PCEP Extensions for Associated Bidirectional Label Switched Paths (LSPs)
draft-barth-pce-association-bidir-03

Versions: 00 01 02 03                                   IPR declarations
PCE Working Group                                               C. Barth
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                               R. Gandhi
Expires: April 6, 2018                               Cisco Systems, Inc.
                                                                  B. Wen
                                                                 Comcast
                                                         October 3, 2017


                        PCEP Extensions for
        Associated Bidirectional Label Switched Paths (LSPs)
               draft-barth-pce-association-bidir-03

Abstract

   The Path Computation Element Communication Protocol (PCEP) provides
   mechanisms for Path Computation Elements (PCEs) to perform path
   computations in response to Path Computation Clients (PCCs) requests.
    The Stateful PCE extensions allow stateful control of Multiprotocol
   Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths
   (LSPs) using PCEP.

   This document defines PCEP extensions for grouping two reverse
   unidirectional MPLS TE LSPs into an Associated Bidirectional LSP when
   using a Stateful PCE for both PCE-Initiated and PCC-Initiated LSPs as
   well as when using a Stateless PCE.


Status of This Memo

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   provisions of BCP 78 and BCP 79.

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Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



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   This document is subject to BCP 78 and the IETF Trust's Legal
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   publication of this document.  Please review these documents
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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  4
     2.1.  Key Word Definitions . . . . . . . . . . . . . . . . . . .  4
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Single-sided Initiation  . . . . . . . . . . . . . . . . .  5
     3.2.  Double-sided Initiation  . . . . . . . . . . . . . . . . .  5
     3.3.  Co-routed Associated Bidirectional LSP . . . . . . . . . .  6
   4.  Protocol Extensions  . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  Association Object . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Bidirectional LSP Association Group TLV  . . . . . . . . .  7
   5.  PCEP Procedure . . . . . . . . . . . . . . . . . . . . . . . .  8
     5.1.  PCE Initiated LSPs . . . . . . . . . . . . . . . . . . . .  8
     5.2.  PCC Initiated LSPs . . . . . . . . . . . . . . . . . . . .  8
     5.3.  Stateless PCE  . . . . . . . . . . . . . . . . . . . . . .  8
     5.4.  State Synchronization  . . . . . . . . . . . . . . . . . .  9
     5.5.  Error Handling . . . . . . . . . . . . . . . . . . . . . .  9
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   7.  Manageability Considerations . . . . . . . . . . . . . . . . .  9
     7.1.  Control of Function and Policy . . . . . . . . . . . . . .  9
     7.2.  Information and Data Models  . . . . . . . . . . . . . . . 10
     7.3.  Liveness Detection and Monitoring  . . . . . . . . . . . . 10
     7.4.  Verify Correct Operations  . . . . . . . . . . . . . . . . 10
     7.5.  Requirements On Other Protocols  . . . . . . . . . . . . . 10
     7.6.  Impact On Network Operations . . . . . . . . . . . . . . . 10
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
     8.1.  Association Types  . . . . . . . . . . . . . . . . . . . . 10
     8.2.  Bidirectional LSP Association Group TLV  . . . . . . . . . 10
       8.2.1.  Flag Fields in Bidirectional LSP Association Group
               TLV  . . . . . . . . . . . . . . . . . . . . . . . . . 11
     8.3.  PCEP Errors  . . . . . . . . . . . . . . . . . . . . . . . 11
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . 14



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   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14


1.  Introduction

   [RFC5440] describes the Path Computation Element Protocol (PCEP) as a
   communication mechanism between a Path Computation Client (PCC) and a
   Path Control Element (PCE), or between PCE and PCC, that enables
   computation of Multiprotocol Label Switching (MPLS) Traffic
   Engineering (TE) Label Switched Paths (LSPs).

   [RFC8231] specifies extensions to PCEP to enable stateful control of
   MPLS TE LSPs.  It describes two modes of operation - Passive Stateful
   PCE and Active Stateful PCE.  In [RFC8231], the focus is on Active
   Stateful PCE where LSPs are provisioned on the PCC and control over
   them is delegated to a PCE.  Further, [I-D.ietf-pce-pce-initiated-
   lsp] describes the setup, maintenance and teardown of PCE-Initiated
   LSPs for the Stateful PCE model.

   [I-D.ietf-pce-association] introduces a generic mechanism to create a
   grouping of LSPs which can then be used to define associations
   between a set of LSPs and/or a set of attributes, for example primary
   and secondary LSP associations, and is equally applicable to the
   active and passive modes of a Stateful PCE [RFC8231] or a stateless
   PCE [RFC5440].

   The MPLS Transport Profile (MPLS-TP) requirements document [RFC5654]
   specifies that MPLS-TP MUST support associated bidirectional point-
   to-point LSPs.  [RFC7551] specifies RSVP signaling extensions for
   binding two reverse unidirectional LSPs [RFC3209] into an associated
   bidirectional LSP.  The fast reroute (FRR) procedures for associated
   bidirectional LSPs are described in [I-D.ietf-teas-assoc-corouted-
   bidir-frr].

   This document specifies PCEP extensions for grouping two reverse
   unidirectional MPLS-TE LSPs into an Associated Bidirectional LSP for
   both single-sided and double-sided initiation cases when using a
   Stateful (both active and passive modes) or Stateless PCE.  The PCEP
   extensions cover the following cases:

   o  A PCE initiates the forward and/ or reverse LSP of a single-sided
      or double-sided bidirectional LSP on a PCC and retains the control
      of the LSP.  The PCE computes the path of the LSP and updates the
      PCC with the information about the path.

   o  A PCC initiates the forward and/ or reverse LSP of a single-sided
      or double-sided bidirectional LSP and retains the control of the
      LSP.  The PCC computes the path of the LSP and reports the PCE



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      with the information about the path (as long as it controls the
      LSP, as in passive Stateful PCE mode).

   o  A PCC initiates the forward and/ or reverse LSP of a single-sided
      or double-sided bidirectional LSP and delegates the control of the
      LSP to a Stateful PCE.  The PCE may compute the path of the LSP
      and update the PCC with the information about the path (as long as
      it controls the LSP, as in active Stateful PCE mode).

   o  A PCC requests co-routed or non co-routed paths for forward and
      reverse LSPs of a bidirectional LSP from a Stateless PCE.


2.  Conventions Used in This Document

2.1.  Key Word Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.2.  Terminology

   The reader is assumed to be familiar with the terminology defined in
   [RFC5440], [RFC7551], [RFC8231], and [I-D.ietf-pce-association].


3.  Overview

   As shown in Figure 1, two reverse unidirectional LSPs can be grouped
   to form an associated bidirectional LSP.  There are two methods of
   initiating the bidirectional LSP association, single-sided and
   double-sided as described in the following sections.


               LSP1 -->          LSP1 -->          LSP1 -->
      +-----+           +-----+           +-----+           +-----+
      |  A  +-----------+  B  +-----------+  C  +-----------+  D  |
      +-----+           +--+--+           +--+--+           +-----+
               <-- LSP2    |                 |     <-- LSP2
                           |                 |
                           |                 |
                        +--+--+           +--+--+
                        |  E  +-----------+  F  |
                        +-----+           +-----+
                                 <-- LSP2

           Figure 1: Example of Associated Bidirectional LSP



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3.1.  Single-sided Initiation

   As specified in [RFC7551], in the single-sided case, the
   bidirectional tunnel is provisioned only on one endpoint node (PCC)
   of the tunnel.  Both forward and reverse LSPs of this tunnel are
   initiated with the Association Type set to "Single-sided
   Bidirectional LSP Association" on the originating endpoint node.  The
   forward and reverse LSPs are identified in the Bidirectional LSP
   Association Group TLV of their PCEP Association Objects.

   The originating endpoint node signals the properties for the revere
   LSP in the RSVP REVERSE_LSP Object [RFC7551] of the forward LSP Path
   message.  The remote endpoint then creates the corresponding reverse
   tunnel and signals the reverse LSP in response to the received RSVP
   Path message.

   The two unidirectional reverse LSPs on the originating endpoint node
   are grouped together using the PCEP Association Object and on the
   remote endpoint node by the RSVP signaled Association Object.

   As shown in Figure 1, the forward tunnel and both the forward LSP
   LSP1 and the reverse LSP LSP2 are initiated on the originating
   endpoint node A, either by the PCE or the PCC.  The creation of
   reverse tunnel and reverse LSP2 on the remote endpoint node D is
   triggered by the RSVP signaled LSP1.

   As specified in [I-D.ietf-teas-assoc-corouted-bidir-frr], for fast-
   reroute bypass tunnel assignment, the LSP starting from the
   originating node is identified as the forward LSP of the single-sided
   initiated bidirectional LSP.

3.2.  Double-sided Initiation

   As specified in [RFC7551], in the double-sided case, the
   bidirectional tunnel is provisioned on both endpoint nodes (PCCs) of
   the tunnel.  The forward and reverse LSPs of this tunnel are
   initiated with the Association Type set to "Double-sided
   Bidirectional LSP Association" on both endpoint nodes.  The forward
   and reverse LSPs are identified in the Bidirectional LSP Association
   Group TLV of their Association Objects.

   The two reverse unidirectional LSPs on both the endpoint nodes are
   grouped together by using the PCEP Association Object.

   As shown in Figure 1, the forward tunnel and LSP1 are initiated on
   the endpoint node A and the reverse tunnel and LSP2 are initiated on
   the endpoint node D, either by the PCE or the PCCs.




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   As specified in [I-D.ietf-teas-assoc-corouted-bidir-frr], for fast-
   reroute bypass tunnel assignment, the LSP with the higher Source
   Address [RFC3209] is identified as the forward LSP of the double-
   sided initiated bidirectional LSP.

3.3.  Co-routed Associated Bidirectional LSP

   In both single-sided and double-sided initiation cases, forward and
   reverse LSPs may be co-routed as shown in Figure 2, where both
   forward and reverse LSPs follow the same congruent path in the
   forward and reverse directions, respectively.


               LSP3 -->          LSP3 -->          LSP3 -->
      +-----+           +-----+           +-----+           +-----+
      |  A  +-----------+  B  +-----------+  C  +-----------+  D  |
      +-----+           +-----+           +-----+           +-----+
              <-- LSP4          <-- LSP4          <-- LSP4

       Figure 2: Example of Co-routed Associated Bidirectional LSP


4.  Protocol Extensions

4.1.  Association Object

   As per [I-D.ietf-pce-association], LSPs are associated by adding them
   to a common association group.  This document defines two new
   Bidirectional LSP Association Groups to be used by the associated
   bidirectional LSPs.  A member of the Bidirectional LSP Association
   Group can take the role of a forward or reverse LSP and follows the
   following rules:

   o  An LSP can not be part of more than one Bidirectional LSP
      Association Group.

   o  The Tunnel (as defined in [RFC3209]) of forward and reverse LSPs
      of the single-sided bidirectional association MUST be the same.

   This document defines two new Association Types for the Association
   Object as follows:

   o  Association Type (TBD1) = Single-sided Bidirectional LSP
      Association Group

   o  Association Type (TBD2) = Double-sided Bidirectional LSP
      Association Group




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   These Association Types are operator-configured associations in
   nature and statically created by the operator on the PCEP peers.  The
   LSP belonging to these associations is conveyed via PCEP messages to
   the PCEP peer.  Operator-configured Association Range TLV [I-D.ietf-
   pce-association] SHOULD NOT be sent for these Association Types, and
   MUST be ignored, so that the entire range of association ID can be
   used for them.

   The Association ID, Association Source, optional Global Association
   Source and optional Extended Association ID in the Bidirectional LSP
   Association Group Object are also operator-configured and populated
   using the procedures defined in [RFC7551].

4.2.  Bidirectional LSP Association Group TLV

   The Bidirectional LSP Association Group TLV is an optional TLV for
   use with the Single-sided and Double-sided Bidirectional LSP
   Association Group Object Types.

   o  The Bidirectional LSP Association Group TLV follows the PCEP TLV
      format from [RFC5440].

   o  The Type (16 bits) of the TLV is TBD3, to be assigned by IANA.

   o  The Length is 4 Bytes.

   o  The value comprises of a single field, the Bidirectional LSP
      Association Flags (32 bits), where each bit represents a flag
      option.

   o  If the Bidirectional LSP Association Group TLV is missing, it
      means the LSP is the forward LSP.

   o  The Bidirectional LSP Association Group 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 format of the Bidirectional LSP Association Group TLV is shown in
   Figure 3:


    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 = TBD3           |             Length            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Reserved                          |C|R|F|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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        Figure 3: Bidirectional LSP Association Group TLV format

   Bidirectional LSP Association Flags are defined as following.

   F (Forward LSP, 1 bit) - Indicates whether the LSP associated is the
     forward LSP of the bidirectional LSP.  If this flag is set, the LSP
     is a forward LSP.

   R (Reverse LSP, 1 bit) - Indicates whether the LSP associated is the
     reverse LSP of the bidirectional LSP.  If this flag is set, the LSP
     is a reverse LSP.

   C (Co-routed LSP, 1 bit) - Indicates whether the bidirectional LSP is
     co-routed.  This flag MUST be set for both the forward and reverse
     LSPs of a co-routed bidirectional LSP.

   The C flag is used by the PCE (for both Stateful and Stateless) to
   compute bidirectional paths of the forward and reverse LSPs.

   The Reserved flags MUST be set to 0 when sent and MUST be ignored
   when received.


5.  PCEP Procedure

5.1.  PCE Initiated LSPs

   As specified in [I-D.ietf-pce-association], Association Groups can be
   created by both Stateful PCE and PCC.

   A Stateful PCE can create and update the forward and reverse LSPs
   independently for both Single-sided and Double-sided bidirectional
   LSP association groups.  The establishment and removal of the
   association relationship can be done on a per LSP basis.  A PCE can
   create and update the association of the LSP on a PCC via PCInitiate
   and PCUpd messages, respectively, using the procedures described in
   [I-D.ietf-pce-association].

5.2.  PCC Initiated LSPs

   A PCC can associate or remove an LSP under its control from the
   bidirectional LSP association group.  The PCC MUST report the change
   in LSP association to Stateful PCE via PCRpt message.

5.3.  Stateless PCE

   For a stateless PCE, it might be useful to associate a path
   computation request to an association group, thus enabling it to



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   associate a common set of configuration parameters or behaviors with
   the request.  A PCC can request co-routed or non co-routed forward
   and reverse direction paths from a stateless PCE for the
   bidirectional LSP association group.

5.4.  State Synchronization

   During state synchronization, a PCC MUST report all the existing
   bidirectional LSP association groups to the Stateful PCE.  After the
   state synchronization, the PCE MUST remove all stale bidirectional
   associations.

5.5.  Error Handling

   The LSPs (forward or reverse) in a single-sided bidirectional LSP
   association group MUST belong to the same TE Tunnel (as defined in
   [RFC3209]).  If a PCE attempts to add an LSP in a single-sided
   bidirectional LSP association group for a different Tunnel, the PCC
   MUST send PCErr with Error-Type = TBD4 (Bidirectional LSP Association
   Error) and Error-Value = 1 (Tunnel mismatch).  Similarly, if a PCC
   attempts to add an LSP to a single-sided bidirectional LSP
   association group at PCE not complying to this rule, the PCE MUST
   send this PCErr.


6.  Security Considerations

   The security considerations described in [RFC5440], [RFC8231], and
   [I-D.ietf-pce-pce-initiated-lsp] apply to the extensions defined in
   this document as well.

   Two new Association Types for the Association Object, Double-sided
   Bidirectional LSP Association Group and Single-sided Associated
   Bidirectional LSP Group are introduced in this document.  Additional
   security considerations related to LSP associations due to a
   malicious PCEP speaker is described in [I-D.ietf-pce-association] and
   apply to these Association Types.  Thus, securing the PCEP session
   using Transport Layer Security (TLS) [I-D.ietf-pce-pceps] is
   recommended.


7.  Manageability Considerations

7.1.  Control of Function and Policy

   The 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].



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7.2.  Information and Data Models

   [RFC7420] describes the PCEP MIB, there are no new MIB Objects
   defined for LSP associations.

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

7.3.  Liveness Detection and Monitoring

   The 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].

7.4.  Verify Correct Operations

   The 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].

7.5.  Requirements On Other Protocols

   The mechanisms defined in this document do not add any new
   requirements on other protocols.

7.6.  Impact On Network Operations

   The 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].


8.  IANA Considerations

8.1.  Association Types

   This document adds new Association Types for the Association Object
   defined [I-D.ietf-pce-association].  IANA is requested to make the
   assignment of values for the sub-registry "ASSOCIATION Type Field"
   (to be created in [I-D.ietf-pce-association]), as follows:

   Value Name                                            Reference
   ---------------------------------------------------------------------
   TBD1 Single-sided Bidirectional LSP Association Group [This document]
   TBD2 Double-sided Bidirectional LSP Association Group [This document]

8.2.  Bidirectional LSP Association Group TLV




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   This document defines a new TLV for carrying additional information
   of LSPs within a Bidirectional LSP Association Group.  IANA is
   requested to add the assignment of a new value in the existing "PCEP
   TLV Type Indicators" registry as follows:

   TLV-Type  Name                                      Reference
   -------------------------------------------------------------------
    TBD3     Bidirectional LSP Association Group TLV   [This document]

8.2.1.  Flag Fields in Bidirectional LSP Association Group TLV

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

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

      o  Description

      o  Reference


   The following values are defined in this document for the Flag field.

   Bit No.     Description                   Reference
   ---------------------------------------------------------
    31         F - Forward LSP               [This document]
    30         R - Reverse LSP               [This document]
    29         C - Co-routed LSP             [This document]

8.3.  PCEP Errors

   IANA is requested to allocate new Error-Type and Error-Value related
   to bidirectional LSP association within the " PCEP-ERROR Object Error
   Types and Values" sub-registry of the PCEP Numbers registry, as
   follows:

   Error-Type  Description                           Reference
   -----------------------------------------------------------------
    TBD4       Bidirectional LSP Association Error   [This document]

               Error-value=1: Tunnel mismatch        [This document]






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9.  References

9.1.  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,
              March 2009.

   [RFC7551]  Zhang, F., Ed., Jing, R., and R. Gandhi, Ed., "RSVP-TE
              Extensions for Associated Bidirectional LSPs", RFC 7551,
              May 2015.

   [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>.

   [RFC8231]  Crabbe, E., Minei, I., Medved, J., and R. Varga, "Pah
              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-association]  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 (work in
              progress).

   [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 (work in progress).

   [I-D.ietf-teas-assoc-corouted-bidir-frr]  Gandhi, R., Ed., Shah, H.,
              and J. Whittaker, "Fast Reroute Procedures for Associated
              Bidirectional Label Switched Paths", draft-ietf-teas-
              assoc-corouted-bidir-frr (work-in-progress).



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9.2.  Informative References

   [RFC5654]  Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed.,
              Sprecher, N., and S. Ueno, "Requirements of an MPLS
              Transport Profile", RFC 5654, September 2009.

   [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, December 2014.

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

   [I-D.ietf-pce-pcep-yang]  Dhody, D., Hardwick, J., Beeram, V., and J.
              Tantsura, "A YANG Data Model for Path Computation Element
              Communications Protocol (PCEP)", draft-ietf-pce-pcep-yang
              (work in progress).
































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Acknowledgments

   TBA.


Authors' Addresses

   Colby Barth
   Juniper Networks

   Email: cbarth@juniper.net


   Rakesh Gandhi
   Cisco Systems, Inc.

   Email: rgandhi@cisco.com


   Bin Wen
   Comcast

   Email: Bin_Wen@cable.comcast.com




























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