
<seriesInfo name='RFC' value='3985'/>
<seriesInfo name='DOI' value='10.17487/RFC3985'/>
</reference>

<reference  anchor="RFC8372" target='https://www.rfc-editor.org/info/rfc8372'>
<front>
<title>MPLS Flow Identification Considerations</title>
<author initials='S.' surname='Bryant' fullname='S. Bryant'><organization /></author>
<author initials='C.' surname='Pignataro' fullname='C. Pignataro'><organization /></author>
<author initials='M.' surname='Chen' fullname='M. Chen'><organization /></author>
<author initials='Z.' surname='Li' fullname='Z. Li'><organization /></author>
<author initials='G.' surname='Mirsky' fullname='G. Mirsky'><organization /></author>
<date year='2018' month='May' />
<abstract><t>This document discusses aspects to consider when developing a solution for MPLS flow identification.  The key application that needs this solution is in-band performance monitoring of MPLS flows when MPLS is used to encapsulate user data packets.</t></abstract>
</front>
<seriesInfo name='RFC' value='8372'/>
<seriesInfo name='DOI' value='10.17487/RFC8372'/>
</reference>

<reference  anchor="RFC6374" target='https://www.rfc-editor.org/info/rfc6374'>
<front>
<title>Packet Loss and Delay Measurement for MPLS Networks</title>
<author initials='D.' surname='Frost' fullname='D. Frost'><organization /></author>
<author initials='S.' surname='Bryant' fullname='S. Bryant'><organization /></author>
<date year='2011' month='September' />
<abstract><t>Many service provider service level agreements (SLAs) depend on the ability to measure and monitor performance metrics for packet loss and one-way and two-way delay, as well as related metrics such as delay variation and channel throughput.  This measurement capability also provides operators with greater visibility into the performance characteristics of their networks, thereby facilitating planning, troubleshooting, and network performance evaluation.  This document specifies protocol mechanisms to enable the efficient and accurate measurement of these performance metrics in MPLS networks.  [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='6374'/>
<seriesInfo name='DOI' value='10.17487/RFC6374'/>
</reference>

<reference  anchor="RFC7258" target='https://www.rfc-editor.org/info/rfc7258'>
<front>
<title>Pervasive Monitoring Is an Attack</title>
<author initials='S.' surname='Farrell' fullname='S. Farrell'><organization /></author>
<author initials='H.' surname='Tschofenig' fullname='H. Tschofenig'><organization /></author>
<date year='2014' month='May' />
<abstract><t>Pervasive monitoring is a technical attack that should be mitigated in the design of IETF protocols, where possible.</t></abstract>
</front>
<seriesInfo name='BCP' value='188'/>
<seriesInfo name='RFC' value='7258'/>
<seriesInfo name='DOI' value='10.17487/RFC7258'/>
</reference>

<reference  anchor="RFC8321" target='https://www.rfc-editor.org/info/rfc8321'>
<front>
<title>Alternate-Marking Method for Passive and Hybrid Performance Monitoring</title>
<author initials='G.' surname='Fioccola' fullname='G. Fioccola' role='editor'><organization /></author>
<author initials='A.' surname='Capello' fullname='A. Capello'><organization /></author>
<author initials='M.' surname='Cociglio' fullname='M. Cociglio'><organization /></author>
<author initials='L.' surname='Castaldelli' fullname='L. Castaldelli'><organization /></author>
<author initials='M.' surname='Chen' fullname='M. Chen'><organization /></author>
<author initials='L.' surname='Zheng' fullname='L. Zheng'><organization /></author>
<author initials='G.' surname='Mirsky' fullname='G. Mirsky'><organization /></author>
<author initials='T.' surname='Mizrahi' fullname='T. Mizrahi'><organization /></author>
<date year='2018' month='January' />
<abstract><t>This document describes a method to perform packet loss, delay, and jitter measurements on live traffic.  This method is based on an Alternate-Marking (coloring) technique.  A report is provided in order to explain an example and show the method applicability.  This technology can be applied in various situations, as detailed in this document, and could be considered Passive or Hybrid depending on the application.</t></abstract>
</front>
<seriesInfo name='RFC' value='8321'/>
<seriesInfo name='DOI' value='10.17487/RFC8321'/>
</reference>

<reference  anchor="RFC7011" target='https://www.rfc-editor.org/info/rfc7011'>
<front>
<title>Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information</title>
<author initials='B.' surname='Claise' fullname='B. Claise' role='editor'><organization /></author>
<author initials='B.' surname='Trammell' fullname='B. Trammell' role='editor'><organization /></author>
<author initials='P.' surname='Aitken' fullname='P. Aitken'><organization /></author>
<date year='2013' month='September' />
<abstract><t>This document specifies the IP Flow Information Export (IPFIX) protocol, which serves as a means for transmitting Traffic Flow information over the network.  In order to transmit Traffic Flow information from an Exporting Process to a Collecting Process, a common representation of flow data and a standard means of communicating them are required.  This document describes how the IPFIX Data and Template Records are carried over a number of transport protocols from an IPFIX Exporting Process to an IPFIX Collecting Process.  This document obsoletes RFC 5101.</t></abstract>
</front>
<seriesInfo name='STD' value='77'/>
<seriesInfo name='RFC' value='7011'/>
<seriesInfo name='DOI' value='10.17487/RFC7011'/>
</reference>

<reference anchor="I-D.bryant-mpls-sfl-control">
<front>
<title>A Simple Control Protocol for MPLS SFLs</title>

<author initials='S' surname='Bryant' fullname='Stewart Bryant'>
    <organization />
</author>

<author initials='G' surname='Swallow' fullname='George Swallow'>
    <organization />
</author>

<author initials='S' surname='Sivabalan' fullname='Siva Sivabalan'>
    <organization />
</author>

<date month='June' day='8' year='2020' />

<abstract><t>In draft-ietf-mpls-sfl-framework the concept of MPLS synonymous flow labels (SFL) was introduced.  This document describes a simple control protocol that runs over an associated control header to request, withdraw, and extend the lifetime of such labels.  It is not the only control protocol that moght be used to support SFL, but it has the benefit of being able to be used without modifying of the existing MPLS control prodocols.  The existance of this design is not intended to restrict the ability to enhance an existing MPLS control protocol to add a similar capability.  A Querier MUST wait a configured time (suggested wait of 60 seconds) before re-attempting a Withdraw request.  No more than three Withdraw requests SHOULD be made.  These restricctions are to prevent overloading the control plane of the actioning router.</t></abstract>

</front>

<seriesInfo name='Internet-Draft' value='draft-bryant-mpls-sfl-control-08' />
<format type='TXT'
        target='http://www.ietf.org/internet-drafts/draft-bryant-mpls-sfl-control-08.txt' />
</reference>

    </references>
  </back>

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