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<rfc number="8741" consensus="true" xmlns:xi="http://www.w3.org/2001/XInclude"
     category="std" docName="draft-ietf-pce-lsp-control-request-11"
     ipr="trust200902" obsoletes="" updates="" submissionType="IETF" xml:lang="en">
     xml:lang="en" tocInclude="true" tocDepth="4" symRefs="true"
     sortRefs="true" version="3">

  <!-- xml2rfc v2v3 conversion 2.37.3 -->
  <front>
    <title abbrev="LSP Control Request">
    Ability for a Stateful Path Computation Element (PCE) to request Request and obtain control
    Obtain Control of a Label Switched Path (LSP)</title>
    <seriesInfo name="RFC" value="8741"/>
    <author fullname="Aswatnarayan Raghuram" initials="A." surname="Raghuram">
      <organization>AT&amp;T</organization>
      <address>
        <postal>
          <street>200 S Laurel Aevenue</street> Avenue</street>
          <city>Middletown</city>
          <region>NJ</region>
          <code>07748</code>
          <country>USA</country>
          <country>United States of America</country>
        </postal>
        <email>ar2521@att.com</email>
      </address>
    </author>
    <author fullname="Al Goddard" initials="A." surname="Goddard">
      <organization>AT&amp;T</organization>
      <address>
        <postal>
          <street>200 S Laurel Aevenue</street> Avenue</street>
          <city>Middletown</city>
          <region>NJ</region>
          <code>07748</code>
          <country>USA</country>
          <country>United States of America</country>
        </postal>
        <email>ag6941@att.com</email>
      </address>
    </author>
    <author fullname="Jay Karthik" initials="J." surname="Karthik">
      <organization>Cisco Systems, Inc.</organization>
      <address>
        <postal>
          <street>125 High Street</street>
          <city>Boston</city>
          <region>Massachusetts</region>
          <code>02110</code>
          <country>USA</country>
          <country>United States of America</country>
        </postal>
        <email>jakarthi@cisco.com</email>
      </address>
    </author>
    <author fullname="Siva Sivabalan" initials="S." surname="Sivabalan">
      <organization>Cisco Systems, Inc.</organization>
      <address>
        <postal>
          <street>2000 Innovation Drive</street>
          <city>Kanata</city>
          <region>Ontario</region>
          <code>K2K 3E8</code>
          <country>Canada</country>
        </postal>
        <email>msiva@cisco.com</email>
      </address>
    </author>
    <author initials="M" surname="Negi" fullname="Mahendra Singh Negi">
      <organization>Huawei Technologies</organization>
      <address>
        <postal>
          <street>Divyashree Techno Park, Whitefield</street>
          <city>Bangalore</city>
          <region>Karnataka</region>
          <code>560066</code>
          <country>India</country>
        </postal>
        <email>mahend.ietf@gmail.com</email>
      </address>
    </author>
    <date year="2019"/> month="February" year="2020"/>
    <workgroup>PCE Working Group</workgroup>

    <abstract>
      <t>A Stateful stateful Path Computation Element (PCE) retains information about
      the placement of Multiprotocol Label Switching (MPLS) Traffic
      Engineering Label Switched Paths (TE LSPs). When a PCE has stateful
      control over LSPs LSPs, it may send indications to LSP head-ends to modify the
      attributes (especially the paths) of the LSPs. A Path Computation Client
      (PCC) that has set up LSPs under local configuration may delegate
      control of those LSPs to a stateful PCE.</t>
      <t>There are use-cases use cases in which a stateful PCE may wish to obtain
      control of locally configured LSPs of which that it is aware of but that have
      not been delegated to the PCE.</t>
      <t>This document describes an extension to the Path Computation Element
   communication
   Communication Protocol (PCEP) to enable a PCE to make requests for
   such control.</t>
    </abstract>
  </front>
  <middle>
    <section anchor="Introduction" title="Introduction">

<t>Stateful Path numbered="true" toc="default">
      <name>Introduction</name>
      <t>"Path Computation Element (PCE) communication Communication Protocol (PCEP) extensions Extensions
      for Stateful PCE"
      <xref target="RFC8231"/> target="RFC8231" format="default"/> specifies a set of
      extensions to PCEP <xref target="RFC5440"/> target="RFC5440" format="default"/> to enable
      stateful control of Traffic Engineering Label Switched Paths (TE LSPs)
      between and across PCEP sessions in compliance with <xref target="RFC4657"/>.
      target="RFC4657" format="default"/>.
It includes mechanisms to
      synchronize LSP state between Path Computation Clients (PCCs) and PCEs,
      delegate control of LSPs to PCE, PCEs, and PCE-control of allow PCEs to control the timing and sequence
      of path computations within and across PCEP sessions. The stateful PCEP
      defines the following two useful network operations:

<list style="symbols">
        <t>Delegation: As
</t>
      <dl newline="false" indent="13" spacing="normal">
        <dt>Delegation:</dt>
        <dd>As per <xref target="RFC8051"/>, target="RFC8051" format="default"/>, an operation to
	grant a PCE temporary rights to modify a
      subset of LSP parameters on one or more LSPs of a PCC.  LSPs are
      delegated from a PCC to a PCE and are referred to as "delegated"
      LSPs.</t>

 <t>Revocation: As
      LSPs.</dd>
        <dt>Revocation:</dt>
        <dd>As per <xref target="RFC8231"/>, target="RFC8231" format="default"/>, an operation
	performed by a PCC on a previously delegated LSP. Revocation revokes
	the rights granted to the PCE in the delegation operation.</t>
</list>
</t> operation.</dd>
      </dl>
      <t>For Redundant Stateful redundant stateful PCEs (section 5.7.4. of <xref target="RFC8231"/>), (<xref target="RFC8231"
      sectionFormat="of" section="5.7.4"/>), during a PCE failure, one of the redundant PCE PCEs
      might want to request to take control over an LSP. The redundant PCEs
      may use a local policy or a proprietary election mechanism to decide
      which PCE would take control. In this case, a mechanism is needed for a
      stateful PCE to request control of one or more LSPs from a PCC, PCC so that
      a newly elected primary PCE can request to take over control.</t>
      <t>In case of virtualized PCEs (vPCEs) running in virtual network
      function (VNF) mode, as the computation load in the network increases, a
      new instance of vPCE could be instantiated to balance the current
      load.
The PCEs could use a proprietary algorithm to decide which LSPs to can
      be assigned to the new vPCE. Thus, having a mechanism for the PCE to
      request control of some LSPs is needed.</t>
      <t>In some deployments, the operator would like to use stateful PCE for
      global optimization algorithms but would still like to keep the control
      of the LSP at the PCC. In such cases, a stateful PCE could request to
      take control during the global optimization and return the delegation
      once done.</t>
      <t>Note that <xref target="RFC8231"/> target="RFC8231" format="default"/> specifies a
      mechanism for a PCC to delegate an orphaned LSP to another PCE. The
      mechanism defined in this document can be used in conjunction to with <xref target="RFC8231"/>.
      target="RFC8231" format="default"/>. Ultimately, it is the PCC that
      decides which PCE to delegate the orphaned LSP to.</t>

<!-- Dhruv commented this section
<t>Some network operators prefer head-end (PCC) based reactivity to network events (e.g., link failure). For example, typically operators would like to reduce the time that backup LSP are being used for fast-reroute protection as the links that a backup LSP traverses may be congested when fast-reroute is active. PCC based LSP failure detection and re-routing mechanisms enable operators to minimize the duration of such congestion and meet operational requirements/constraints. As such, during normal operations, it may be preferable for PCC to have full control of its LSPs. However, operators shall prefer to use PCE for planned events such as centralized optimization and placement of LSPs. In this case, it is preferable for a PCE to obtain the control of one or more LSPs from a PCC, rather than waiting for the PCC to delegate the control. Once the PCE completes its operation, it relinquishes the control of the LSPs. Such capability enables operators  to combine the benefits of both centralized and distributed control of TE LSPs to get the best of both worlds.</t>
-->

      <t>This specification provides a simple extension: by using it extension that allows a PCE can
     to request control of one or more LSPs from any PCC over the stateful
      PCEP session. The procedures for granting and relinquishing control of
      the LSPs are specified in accordance with the specification <xref target="RFC8231"/>
      target="RFC8231" format="default"/> unless explicitly set aside in this document. </t>
      document.</t>
    </section>
    <!-- Introduction -->
    <section title="Terminology"> numbered="true" toc="default">
      <name>Terminology</name>
      <t> This document uses the following terms defined in <xref target="RFC5440"/>:
	<list style="hanging">
     <t hangText="  PCC:">Path target="RFC5440" format="default"/>:
      </t>

      <dl newline="false" spacing="normal" indent="6">
        <dt>  PCC:</dt>
        <dd>Path Computation Client.</t>
     <t hangText="  PCE:">Path Client</dd>
        <dt>  PCE:</dt>
        <dd>Path Computation Element.</t>
     <t hangText="  PCEP:">Path Element</dd>
        <dt>  PCEP:</dt>
        <dd>Path Computation Element communication Protocol.</t>
     </list>
</t> Protocol</dd>
      </dl>
      <t>This document uses the following terms defined in <xref target="RFC8231"/>:
  <list style="hanging">
     <t hangText="  PCRpt:">Path target="RFC8231" format="default"/>:
      </t>
      <dl newline="false" spacing="normal" indent="6">
        <dt>  PCRpt:</dt>
        <dd>Path Computation State Report message.</t>
     <t hangText="  PCUpd:">Path message</dd>
        <dt>  PCUpd:</dt>
        <dd>Path Computation Update Request message.</t>
     <t hangText="  PLSP-ID:">A message</dd>
        <dt>  PLSP-ID:</dt>
        <dd>A PCEP-specific identifier for the LSP.</t>
     <t hangText="  SRP:">Stateful LSP</dd>
        <dt>  SRP:</dt>
        <dd>Stateful PCE Request Parameters.</t>
      </list>
</t> Parameters</dd>
      </dl>
      <t>Readers of this document are expected to have some familiarity with <xref target="RFC8231"/>.</t> target="RFC8231" format="default"/>.</t>
      <section 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>
    <!-- Terminology -->
    <section anchor="LSP-Gain-Flag" title="LSP numbered="true" toc="default">
      <name>LSP Control Request Flag"> Flag</name>
      <t>The Stateful PCE Request Parameters (SRP) object is defined in Section 7.2 of
      <xref target="RFC8231"/> target="RFC8231" sectionFormat="of" section="7.2"/> and it includes
      a Flags field.</t>

<!-- changed from LSp to SRP by Dhruv
 <figure anchor="LSP-Object" title="The LSP Object">
        <artwork align="center"><![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
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |          PLSP-ID                      |Flags|G|C|    O|A|R|S|D|
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                             TLVs                              |
  ~                                                               ~
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ]]></artwork>
      </figure>
      -->
      <!--
 <figure anchor="SRP-Object" title="The SRP Object">
        <artwork align="center"><![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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Flags                            |C|R|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SRP-ID-number                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      //                      Optional TLVs                          //
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        ]]></artwork>
      </figure> -->

      <t>A new flag, the "LSP-Control Request Flag" (C) - TBD, Request" flag (30), also called the C
      flag, is introduced in the SRP object. On In a PCUpd message, a PCE sets
      the C Flag flag to 1 to indicate that it wishes to gain control of LSPs. The
      LSPs are identified by the PLSP-ID in the LSP object following the SRP
      object. A PLSP-ID of value other than 0 and 0xFFFFF is used to identify
      the LSP for which the PCE requests control. The A PLSP-ID value of 0
      indicates that the PCE is requesting control of all LSPs originating
      from the PCC that it wishes to delegate.  The C Flag flag has no meaning in
      other PCEP messages that carry SRP objects and for which the C flag MUST
      <bcp14>MUST</bcp14> be set to 0 on transmission and MUST <bcp14>MUST</bcp14>
      be ignored on receipt.</t>
      <t>The C flag is ignored in case the R flag <xref target="RFC8281"/> in the SRP object
      is set.</t>
    </section>
    <section anchor="Operation" title="Operation"> numbered="true" toc="default">
      <name>Operation</name>
      <t>During normal operation, a PCC that wishes to delegate the control of
      an LSP sets the D Flag (delegate, Section 7.3 of <xref target="RFC8231"/>) Delegate (D) flag (<xref target="RFC8231"
      sectionFormat="of" section="7.3"/>) to 1 in all PCRpt messages pertaining to the
      LSP. The PCE confirms the delegation by setting the D Flag flag to 1 in all PCUpd
      messages pertaining to the LSP. The PCC revokes the control of the LSP
      from the PCE by setting the D Flag flag to 0 in PCRpt messages pertaining to the
      LSP. If the PCE wishes to relinquish the control of the LSP, it sets the
      D Flag flag to 0 in all PCUpd messages pertaining to the LSP.</t>

      <t>If a PCE wishes to gain control over an LSP, it sends a PCUpd message
      with the C Flag flag set to 1 in the SRP object. The LSP for which the PCE requests
      control is identified by the PLSP-ID in the associated LSP object. The A
      PLSP-ID value of 0 indicates that the PCE wants control over all LSPs
      originating from the PCC. <!--A PCC that receives a PCUpd message with C Flag set to 1 and PLSP-ID of 0 MUST NOT trigger the error condition for unknown PLSP-ID in an LSP update request as per <xref target="RFC8231"/>.-->
An implementation of this feature needs to make
      sure to check for the LSP control feature (C flag set to 1) before any
      check for PLSP-ID (as prescribed in per <xref target="RFC8231"/>). target="RFC8231"
      format="default"/>). The D Flag flag and C Flag flag are mutually exclusive in a
      PCUpd message. The PCE MUST NOT <bcp14>MUST NOT</bcp14> send a control request
      for the LSP which that is already delegated to the PCE, i.e. i.e., if the D Flag flag is
      set in the PCUpd message, then the C Flag MUST NOT flag <bcp14>MUST NOT</bcp14> be
      set. If a PCC receives a PCUpd message with the D Flag flag set in the LSP object (i.e.
      (i.e., LSP is already delegated) and
the C Flag flag is also set (i.e. (i.e., PCE is making a control request), the PCC MUST
<bcp14>MUST</bcp14> ignore the C Flag. flag. A PCC can decide to delegate the
control of the LSP at its own discretion. If the PCC grants or denies the
control, it sends a PCRpt message with the D Flag flag set to 1 and 0 respectively 0, respectively, in
accordance with stateful PCEP <xref target="RFC8231"/>. target="RFC8231" format="default"/>. If
the PCC does not grant the control, it MAY <bcp14>MAY</bcp14> choose to not
respond, and the PCE MAY <bcp14>MAY</bcp14> choose to retry requesting the control control,
preferably using an exponentially increasing timer. Note that, if the PCUpd
message with the C Flag flag set is received for a currently non-delegated LSP (for
which the PCE is requesting delegation), this MUST NOT <bcp14>MUST NOT</bcp14> trigger
the error handling as specified in <xref target="RFC8231"/> target="RFC8231" format="default"/>
(a PCErr with Error-type=19 (Invalid Operation) and error-value 1 (Attempted
LSP Update Request for a non-delegated
   LSP)).</t>
      <t>As per <xref target="RFC8231"/>, target="RFC8231" format="default"/>, a PCC cannot
      delegate an LSP to more than one PCE at any time. If a PCE requests
      control of an LSP that has already been delegated by the PCC to another
      PCE, the PCC MAY <bcp14>MAY</bcp14> ignore the request, request or MAY
      <bcp14>MAY</bcp14> revoke
   the delegation to the first PCE before delegating it to the second. This
      choice is a matter of local policy.</t>

<!--<t>It should be noted that a legacy implementation of PCC, that does not understand the C Flag in PCUpd message, would simply ignore the flag (and the request to grant control over the LSP). At the same time it would trigger the error condition as specified in <xref target="RFC8231"/> (a PCErr with Error-type=19 (Invalid Operation)
   and error-value 1 (Attempted LSP Update Request for a non-delegated
   LSP)).</t>-->

   <t>It

      <t>
   It should be noted that a legacy implementation of PCC that does not
   support this extension would may receive an LSP control request: a PCUpd
   message with the C flag set and the D flag (delegate) unset, it unset. The legacy implementation
   would ignore the C flag and trigger the error condition for the D flag flag, as
   specified in <xref target="RFC8231"/> (a target="RFC8231" format="default"/> (i.e., a PCErr with
   Error-type=19 (Invalid Operation) and error-value 1 (Attempted LSP Update
   Request for a non-delegated LSP)). Further, in case of a PLSP-ID value of
   0, the error condition condition, as specified in <xref target="RFC8231"/> (a target="RFC8231"
   format="default"/>, (i.e., a PCErr with Error-type=19 (Invalid Operation)
   and error-value 3 (Attempted LSP Update Request for an LSP identified by an
   unknown PSP-ID)) would be triggered.</t>
      <t><xref target="RFC8281"/> target="RFC8281" format="default"/> describes the setup,
   maintenance
   maintenance, and teardown of PCE-initiated LSPs under the stateful PCE
   model. It also specifies how a PCE may obtain control over an orphaned LSP
   that was PCE-initiated. A PCE implementation can apply the mechanism described
   in this document in conjunction with those in <xref target="RFC8281"/>.</t>

</section>
<section anchor="Imp" title="Implementation Status">
<t>[Note to the RFC Editor - remove this section before publication, as well as remove the reference to RFC 7942.]</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 has been spent to verify 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 anchor="Onos" title="Huawei's Proof of Concept based on ONOS">
  <t>The PCE function was developed in the ONOS open source platform. This extension was implemented on a private version as a proof of concept to enable multi-instance support.
  <list style="symbols">
    <t>Organization: Huawei</t>
    <t>Implementation: Huawei's PoC based on ONOS</t>
    <t>Description: PCEP as a southbound plugin was added to ONOS. To support multi-instance ONOS deployment in a cluster, this extension in PCEP is used. Refer https://wiki.onosproject.org/display/ONOS/PCEP+Protocol</t>
    <t>Maturity Level: Prototype</t>
    <t>Coverage: Full</t>
    <t>Contact: satishk@huawei.com</t>
  </list></t>
</section> target="RFC8281"
   format="default"/>.</t>
    </section>
    <section anchor="Security" title="Security Considerations"> numbered="true" toc="default">
      <name>Security Considerations</name>
      <t>The security considerations listed in <xref target="RFC8231"/> target="RFC8231"
      format="default"/> and <xref target="RFC8281"/> target="RFC8281" format="default"/>
   apply to this document as well. However, this document also
   introduces a new attack vector. An attacker may flood the PCC with request requests
   to delegate all of its LSPs
   at a rate which that exceeds the PCC's ability to process them, either by
   spoofing messages or by compromising the PCE itself.
   The PCC SHOULD <bcp14>SHOULD</bcp14> be configured with a threshold rate for the
      delegation requests received from the PCE. If the threshold is reached,
      it is RECOMMENDED <bcp14>RECOMMENDED</bcp14> to log the issue.</t>
      <t>A PCC is the ultimate arbiter of delegation. As per <xref target="RFC8231"/>,
      target="RFC8231" format="default"/>, a local policy at the PCC is used to
      influence the delegation. A PCC can also revoke the delegation at any
      time. A PCC need not blindly trust the control requests and SHOULD
      <bcp14>SHOULD</bcp14> take local policy and other factors into
      consideration before honoring the request. </t>
      <t>Note that, that a PCE may not be sure if a PCC supports this feature. A
      PCE would try sending a control request to a 'legacy' PCC, which PCC that would
      in turn respond with an error error, as described in <xref target="Operation"/>. So target="Operation"
      format="default"/>. So, a PCE would learn this fact only when it wants to
      take control over an LSP. A PCE might also be susceptible to a downgrade
      attacks by falsifying the error condition.</t>
      <t>As per <xref target="RFC8231"/>, target="RFC8231" format="default"/>, it is RECOMMENDED <bcp14>RECOMMENDED</bcp14>
   that these PCEP extensions only be activated on authenticated and
   encrypted sessions across PCEs and PCCs belonging to the same
   administrative authority, using Transport Layer Security (TLS)
   <xref target="RFC8253"/>, target="RFC8253" format="default"/>, as per the recommendations and
   best current practices in
   BCP 195 <xref target="RFC7525"/> target="RFC7525" format="default"/> (unless explicitly
   excluded in <xref target="RFC8253"/>). target="RFC8253" format="default"/>).
      </t>
    </section>
    <section anchor="IANA" title="IANA Considerations">

 <section anchor="IANA-srp" title="SRP Object Flags"> numbered="true" toc="default">
      <name>IANA Considerations</name>

        <t>IANA maintains a registry called the "Path Computation Element Protocol (PCEP) Numbers" registry.  It contains a subregistry called has allocated the "SRP Object Flag Field" registry.  This document requests IANA to allocate following code point in the "SRP Object Flag
        Field" subregistry.</t>

 <texttable style="none" suppress-title="true" title="" subregistry in the "Path Computation Element Protocol (PCEP)
        Numbers" registry.</t>
        <table align="center">
  <ttcol align="left" width="20%">Bit</ttcol>
  <ttcol align="left" width="30%">Description</ttcol>
  <ttcol align="left" width="20%">Reference</ttcol>
  <c>TBD</c>
  <c>LSP-Control Request Flag</c>
  <c>This document</c>
  </texttable></section>
          <thead>
            <tr>
              <th align="left">Bit</th>
              <th align="left">Description</th>
              <th align="left">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">30</td>
              <td align="left">LSP Control Request</td>
              <td align="left">RFC 8741</td>
            </tr>
          </tbody>
        </table>
      </section>

    <section title="Manageability Considerations" toc="default"> toc="default" numbered="true">
      <name>Manageability Considerations</name>
      <t>
  All manageability requirements and considerations listed in <xref
  target="RFC5440" pageno="false" format="default"/>
  and <xref target="RFC8231" pageno="false" format="default"/>
  apply to PCEP protocol extensions defined in this document. In addition,
  requirements and considerations listed in this section apply.
      </t>
      <section title="Control toc="default" numbered="true">
        <name>Control of Function and Policy" toc="default"> Policy</name>

        <t>
  A PCC implementation SHOULD <bcp14>SHOULD</bcp14> allow the operator to configure
  the policy based on rules that specify the conditions under which it honors the
  request to control the LSPs. This includes the handling of the case where an
  LSP control request is received for an LSP that is currently delegated to
  some other PCE. A PCC implementation SHOULD <bcp14>SHOULD</bcp14> also allow the
  operator to configure the threshold rate based on which it accepts for the delegation requests
  received from the PCE. Further, the operator MAY <bcp14>MAY</bcp14> be allowed
  to trigger the LSP control request for a particular LSP at the PCE.  A PCE
  implementation SHOULD <bcp14>SHOULD</bcp14> also allow the operator to configure an
  exponentially increasing timer to retry the control requests for which the
  PCE did not get a response.
        </t>
      </section>
      <section title="Information toc="default" numbered="true">
        <name>Information and Data Models" toc="default"> Models</name>
        <t>The PCEP YANG module <xref target="I-D.ietf-pce-pcep-yang"/> target="I-D.ietf-pce-pcep-yang"
	format="default"/> could be extended to include a mechanism to trigger
	the LSP control request.</t>
      </section>
      <section title="Liveness toc="default" numbered="true">
        <name>Liveness Detection and Monitoring" toc="default"> Monitoring</name>
        <t>
  Mechanisms defined in this document do not imply any new liveness detection
  and monitoring requirements in addition to those already listed in <xref
  target="RFC5440" pageno="false" format="default"/>.
        </t>
      </section>
      <section title="Verify toc="default" numbered="true">
        <name>Verify Correct Operations" toc="default"> Operations</name>
        <t>
  Mechanisms defined in this document do not imply any new operation
  verification requirements in addition to those already listed in <xref
  target="RFC5440" pageno="false" format="default"/>
  and <xref target="RFC8231" pageno="false" format="default"/>.
        </t>
      </section>
      <section title="Requirements On toc="default" numbered="true">
        <name>Requirements on Other Protocols" toc="default"> Protocols</name>
        <t>Mechanisms defined in this document do not imply any new
	requirements on other protocols.</t>
      </section>
      <section title="Impact On toc="default" numbered="true">
        <name>Impact on Network Operations" toc="default"> Operations</name>
        <t>
  Mechanisms defined in <xref target="RFC5440" pageno="false" format="default"/>
  and
  <xref target="RFC8231" pageno="false" format="default"/> also apply to PCEP extensions defined in this document.
  Further, the mechanism described in this document can help the operator to
	request control of the LSPs at a particular PCE.</t>
      </section>
    </section>

  </middle>
  <back>

<displayreference target="I-D.ietf-pce-pcep-yang" to="PCEP-YANG"/>

    <references>
      <name>References</name>
      <references>
        <name>Normative References</name>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5440.xml"/>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8231.xml"/>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8281.xml"/>
      </references>
      <references>
        <name>Informative References</name>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.4657.xml"/>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.7525.xml"/>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8051.xml"/>
        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8253.xml"/>

<!-- ietf-pce-pcep-yang I-D Exists -->

        <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-pce-pcep-yang.xml"/>

      </references>
    </references>
    <section anchor="Acknowledgement" title="Acknowledgements"> numbered="false" toc="default">
      <name>Acknowledgements</name>
      <t>Thanks to Jonathan Hardwick to remind <contact fullname="Jonathan Hardwick"/> for reminding the authors to not use
      suggested values in IANA section.</t>
      <t>Thanks to Adrian Farrel, Haomian Zheng and Tomonori Takeda <contact fullname="Adrian Farrel"/>, <contact
      fullname="Haomian Zheng"/>, and <contact fullname="Tomonori Takeda"/> for their
      valuable comments.</t>
      <t>Thanks to Shawn <contact fullname="Shawn M. Emery Emery"/> for security directorate's his Security Directorate review.</t>
      <t>Thanks to Francesca Palombini <contact fullname="Francesca Palombini"/> for GENART review.</t>
      <t>Thanks to Benjamin Kaduk, Martin Vigoureux, Alvaro Retana, and Barry Leiba <contact fullname="Benjamin Kaduk"/>, <contact
      fullname="Martin Vigoureux"/>, <contact fullname="Alvaro Retana"/>, and
      <contact fullname="Barry Leiba"/> for IESG reviews.</t>
    </section>

</middle>

<back>

<references title="Normative References">
      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml"?>
      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5440.xml"?>
      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.8174.xml"?>

      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.8231.xml"?>
      <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.8281.xml"?>

</references>
<references title="Informative References">
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.4657.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.7525.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.7942.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.8051.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.8253.xml"?>

<?rfc include="http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ietf-pce-pcep-yang"?>

</references>
    <section title="Contributor Addresses" toc="default">
    <t>
    <figure title="" suppress-title="false" align="left" alt="" width="" height="">
          <artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Dhruv Dhody anchor="constributors" numbered="false">

      <name>Contributors</name>
<t>The following people contributed substantially to the content of this
document and should be considered coauthors:</t>
      <contact fullname="Dhruv Dhody">
       <organization> Huawei Technologies
Divyashree Technologies</organization>
       <address>
        <postal>
         <street>Divyashree Techno Park, Whitefield
Bangalore, Karnataka  560066
India

EMail: dhruv.ietf@gmail.com

        ]]></artwork>
        </figure>
      </t>

    <t>
    <figure title="" suppress-title="false" align="left" alt="" width="" height="">
          <artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Jon Parker
Cisco Whitefield</street>
         <city>Bangalore</city>
         <region>Karnataka</region>
         <code>560066</code>
         <country>India</country>
        </postal>
        <email>dhruv.ietf@gmail.com</email>
       </address>
      </contact>

      <contact fullname="Jon Parker">
       <organization>Cisco Systems, Inc.
2000 Inc.</organization>
       <address>
        <postal>
         <street>2000 Innovation Drive
Kanata, Ontario  K2K 3E8
Canada

EMail: jdparker@cisco.com

        ]]></artwork>
        </figure>
      </t>

    <t>
    <figure title="" suppress-title="false" align="left" alt="" width="" height="">
          <artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Chaitanya Yadlapalli
AT&T
200 Drive</street>
         <city>Kanata</city>
         <region>Ontario</region>
         <code>K2K 3E8</code>
         <country>Canada</country>
        </postal>
        <email>jdparker@cisco.com</email>
       </address>
      </contact>

      <contact fullname="Chaitanya Yadlapalli">
       <organization>AT&amp;T</organization>
       <address>
        <postal>
         <street>200 S Laurel Aevenue
Middletown NJ 07748
USA

EMail: cy098d@att.com
        ]]></artwork>
        </figure>
      </t> Avenue</street>
         <city>Middletown</city>
         <region>NJ</region>
         <code>07748</code>
         <country>United States of America</country>
        </postal>
        <email>cy098@att.com</email>
       </address>
     </contact>
    </section>

  </back>
</rfc>