PCEP Extensions for MPSL-TE LSP Path Protection with stateful PCE
draft-ananthakrishnan-pce-stateful-path-protection-04

Versions: 00 01 02 03 04                                                
PCE Working Group                                     H. Ananthakrishnan
Internet-Draft                                             Packet Design
Intended status: Standards Track                            S. Sivabalan
Expires: March 30, 2018                                            Cisco
                                                                C. Barth
                                                                R. Torvi
                                                        Juniper Networks
                                                                I. Minei
                                                             Google, Inc
                                                               E. Crabbe
                                                  Individual Contributor
                                                                D. Dhody
                                                     Huawei Technologies
                                                      September 26, 2017


   PCEP Extensions for MPSL-TE LSP Path Protection with stateful PCE
         draft-ananthakrishnan-pce-stateful-path-protection-04

Abstract

   A stateful Path Computation Element (PCE) is capable of computing as
   well as controlling via Path Computation Element Protocol (PCEP)
   Multiprotocol Label Switching Traffic Engineering Label Switched
   Paths (MPLS LSP).  Furthermore, it is also possible for a stateful
   PCE to create, maintain, and delete LSPs.  This document describes
   PCEP extension to associate two or more LSPs to provide end-to-end
   path protection.

Status of This Memo

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

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

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 30, 2018.






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Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Path Protection Association Type  . . . . . . . . . . . .   5
     3.2.  Path Protection Association TLV . . . . . . . . . . . . .   6
   4.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  PCC Initiated LSPs  . . . . . . . . . . . . . . . . . . .   7
     4.2.  PCE Initiated LSPs  . . . . . . . . . . . . . . . . . . .   7
     4.3.  State Synchronization . . . . . . . . . . . . . . . . . .   8
     4.4.  Session Termination . . . . . . . . . . . . . . . . . . .   8
     4.5.  Error Handling  . . . . . . . . . . . . . . . . . . . . .   8
   5.  Other considerations  . . . . . . . . . . . . . . . . . . . .   8
   6.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   9
     6.1.  Association Type  . . . . . . . . . . . . . . . . . . . .   9
     6.2.  PPAG TLV  . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.3.  PCEP Errors . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  Manageability Considerations  . . . . . . . . . . . . . . . .  11
     8.1.  Control of Function and Policy  . . . . . . . . . . . . .  11
     8.2.  Information and Data Models . . . . . . . . . . . . . . .  11
     8.3.  Liveness Detection and Monitoring . . . . . . . . . . . .  11
     8.4.  Verify Correct Operations . . . . . . . . . . . . . . . .  11
     8.5.  Requirements On Other Protocols . . . . . . . . . . . . .  11
     8.6.  Impact On Network Operations  . . . . . . . . . . . . . .  11
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     10.2.  Information References . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14




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1.  Introduction

   [RFC5440] describes PCEP for communication between a Path Computation
   Client (PCC) and a PCE or between one a pair of PCEs as per
   [RFC4655].  A PCE computes paths for MPLS-TE LSPs based on various
   constraints and optimization criteria.

   Stateful pce [RFC8231] specifies a set of extensions to PCEP to
   enable stateful control of paths such as MPLS TE LSPs between and
   across PCEP sessions in compliance with [RFC4657].  It includes
   mechanisms to effect LSP state synchronization between PCCs and PCEs,
   delegation of control of LSPs to PCEs, and PCE control of timing and
   sequence of path computations within and across PCEP sessions and
   focuses on a model where LSPs are configured on the PCC and control
   over them is delegated to the PCE.  Furthermore, a mechanism to
   dynamically instantiate LSPs on a PCC based on the requests from a
   stateful PCE or a controller using stateful PCE, is specified in
   [I-D.ietf-pce-pce-initiated-lsp].

   Path protection refers to a paradigm in which the working LSP is
   protected by one or more protection LSP(s).  When the working LSP
   fails, protection LSP(s) is/are activated.  When the working LSPs are
   computed and controlled by the PCE, there is benefit in a mode of
   operation where protection LSPs are as well.

   This document specifies a stateful PCEP extension to associate two or
   more LSPs for the purpose of setting up path protection.  The
   proposed extension covers the following scenarios:

   o  A PCC initiates a protection LSP and retains the control of the
      LSP.  The PCC computes the path itself or makes a request for path
      computation to a PCE.  After the path setup, it reports the
      information and state of the path to the PCE.  This is the passive
      stateful mode [RFC8051].

   o  A PCC initiates a protection LSP and delegates the control of the
      LSP to a stateful PCE.  The PCE may compute the path for the LSP
      and update the PCC with the information about the path as long as
      it controls the LSP.  This is the active stateful mode [RFC8051].

   o  A protection LSP could be initiated by a stateful PCE, which
      retains the control of the LSP.  The PCE is responsible for
      computing the path of the LSP and updating to the PCC with the
      information about the path.  This is the PCE Initiated mode
      [I-D.ietf-pce-pce-initiated-lsp].

   Note that protection LSP can be established prior to the failure (in
   which case the LSP is said to me in standby mode) or post failure of



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   the corresponding working LSP according to the operator choice/
   policy.

   [I-D.ietf-pce-association-group] introduces a generic mechanism to
   create a grouping of LSPs which can then be used to define
   associations between a set of LSPs that is equally applicable to
   stateful PCE (active and passive modes) and stateless PCE.

   This document specifies a PCEP extension to associate one working LSP
   with one or more protection LSPs using the generic association
   mechanism.

   This document describes a PCEP extension to associate protection LSPs
   by creating Path Protection Association Group (PPAG) and encoding
   this association in PCEP messages for stateful PCEP sessions.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Terminology

   The following terminologies are used in this document:

   ERO:  Explicit Route Object.

   LSP:  Label Switched Path.

   PCC:  Path Computation Client.

   PCE:  Path Computation Element

   PCEP:  Path Computation Element Protocol.

   PPAG:  Path Protection Association Group.

   TLV:  Type, Length, and Value.

3.  PCEP Extensions








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3.1.  Path Protection Association Type

   LSPs are not associated by listing the other LSPs with which they
   interact, but rather by making them belong to an association group
   referred to as "Path Protection Association Group" (PPAG) in this
   document.  All LSPs join a PPAG individually.  PPAG is based on the
   generic Association object used to associate two or more LSPs
   specified in [I-D.ietf-pce-association-group].  A member of a PPAG
   can take the role of working or protection LSP.  This document
   defines a new association type called "Path Protection Association
   Type" of value TBD1.  A PPAG can have one working LSP and/or one or
   more protection LSPs.  The source, destination and Tunnel ID (as
   carried in LSP-IDENTIFIERS TLV [RFC8231], with description as per
   [RFC3209]) of all LSPs within a PPAG MUST be the same.  As per
   [RFC3209], TE tunnel is used to associate a set of LSPs during
   reroute or to spread a traffic trunk over multiple paths.

   The format of the Association object used for PPAG is specified in
   [I-D.ietf-pce-association-group] and reproduced in this document for
   easy reference in Figure 1 and Figure 2.


      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Reserved            |              Flags            |R|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Association type = TBD1    |          Association            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                IPv4 Association Source                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      //            Optional TLVs                                    //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


               Figure 1: PPAG IPv4 ASSOCIATION Object format















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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Reserved            |              Flags            |R|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Association Type = TBD1     |          Association            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |                IPv6 Association Source                        |
     |                                                               |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //            Optional TLVs                                    //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


               Figure 2: PPAG IPv6 ASSOCIATION Object format

   This document defines a new Association type, the Path Protection
   Association type, value will be assigned by IANA (TBD1).

   This Association-Type is dynamic in nature and created by the PCC or
   PCE for the LSPs belonging to the same TE tunnel (as described in
   [RFC3209]) originating at the same head node and terminating at the
   same destination.  These associations are conveyed via PCEP messages
   to the PCEP peer.  Operator-configured Association Range SHOULD NOT
   be set for this association-type and MUST be ignored.

3.2.  Path Protection Association TLV

   The Path Protection Association TLV is an optional TLV for use with
   the Path Protection Association Object Type.  The Path Protection
   Association TLV MUST NOT be present more than once.  If it appears
   more than once, only the first occurrence is processed and any others
   MUST be ignored.

   The Path Protection Association TLV follows the PCEP TLV format of
   [RFC5440].

   The type (16 bits) of the TLV is to be assigned by IANA.  The length
   field is 16 bit-long and has a fixed value of 4.

   The value comprises a single field, the Path Protection Association
   Flags (32 bits), where each bit represents a flag option.

   The format of the Path Protection Association TLV (Figure 3) is as
   follows:




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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Type = TBD2         |              Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Path Protection Association Flags                |S|P|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


             Figure 3: Path Protection Association TLV format

   P (PROTECTION-LSP 1 bit) - Indicates whether the LSP associated with
   the PPAG is working or protection LSP.  If this flag is set, the LSP
   is a protection LSP.

   S (STANDBY 1 bit)- When the P flag is set, the S flag indicates
   whether the protection LSP associated with the PPAG is in standby
   mode.  The S flag is ignored if the P flag is not set.

   Unassigned bits are considered reserved.  They MUST be set to 0 on
   transmission and MUST be ignored on receipt.  If the Path Protection
   Association TLV is missing, it means the LSP is the working LSP.

4.  Operation

   LSPs are associated with other LSPs with which they interact by
   adding them to a common association group via ASSOCIATION object.
   All procedures and error-handling for the ASSOCIATION object is as
   per [I-D.ietf-pce-association-group].

4.1.  PCC Initiated LSPs

   A PCC can associate a set of LSPs under its control for path
   protection purpose.  Similarly, the PCC can remove on or more LSPs
   under its control from the corresponding PPAG.  In both cases, the
   PCC must report the change in association to PCE(s) via PCRpt
   message.  A PCC can also delegate the working and protection LSPs to
   a stateful PCE, where PCE would control the LSPs.  The stateful PCE
   could update the paths and attributes of the LSPs in the association
   group via PCUpd message.  A PCE could also update the association to
   PCC via PCUpd message.  The procedures are described in
   [I-D.ietf-pce-association-group].

4.2.  PCE Initiated LSPs

   A PCE can create/update working and protection LSPs independently.
   As specified in [I-D.ietf-pce-association-group], Association Groups
   can be created by both PCE and PCC.



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   Further, a PCE can remove a protection LSP from a PPAG as specified
   in [I-D.ietf-pce-association-group].

4.3.  State Synchronization

   During state synchronization, a PCC MUST report all the existing path
   protection association groups as well as any path protection flags to
   PCE(s).  Following the state synchronization, the PCE would remove
   all stale information as per [I-D.ietf-pce-association-group].

4.4.  Session Termination

   As per [I-D.ietf-pce-association-group] the association information
   is cleared along with the LSP state information.  When a PCEP session
   is terminated, after expiry of State Timeout Interval at PCC, the LSP
   state associated with that PCEP session is reverted to operator-
   defined default parameters or behaviors as per [RFC8231].  Same
   procedure is also followed for the association information.  On
   session termination at the PCE, when the LSP state reported by PCC is
   cleared, the association information is also cleared.  Where there
   are no LSPs in a association group, the association is considered to
   be deleted..

4.5.  Error Handling

   All LSPs (working or protection) within a PPAG MUST belong to the
   same TE Tunnel (as described in [RFC3209]) and have the same source
   and destination.  If a PCE attempts to add an LSP to a PPAG and the
   Tunnel ID (as carried in LSP-IDENTIFIERS TLV [RFC8231], with
   description as per [RFC3209]) or source or destination of the LSP is
   different from the LSP(s) in the PPAG, the PCC MUST send PCErr with
   Error-Type= TBD (Association Error) [I-D.ietf-pce-association-group]
   and Error-Value = TBD3 (Tunnel ID or End points mismatch for Path
   Protection Association).

   There MUST be only one working LSP within a PPAG.  If a PCEP Speaker
   attempts to add another working LSP, the PCEP peer MUST send PCErr
   with Error-Type=TBD (Association Error)
   [I-D.ietf-pce-association-group] and Error-Value = TBD4 (Attempt to
   add another working LSP for Path Protection Association).

5.  Other considerations

   The diversity requirement for a group of LSPs is handled via another
   association type called "Disjointness Association", as described in
   [I-D.ietf-pce-association-diversity].  The diversity requirements for
   the the protection LSP are also handled by including both ASSOCIATION
   object for the group of LSPs.



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6.  IANA considerations

6.1.  Association Type

   This document defines a new association type, originally defined in
   [I-D.ietf-pce-association-group], for path protection.  IANA is
   requested to make the assignment of a new value for the sub-registry
   "ASSOCIATION Type Field" (request to be created in
   [I-D.ietf-pce-association-group]), as follows:

   +----------------------+-------------------------+------------------+
   | Association Type     | Association Name        | Reference        |
   | Value                |                         |                  |
   +----------------------+-------------------------+------------------+
   | TBD1                 | Path Protection         | This             |
   |                      | Association             | document         |
   +----------------------+-------------------------+------------------+

6.2.  PPAG TLV

   This document defines a new TLV for carrying additional information
   of LSPs within a path protection association group.  IANA is
   requested to make the assignment of a new value for the existing
   "PCEP TLV Type Indicators" registry as follows:

   +---------------+-----------------------------------+---------------+
   | TLV Type      | TLV Name                          | Reference     |
   | Value         |                                   |               |
   +---------------+-----------------------------------+---------------+
   | TBD2          | Path Protection Association Group | This document |
   |               | TLV                               |               |
   +---------------+-----------------------------------+---------------+

   This document requests that a new sub-registry, named "Path
   protection Association Group TLV Flag Field", is created within the
   "Path Computation Element Protocol (PCEP) Numbers" registry to manage
   the Flag field in the Path Protection Association Group TLV.  New
   values are to be assigned by Standards Action [RFC8126].  Each bit
   should be tracked with the following qualities:

   Each bit should be tracked with the following qualities:

   o  Bit number (count from 0 as the most significant bit)

   o  Name flag

   o  Reference




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           +------------+--------------------+----------------+
           | Bit Number |        Name        |   Reference    |
           +------------+--------------------+----------------+
           |     31     | P - PROTECTION-LSP | This document  |
           |     30     |    S - STANDBY     | This document  |
           +------------+--------------------+----------------+

                             Table 1: PPAG TLV

6.3.  PCEP Errors

   This document defines new Error-Type and Error-Value related to path
   protection association.  IANA is requested to allocate new error
   values within the "PCEP-ERROR Object Error Types and Values" sub-
   registry of the PCEP Numbers registry, as follows:

   +------------+-------------------+----------------------------------+
   | Error-Type | Meaning           | Reference                        |
   +------------+-------------------+----------------------------------+
   | TBD        | Association error | [I-D.ietf-pce-association-group] |
   |            | Error-value=TBD3: | This document                    |
   |            | Tunnel ID or End  |                                  |
   |            | points mismatch   |                                  |
   |            | for Path          |                                  |
   |            | Protection        |                                  |
   |            | Association       |                                  |
   |            | Error-value=TBD4: | This document                    |
   |            | Attempt to add    |                                  |
   |            | another working   |                                  |
   |            | LSP for Path      |                                  |
   |            | Protection        |                                  |
   |            | Association       |                                  |
   +------------+-------------------+----------------------------------+

7.  Security Considerations

   The security considerations described in [RFC8231],
   [I-D.ietf-pce-pce-initiated-lsp], and [RFC5440] apply to the
   extensions described in this document as well.  Additional
   considerations related to associations where a malicious PCEP speaker
   could be spoofed and could be used as an attack vector by creating
   associations is described in [I-D.ietf-pce-association-group].  Thus
   securing the PCEP session using Transport Layer Security (TLS)
   [I-D.ietf-pce-pceps], as per the recommendations and best current
   practices in [RFC7525], is RECOMMENDED.






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8.  Manageability Considerations

8.1.  Control of Function and Policy

   Mechanisms defined in this document do not imply any control or
   policy requirements in addition to those already listed in [RFC5440],
   [RFC8231], and [I-D.ietf-pce-pce-initiated-lsp].

8.2.  Information and Data Models

   [RFC7420] describes the PCEP MIB, there are no new MIB Objects for
   this document.

   The PCEP YANG module [I-D.ietf-pce-pcep-yang] supports associations.

8.3.  Liveness Detection and Monitoring

   Mechanisms defined in this document do not imply any new liveness
   detection and monitoring requirements in addition to those already
   listed in [RFC5440], [RFC8231], and [I-D.ietf-pce-pce-initiated-lsp].

8.4.  Verify Correct Operations

   Mechanisms defined in this document do not imply any new operation
   verification requirements in addition to those already listed in
   [RFC5440], [RFC8231], and [I-D.ietf-pce-pce-initiated-lsp].

8.5.  Requirements On Other Protocols

   Mechanisms defined in this document do not imply any new requirements
   on other protocols.

8.6.  Impact On Network Operations

   Mechanisms defined in this document do not have any impact on network
   operations in addition to those already listed in [RFC5440],
   [RFC8231], and [I-D.ietf-pce-pce-initiated-lsp].

9.  Acknowledgments

   We would like to thank Jeff Tantsura and Xian Zhang for their
   contributions to this document.

10.  References







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10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
              <https://www.rfc-editor.org/info/rfc3209>.

   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,
              <https://www.rfc-editor.org/info/rfc5440>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8231]  Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
              Computation Element Communication Protocol (PCEP)
              Extensions for Stateful PCE", RFC 8231,
              DOI 10.17487/RFC8231, September 2017,
              <https://www.rfc-editor.org/info/rfc8231>.

   [I-D.ietf-pce-pce-initiated-lsp]
              Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
              Extensions for PCE-initiated LSP Setup in a Stateful PCE
              Model", draft-ietf-pce-pce-initiated-lsp-10 (work in
              progress), June 2017.

   [I-D.ietf-pce-association-group]
              Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
              Dhody, D., and Y. Tanaka, "PCEP Extensions for
              Establishing Relationships Between Sets of LSPs", draft-
              ietf-pce-association-group-04 (work in progress), August
              2017.







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10.2.  Information References

   [RFC4655]  Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
              Element (PCE)-Based Architecture", RFC 4655,
              DOI 10.17487/RFC4655, August 2006,
              <https://www.rfc-editor.org/info/rfc4655>.

   [RFC4657]  Ash, J., Ed. and J. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol Generic
              Requirements", RFC 4657, DOI 10.17487/RFC4657, September
              2006, <https://www.rfc-editor.org/info/rfc4657>.

   [RFC7420]  Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
              Hardwick, "Path Computation Element Communication Protocol
              (PCEP) Management Information Base (MIB) Module",
              RFC 7420, DOI 10.17487/RFC7420, December 2014,
              <https://www.rfc-editor.org/info/rfc7420>.

   [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
              2015, <https://www.rfc-editor.org/info/rfc7525>.

   [RFC8051]  Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
              Stateful Path Computation Element (PCE)", RFC 8051,
              DOI 10.17487/RFC8051, January 2017,
              <https://www.rfc-editor.org/info/rfc8051>.

   [I-D.ietf-pce-pceps]
              Lopez, D., Dios, O., Wu, Q., and D. Dhody, "Secure
              Transport for PCEP", draft-ietf-pce-pceps-18 (work in
              progress), September 2017.

   [I-D.ietf-pce-pcep-yang]
              Dhody, D., Hardwick, J., Beeram, V., and j.
              jefftant@gmail.com, "A YANG Data Model for Path
              Computation Element Communications Protocol (PCEP)",
              draft-ietf-pce-pcep-yang-05 (work in progress), June 2017.

   [I-D.ietf-pce-association-diversity]
              Litkowski, S., Sivabalan, S., Barth, C., and D. Dhody,
              "Path Computation Element communication Protocol extension
              for signaling LSP diversity constraint", draft-ietf-pce-
              association-diversity-02 (work in progress), September
              2017.





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Authors' Addresses

   Hariharan Ananthakrishnan
   Packet Design
   1 South Almaden Blvd, #1150,
   San Jose, CA, 95113
   USA

   EMail: hari@packetdesign.com


   Siva Sivabalan
   Cisco
   2000 Innovation Drive
   Kananta, Ontaria K2K 3E8
   Canada

   EMail: msiva@cisco.com


   Colby Barth
   Juniper Networks
   1194 N Mathilda Ave,
   Sunnyvale, CA, 94086
   USA

   EMail: cbarth@juniper.net


   Raveendra Torvi
   Juniper Networks
   1194 N Mathilda Ave,
   Sunnyvale, CA, 94086
   USA

   EMail: rtorvi@juniper.net


   Ina Minei
   Google, Inc
   1600 Amphitheatre Parkway
   Mountain View, CA, 94043
   USA

   EMail: inaminei@google.com






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   Edward Crabbe
   Individual Contributor

   EMail: edward.crabbe@gmail.com


   Dhruv Dhody
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: dhruv.ietf@gmail.com






































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