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Versions: (draft-pkd-pce-pcep-yang) 00 01 02 03 04 05 06 07 08 09 10 11

PCE Working Group                                          D. Dhody, Ed.
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                             J. Hardwick
Expires: September 25, 2019                                   Metaswitch
                                                               V. Beeram
                                                        Juniper Networks
                                                             J. Tantsura
                                                          March 24, 2019


 A YANG Data Model for Path Computation Element Communications Protocol
                                 (PCEP)
                      draft-ietf-pce-pcep-yang-10

Abstract

   This document defines a YANG data model for the management of Path
   Computation Element communications Protocol (PCEP) for communications
   between a Path Computation Client (PCC) and a Path Computation
   Element (PCE), or between two PCEs.  The data model includes
   configuration and state data.

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
   and may be updated, replaced, or obsoleted by other documents at any
   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 September 25, 2019.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology and Notation  . . . . . . . . . . . . . . . . . .   3
     3.1.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Prefixes in Data Node Names . . . . . . . . . . . . . . .   5
     3.3.  Refrences in the Model  . . . . . . . . . . . . . . . . .   5
   4.  Objectives  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  The Design of PCEP Data Model . . . . . . . . . . . . . . . .   8
     5.1.  The Overview of PCEP Data Model . . . . . . . . . . . . .   8
     5.2.  The Entity  . . . . . . . . . . . . . . . . . . . . . . .   9
     5.3.  The Peer Lists  . . . . . . . . . . . . . . . . . . . . .   9
     5.4.  The Session Lists . . . . . . . . . . . . . . . . . . . .  10
     5.5.  Notifications . . . . . . . . . . . . . . . . . . . . . .  10
     5.6.  RPC . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.7.  The Full PCEP Data Model  . . . . . . . . . . . . . . . .  11
   6.  The Design of PCEP Statistics Data Model  . . . . . . . . . .  17
   7.  Advanced PCE Features . . . . . . . . . . . . . . . . . . . .  20
     7.1.  Stateful PCE's LSP-DB . . . . . . . . . . . . . . . . . .  20
   8.  Open Issues and Next Step . . . . . . . . . . . . . . . . . .  21
     8.1.  The PCE-Initiated LSP . . . . . . . . . . . . . . . . . .  21
   9.  Other Considerations  . . . . . . . . . . . . . . . . . . . .  21
     9.1.  PCEP over TLS (PCEPS) . . . . . . . . . . . . . . . . . .  21
   10. PCEP YANG Modules . . . . . . . . . . . . . . . . . . . . . .  21
     10.1.  ietf-pcep module . . . . . . . . . . . . . . . . . . . .  21
     10.2.  ietf-pcep-stats module . . . . . . . . . . . . . . . . .  78
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  98
   12. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  99
   13. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  99
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  99
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  99
     14.2.  Informative References . . . . . . . . . . . . . . . . . 103
   Appendix A.  Example  . . . . . . . . . . . . . . . . . . . . . . 104
   Appendix B.  Contributor Addresses  . . . . . . . . . . . . . . . 107
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . 108

1.  Introduction

   The Path Computation Element (PCE) defined in [RFC4655] is an entity
   that is capable of computing a network path or route based on a
   network graph, and applying computational constraints.  A Path



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   Computation Client (PCC) may make requests to a PCE for paths to be
   computed.

   PCEP is the communication protocol between a PCC and PCE and is
   defined in [RFC5440].  PCEP interactions include path computation
   requests and path computation replies as well as notifications of
   specific states related to the use of a PCE in the context of
   Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS)
   Traffic Engineering (TE).  [RFC8231] specifies extensions to PCEP to
   enable stateful control of MPLS TE LSPs.

   This document defines a YANG [RFC7950] data model for the management
   of PCEP speakers.  It is important to establish a common data model
   for how PCEP speakers are identified, configured, and monitored.  The
   data model includes configuration data and state data.

   This document contains a specification of the PCEP YANG module,
   "ietf-pcep" which provides the PCEP [RFC5440] data model.

   The PCEP operational state is included in the same tree as the PCEP
   configuration consistent with Network Management Datastore
   Architecture [RFC8342].  The origin of the data is indicated as per
   the origin metadata annotation.

2.  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.

3.  Terminology and Notation

   This document uses the terminology defined in [RFC4655] and
   [RFC5440].  In particular, it uses the following acronyms.

   o  Path Computation Request message (PCReq).

   o  Path Computation Reply message (PCRep).

   o  Notification message (PCNtf).

   o  Error message (PCErr).

   o  Request Parameters object (RP).

   o  Synchronization Vector object (SVEC).



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   o  Explicit Route object (ERO).

   This document also uses the following terms defined in [RFC7420]:

   o  PCEP entity: a local PCEP speaker.

   o  PCEP peer: to refer to a remote PCEP speaker.

   o  PCEP speaker: where it is not necessary to distinguish between
      local and remote.

   Further, this document also uses the following terms defined in
   [RFC8231] :

   o  Stateful PCE, Passive Stateful PCE, Active Stateful PCE

   o  Delegation, Revocation, Redelegation

   o  LSP State Report, Path Computation Report message (PCRpt).

   o  LSP State Update, Path Computation Update message (PCUpd).

   [RFC8281] :

   o  PCE-initiated LSP, Path Computation LSP Initiate Message
      (PCInitiate).

   [RFC8408] :

   o  Path Setup Type (PST).

   [I-D.ietf-pce-segment-routing] :

   o  Segment Routing (SR).

   [RFC6241] :

   o  Configuration data.

   o  State data.

3.1.  Tree Diagrams

   A simplified graphical representation of the data model is used in
   this document.  The meaning of the symbols in these diagrams is
   defined in [RFC8340].





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3.2.  Prefixes in Data Node Names

   In this document, names of data nodes and other data model objects
   are often used without a prefix, as long as it is clear from the
   context in which YANG module each name is defined.  Otherwise, names
   are prefixed using the standard prefix associated with the
   corresponding YANG module, as shown in Table 1.

   +-----------+-----------------+-------------------------------------+
   | Prefix    | YANG module     | Reference                           |
   +-----------+-----------------+-------------------------------------+
   | yang      | ietf-yang-types | [RFC6991]                           |
   | inet      | ietf-inet-types | [RFC6991]                           |
   | te        | ietf-te         | [I-D.ietf-teas-yang-te]             |
   | te-types  | ietf-te-types   | [I-D.ietf-teas-yang-te]             |
   | key-chain | ietf-key-chain  | [RFC8177]                           |
   | nacm      | ietf-netconf-   | [RFC8341]                           |
   |           | acm             |                                     |
   | tls-      | ietf-tls-server | [I-D.ietf-netconf-tls-client-server |
   | server    |                 | ]                                   |
   | tls-      | ietf-tls-client | [I-D.ietf-netconf-tls-client-server |
   | client    |                 | ]                                   |
   | ospf      | ietf-ospf       | [I-D.ietf-ospf-yang]                |
   | isis      | ietf-isis       | [I-D.ietf-isis-yang-isis-cfg]       |
   +-----------+-----------------+-------------------------------------+

             Table 1: Prefixes and corresponding YANG modules

3.3.  Refrences in the Model

   Following documents are refrenced in the model defined in this
   document -

   +----------------------------+--------------------------------------+
   | Documents                  | Reference                            |
   +----------------------------+--------------------------------------+
   | RSVP-TE: Extensions to     | [RFC3209]                            |
   | RSVP for LSP Tunnels       |                                      |
   | OSPF Protocol Extensions   | [RFC5088]                            |
   | for Path Computation       |                                      |
   | Element (PCE) Discovery    |                                      |
   | IS-IS Protocol Extensions  | [RFC5089]                            |
   | for Path Computation       |                                      |
   | Element (PCE) Discovery    |                                      |
   | Path Computation Element   | [RFC5440]                            |
   | (PCE) Communication        |                                      |
   | Protocol (PCEP)            |                                      |
   | Preserving Topology        | [RFC5520]                            |



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   | Confidentiality in Inter-  |                                      |
   | Domain Path Computation    |                                      |
   | Using a Path-Key-Based     |                                      |
   | Mechanism                  |                                      |
   | Encoding of Objective      | [RFC5541]                            |
   | Functions in the Path      |                                      |
   | Computation Element        |                                      |
   | Communication Protocol     |                                      |
   | (PCEP)                     |                                      |
   | Path Computation Element   | [RFC5557]                            |
   | Communication Protocol     |                                      |
   | (PCEP) Requirements and    |                                      |
   | Protocol Extensions in     |                                      |
   | Support of Global          |                                      |
   | Concurrent Optimization    |                                      |
   | Common YANG Data Types     | [RFC6991]                            |
   | YANG Data Model for Key    | [RFC8177]                            |
   | Chains                     |                                      |
   | Path Computation Element   | [RFC8231]                            |
   | Communication Protocol     |                                      |
   | (PCEP) Extensions for      |                                      |
   | Stateful PCE               |                                      |
   | Optimizations of Label     | [RFC8232]                            |
   | Switched Path State        |                                      |
   | Synchronization Procedures |                                      |
   | for a Stateful PCE         |                                      |
   | PCEPS: Usage of TLS to     | [RFC8253]                            |
   | Provide a Secure Transport |                                      |
   | for the Path Computation   |                                      |
   | Element Communication      |                                      |
   | Protocol (PCEP)            |                                      |
   | Path Computation Element   | [RFC8281]                            |
   | Communication Protocol     |                                      |
   | (PCEP) Extensions for PCE- |                                      |
   | Initiated LSP Setup in a   |                                      |
   | Stateful PCE Model         |                                      |
   | Extensions to the Path     | [RFC8306]                            |
   | Computation Element        |                                      |
   | Communication Protocol     |                                      |
   | (PCEP) for Point-to-       |                                      |
   | Multipoint Traffic         |                                      |
   | Engineering Label Switched |                                      |
   | Paths                      |                                      |
   | Network Configuration      | [RFC8341]                            |
   | Access Control Model       |                                      |
   | Conveying Path Setup Type  | [RFC8408]                            |
   | in PCE Communication       |                                      |
   | Protocol (PCEP) Messages   |                                      |



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   | Traffic Engineering Common | [I-D.ietf-teas-yang-te-types]        |
   | YANG Types                 |                                      |
   | A YANG Data Model for      | [I-D.ietf-teas-yang-te]              |
   | Traffic Engineering        |                                      |
   | Tunnels and Interfaces     |                                      |
   | YANG Groupings for TLS     | [I-D.ietf-netconf-tls-client-server] |
   | Clients and TLS Servers    |                                      |
   | PCEP Extensions for        | [I-D.ietf-pce-segment-routing]       |
   | Segment Routing            |                                      |
   | PCEP Extensions for        | [I-D.ietf-pce-association-group]     |
   | Establishing Relationships |                                      |
   | Between Sets of LSPs       |                                      |
   | YANG Data Model for OSPF   | [I-D.ietf-ospf-yang]                 |
   | Protocol                   |                                      |
   | YANG Data Model for IS-IS  | [I-D.ietf-isis-yang-isis-cfg]        |
   | Protocol                   |                                      |
   | PCEP extensions for GMPLS  | [I-D.ietf-pce-gmpls-pcep-extensions] |
   +----------------------------+--------------------------------------+

                  Table 2: Refrences in the YANG modules

4.  Objectives

   This section describes some of the design objectives for the model:

   o  In case of existing implementations, it needs to map the data
      model defined in this document to their proprietary native data
      model.  To facilitate such mappings, the data model should be
      simple.

   o  The data model should be suitable for new implementations to use
      as is.

   o  Mapping to the PCEP MIB Module should be clear.

   o  The data model should allow for static configurations of peers.

   o  The data model should include read-only counters in order to
      gather statistics for sent and received PCEP messages, received
      messages with errors, and messages that could not be sent due to
      errors.  This could be in a separate model which augments the base
      data model.

   o  It should be fairly straightforward to augment the base data model
      for advanced PCE features.






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5.  The Design of PCEP Data Model

5.1.  The Overview of PCEP Data Model

   The PCEP YANG module defined in this document has all the common
   building blocks for the PCEP protocol.

   module: ietf-pcep
       +--rw pcep!
          +--rw entity
             +--rw addr                          inet:ip-address
             +--rw enabled?                      boolean
             +--rw role                          pcep-role
             +--rw description?                  string
             +--rw speaker-entity-id?            string
             |       {stateful-sync-opt}?
             +--rw admin-status?                 pcep-admin-status
             +--ro index?                        uint32
             +--ro oper-status?                  pcep-oper-status
             +--rw domain
             |  +--rw domain* [domain-type domain]
             |        ...
             +--rw capability

             |        ...
             +--rw pce-info
             |  +--rw scope
             |  |     ...
             |  +--rw neigh-domains
             |  |     ...
             |  +--rw path-key {path-key}?
             |        ...

             +--ro lsp-db {stateful}?
             |  +--ro db-ver?             uint64
             |  |       {stateful-sync-opt}?
             |  +--ro association-list*
             |  |       [id source global-source extended-id]
             |  |     ...
             |  +--ro lsp* [plsp-id pcc-id]
             |        ...
             +--ro path-keys {path-key}?
             |  +--ro path-keys* [path-key]
             |        ...
             +--rw peers
                +--rw peer* [addr]

                   +--ro sessions



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                      +--ro session* [initiator]
                         ...

     rpcs:
       +---x trigger-resync {stateful,stateful-sync-opt}?
          +---w input
             +---w pcc?   -> /pcep/entity/peers/peer/addr

     notifications:
       +---n pcep-session-up
       |  ...
       +---n pcep-session-down
       |  ...
       +---n pcep-session-local-overload
       |  ...
       +---n pcep-session-local-overload-clear
       |  ...
       +---n pcep-session-peer-overload
       |  ...
       +---n pcep-session-peer-overload-clear
          ...

5.2.  The Entity

   The PCEP yang module may contain status information for the local
   PCEP entity.

   The entity has an IP address (using ietf-inet-types [RFC6991]) and a
   "role" leaf (the local entity PCEP role) as mandatory.

   Note that, the PCEP MIB module [RFC7420] uses an entity list and a
   system generated entity index as a primary index to the read only
   entity table.  If the device implements the PCEP MIB, the "index"
   leaf MUST contain the value of the corresponding pcePcepEntityIndex
   and only one entity is assumed.

5.3.  The Peer Lists

   The peer list contains peer(s) that the local PCEP entity knows
   about.  A PCEP speaker is identified by its IP address.  If there is
   a PCEP speaker in the network that uses multiple IP addresses then it
   looks like multiple distinct peers to the other PCEP speakers in the
   network.

   Since PCEP sessions can be ephemeral, the peer list tracks a peer
   even when no PCEP session currently exists to that peer.  The
   statistics contained are an aggregate of the statistics for all
   successive sessions to that peer.



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   To limit the quantity of information that is stored, an
   implementation MAY choose to discard this information if and only if
   no PCEP session exists to the corresponding peer.

   The data model for PCEP peer presented in this document uses a flat
   list of peers.  Each peer in the list is identified by its IP address
   (addr-type, addr).

   There is a list for static peer configuration and operational state
   of all peers (i.e.static as well as discovered)("/pcep/entity/
   peers").  The list is used to enable remote PCE configuration at PCC
   (or PCE) and has the operational state of these peers as well as the
   remote PCE peer which were discovered and PCC peers that have
   initiated session.

5.4.  The Session Lists

   The session list contains PCEP session that the PCEP entity (PCE or
   PCC) is currently participating in.  The statistics in session are
   semantically different from those in peer since the former applies to
   the current session only, whereas the latter is the aggregate for all
   sessions that have existed to that peer.

   Although [RFC5440] forbids more than one active PCEP session between
   a given pair of PCEP entities at any given time, there is a window
   during session establishment where two sessions may exist for a given
   pair, one representing a session initiated by the local PCEP entity
   and the other representing a session initiated by the peer.  If
   either of these sessions reaches active state first, then the other
   is discarded.

   The data model for PCEP session presented in this document uses a
   flat list of sessions.  Each session in the list is identified by its
   initiator.  This index allows two sessions to exist transiently for a
   given peer, as discussed above.

5.5.  Notifications

   This YANG model defines a list of notifications to inform client of
   important events detected during the protocol operation.  The
   notifications defined cover the PCEP MIB notifications.

5.6.  RPC

   This YANG model defines a RPC to trigger state resynchronization to a
   particular PCEP peer.





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5.7.  The Full PCEP Data Model

   The module, "ietf-pcep", defines the basic components of a PCE
   speaker.  The tree depth in the tree is set to 10.

module: ietf-pcep
    +--rw pcep!
       +--rw entity
          +--rw addr                          inet:ip-address
          +--rw enabled?                      boolean
          +--rw role                          pcep-role
          +--rw description?                  string
          +--rw speaker-entity-id?            string {sync-opt}?
          +--rw admin-status?                 boolean
          +--ro index?                        uint32
          +--ro oper-status?                  pcep-oper-status
          +--rw domain
          |  +--rw domain* [domain-type domain]
          |     +--rw domain-type    domain-type
          |     +--rw domain         domain
          +--rw capability
          |  +--rw capability?             bits
          |  +--rw pce-initiated?          boolean {pce-initiated}?
          |  +--rw include-db-ver?         boolean
          |  |       {stateful,sync-opt}?
          |  +--rw trigger-resync?         boolean
          |  |       {stateful,sync-opt}?
          |  +--rw trigger-initial-sync?   boolean
          |  |       {stateful,sync-opt}?
          |  +--rw incremental-sync?       boolean
          |  |       {stateful,sync-opt}?
          |  +--rw sr {sr}?
          |     +--rw enabled?     boolean
          |     +--rw msd-limit?   boolean
          |     +--rw nai?         boolean
          +--rw msd?                          uint8 {sr}?
          +--rw pce-info
          |  +--rw scope
          |  |  +--rw path-scope?         bits
          |  |  +--rw intra-area-pref?    uint8
          |  |  +--rw inter-area-pref?    uint8
          |  |  +--rw inter-as-pref?      uint8
          |  |  +--rw inter-layer-pref?   uint8
          |  +--rw neigh-domains
          |  |  +--rw domain* [domain-type domain]
          |  |     +--rw domain-type    domain-type
          |  |     +--rw domain         domain
          |  +--rw path-key {path-key}?



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          |     +--rw enabled?         boolean
          |     +--rw discard-timer?   uint32
          |     +--rw reuse-time?      uint32
          |     +--rw pce-id?          inet:ip-address
          +--rw connect-timer?                uint16
          +--rw connect-max-retry?            uint32
          +--rw init-backoff-timer?           uint16
          +--rw max-backoff-timer?            uint32
          +--rw open-wait-timer?              uint16
          +--rw keep-wait-timer?              uint16
          +--rw keep-alive-timer?             uint8
          +--rw dead-timer?                   uint8
          +--rw allow-negotiation?            boolean
          +--rw max-keep-alive-timer?         uint8
          +--rw max-dead-timer?               uint8
          +--rw min-keep-alive-timer?         uint8
          +--rw min-dead-timer?               uint8
          +--rw sync-timer?                   uint16 {svec}?
          +--rw request-timer?                uint16
          +--rw max-sessions?                 uint32
          +--rw max-unknown-reqs?             uint32
          +--rw max-unknown-msgs?             uint32
          +--rw pcep-notification-max-rate    uint32
          +--rw stateful-parameter {stateful}?
          |  +--rw state-timeout?          uint32
          |  +--rw redelegation-timeout?   uint32
          |  +--rw rpt-non-pcep-lsp?       boolean
          +--rw of-list {objective-function}?
          |  +--rw objective-function* [of]
          |     +--rw of    identityref
          +--ro lsp-db {stateful}?
          |  +--ro db-ver?             uint64 {sync-opt}?
          |  +--ro association-list*
          |  |       [type id source global-source extended-id]
          |  |       {association}?
          |  |  +--ro type             identityref
          |  |  +--ro id               uint16
          |  |  +--ro source           inet:ip-address
          |  |  +--ro global-source    uint32
          |  |  +--ro extended-id      string
          |  |  +--ro lsp* [plsp-id pcc-id]
          |  |     +--ro plsp-id    -> /pcep/entity/lsp-db/lsp/plsp-id
          |  |     +--ro pcc-id     -> /pcep/entity/lsp-db/lsp/pcc-id
          |  +--ro lsp* [plsp-id pcc-id]
          |     +--ro plsp-id               uint32
          |     +--ro pcc-id                inet:ip-address
          |     +--ro lsp-ref
          |     |  +--ro source?



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          |     |  |       -> /te:te/lsps-state/lsp/source
          |     |  +--ro destination?
          |     |  |       -> /te:te/lsps-state/lsp/destination
          |     |  +--ro tunnel-id?
          |     |  |       -> /te:te/lsps-state/lsp/tunnel-id
          |     |  +--ro lsp-id?
          |     |  |       -> /te:te/lsps-state/lsp/lsp-id
          |     |  +--ro extended-tunnel-id?   leafref
          |     +--ro admin-state?          boolean
          |     +--ro operational-state?    operational-state
          |     +--ro delegated
          |     |  +--ro enabled?   boolean
          |     |  +--ro peer?      -> /pcep/entity/peers/peer/addr
          |     |  +--ro srp-id?    uint32
          |     +--ro initiation {pce-initiated}?
          |     |  +--ro enabled?   boolean
          |     |  +--ro peer?      -> /pcep/entity/peers/peer/addr
          |     +--ro symbolic-path-name?   string
          |     +--ro last-error?           identityref
          |     +--ro pst?                  identityref
          |     +--ro association-list*
          |             [type id source global-source extended-id]
          |             {association}?
          |        +--ro type             leafref
          |        +--ro id
          |        |       -> /pcep/entity/lsp-db/association-list/id
          |        +--ro source           leafref
          |        +--ro global-source    leafref
          |        +--ro extended-id      leafref
          +--ro path-keys {path-key}?
          |  +--ro path-keys* [path-key]
          |     +--ro path-key         uint16
          |     +--ro cps
          |     |  +--ro explicit-route-objects* [index]
          |     |     +--ro index                  uint32
          |     |     +--ro (type)?
          |     |        +--:(numbered-node-hop)
          |     |        |  +--ro numbered-node-hop
          |     |        |     +--ro node-id     te-node-id
          |     |        |     +--ro hop-type?   te-hop-type
          |     |        +--:(numbered-link-hop)
          |     |        |  +--ro numbered-link-hop
          |     |        |     +--ro link-tp-id    te-tp-id
          |     |        |     +--ro hop-type?     te-hop-type
          |     |        |     +--ro direction?    te-link-direction
          |     |        +--:(unnumbered-link-hop)
          |     |        |  +--ro unnumbered-link-hop
          |     |        |     +--ro link-tp-id    te-tp-id



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          |     |        |     +--ro node-id       te-node-id
          |     |        |     +--ro hop-type?     te-hop-type
          |     |        |     +--ro direction?    te-link-direction
          |     |        +--:(as-number)
          |     |        |  +--ro as-number-hop
          |     |        |     +--ro as-number    inet:as-number
          |     |        |     +--ro hop-type?    te-hop-type
          |     |        +--:(label)
          |     |           +--ro label-hop
          |     |              +--ro te-label
          |     |                    ...
          |     +--ro pcc-original?    -> /pcep/entity/peers/peer/addr
          |     +--ro req-id?          uint32
          |     +--ro retrieved?       boolean
          |     +--ro pcc-retrieved?   -> /pcep/entity/peers/peer/addr
          |     +--ro creation-time?   yang:timestamp
          |     +--ro discard-time?    uint32
          |     +--ro reuse-time?      uint32
          +--rw peers
             +--rw peer* [addr]
                +--rw addr                    inet:ip-address
                +--rw role                    pcep-role
                +--rw description?            string
                +--rw domain
                |  +--rw domain* [domain-type domain]
                |     +--rw domain-type    domain-type
                |     +--rw domain         domain
                +--rw capability
                |  +--rw capability?             bits
                |  +--rw pce-initiated?          boolean
                |  |       {pce-initiated}?
                |  +--rw include-db-ver?         boolean
                |  |       {stateful,sync-opt}?
                |  +--rw trigger-resync?         boolean
                |  |       {stateful,sync-opt}?
                |  +--rw trigger-initial-sync?   boolean
                |  |       {stateful,sync-opt}?
                |  +--rw incremental-sync?       boolean
                |  |       {stateful,sync-opt}?
                |  +--rw sr {sr}?
                |     +--rw enabled?     boolean
                |     +--rw msd-limit?   boolean
                |     +--rw nai?         boolean
                +--rw msd?                    uint8 {sr}?
                +--rw pce-info
                |  +--rw scope
                |  |  +--rw path-scope?         bits
                |  |  +--rw intra-area-pref?    uint8



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                |  |  +--rw inter-area-pref?    uint8
                |  |  +--rw inter-as-pref?      uint8
                |  |  +--rw inter-layer-pref?   uint8
                |  +--rw neigh-domains
                |     +--rw domain* [domain-type domain]
                |        +--rw domain-type    domain-type
                |        +--rw domain         domain
                +--rw delegation-pref?        uint8 {stateful}?
                +--rw auth
                |  +--rw (auth-type-selection)?
                |     +--:(auth-key-chain)
                |     |  +--rw key-chain?            kc:key-chain-ref
                |     +--:(auth-key)
                |     |  +--rw crypto-algorithm      identityref
                |     |  +--rw (key-string-style)?
                |     |     +--:(keystring)
                |     |     |  +--rw keystring?            string
                |     |     +--:(hexadecimal) {kc:hex-key-string}?
                |     |        +--rw hexadecimal-string?
                |     |                yang:hex-string
                |     +--:(auth-tls) {tls}?
                |        +--rw (role)?
                |           +--:(server)
                |           |  +--rw tls-server
                |           |        ...
                |           +--:(client)
                |              +--rw tls-client
                |                    ...
                +--ro discontinuity-time?     yang:timestamp
                +--ro initiate-session?       boolean
                +--ro session-exists?         boolean
                +--ro session-up-time?        yang:timestamp
                +--ro session-fail-time?      yang:timestamp
                +--ro session-fail-up-time?   yang:timestamp
                +--ro sessions
                   +--ro session* [initiator]
                      +--ro initiator               pcep-initiator
                      +--ro role?                   -> /pcep/entity/role
                      +--ro state-last-change?      yang:timestamp
                      +--ro state?                  pcep-sess-state
                      +--ro session-creation?       yang:timestamp
                      +--ro connect-retry?          yang:counter32
                      +--ro local-id?               uint8
                      +--ro remote-id?              uint8
                      +--ro keepalive-timer?        uint8
                      +--ro peer-keepalive-timer?   uint8
                      +--ro dead-timer?             uint8
                      +--ro peer-dead-timer?        uint8



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                      +--ro ka-hold-time-rem?       uint8
                      +--ro overloaded?             boolean
                      +--ro overload-time?          uint32
                      +--ro peer-overloaded?        boolean
                      +--ro peer-overload-time?     uint32
                      +--ro lspdb-sync?             sync-state
                      |       {stateful}?
                      +--ro recv-db-ver?            uint64
                      |       {stateful,sync-opt}?
                      +--ro of-list {objective-function}?
                      |  +--ro objective-function* [of]
                      |     +--ro of    identityref
                      +--ro pst-list
                      |  +--ro path-setup-type* [pst]
                      |     +--ro pst    identityref
                      +--ro assoc-type-list {association}?
                      |  +--ro assoc-type* [at]
                      |     +--ro at    identityref
                      +--ro speaker-entity-id?      string
                      |       {sync-opt}?
                      +--ro discontinuity-time?     yang:timestamp

  rpcs:
    +---x trigger-resync {stateful,sync-opt}?
       +---w input
          +---w pcc?   -> /pcep/entity/peers/peer/addr

  notifications:
    +---n pcep-session-up
    |  +--ro peer-addr?           -> /pcep/entity/peers/peer/addr
    |  +--ro session-initiator?
    |  |       -> /pcep/entity/peers/peer/sessions/session/initiator
    |  +--ro state-last-change?   yang:timestamp
    |  +--ro state?               pcep-sess-state
    +---n pcep-session-down
    |  +--ro peer-addr?           -> /pcep/entity/peers/peer/addr
    |  +--ro session-initiator?   pcep-initiator
    |  +--ro state-last-change?   yang:timestamp
    |  +--ro state?               pcep-sess-state
    +---n pcep-session-local-overload
    |  +--ro peer-addr?           -> /pcep/entity/peers/peer/addr
    |  +--ro session-initiator?
    |  |       -> /pcep/entity/peers/peer/sessions/session/initiator
    |  +--ro overloaded?          boolean
    |  +--ro overload-time?       uint32
    +---n pcep-session-local-overload-clear
    |  +--ro peer-addr?    -> /pcep/entity/peers/peer/addr
    |  +--ro overloaded?   boolean



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    +---n pcep-session-peer-overload
    |  +--ro peer-addr?            -> /pcep/entity/peers/peer/addr
    |  +--ro session-initiator?
    |  |       -> /pcep/entity/peers/peer/sessions/session/initiator
    |  +--ro peer-overloaded?      boolean
    |  +--ro peer-overload-time?   uint32
    +---n pcep-session-peer-overload-clear
       +--ro peer-addr?         -> /pcep/entity/peers/peer/addr
       +--ro peer-overloaded?   boolean


6.  The Design of PCEP Statistics Data Model

   The module, "ietf-pcep-stats", augments the ietf-pcep module to
   include statistics at the PCEP peer and session level.


   module: ietf-pcep-stats
     augment /p:pcep/p:entity/p:peers/p:peer:
       +--ro num-sess-setup-ok?     yang:counter32
       +--ro num-sess-setup-fail?   yang:counter32
       +--ro pcep-stats
          +--ro avg-rsp-time?               uint32
          +--ro lwm-rsp-time?               uint32
          +--ro hwm-rsp-time?               uint32
          +--ro num-pcreq-sent?             yang:counter32
          +--ro num-pcreq-rcvd?             yang:counter32
          +--ro num-pcrep-sent?             yang:counter32
          +--ro num-pcrep-rcvd?             yang:counter32
          +--ro num-pcerr-sent?             yang:counter32
          +--ro num-pcerr-rcvd?             yang:counter32
          +--ro num-pcntf-sent?             yang:counter32
          +--ro num-pcntf-rcvd?             yang:counter32
          +--ro num-keepalive-sent?         yang:counter32
          +--ro num-keepalive-rcvd?         yang:counter32
          +--ro num-unknown-rcvd?           yang:counter32
          +--ro num-corrupt-rcvd?           yang:counter32
          +--ro num-req-sent?               yang:counter32
          +--ro num-req-sent-pend-rep?      yang:counter32
          +--ro num-req-sent-ero-rcvd?      yang:counter32
          +--ro num-req-sent-nopath-rcvd?   yang:counter32
          +--ro num-req-sent-cancel-rcvd?   yang:counter32
          +--ro num-req-sent-error-rcvd?    yang:counter32
          +--ro num-req-sent-timeout?       yang:counter32
          +--ro num-req-sent-cancel-sent?   yang:counter32
          +--ro num-req-rcvd?               yang:counter32
          +--ro num-req-rcvd-pend-rep?      yang:counter32
          +--ro num-req-rcvd-ero-sent?      yang:counter32



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          +--ro num-req-rcvd-nopath-sent?   yang:counter32
          +--ro num-req-rcvd-cancel-sent?   yang:counter32
          +--ro num-req-rcvd-error-sent?    yang:counter32
          +--ro num-req-rcvd-cancel-rcvd?   yang:counter32
          +--ro num-rep-rcvd-unknown?       yang:counter32
          +--ro num-req-rcvd-unknown?       yang:counter32
          +--ro svec {p:svec}?
          |  +--ro num-svec-sent?       yang:counter32
          |  +--ro num-svec-req-sent?   yang:counter32
          |  +--ro num-svec-rcvd?       yang:counter32
          |  +--ro num-svec-req-rcvd?   yang:counter32
          +--ro stateful {p:stateful}?
          |  +--ro num-pcrpt-sent?             yang:counter32
          |  +--ro num-pcrpt-rcvd?             yang:counter32
          |  +--ro num-pcupd-sent?             yang:counter32
          |  +--ro num-pcupd-rcvd?             yang:counter32
          |  +--ro num-rpt-sent?               yang:counter32
          |  +--ro num-rpt-rcvd?               yang:counter32
          |  +--ro num-rpt-rcvd-error-sent?    yang:counter32
          |  +--ro num-upd-sent?               yang:counter32
          |  +--ro num-upd-rcvd?               yang:counter32
          |  +--ro num-upd-rcvd-unknown?       yang:counter32
          |  +--ro num-upd-rcvd-undelegated?   yang:counter32
          |  +--ro num-upd-rcvd-error-sent?    yang:counter32
          |  +--ro initiation {p:pce-initiated}?
          |     +--ro num-pcinitiate-sent?            yang:counter32
          |     +--ro num-pcinitiate-rcvd?            yang:counter32
          |     +--ro num-initiate-sent?              yang:counter32
          |     +--ro num-initiate-rcvd?              yang:counter32
          |     +--ro num-initiate-rcvd-error-sent?   yang:counter32
          +--ro path-key {p:path-key}?
          |  +--ro num-unknown-path-key?      yang:counter32
          |  +--ro num-exp-path-key?          yang:counter32
          |  +--ro num-dup-path-key?          yang:counter32
          |  +--ro num-path-key-no-attempt?   yang:counter32
          +--ro num-req-sent-closed?        yang:counter32
          +--ro num-req-rcvd-closed?        yang:counter32
     augment /p:pcep/p:entity/p:peers/p:peer/p:sessions/p:session:
       +--ro pcep-stats
          +--ro avg-rsp-time?               uint32
          +--ro lwm-rsp-time?               uint32
          +--ro hwm-rsp-time?               uint32
          +--ro num-pcreq-sent?             yang:counter32
          +--ro num-pcreq-rcvd?             yang:counter32
          +--ro num-pcrep-sent?             yang:counter32
          +--ro num-pcrep-rcvd?             yang:counter32
          +--ro num-pcerr-sent?             yang:counter32
          +--ro num-pcerr-rcvd?             yang:counter32



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          +--ro num-pcntf-sent?             yang:counter32
          +--ro num-pcntf-rcvd?             yang:counter32
          +--ro num-keepalive-sent?         yang:counter32
          +--ro num-keepalive-rcvd?         yang:counter32
          +--ro num-unknown-rcvd?           yang:counter32
          +--ro num-corrupt-rcvd?           yang:counter32
          +--ro num-req-sent?               yang:counter32
          +--ro num-req-sent-pend-rep?      yang:counter32
          +--ro num-req-sent-ero-rcvd?      yang:counter32
          +--ro num-req-sent-nopath-rcvd?   yang:counter32
          +--ro num-req-sent-cancel-rcvd?   yang:counter32
          +--ro num-req-sent-error-rcvd?    yang:counter32
          +--ro num-req-sent-timeout?       yang:counter32
          +--ro num-req-sent-cancel-sent?   yang:counter32
          +--ro num-req-rcvd?               yang:counter32
          +--ro num-req-rcvd-pend-rep?      yang:counter32
          +--ro num-req-rcvd-ero-sent?      yang:counter32
          +--ro num-req-rcvd-nopath-sent?   yang:counter32
          +--ro num-req-rcvd-cancel-sent?   yang:counter32
          +--ro num-req-rcvd-error-sent?    yang:counter32
          +--ro num-req-rcvd-cancel-rcvd?   yang:counter32
          +--ro num-rep-rcvd-unknown?       yang:counter32
          +--ro num-req-rcvd-unknown?       yang:counter32
          +--ro svec {p:svec}?
          |  +--ro num-svec-sent?       yang:counter32
          |  +--ro num-svec-req-sent?   yang:counter32
          |  +--ro num-svec-rcvd?       yang:counter32
          |  +--ro num-svec-req-rcvd?   yang:counter32
          +--ro stateful {p:stateful}?
          |  +--ro num-pcrpt-sent?             yang:counter32
          |  +--ro num-pcrpt-rcvd?             yang:counter32
          |  +--ro num-pcupd-sent?             yang:counter32
          |  +--ro num-pcupd-rcvd?             yang:counter32
          |  +--ro num-rpt-sent?               yang:counter32
          |  +--ro num-rpt-rcvd?               yang:counter32
          |  +--ro num-rpt-rcvd-error-sent?    yang:counter32
          |  +--ro num-upd-sent?               yang:counter32
          |  +--ro num-upd-rcvd?               yang:counter32
          |  +--ro num-upd-rcvd-unknown?       yang:counter32
          |  +--ro num-upd-rcvd-undelegated?   yang:counter32
          |  +--ro num-upd-rcvd-error-sent?    yang:counter32
          |  +--ro initiation {p:pce-initiated}?
          |     +--ro num-pcinitiate-sent?            yang:counter32
          |     +--ro num-pcinitiate-rcvd?            yang:counter32
          |     +--ro num-initiate-sent?              yang:counter32
          |     +--ro num-initiate-rcvd?              yang:counter32
          |     +--ro num-initiate-rcvd-error-sent?   yang:counter32
          +--ro path-key {p:path-key}?



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             +--ro num-unknown-path-key?      yang:counter32
             +--ro num-exp-path-key?          yang:counter32
             +--ro num-dup-path-key?          yang:counter32
             +--ro num-path-key-no-attempt?   yang:counter32



7.  Advanced PCE Features

   This document contains a specification of the base PCEP YANG module,
   "ietf-pcep" which provides the basic PCEP [RFC5440] data model.

   This document further handles advanced PCE features like -

   o  Capability and Scope

   o  Domain information (local/neighbour)

   o  Path-Key

   o  OF

   o  GCO

   o  P2MP

   o  GMPLS

   o  Inter-Layer

   o  Stateful PCE

   o  Segement Routing

   o  Authentication including PCEPS (TLS)

7.1.  Stateful PCE's LSP-DB

   In the operational state of PCEP which supports stateful PCE mode,
   the list of LSP state are maintained in LSP-DB.  The key is the PLSP-
   ID and the PCC IP address.

   The PCEP data model contains the operational state of LSPs
   (/pcep/entity/lsp-db/lsp/) with PCEP specific attributes.  The
   generic TE attributes of the LSP are defined in
   [I-D.ietf-teas-yang-te].  A reference to LSP state in TE model is
   maintained.




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8.  Open Issues and Next Step

   This section is added so that open issues can be tracked.  This
   section would be removed when the document is ready for publication.

8.1.  The PCE-Initiated LSP

   The TE Model at [I-D.ietf-teas-yang-te] should support creating of
   tunnels at the controller (PCE) and marking them as PCE-Initiated.
   The LSP-DB in the PCEP Yang (/pcep/entity/lsp-db/lsp/initiation) also
   marks the LSPs which are PCE-initiated.

9.  Other Considerations

9.1.  PCEP over TLS (PCEPS)

   [RFC8253] describe the use of TLS in PCEP.  The peer acting as the
   PCEP client MUST act as the TLS client.  The TLS client actively
   opens the TLS connection and the TLS server passively listens for the
   incoming TLS connections.  The well-known TCP port number 4189 is
   used by PCEP servers to listen for TCP connections established by
   PCEP over TLS clients.  The TLS client MUST send the TLS ClientHello
   message to begin the TLS handshake.  The TLS server MUST send a
   CertificateRequest in order to request a certificate from the TLS
   client.  Once the TLS handshake has finished, the client and the
   server MAY begin to exchange PCEP messages.  Client and server
   identity verification is done before the PCEP open message is sent.
   This means that the identity verification is completed before the
   PCEP session is started..

10.  PCEP YANG Modules

10.1.  ietf-pcep module

   RFC Ed.: In this section, replace all occurrences of 'XXXX' with the
   actual RFC number and all occurrences of the revision date below with
   the date of RFC publication (and remove this note).


 <CODE BEGINS> file "ietf-pcep@2019-03-24.yang"
 module ietf-pcep {

   yang-version 1.1;

   namespace "urn:ietf:params:xml:ns:yang:ietf-pcep";
   prefix p;

   import ietf-inet-types {



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     prefix "inet";
     reference
       "RFC 6991: Common YANG Data Types";
   }

   import ietf-yang-types {
     prefix "yang";
     reference
       "RFC 6991: Common YANG Data Types";
   }

   import ietf-te {
     prefix "te";
     reference
       "I-D.ietf-teas-yang-te: A YANG Data Model for Traffic
       Engineering Tunnels and Interfaces";
   }

   import ietf-te-types {
     prefix "te-types";
     reference
       "I-D.ietf-teas-yang-te-types: Traffic Engineering Common YANG
       Types";
   }

   import ietf-key-chain {
     prefix "kc";
     reference
       "RFC 8177: YANG Data Model for Key Chains";
   }

   import ietf-netconf-acm {
     prefix "nacm";
     reference
       "RFC 8341: Network Configuration Protocol (NETCONF) Access
       Control Model";
    }

   import ietf-tls-server {
     prefix "ts";
     reference
       "I-D.ietf-netconf-tls-client-server: YANG Groupings for TLS
       Clients and TLS Servers";
    }

   import ietf-tls-client {
      prefix "tc";
      reference



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         "I-D.ietf-netconf-tls-client-server: YANG Groupings for TLS
         Clients and TLS Servers";
   }

   import ietf-ospf {
     prefix "ospf";
     reference
       "I-D.ietf-ospf-yang: YANG Data Model for OSPF Protocol";
   }

   import ietf-isis {
     prefix "isis";
     reference
       "I-D.ietf-isis-yang-isis-cfg: YANG Data Model for IS-IS
       Protocol";
   }

   organization
     "IETF PCE (Path Computation Element) Working Group";

   contact
     "WG Web:  <http://tools.ietf.org/wg/pce/>
     WG List:  <mailto:pce@ietf.org>
     Editor:   Dhruv Dhody
               <mailto:dhruv.ietf@gmail.com>";

   description
     "The YANG module defines a generic configuration and
     operational model for PCEP.

     Copyright (c) 2019 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC XXXX; see the
     RFC itself for full legal notices.";

   revision 2019-03-24 {
     description "Initial revision.";
     reference
       "RFC XXXX:  A YANG Data Model for Path Computation
       Element Communications Protocol (PCEP)";



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   }

   /*
    * Typedefs
    */
   typedef pcep-role {
     type enumeration {
       enum unknown {
         value "0";
         description
           "An unknown role";
       }
       enum pcc {
         value "1";
         description
           "The role of a Path Computation Client";
       }
       enum pce {
         value "2";
         description
           "The role of Path Computation Element";
       }
       enum pcc-and-pce {
         value "3";
         description
           "The role of both Path Computation Client and
           Path Computation Element";
       }
     }
     description
       "The role of a PCEP speaker.
       Takes one of the following values
       - unknown(0): the role is not known.
       - pcc(1): the role is of a Path Computation
         Client (PCC).
       - pce(2): the role is of a Path Computation
         Server (PCE).
       - pccAndPce(3): the role is of both a PCC and
         a PCE.";
   }

   typedef pcep-oper-status {
     type enumeration {
       enum oper-status-up {
         value "1";
         description
           "The PCEP entity is active";
       }



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       enum oper-status-down {
         value "2";
         description
           "The PCEP entity is inactive";
       }
         enum oper-status-going-up {
         value "3";
         description
           "The PCEP entity is activating";
       }
       enum oper-status-going-down {
         value "4";
         description
           "The PCEP entity is deactivating";
       }
       enum oper-status-failed {
         value "5";
         description
           "The PCEP entity has failed and will recover
           when possible.";
       }
       enum oper-status-failed-perm {
         value "6";
         description
           "The PCEP entity has failed and will not recover
           without operator intervention";
       }
     }
     description
       "The operational status of the PCEP entity.
       Takes one of the following values
       - oper-status-up(1): Active
       - oper-status-down(2): Inactive
       - oper-status-going-up(3): Activating
       - oper-status-going-down(4): Deactivating
       - oper-status-failed(5): Failed
       - oper-status-failed-perm(6): Failed Permanantly";
     reference
       "RFC 5440: Path Computation Element (PCE) Communication
       Protocol (PCEP)";
   }

   typedef pcep-initiator {
     type enumeration {
       enum local {
         value "1";
         description
           "The local PCEP entity initiated the session";



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       }
       enum remote {
         value "2";
         description
           "The remote PCEP peer initiated the session";
       }
     }
     description
       "The initiator of the session, that is, whether the TCP
       connection was initiated by the local PCEP entity or
       the remote peer.
       Takes one of the following values
       - local(1): Initiated locally
       - remote(2): Initiated remotely";
   }

   typedef pcep-sess-state {
     type enumeration {
       enum tcp-pending {
         value "1";
         description
           "The tcp-pending state of PCEP session.";
       }
       enum open-wait {
         value "2";
         description
           "The open-wait state of PCEP session.";
       }
       enum keep-wait {
         value "3";
         description
           "The keep-wait state of PCEP session.";
       }
       enum session-up {
         value "4";
         description
           "The session-up state of PCEP session.";
       }
     }
     description
       "The current state of the session.
       The set of possible states excludes the idle state
       since entries do not exist in the idle state.
       Takes one of the following values
       - tcp-pending(1): PCEP TCP Pending state
       - open-wait(2): PCEP Open Wait state
       - keep-wait(3): PCEP Keep Wait state
       - session-up(4): PCEP Session Up state";



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     reference
       "RFC 5440: Path Computation Element (PCE) Communication
       Protocol (PCEP)";
   }

   typedef domain-type {
     type enumeration {
       enum ospf-area {
         value "1";
         description
           "The OSPF area.";
       }
       enum isis-area {
         value "2";
         description
           "The IS-IS area.";
       }
       enum as {
         value "3";
         description
           "The Autonomous System (AS).";
       }
     }
     description
       "The PCE Domain Type";
   }

   typedef domain-ospf-area {
     type ospf:area-id-type;
     description
       "OSPF Area ID.";
     reference
       "I-D.ietf-ospf-yang: YANG Data Model for OSPF Protocol";
   }

   typedef domain-isis-area {
     type isis:area-address;
     description
       "IS-IS Area ID.";
     reference
       "I-D.ietf-isis-yang-isis-cfg: YANG Data Model for IS-IS
       Protocol";
   }

   typedef domain-as {
     type inet:as-number;
     description
       "Autonomous System number.";



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   }

   typedef domain {
     type union {
       type domain-ospf-area;
       type domain-isis-area;
       type domain-as;
     }
     description
       "The Domain Information";
   }

   typedef operational-state {
     type enumeration {
       enum down {
         value "0";
         description
           "not active.";
       }
       enum up {
         value "1";
         description
           "signalled.";
       }
       enum active {
         value "2";
         description
           "up and carrying traffic.";
       }
       enum going-down {
         value "3";
         description
           "LSP is being torn down, resources are
           being released.";
       }
       enum going-up {
         value "4";
         description
           "LSP is being signalled.";
       }
     }
     description
       "The operational status of the LSP";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }




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   typedef sync-state {
     type enumeration {
       enum pending {
         value "0";
         description
           "The state synchronization
           has not started.";
       }
       enum ongoing {
         value "1";
         description
           "The state synchronization
           is ongoing.";
       }
       enum finished {
         value "2";
         description
           "The state synchronization
           is finished.";
       }
     }
     description
       "The LSP-DB state synchronization operational
       status.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   /*
    * Features
    */

   feature svec {
     description
       "Support synchronized path computation.";
     reference
       "RFC 5440: Path Computation Element (PCE) Communication
       Protocol (PCEP)";
   }

   feature gmpls {
     description
       "Support GMPLS.";
     reference
       "I-D.ietf-pce-gmpls-pcep-extensions: PCEP extensions for
       GMPLS";
   }



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   feature objective-function {
     description
       "Support OF as per RFC 5541.";
     reference
       "RFC 5541: Encoding of Objective Functions in the Path
       Computation Element Communication Protocol (PCEP)";
   }

   feature global-concurrent {
     description
       "Support GCO as per RFC 5557.";
     reference
       "RFC 5557: Path Computation Element Communication Protocol
       (PCEP) Requirements and Protocol Extensions in Support of
       Global Concurrent Optimization";
   }

   feature path-key {
     description
       "Support path-key as per RFC 5520.";
     reference
       "RFC 5520: Preserving Topology Confidentiality in Inter-
       Domain Path Computation Using a Path-Key-Based Mechanism";
   }

   feature p2mp {
     description
       "Support P2MP as per RFC 8306.";
     reference
       "RFC 8306: Extensions to the Path Computation Element
       Communication Protocol (PCEP) for Point-to-Multipoint
       Traffic Engineering Label Switched Paths";
   }

   feature stateful {
     description
       "Support stateful PCE as per RFC 8231.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   feature sync-opt {
     description
       "Support stateful sync optimization
       as per RFC 8232";
     reference
       "RFC 8232: Optimizations of Label Switched Path State



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       Synchronization Procedures for a Stateful PCE";
   }

   feature pce-initiated {
     description
       "Support PCE-Initiated LSP as per
       RFC 8281.";
     reference
       "RFC 8281: Path Computation Element Communication Protocol
       (PCEP) Extensions for PCE-Initiated LSP Setup in a Stateful
       PCE Model";
   }

   feature tls {
     description
       "Support PCEP over TLS as per
       RFC 8253.";
     reference
       "RFC 8253: PCEPS: Usage of TLS to Provide a Secure Transport
       for the Path Computation Element Communication Protocol
       (PCEP)";
   }

   feature sr {
     description
       "Support Segment Routing for PCE.";
     reference
       "I-D.ietf-pce-segment-routing: PCEP Extensions for Segment
       Routing";
   }

   feature association {
     description
       "Support Association in PCEP.";
     reference
       "I-D.ietf-pce-association-group: PCEP Extensions for
       Establishing Relationships Between Sets of LSPs";
   }

   /*
   * Identities
   */

   identity lsp-error {
     if-feature stateful;
     description
       "Base LSP error";
     reference



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       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity no-error-lsp-error {
     base lsp-error;
     if-feature stateful;
     description
       "No error, LSP is fine.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity unknown-lsp-error {
     base lsp-error;
     if-feature stateful;
     description
       "Unknown reason.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity limit-lsp-error {
     base lsp-error;
     if-feature stateful;
     description
       "Limit reached for PCE-controlled LSPs.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity pending-lsp-error {
     base lsp-error;
     if-feature stateful;
     description
       "Too many pending LSP update requests.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity unacceptable-lsp-error {
     base lsp-error;
     if-feature stateful;
     description



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       "Unacceptable parameters.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity internal-lsp-error {
     base lsp-error;
     if-feature stateful;
     description
       "Internal error.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity admin-lsp-error {
     base lsp-error;
     if-feature stateful;
     description
       "LSP administratively brought down.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity preempted-lsp-error {
     base lsp-error;
     if-feature stateful;
     description
       "LSP preempted.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   identity rsvp-lsp-error {
     base lsp-error;
     if-feature stateful;
     description
       "RSVP signaling error.";
     reference
       "RFC 8231: Path Computation Element Communication Protocol
       (PCEP) Extensions for Stateful PCE";
   }

   /*
    * Groupings



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    */


   grouping pce-scope{
     description
       "This grouping defines PCE path computation scope
       information which maybe relevant to PCE selection.
       This information corresponds to PCE auto-discovery
       information.";
     reference
       "RFC 5088: OSPF Protocol Extensions for Path
       Computation Element (PCE) Discovery
       RFC 5089: IS-IS Protocol Extensions for Path
       Computation Element (PCE) Discovery";
     leaf path-scope{
       type bits{
         bit intra-area-scope{
           description
             "PCE can compute intra-area paths.";
         }
         bit inter-area-scope{
           description
             "PCE can compute inter-area paths.";
         }
         bit inter-area-scope-default{
           description
             "PCE can act as a default PCE for inter-area
             path computation.";
         }
         bit inter-as-scope{
           description
             "PCE can compute inter-AS paths.";
         }
         bit inter-as-scope-default{
           description
             "PCE can act as a default PCE for inter-AS
             path computation.";
         }
         bit inter-layer-scope{
           description
             "PCE can compute inter-layer paths.";
         }
       }
       description
         "The field corresponding to the path scope bits";
     }

     leaf intra-area-pref{



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       type uint8{
         range "0..7";
       }
       description
         "The PCE's preference for intra-area TE LSP
         computation.";
     }

     leaf inter-area-pref{
       type uint8{
         range "0..7";
       }
       description
         "The PCE's preference for inter-area TE LSP
         computation.";
     }

     leaf inter-as-pref{
       type uint8{
         range "0..7";
       }
       description
         "The PCE's preference for inter-AS TE LSP
         computation.";
     }

     leaf inter-layer-pref{
       type uint8{
       range "0..7";
       }
       description
         "The PCE's preference for inter-layer TE LSP
         computation.";
     }
   }//pce-scope

   grouping domain{
     description
       "This grouping specifies a Domain where the
       PCEP speaker has topology visibility.";
     leaf domain-type{
       type domain-type;
       description
         "The domain type.";
     }
     leaf domain{
       type domain;
       description



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         "The domain Information.";
     }
   }//domain



   grouping info{
     description
       "This grouping specifies all information which
       maybe relevant to both PCC and PCE.
       This information corresponds to PCE auto-discovery
       information.";
     container domain{
       description
         "The local domain for the PCEP entity";
       list domain{
         key "domain-type domain";
         description
           "The local domain.";
         uses domain{
           description
             "The local domain for the PCEP entity.";
         }
       }
     }
     container capability{
       description
         "The PCEP entity capability information of local
         PCEP entity. This maybe relevant to PCE selection
         as well. This information corresponds to PCE auto-
         discovery information.";
       reference
         "RFC 5088: OSPF Protocol Extensions for Path
         Computation Element (PCE) Discovery
         RFC 5089: IS-IS Protocol Extensions for Path
         Computation Element (PCE) Discovery";
       leaf capability{
         type bits{
           bit gmpls{
             if-feature gmpls;
             description
               "Path computation with GMPLS link
               constraints.";
           }
           bit bi-dir{
             description
               "Bidirectional path computation.";
           }



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           bit diverse{
             description
               "Diverse path computation.";
           }
           bit load-balance{
             description
               "Load-balanced path computation.";
           }
           bit synchronize{
             if-feature svec;
             description
               "Synchronized paths computation.";
           }
           bit objective-function{
             if-feature objective-function;
             description
               "Support for multiple objective functions.";
           }
           bit add-path-constraint{
             description
               "Support for additive path constraints (max
               hop count, etc.).";
           }
           bit prioritization{
             description
               "Support for request prioritization.";
           }
           bit multi-request{
             description
               "Support for multiple requests per message.";
           }
           bit global-concurrent{
             if-feature global-concurrent;
             description
               "Support for Global Concurrent Optimization
               (GCO).";
           }
           bit p2mp{
             if-feature p2mp;
             description
               "Support for P2MP path computation.";
           }
           bit active{
             if-feature stateful;
             description
               "Support for active stateful PCE.";
           }
           bit passive{



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             if-feature stateful;
             description
               "Support for passive stateful PCE.";
           }
           bit p2mp-active{
             if-feature stateful;
             if-feature p2mp;
             description
               "Support for active stateful PCE for P2MP.";
           }
           bit p2mp-passive{
             if-feature stateful;
             if-feature p2mp;
             description
               "Support for passive stateful PCE for P2MP.";
           }
           bit p2mp-pce-initiated{
             if-feature stateful;
             if-feature pce-initiated;
             if-feature p2mp;
             description
               "Support for PCE-initiated LSP for P2MP.";
           }
         }
         description
           "The bits string indicating the capabiliies";
         reference
           "RFC 5088: OSPF Protocol Extensions for Path
           Computation Element (PCE) Discovery
           RFC 5089: IS-IS Protocol Extensions for Path
           Computation Element (PCE) Discovery";
       }
       leaf pce-initiated{
         if-feature pce-initiated;
         type boolean;
         description
           "Set to true if PCE-initiated LSP capability is
           enabled.";
         reference
           "RFC 8281: Path Computation Element Communication
           Protocol (PCEP) Extensions for PCE-Initiated LSP
           Setup in a Stateful PCE Model";
       }
       leaf include-db-ver{
         if-feature stateful;
         if-feature sync-opt;
         type boolean;
         description



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           "Support inclusion of LSP-DB-VERSION
           in LSP object";
         reference
           "RFC 8232: Optimizations of Label Switched Path State
           Synchronization Procedures for a Stateful PCE";
       }
       leaf trigger-resync{
         if-feature stateful;
         if-feature sync-opt;
         type boolean;
         description
           "Support PCE triggered re-synchronization";
         reference
           "RFC 8232: Optimizations of Label Switched Path State
           Synchronization Procedures for a Stateful PCE";
       }
       leaf trigger-initial-sync{
         if-feature stateful;
         if-feature sync-opt;
         type boolean;
         description
           "PCE triggered initial synchronization";
         reference
           "RFC 8232: Optimizations of Label Switched Path State
           Synchronization Procedures for a Stateful PCE";
       }
       leaf incremental-sync{
         if-feature stateful;
         if-feature sync-opt;
         type boolean;
         description
           "Support incremental (delta) sync";
         reference
           "RFC 8232: Optimizations of Label Switched Path State
           Synchronization Procedures for a Stateful PCE";
       }
       container sr{
         if-feature sr;
         description
           "If segment routing is supported";
         reference
           "I-D.ietf-pce-segment-routing: PCEP Extensions for Segment
           Routing";
         leaf enabled{
           type boolean;
           description
             "Set to true if SR is enabled";
         }



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         leaf msd-limit{
           type boolean;
           default false;
           description
             "True indicates no limit on MSD, the
             leaf msd is ignored";
         }
         leaf nai{
           type boolean;
           default false;
           description
             "True indicates capability to resolve NAI
             to SID";
         }
       }//sr
     }//capability
     leaf msd{
       if-feature sr;
       type uint8;
       description
         "Maximum SID Depth for SR";
       reference
         "I-D.ietf-pce-segment-routing: PCEP Extensions for Segment
         Routing";
     }
   }//info

   grouping pce-info{
     description
       "This grouping specifies all PCE information
       which maybe relevant to the PCE selection.
       This information corresponds to PCE auto-discovery
       information.";
     container scope{
       description
         "The path computation scope";
       uses pce-scope;
     }

     container neigh-domains{
       description
         "The list of neighbour PCE-Domain
         toward which a PCE can compute
         paths";
       list domain{
           key "domain-type domain";
           description
             "The neighbour domain.";



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           uses domain{
             description
               "The PCE neighbour domain.";
           }
       }
     }
   }//pce-info

   grouping notification-instance-hdr {
     description
       "This group describes common instance specific data
       for notifications.";

     leaf peer-addr {
       type leafref {
         path "/pcep/entity/peers/peer/addr";
       }
       description
         "Reference to peer address";
     }
   }// notification-instance-hdr

   grouping notification-session-hdr {
     description
       "This group describes common session instance specific
       data for notifications.";

     leaf session-initiator {
       type leafref {
         path "/pcep/entity/peers/peer/sessions/" +
              "session/initiator";
       }
       description
         "Reference to pcep session initiator leaf";
     }
   }// notification-session-hdr

   grouping of-list {
     description
       "List of OF";
     reference
       "RFC 5541: Encoding of Objective Functions in the Path
       Computation Element Communication Protocol (PCEP)";
     list objective-function{
       key "of";
       description
         "The list of authorized OF";
       leaf of {



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         type identityref{
           base te-types:objective-function-type;
         }
         description
           "The OF authorized";
       }
     }
   }

   /*
    * Configuration data nodes
    */
   container pcep{

     presence
       "The PCEP is enabled";

     description
       "Parameters for list of configured PCEP entities
       on the device.";

     container entity {
       description
         "The configured PCEP entity on the device.";

       leaf addr {
         type inet:ip-address;
         mandatory true;
         description
           "The local Internet address of this PCEP entity.
           If operating as a PCE server, the PCEP entity
           listens on this address. If operating as a PCC,
           the PCEP entity binds outgoing TCP connections
           to this address. It is possible for the PCEP entity
           to operate both as a PCC and a PCE Server, in which
           case it uses this address both to listen for incoming
           TCP connections and to bind outgoing TCP connections.";
       }

       leaf enabled {
         type boolean;
         default true;
         description
           "The administrative status of this PCEP
           Entity.";
       }

       leaf role {



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         type pcep-role;
         mandatory true;
         description
           "The role that this entity can play.
           Takes one of the following values.
           - unknown(0): this PCEP Entity role is not
           known.
           - pcc(1): this PCEP Entity is a PCC.
           - pce(2): this PCEP Entity is a PCE.
           - pcc-and-pce(3): this PCEP Entity is both
           a PCC and a PCE.";
       }

       leaf description {
         type string;
         description
           "Description of the PCEP entity configured
           by the user";
       }

       leaf speaker-entity-id{
         if-feature sync-opt;
         type string;
         description
           "The Speaker Entity Identifier";
         reference
           "RFC 8232: Optimizations of Label Switched
           Path State  Synchronization Procedures for
           a Stateful PCE";
       }

       leaf admin-status {
         type boolean;
         default true;
         description
           "The administrative status of this PCEP Entity.
           The value true represents admin status as up.
           This is the desired operational status as
           currently set by an operator or by default in
           the implementation. The value of oper-status
           represents the current status of an attempt to
           reach this desired status.";
       }

       leaf index{
         type uint32;
         config "false";
         description



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           "The index of the operational PECP entity";
       }

       leaf oper-status {
         type pcep-oper-status;
         config "false";
         description
           "The operational status of the PCEP entity.
           Takes one of the following values.
           - oper-status-up(1): the PCEP entity is active.
           - oper-status-down(2): the PCEP entity is inactive.
           - oper-status-going-up(3): the PCEP entity is
           activating.
           - oper-status-going-down(4): the PCEP entity is
           deactivating.
           - oper-status-failed(5): the PCEP entity has
           failed and will recover when possible.
           - oper-status-failed-perm(6): the PCEP entity
           has failed and will not recover without
           operator intervention.";
       }

       uses info {
         description
           "Local PCEP entity information";
       }

       container pce-info {
         when "../role = 'pce'" +
              "or " +
              "../role = 'pcc-and-pce'"
         {
           description
             "These fields are applicable when the role is PCE.";
         }
         description
           "The Local PCE Entity PCE information";
         uses pce-info {
           description
             "Local PCE information";
         }
         container path-key {
           if-feature path-key;
           description
             "Path-Key Configuration";
           reference
             "RFC 5520: Preserving Topology Confidentiality in Inter-
             Domain Path Computation Using a Path-Key-Based Mechanism";



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           leaf enabled {
             type boolean;
             description
               "Enabled or Disabled";
           }
           leaf discard-timer {
             type uint32;
             units "minutes";
             default 10;
             description
               "A timer to discard unwanted path-keys";
           }
           leaf reuse-time {
             type uint32;
             units "minutes";
             default 30;
             description
               "A time after which the path-keys could be reused";
           }
           leaf pce-id {
             type inet:ip-address;
             description
               "PCE Address to be used in each Path-Key Subobject
               (PKS)";
           }
         }
       }
       leaf connect-timer {
         type uint16 {
           range "1..65535";
         }
         units "seconds";
         default 60;
         description
           "The time in seconds that the PCEP entity will wait
           to establish a TCP connection with a peer.  If a
           TCP connection is not established within this time
           then PCEP aborts the session setup attempt.";
         reference
           "RFC 5440: Path Computation Element (PCE) Communication
           Protocol (PCEP)";
       }
       leaf connect-max-retry {
         type uint32;
         default 5;
         description
           "The maximum number of times the system tries to
           establish a TCP connection to a peer before the



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           session with the peer transitions to the idle
           state.";
         reference
           "RFC 5440: Path Computation Element (PCE) Communication
           Protocol (PCEP)";
       }

       leaf init-backoff-timer {
         type uint16 {
           range "1..65535";
         }
         units "seconds";
         description
           "The initial back-off time in seconds for retrying
           a failed session setup attempt to a peer.
           The back-off time increases for each failed
           session setup attempt, until a maximum back-off
           time is reached.  The maximum back-off time is
           max-backoff-timer.";
         reference
           "RFC 5440: Path Computation Element (PCE) Communication
           Protocol (PCEP)";
       }

       leaf max-backoff-timer {
         type uint32;
           units "seconds";
         description
           "The maximum back-off time in seconds for retrying
           a failed session setup attempt to a peer.
           The back-off time increases for each failed session
           setup attempt, until this maximum value is reached.
           Session setup attempts then repeat periodically
           without any further increase in back-off time.";
         reference
           "RFC 5440: Path Computation Element (PCE) Communication
           Protocol (PCEP)";
       }

       leaf open-wait-timer {
         type uint16 {
           range "1..65535";
         }
         units "seconds";
         default 60;
         description
           "The time in seconds that the PCEP entity will wait
           to receive an Open message from a peer after the



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           TCP connection has come up.
           If no Open message is received within this time then
           PCEP terminates the TCP connection and deletes the
           associated sessions.";
         reference
           "RFC 5440: Path Computation Element (PCE) Communication
           Protocol (PCEP)";
       }

       leaf keep-wait-timer {
         type uint16 {
           range "1..65535";
         }
         units "seconds";
         default 60;
         description
           "The time in seconds that the PCEP entity will wait
           to receive a Keepalive or PCErr message from a peer
           during session initialization after receiving an
           Open message.  If no Keepalive or PCErr message is
           received within this time then PCEP terminates the
           TCP connection and deletes the associated
           sessions.";
         reference
           "RFC 5440: Path Computation Element (PCE) Communication
           Protocol (PCEP)";
       }

       leaf keep-alive-timer {
         type uint8;
         units "seconds";
         default 30;
         description
           "The keep alive transmission timer that this PCEP
           entity will propose in the initial OPEN message of
           each session it is involved in.  This is the
           maximum time between two consecutive messages sent
           to a peer. Zero means that the PCEP entity prefers
           not to send Keepalives at all.
           Note that the actual Keepalive transmission
           intervals, in either direction of an active PCEP
           session, are determined by negotiation between the
           peers as specified by RFC 5440, and so may differ
           from this configured value.";
         reference
           "RFC 5440: Path Computation Element (PCE) Communication
           Protocol (PCEP)";
       }



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       leaf dead-timer {
         type uint8;
         units "seconds";
         must "(. > ../keep-alive-timer)" {
           error-message "The dead timer must be "
              + "larger than the keep alive timer";
         }
         default 120;
         description
           "The dead timer that this PCEP entity will propose
           in the initial OPEN message of each session it is
           involved in. This is the time after which a peer
           should declare a session down if it does not
           receive any PCEP messages. Zero suggests that the
           peer does not run a dead timer at all.";
         reference
           "RFC 5440: Path Computation Element (PCE) Communication
           Protocol (PCEP)";
       }

       leaf allow-negotiation{
         type boolean;
         description
           "Whether the PCEP entity will permit negotiation of
           session parameters.";
       }

       leaf max-keep-alive-timer{
         type uint8;
         units "seconds";
         description
           "In PCEP session parameter negotiation in seconds,
           the maximum value that this PCEP entity will
           accept from a peer for the interval between
           Keepalive transmissions. Zero means that the PCEP
           entity will allow no Keepalive transmission at
           all.";
       }

       leaf max-dead-timer{
         type uint8;
         units "seconds";
         description
           "In PCEP session parameter negotiation in seconds,
           the maximum value that this PCEP entity will accept
           from a peer for the Dead timer.  Zero means that
           the PCEP entity will allow not running a Dead
           timer.";



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       }

       leaf min-keep-alive-timer{
         type uint8;
         units "seconds";
         description
           "In PCEP session parameter negotiation in seconds,
           the minimum value that this PCEP entity will
           accept for the interval between Keepalive
           transmissions. Zero means that the PCEP entity
           insists on no Keepalive transmission at all.";
       }

       leaf min-dead-timer{
         type uint8;
         units "seconds";
         description
           "In PCEP session parameter negotiation in
           seconds, the minimum value that this PCEP entity
           will accept for the Dead timer.  Zero means that
           the PCEP entity insists on not running a Dead
           timer.";
       }

       leaf sync-timer{
         if-feature svec;
         type uint16;
         units "seconds";
         default 60;
         description
           "The value of SyncTimer in seconds is used in the
           case of synchronized path computation request
           using the SVEC object. Consider the case where a
           PCReq message is received by a PCE that contains
           the SVEC object referring to M synchronized path
           computation requests.  If after the expiration of
           the SyncTimer all the M path computation requests
           have not been, received a protocol error is
           triggered and the PCE MUST cancel the whole set
           of path computation requests.
           The aim of the SyncTimer is to avoid the storage
           of unused synchronized requests should one of
           them get lost for some reasons (for example, a
           misbehaving PCC).
           Zero means that the PCEP entity does not use the
           SyncTimer.";
         reference
           "RFC 5440: Path Computation Element (PCE)



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           Communication Protocol (PCEP)";
       }

       leaf request-timer{
         type uint16 {
           range "1..65535";
         }
         units "seconds";
         description
           "The maximum time that the PCEP entity will wait
           for a response to a PCReq message.";
       }

       leaf max-sessions{
         type uint32;
         description
           "Maximum number of sessions involving this PCEP
           entity that can exist at any time.";
       }

       leaf max-unknown-reqs{
         type uint32;
         default 5;
         description
           "The maximum number of unrecognized requests and
           replies that any session on this PCEP entity is
           willing to accept per minute before terminating
           the session.
           A PCRep message contains an unrecognized reply
           if it contains an RP object whose request ID
           does not correspond to any in-progress request
           sent by this PCEP entity.
           A PCReq message contains an unrecognized request
           if it contains an RP object whose request ID is
           zero.";
           reference
           "RFC 5440: Path Computation Element (PCE)
           Communication Protocol (PCEP)";
       }

       leaf max-unknown-msgs{
         type uint32;
         default 5;
         description
           "The maximum number of unknown messages that any
           session on this PCEP entity is willing to accept
           per minute before terminating the session.";
         reference



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           "RFC 5440: Path Computation Element (PCE)
           Communication Protocol (PCEP)";
       }

       leaf pcep-notification-max-rate {
         type uint32;
         mandatory true;
         description
           "This variable indicates the maximum number of
           notifications issued per second. If events
           occur more rapidly, the implementation may
           simply fail to emit these notifications during
           that period, or may queue them until an
           appropriate time. A value of 0 means no
           notifications are emitted and all should be
           discarded (that is, not queued).";
       }
       container stateful-parameter{
         if-feature stateful;
         description
           "The configured stateful PCE parameters";
         leaf state-timeout{
           type uint32;
           units "seconds";
           description
             "When a PCEP session is terminated, a PCC
             waits for this time period before flushing
             LSP state associated with that PCEP session
             and reverting to operator-defined default
             parameters or behaviours.";
         }
         leaf redelegation-timeout{
           when "../../role = 'pcc'" +
                "or " +
                "../../role = 'pcc-and-pce'"
           {
             description
               "This field is applicable when the role is
               PCC";
           }
           type uint32;
           units "seconds";
           description
             "When a PCEP session is terminated, a PCC
             waits for this time period before revoking
             LSP delegation to a PCE and attempting to
             redelegate LSPs associated with the
             terminated PCEP session to an alternate



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             PCE.";
         }
         leaf rpt-non-pcep-lsp{
           when "../../role = 'pcc'" +
                "or " +
                "../../role = 'pcc-and-pce'"
           {
             description
               "This field is applicable when the role is
               PCC";
           }
           type boolean;
           default true;
           description
             "If set, a PCC reports LSPs that are not
             controlled by any PCE (for example, LSPs
             that are statically configured at the
             PCC). ";
           }
           reference
             "RFC 8231: Path Computation Element Communication Protocol
             (PCEP) Extensions for Stateful PCE";
         }
         container of-list{
           when "../role = 'pce'" +
                "or " +
                "../role = 'pcc-and-pce'"
           {
             description
               "These field are applicable when the role is
               PCE";
           }
           if-feature objective-function;

           uses of-list;

           description
             "The authorized OF-List at PCE for all peers";
         }
         container lsp-db{
           if-feature stateful;
           config false;
           description
             "The LSP-DB";
           leaf db-ver{
             when "../../role = 'pcc'" +
                  "or " +
                  "../../role = 'pcc-and-pce'"



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             {
               description
                 "This field is applicable when the role is
                 PCC";
             }
             if-feature sync-opt;
             type uint64;
             description
               "The LSP State Database Version Number";
           }
           list association-list {
             if-feature association;
             key "type id source global-source extended-id";
             description
               "List of all PCEP associations";
             reference
               "I-D.ietf-pce-association-group: PCEP
               Extensions for Establishing Relationships
               Between Sets of LSPs";
             leaf type {
               type identityref {
                 base te-types:association-type;
               }
               description
                 "The PCEP association type";
             }
             leaf id {
               type uint16;
               description
                 "PCEP Association ID";
             }
             leaf source {
               type inet:ip-address;
               description
                 "PCEP Association Source.";
             }
             leaf global-source {
               type uint32;
               description
                 "PCEP Association Global Source.";
             }
             leaf extended-id{
               type string;
               description
                 "Additional information to support unique
                 identification.";
             }
             list lsp {



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               key "plsp-id pcc-id";
               description
                 "List of all LSP in this association";
               leaf plsp-id {
                 type leafref {
                   path "/pcep/entity/lsp-db/"
                        + "lsp/plsp-id";
                 }
                 description
                   "Reference to PLSP-ID in LSP-DB";
               }
               leaf pcc-id {
                 type leafref {
                   path "/pcep/entity/lsp-db/"
                        + "lsp/pcc-id";
                 }
                 description
                   "Reference to PCC-ID in LSP-DB";
               }
             }
           }
           list lsp {
             key "plsp-id pcc-id";
             description
               "List of all LSPs in LSP-DB";
             leaf plsp-id{
               type uint32{
                 range "1..1048575";
               }
               description
                 "A PCEP-specific identifier for the LSP.  A PCC
                 creates a unique PLSP-ID for each LSP that is
                 constant for the lifetime of a PCEP session.
                 PLSP-ID is 20 bits with 0 and 0xFFFFF are
                 reserved";
             }
             leaf pcc-id{
               type inet:ip-address;
               description
                 "The local internet address of the PCC, that
                 generated the PLSP-ID.";
             }
             container lsp-ref{
               description
                 "reference to ietf-te lsp state";

               leaf source {
                 type leafref {



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                   path "/te:te/te:lsps-state/te:lsp/te:source";
                 }
                 description
                   "Tunnel sender address extracted from
                   SENDER_TEMPLATE object";
                 reference
                   "RFC 3209: RSVP-TE: Extensions to RSVP for
                   LSP Tunnels";
               }
               leaf destination {
                 type leafref {
                   path "/te:te/te:lsps-state/te:lsp/te:"
                        + "destination";
                 }
                 description
                   "Tunnel endpoint address extracted from
                   SESSION object";
                 reference
                   "RFC 3209: RSVP-TE: Extensions to RSVP for
                   LSP Tunnels";
               }
               leaf tunnel-id {
                 type leafref {
                   path "/te:te/te:lsps-state/te:lsp/te:tunnel-id";
                 }
                 description
                   "Tunnel identifier used in the SESSION
                   that remains constant over the life
                   of the tunnel.";
                 reference
                   "RFC 3209: RSVP-TE: Extensions to RSVP for
                   LSP Tunnels";
               }
               leaf lsp-id {
                 type leafref {
                   path "/te:te/te:lsps-state/te:lsp/te:lsp-id";
                 }
                 description
                   "Identifier used in the SENDER_TEMPLATE
                   and the FILTER_SPEC that can be changed
                   to allow a sender to share resources with
                   itself.";
                 reference
                   "RFC 3209: RSVP-TE: Extensions to RSVP for
                   LSP Tunnels";
               }
               leaf extended-tunnel-id {
                 type leafref {



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                   path "/te:te/te:lsps-state/te:lsp/te:"
                        + "extended-tunnel-id";
                 }
                 description
                   "Extended Tunnel ID of the LSP.";
                 reference
                   "RFC 3209: RSVP-TE: Extensions to RSVP for
                   LSP Tunnels";
               }
             }

             leaf admin-state{
               type boolean;
               description
                 "The desired operational state";
             }
             leaf operational-state{
               type operational-state;
               description
                 "The operational status of the LSP";
             }
             container delegated{
               description
                 "The delegation related parameters";
               leaf enabled{
                 type boolean;
                 description
                   "LSP is delegated or not";
               }
               leaf peer{
                 type leafref {
                   path "/pcep/entity/peers/peer/addr";
                 }
                 must "(../enabled = true())"
                 {
                   error-message
                     "The LSP must be delegated";
                 }
                 description
                   "At the PCC, the reference to the PCEP peer to
                   which LSP is delegated; At the PCE, the
                   reference to the PCEP peer which delegated this
                   LSP";
               }
               leaf srp-id{
                 type uint32;
                 description
                   "The last SRP-ID-number associated with this



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                   LSP.";
               }
             }
             container initiation {
               if-feature pce-initiated;
               description
                 "The PCE initiation related parameters";
               reference
                 "RFC 8281: Path Computation Element Communication
                 Protocol (PCEP) Extensions for PCE-Initiated LSP
                 Setup in a Stateful PCE Model";
               leaf enabled{
                 type boolean;
                 description
                   "Set to true if this LSP is initiated by a PCE";
               }
               leaf peer{
                 type leafref {
                   path "/pcep/entity/peers/peer/addr";
                 }
                 must "(../enabled = true())"
                 {
                   error-message
                     "The LSP must be PCE-Initiated";
                 }
                 description
                   "At the PCC, the reference to the PCEP peer
                   that initiated this LSP; At the PCE, the
                   reference to the PCEP peer where the LSP
                   is initiated";
               }
             }
             leaf symbolic-path-name{
               type string;
               description
                 "The symbolic path name associated with the LSP.";
               reference
                 "RFC 8231: Path Computation Element Communication
                 Protocol (PCEP) Extensions for Stateful PCE";
             }
             leaf last-error{
               type identityref {
                 base lsp-error;
               }
               description
                 "The last error for the LSP.";
             }
             leaf pst{



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               type identityref{
                 base te-types:path-signaling-type;
               }
               default "te-types:path-setup-rsvp";
               description
                 "The Path Setup Type";
               reference
                 "RFC 8408: Conveying Path Setup Type in PCE
                 Communication Protocol (PCEP) Messages";
             }
             list association-list {
               if-feature association;
               key "type id source global-source extended-id";
               description
                 "List of all PCEP associations";
               leaf type {
                 type leafref {
                 path "/pcep/entity/lsp-db/"
                      + "association-list/type";
                 }
                 description
                   "PCEP Association Type";
               }
               leaf id {
                 type leafref {
                 path "/pcep/entity/lsp-db/"
                      + "association-list/id";
                 }
                 description
                   "PCEP Association ID";
               }
               leaf source {
                 type leafref {
                 path "/pcep/entity/lsp-db/"
                      + "association-list/source";
                 }
                 description
                   "PCEP Association Source.";
               }
               leaf global-source {
                 type leafref {
                   path "/pcep/entity/lsp-db/"
                        + "association-list/global-source";
                 }
                 description
                   "PCEP Association Global Source.";
               }
               leaf extended-id{



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                 type leafref {
                   path "/pcep/entity/lsp-db/"
                        + "association-list/extended-id";
                 }
                 description
                   "Additional information to
                   support unique identification.";
               }
               reference
                 "I-D.ietf-pce-association-group: PCEP
                 Extensions for Establishing Relationships
                 Between Sets of LSPs";
             }
           }
         }
         container path-keys {
           when "../role = 'pce' or ../role = 'pcc-and-pce'" {
             description
               "These fields are applicable when the role is
               PCE";
           }
           if-feature path-key;
           config false;
           description
             "The path-keys generated by the PCE";
           reference
             "RFC 5520: Preserving Topology Confidentiality
             in Inter-Domain Path Computation Using a Path-
             Key-Based Mechanism";
           list path-keys{
             key "path-key";
             description
               "The list of path-keys generated by the PCE";
             leaf path-key {
               type uint16;
               description
                 "The identifier, or token used to represent
                 the Confidential Path Segment (CPS) within
                 the context of the PCE";
             }
             container cps {
               description
                 "The Confidential Path Segment (CPS)";
               list explicit-route-objects {
                 key "index";
                 description
                   "List of explicit route objects";
                 leaf index {



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                   type uint32;
                   description
                     "ERO subobject index";
                 }
                 uses te-types:explicit-route-hop;
               }
             }
             leaf pcc-original {
               type leafref {
                 path "/pcep/entity/peers/peer/addr";
               }
               description
                 "Reference to PCC peer address of
                 the original request";
             }
             leaf req-id {
               type uint32;
               description
                 "The request ID of the original PCReq.";
             }
             leaf retrieved  {
               type boolean;
               description
                 "If path-key has been retrieved yet";
             }
             leaf pcc-retrieved {
               type leafref {
                 path "/pcep/entity/peers/peer/addr";
               }
               must "(../retrieved = true())"
               {
                 error-message
                   "The Path-key should be retreived";
               }
               description
                 "Reference to PCC peer address which
                 retreived the path-key";
             }
             leaf creation-time {
               type yang:timestamp;
               description
                 "The timestamp value at the time this Path-Key
                 was created.";
             }
             leaf discard-time {
               type uint32;
               units "minutes";
               description



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                 "A time after which this path-keys will be
                 discarded";
             }
             leaf reuse-time {
               type uint32;
               units "minutes";
               description
                 "A time after which this path-keys could be
                 reused";
             }
           }
         }
         container peers{
           description
             "The list of configured peers for the
             entity (remote PCE)";
           list peer{
             key "addr";
             description
               "The peer configured for the entity.
               (remote PCE)";

             leaf addr {
               type inet:ip-address;
               description
                 "The local Internet address of this
                 PCEP peer.";
             }
             leaf role {
               type pcep-role;
               mandatory true;
               description
                 "The role of the PCEP Peer.
                 Takes one of the following values.
                 - unknown(0): this PCEP peer role is not
                 known.
                 - pcc(1): this PCEP peer is a PCC.
                 - pce(2): this PCEP peer is a PCE.
                 - pcc-and-pce(3): this PCEP peer
                 is both a PCC and a PCE.";
             }

             leaf description {
               type string;
               description
                 "Description of the PCEP peer
                 configured by the user";
             }



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             uses info {
               description
                 "PCE Peer information";
             }

             container pce-info {
               uses pce-info {
               description
                 "PCE Peer information";
               }
               description
                 "The PCE Peer information";
             }

             leaf delegation-pref{
               if-feature stateful;
               type uint8{
                 range "0..7";
               }
               description
                 "The PCE peer delegation preference.";
             }
             container auth {
               description
                 "The Authentication options";
               choice auth-type-selection {
                 description
                   "Options for expressing authentication
                   setting.";
                 case auth-key-chain {
                   leaf key-chain {
                     type kc:key-chain-ref;
                     description
                       "key-chain name.";
                   }
                 }
                 case auth-key {
                   leaf crypto-algorithm {
                     type identityref {
                       base kc:crypto-algorithm;
                     }
                     mandatory true;
                     description
                       "Cryptographic algorithm associated
                       with key.";
                   }
                   choice key-string-style {
                     description



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                       "Key string styles";
                     case keystring {
                       leaf keystring {
                         nacm:default-deny-all;
                         type string;
                         description
                           "Key string in ASCII format.";
                       }
                     }
                     case hexadecimal {
                       if-feature "kc:hex-key-string";
                       leaf hexadecimal-string {
                         nacm:default-deny-all;
                         type yang:hex-string;
                         description
                           "Key in hexadecimal string format. When
                           compared to ASCII, specification in
                           hexadecimal affords greater key entropy
                           with the same number of internal
                           key-string octets.  Additionally, it
                           discourages usage of well-known words or
                           numbers.";
                       }
                     }
                   }
                 }
                 case auth-tls {
                   if-feature tls;
                   choice role{
                     description
                       "The role of the local entity";
                   case server {
                     container tls-server {
                       uses ts:tls-server-grouping {
                     description
                       "Server TLS information.";
                     }
                     description
                       "TLS related information";
                     }
                   }
                   case client{
                     container tls-client {
                       uses tc:tls-client-grouping {
                       description
                         "Client TLS information.";
                       }
                       description



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                         "TLS related information";
                     }
                   }
                 }
               }
             }
           }

           leaf discontinuity-time {
             type yang:timestamp;
             config false;
             description
               "The timestamp of the time when the information and
               statistics were last reset.";
           }

           leaf initiate-session {
             type boolean;
             config false;
             description
               "Indicates whether the local PCEP entity initiates
               sessions to this peer, or waits for the peer to
               initiate a session.";
           }

           leaf session-exists{
             type boolean;
             config false;
             description
               "Indicates whether a session with
               this peer currently exists.";
           }

           leaf session-up-time{
             type yang:timestamp;
             config false;
             description
               "The timestamp value of the last time a
               session with this peer was successfully
               established.";
           }

           leaf session-fail-time{
             type yang:timestamp;
             config false;
             description
               "The timestamp value of the last time a
               session with this peer failed to be



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               established.";
           }

           leaf session-fail-up-time{
             type yang:timestamp;
             config false;
             description
               "The timestamp value of the last time a
               session with this peer failed from
               active.";
           }

           container sessions {
             config false;
             description
               "This entry represents a single PCEP
               session in which the local PCEP entity participates.
               This entry exists only if the corresponding PCEP
               session has been initialized by some event, such as
               manual user configuration, auto-discovery of a peer,
               or an incoming TCP connection.";

             list session {
               key "initiator";
               description
                 "The list of sessions, note that for a time being
                 two sessions may exist for a peer";

               leaf initiator {
                 type pcep-initiator;
                 description
                   "The initiator of the session,that is, whether
                   the TCP connection was initiated by the local
                   PCEP entity or the peer.
                   There is a window during session
                   initialization where two sessions can exist
                   between a pair of PCEP speakers, each
                   initiated by one of the speakers. One of
                   these sessions is always discarded before it
                   leaves OpenWait state. However, before it is
                   discarded, two sessions to the given peer
                   appear transiently in this yang module. The
                   sessions are distinguished by who initiated
                   them, and so this field is the key.";
               }

               leaf role {
                 type leafref {



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                   path "/pcep/entity/role";
                 }
                 description
                   "The reference to peer role .";
               }

               leaf state-last-change {
                 type yang:timestamp;
                 description
                   "The timestamp value at the time this
                   session entered its current state as
                   denoted by the state leaf.";
               }

               leaf state {
                 type pcep-sess-state;
                 description
                   "The current state of the session.
                   The set of possible states excludes the
                   idle state since entries do not exist
                   in the idle state.";
               }

               leaf session-creation {
                 type yang:timestamp;
                 description
                   "The timestamp value at the time this
                   session was created.";
               }

               leaf connect-retry {
                 type yang:counter32;
                 description
                   "The number of times that the local PCEP
                   entity has attempted to establish a TCP
                   connection for this session without
                   success. The PCEP entity gives up when
                   this reaches connect-max-retry.";
               }

               leaf local-id {
                 type uint8;
                 description
                   "The value of the PCEP session ID used by
                   the local PCEP entity in the Open message
                   for this session. If state is tcp-pending
                   then this is the session ID that will be
                   used in the Open message. Otherwise, this



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                   is the session ID that was sent in the
                   Open message.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }

               leaf remote-id {
                 type uint8;
                 must "((../state != 'tcp-pending'" +
                      "and " +
                      "../state != 'open-wait' )" +
                      "or " +
                      "((../state = 'tcp-pending'" +
                      " or " +
                      "../state = 'open-wait' )" +
                      "and (. = 0)))" {
                   error-message
                     "Invalid remote-id";
                   description
                     "If state is tcp-pending or open-wait then
                     this leaf is not used and MUST be set to
                     zero.";
                 }
                 description
                   "The value of the PCEP session ID used by the
                   peer in its Open message for this session.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }

               leaf keepalive-timer {
                 type uint8;
                 units "seconds";
                 must "(../state = 'session-up'" +
                      "or " +
                      "(../state != 'session-up'" +
                      "and (. = 0)))" {
                   error-message
                     "Invalid keepalive timer";
                   description
                   "This field is used if and only if state is
                   session-up. Otherwise, it is not used and
                   MUST be set to zero.";
                 }
                 description
                   "The agreed maximum interval at which the local



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                   PCEP entity transmits PCEP messages on this PCEP
                   session.  Zero means that the local PCEP entity
                   never sends Keepalives on this session.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }

               leaf peer-keepalive-timer {
                 type uint8;
                 units "seconds";
                 must "(../state = 'session-up'" +
                      "or "   +
                      "(../state != 'session-up'" +
                      "and " +
                      "(. = 0)))" {
                   error-message
                     "Invalid Peer keepalive timer";
                   description
                     "This field is used if and only if state is
                     session-up. Otherwise, it is not used and MUST
                     be set to zero.";
                 }
                 description
                   "The agreed maximum interval at which the peer
                   transmits PCEP messages on this PCEP session.
                   Zero means that the peer never sends Keepalives
                   on this session.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }

               leaf dead-timer {
                 type uint8;
                 units "seconds";
                 description
                   "The dead timer interval for this PCEP session.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }

               leaf peer-dead-timer {
                 type uint8;
                 units "seconds";
                 must "((../state != 'tcp-pending'" +
                      "and " +



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                      "../state != 'open-wait' )" +
                      "or " +
                      "((../state = 'tcp-pending'" +
                      " or " +
                      "../state = 'open-wait' )" +
                      "and " +
                      "(. = 0)))" {
                   error-message
                     "Invalid Peer Dead timer";
                   description
                   "If state is tcp-pending or open-wait then this
                   leaf is not used and MUST be set to zero.";
                 }
                 description
                   "The peer's dead-timer interval
                   for this PCEP session.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }

               leaf ka-hold-time-rem {
                 type uint8;
                 units "seconds";
                 must "((../state != 'tcp-pending'" +
                      "and " +
                      "../state != 'open-wait' ) " +
                      "or " +
                      "((../state = 'tcp-pending'" +
                      "or " +
                      "../state = 'open-wait' )" +
                      "and " +
                      "(. = 0)))" {
                   error-message
                     "Invalid Keepalive hold time remaining";
                   description
                     "If state is tcp-pending or open-wait then this
                     field is not used and MUST be set to zero.";
                 }
                 description
                   "The keep alive hold time remaining for this
                   session.";
               }
               leaf overloaded {
                 type boolean;
                 description
                   "If the local PCEP entity has informed the peer that
                   it is currently overloaded, then this is set to true.



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                   Otherwise, it is set to false.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }
               leaf overload-time {
                 type uint32;
                 units "seconds";
                 must "((../overloaded = true()) " +
                      "or ((../overloaded != true()) " +
                      "and (. = 0)))" {
                   error-message
                     "Invalid overload-time";
                   description
                     "This field is only used if overloaded is set to
                     true. Otherwise, it is not used and MUST be set
                     to zero.";
                 }
                 description
                   "The interval of time that is remaining until the
                   local PCEP entity will cease to be overloaded on
                   this session.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }
               leaf peer-overloaded {
                 type boolean;
                 description
                   "If the peer has informed the local PCEP entity
                   that it is currently overloaded, then this is
                   set to true. Otherwise, it is set to false.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }

               leaf peer-overload-time {
                 type uint32;
                 units "seconds";
                 must "((../peer-overloaded = " +
                      "true()) or " +
                      "((../peer-overloaded !=" +
                      "true())" +
                      " and " +
                      "(. = 0)))" {
                   error-message
                     "Invalid peer overload time";



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                     description
                       "This field is only used if peer-overloaded
                       is set to true. Otherwise, it is not used
                       and MUST be set to zero.";
                 }
                 description
                   "The interval of time that is remaining until
                   the peer will cease to be overloaded.  If it
                   is not known how long the peer will stay in
                   overloaded state, this leaf is set to zero.";
                 reference
                   "RFC 5440: Path Computation Element (PCE)
                   Communication Protocol (PCEP)";
               }
               leaf lspdb-sync {
                 if-feature stateful;
                 type sync-state;
                 description
                   "The LSP-DB state synchronization status.";
                 reference
                   "RFC 8231: Path Computation Element Communication
                   Protocol (PCEP) Extensions for Stateful PCE";
               }

               leaf recv-db-ver{
                 when "../role = 'pcc'" +
                      "or " +
                      "../role = 'pcc-and-pce'"
                 {
                   description
                     "This field is applicable when the role is
                     PCC";
                 }

                 if-feature stateful;
                 if-feature sync-opt;

                 type uint64;

                 description
                   "The last received LSP State Database Version
                   Number";
                 reference
                   "RFC 8231: Path Computation Element Communication
                   Protocol (PCEP) Extensions for Stateful PCE";
               }
               container of-list{
                 when "../role = 'pce'" +



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                      "or " +
                      "../role = 'pcc-and-pce'"
                 {
                   description
                     "These fields are applicable when the role is
                     PCE";
                 }
                 if-feature objective-function;

                 uses of-list;

                 description
                   "Indicate the list of supported OF on this
                   session";
                 reference
                   "RFC 5541: Encoding of Objective Functions in
                   the Path  Computation Element Communication
                   Protocol (PCEP)";

               }

               container pst-list{
                 when "../role = 'pce'" +
                      "or " +
                      "../role = 'pcc-and-pce'"
                 {
                   description
                     "These fields are applicable when the role is
                     PCE";
                 }
                 description
                   "Indicate the list of supported
                   PST on this session";
                 reference
                   "RFC 8408: Conveying Path Setup Type in PCE
                   Communication Protocol (PCEP) Messages";

                 list path-setup-type{
                   key "pst";

                   description
                     "The list of authorized PST";

                   leaf pst {
                     type identityref{
                       base te-types:path-signaling-type;
                     }
                     description



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                       "The PST authorized";
                   }
                 }
               }
               container assoc-type-list{
                 if-feature association;
                 description
                   "Indicate the list of supported association types
                   on this session";
                 reference
                   "I-D.ietf-pce-association-group: PCEP
                   Extensions for Establishing Relationships
                   Between Sets of LSPs";

                 list assoc-type{
                   key "at";

                   description
                     "The list of authorized association types";

                   leaf at {
                     type identityref {
                       base te-types:association-type;
                     }
                     description
                       "The association type authorized";
                   }
                 }
               }
               leaf speaker-entity-id{
                 if-feature sync-opt;
                 type string;
                 description
                   "The Speaker Entity Identifier";
                 reference
                   "RFC 8232: Optimizations of Label Switched
                   Path State  Synchronization Procedures for
                   a Stateful PCE";
               }

               leaf discontinuity-time {
                 type yang:timestamp;
                 description
                   "The timestamp value of the time when the
                   statistics were last reset.";
               }
             } // session
           } // sessions



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         }//peer
       }//peers
     }//entity
   }//pcep

   /*
   * Notifications
   */
   notification pcep-session-up {
     description
       "This notification is sent when the value of
       '/pcep/peers/peer/sessions/session/state'
       enters the 'session-up' state.";

     uses notification-instance-hdr;

     uses notification-session-hdr;

     leaf state-last-change {
       type yang:timestamp;
       description
         "The timestamp value at the time this session
         entered its current state as denoted by the state
         leaf.";
     }

     leaf state {
       type pcep-sess-state;
       description
         "The current state of the session.
         The set of possible states excludes the idle state
         since entries do not exist in the idle state.";
       }
       reference
         "RFC 5440: Path Computation Element (PCE) Communication
         Protocol (PCEP)";
   } //notification

   notification pcep-session-down {
     description
       "This notification is sent when the value of
       '/pcep/peers/peer/sessions/session/state'
       leaves the 'session-up' state.";

     uses notification-instance-hdr;

     leaf session-initiator {
       type pcep-initiator;



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       description
         "The initiator of the session.";
     }

     leaf state-last-change {
       type yang:timestamp;
       description
         "The timestamp value at the time this session
         entered its current state as denoted by the state
         leaf.";
     }

     leaf state {
     type pcep-sess-state;
     description
       "The current state of the session.
       The set of possible states excludes the idle state
       since entries do not exist in the idle state.";
     }
     reference
       "RFC 5440: Path Computation Element (PCE) Communication
       Protocol (PCEP)";
   } //notification

   notification pcep-session-local-overload {
     description
       "This notification is sent when the local PCEP entity
       enters overload state for a peer.";

     uses notification-instance-hdr;

     uses notification-session-hdr;

     leaf overloaded {
       type boolean;
       description
         "If the local PCEP entity has informed the peer
         that it is currently overloaded, then this is set
         to true. Otherwise, it is set to false.";
     }

     leaf overload-time {
     type uint32;
     units "seconds";
     description
       "The interval of time that is remaining until the
       local PCEP entity will cease to be overloaded on
       this session.";



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     }
     reference
       "RFC 5440: Path Computation Element (PCE) Communication
       Protocol (PCEP)";
   } //notification

   notification pcep-session-local-overload-clear {
     description
       "This notification is sent when the local PCEP entity
       leaves overload state for a peer.";

     uses notification-instance-hdr;

     leaf overloaded {
       type boolean;
       description
         "If the local PCEP entity has informed the peer
         that it is currently overloaded, then this is set
         to true.  Otherwise, it is set to false.";
       }
     reference
       "RFC 5440: Path Computation Element (PCE) Communication
       Protocol (PCEP)";
   } //notification

   notification pcep-session-peer-overload {
     description
       "This notification is sent when a peer enters overload
       state.";

     uses notification-instance-hdr;

     uses notification-session-hdr;

     leaf peer-overloaded {
       type boolean;
       description
         "If the peer has informed the local PCEP entity that
         it is currently overloaded, then this is set to
         true. Otherwise, it is set to false.";
     }

     leaf peer-overload-time {
       type uint32;
       units "seconds";
       description
         "The interval of time that is remaining until the
         peer will cease to be overloaded.  If it is not



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         known how long the peer will stay in overloaded
         state, this leaf is set to zero.";
     }
     reference
       "RFC 5440: Path Computation Element (PCE) Communication
       Protocol (PCEP)";
   } //notification

   notification pcep-session-peer-overload-clear {
     description
       "This notification is sent when a peer leaves overload
       state.";

     uses notification-instance-hdr;

     leaf peer-overloaded {
       type boolean;
       description
         "If the peer has informed the local PCEP entity that
         it is currently overloaded, then this is set to
         true. Otherwise, it is set to false.";
       }
       reference
         "RFC 5440: Path Computation Element (PCE) Communication
         Protocol (PCEP)";
   } //notification

   /*
    * RPC
    */

   rpc trigger-resync {
     if-feature stateful;
     if-feature sync-opt;
     description
       "Trigger the resyncrinization at the PCE";
     reference
       "RFC 8232: Optimizations of Label Switched Path State
       Synchronization Procedures for a Stateful PCE";
     input {
       leaf pcc {
         type leafref {
           path "/pcep/entity/peers/peer/addr";
         }
         description
           "The IP address to identify the PCC. The state
           syncronization is re-triggered for all LSPs from
           the PCC. The rpc on the PCC will be ignored.";



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       }
     }//input
   }//rpc

 }//module
 <CODE ENDS>

10.2.  ietf-pcep-stats module


   <CODE BEGINS> file "ietf-pcep-stats@2019-03-24.yang"
   module ietf-pcep-stats {

     yang-version 1.1;

     namespace "urn:ietf:params:xml:ns:yang:ietf-pcep-stats";

     prefix ps;

     import ietf-pcep {
       prefix p;
       reference
         "RFC XXXX: A YANG Data Model for Path Computation
         Element Communications Protocol (PCEP)";
     }

     import ietf-yang-types {
       prefix "yang";
       reference
         "RFC 6991: Common YANG Data Types";
     }

     organization
       "IETF PCE (Path Computation Element) Working Group";

     contact
       "WG Web:  <http://tools.ietf.org/wg/pce/>
       WG List:  <mailto:pce@ietf.org>
       Editor:   Dhruv Dhody
                 <mailto:dhruv.ietf@gmail.com>";

     description
       "The YANG module augments the PCEP yang operational
       model with statistics, counters and telemetry data.

       Copyright (c) 2019 IETF Trust and the persons identified as
       authors of the code.  All rights reserved.




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       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD License
       set forth in Section 4.c of the IETF Trust's Legal Provisions
       Relating to IETF Documents
       (http://trustee.ietf.org/license-info).

       This version of this YANG module is part of RFC XXXX; see the
       RFC itself for full legal notices.";

     revision 2019-03-24 {
       description "Initial revision.";
       reference
         "RFC XXXX:  A YANG Data Model for Path Computation
         Element Communications Protocol (PCEP)";
     }

     /*
      * Groupings
      */

     grouping pcep-stats{
       description
         "This grouping defines statistics for PCEP. It is used
         for both peer and current session.";
       leaf avg-rsp-time{
         when "../../p:role = 'pce'" +
              "or " +
              "../../p:role = 'pcc-and-pce'"
         {
           description
             "Valid for PCEP Peer as PCE";
         }
         type uint32;
         units "milliseconds";

         description
           "The average response time. If an average response time
           has not been calculated then this leaf has the value
           zero.";
       }

       leaf lwm-rsp-time{
         when "../../p:role = 'pce'" +
              "or " +
              "../../p:role = 'pcc-and-pce'"
         {
           description



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             "Valid for PCEP Peer as PCE";
         }
         type uint32;
         units "milliseconds";

         description
           "The smallest (low-water mark) response time seen.
           If no responses have been received then this leaf has
           the value zero.";
       }

       leaf hwm-rsp-time{
         when "../../p:role = 'pce'" +
              "or " +
              "../../p:role = 'pcc-and-pce'"
         {
           description
             "Valid for PCEP Peer as PCE";
         }
         type uint32;
         units "milliseconds";

         description
           "The greatest (high-water mark) response time seen.
           If no responses have been received then this object
           has the value zero.";
       }

       leaf num-pcreq-sent{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
              "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
            "The number of PCReq messages sent.";
       }

       leaf num-pcreq-rcvd{
         when "../../p:role = 'pcc'" +
              "or " +
              "../../p:role = 'pcc-and-pce'"
         {
           description
             "Valid for PCEP Peer as PCC";



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         }
         type yang:counter32;
         description
           "The number of PCReq messages received.";
       }

       leaf num-pcrep-sent{
         when "../../p:role = 'pcc'" +
              "or " +
              "../../p:role = 'pcc-and-pce'"
         {
           description
             "Valid for PCEP Peer as PCC";
         }

         type yang:counter32;
         description
           "The number of PCRep messages sent.";
         }

         leaf num-pcrep-rcvd{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }

           type yang:counter32;
           description
             "The number of PCRep messages received.";
         }

         leaf num-pcerr-sent{
           type yang:counter32;
           description
             "The number of PCErr messages sent.";
         }

         leaf num-pcerr-rcvd{
           type yang:counter32;
           description
             "The number of PCErr messages received.";
         }

         leaf num-pcntf-sent{
           type yang:counter32;



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           description
             "The number of PCNtf messages sent.";
         }

         leaf num-pcntf-rcvd{
           type yang:counter32;
           description
             "The number of PCNtf messages received.";
         }

         leaf num-keepalive-sent{
           type yang:counter32;
           description
             "The number of Keepalive messages sent.";
         }

         leaf num-keepalive-rcvd{
           type yang:counter32;
           description
             "The number of Keepalive messages received.";
         }

         leaf num-unknown-rcvd{
           type yang:counter32;
           description
           "The number of unknown messages received.";
         }

         leaf num-corrupt-rcvd{
           type yang:counter32;
           description
             "The number of corrupted PCEP message received.";
         }

         leaf num-req-sent{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of requests sent.  A request corresponds
             1:1 with an RP object in a PCReq message. This might
             be greater than num-pcreq-sent because multiple
             requests can be batched into a single PCReq



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             message.";
         }

         leaf num-req-sent-pend-rep{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of requests that have been sent for
             which a response is still pending.";
         }

         leaf num-req-sent-ero-rcvd{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of requests that have been sent for
             which a response with an ERO object was received.
             Such responses indicate that a path was
             successfully computed by the peer.";
         }

         leaf num-req-sent-nopath-rcvd{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of requests that have been sent for
             which a response with a NO-PATH object was
             received. Such responses indicate that the peer
             could not find a path to satisfy the
             request.";



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         }

         leaf num-req-sent-cancel-rcvd{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of requests that were cancelled with
             a PCNtf message. This might be different than
             num-pcntf-rcvd because not all PCNtf messages are
             used to cancel requests, and a single PCNtf message
             can cancel multiple requests.";
         }

         leaf num-req-sent-error-rcvd{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of requests that were rejected with a
             PCErr message. This might be different than
             num-pcerr-rcvd because not all PCErr messages are
             used to reject requests, and a single PCErr message
             can reject multiple requests.";
         }

         leaf num-req-sent-timeout{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of requests that have been sent to a peer
             and have been abandoned because the peer has taken too



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             long to respond to them.";
         }

         leaf num-req-sent-cancel-sent{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of requests that were sent to the peer and
             explicitly cancelled by the local PCEP entity sending
             a PCNtf.";
         }

         leaf num-req-rcvd{
           when "../../p:role = 'pcc'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCC";
           }
           type yang:counter32;
           description
             "The number of requests received.  A request
             corresponds 1:1 with an RP object in a PCReq
             message.
             This might be greater than num-pcreq-rcvd because
             multiple requests can be batched into a single
             PCReq message.";
         }

         leaf num-req-rcvd-pend-rep{
           when "../../p:role = 'pcc'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCC";
           }
           type yang:counter32;
           description
             "The number of requests that have been received for
             which a response is still pending.";



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         }

         leaf num-req-rcvd-ero-sent{
           when "../../p:role = 'pcc'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCC";
           }
           type yang:counter32;
           description
             "The number of requests that have been received for
             which a response with an ERO object was sent.  Such
             responses indicate that a path was successfully
             computed by the local PCEP entity.";
         }

         leaf num-req-rcvd-nopath-sent{
           when "../../p:role = 'pcc'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCC";
           }
           type yang:counter32;
           description
             "The number of requests that have been received for
             which a response with a NO-PATH object was sent. Such
             responses indicate that the local PCEP entity could
             not find a path to satisfy the request.";
         }

         leaf num-req-rcvd-cancel-sent{
           when "../../p:role = 'pcc'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCC";
           }
           type yang:counter32;
           description
             "The number of requests received that were cancelled
             by the local PCEP entity sending a PCNtf message.
             This might be different than num-pcntf-sent because
             not all PCNtf messages are used to cancel requests,



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             and a single PCNtf message can cancel multiple
             requests.";
         }

         leaf num-req-rcvd-error-sent{
           when "../../p:role = 'pcc'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCC";
           }
           type yang:counter32;
           description
             "The number of requests received that were cancelled
             by the local PCEP entity sending a PCErr message.
             This might be different than num-pcerr-sent because
             not all PCErr messages are used to cancel requests,
             and a single PCErr message can cancel multiple
             requests.";
         }

         leaf num-req-rcvd-cancel-rcvd{
           when "../../p:role = 'pcc'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCC";
           }
           type yang:counter32;
           description
             "The number of requests that were received from the
             peer and explicitly cancelled by the peer sending
             a PCNtf.";
         }
         leaf num-rep-rcvd-unknown{
           when "../../p:role = 'pce'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCE";
           }
           type yang:counter32;
           description
             "The number of responses to unknown requests
             received. A response to an unknown request is a



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             response whose RP object does not contain the
             request ID of any request that is currently
             outstanding on the session.";
         }

         leaf num-req-rcvd-unknown{
           when "../../p:role = 'pcc'" +
                "or " +
                "../../p:role = 'pcc-and-pce'"
           {
             description
               "Valid for PCEP Peer as PCC";
           }
           type yang:counter32;
           description
             "The number of unknown requests that have been
             received. An unknown request is a request
             whose RP object contains a request ID of zero.";
         }

         container svec{
           if-feature p:svec;
           description
             "If synchronized path computation is supported";
           leaf num-svec-sent{
             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of SVEC objects sent in PCReq messages.
               An SVEC object represents a set of synchronized
               requests.";
           }
           leaf num-svec-req-sent{
             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description



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               "The number of requests sent that appeared in one
               or more SVEC objects.";
           }

           leaf num-svec-rcvd{
             when "../../../p:role = 'pcc'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of SVEC objects received in PCReq
               messages. An SVEC object represents a set of
               synchronized requests.";
           }

           leaf num-svec-req-rcvd{
             when "../../../p:role = 'pcc'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of requests received that appeared
               in one or more SVEC objects.";
           }
         }//svec
         container stateful{
           if-feature p:stateful;
           description
             "Stateful PCE related statistics";
           leaf num-pcrpt-sent{
             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of PCRpt messages sent.";



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           }

           leaf num-pcrpt-rcvd{
             when "../../../p:role = 'pcc'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of PCRpt messages received.";
           }

           leaf num-pcupd-sent{
             when "../../../p:role = 'pcc'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of PCUpd messages sent.";
           }

           leaf num-pcupd-rcvd{
             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of PCUpd messages received.";
           }

           leaf num-rpt-sent{
             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";



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             }
             type yang:counter32;
             description
               "The number of LSP Reports sent.  A LSP report
               corresponds 1:1 with an LSP object in a PCRpt
               message. This might be greater than
               num-pcrpt-sent because multiple reports can
               be batched into a single PCRpt message.";
           }

           leaf num-rpt-rcvd{
             when "../../../p:role = 'pcc'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of LSP Reports received.  A LSP report
               corresponds 1:1 with an LSP object in a PCRpt
               message.
               This might be greater than num-pcrpt-rcvd because
               multiple reports can be batched into a single
               PCRpt message.";
           }

           leaf num-rpt-rcvd-error-sent{
             when "../../../p:role = 'pcc'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of reports of LSPs received that were
               responded by the local PCEP entity by sending a
               PCErr message.";
           }

           leaf num-upd-sent{
             when "../../../p:role = 'pcc'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {



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               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of LSP updates sent.  A LSP update
               corresponds 1:1 with an LSP object in a PCUpd
               message. This might be greater than
               num-pcupd-sent because multiple updates can
               be batched into a single PCUpd message.";
           }

           leaf num-upd-rcvd{
             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of LSP Updates received.  A LSP update
               corresponds 1:1 with an LSP object in a PCUpd
               message.
               This might be greater than num-pcupd-rcvd because
               multiple updates can be batched into a single
               PCUpd message.";
           }

           leaf num-upd-rcvd-unknown{
             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of updates to unknown LSPs
               received. An update to an unknown LSP is a
               update whose LSP object does not contain the
               PLSP-ID of any LSP that is currently
               present.";
           }

           leaf num-upd-rcvd-undelegated{



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             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of updates to not delegated LSPs
               received. An update to an undelegated LSP is a
               update whose LSP object does not contain the
               PLSP-ID of any LSP that is currently
               delegated to current PCEP session.";
           }

           leaf num-upd-rcvd-error-sent{
             when "../../../p:role = 'pce'" +
                  "or " +
                  "../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of updates to LSPs received that were
               responded by the local PCEP entity by sending a
               PCErr message.";
          }

         container initiation {
           if-feature p:pce-initiated;
           description
             "PCE-Initiated related statistics";
           leaf num-pcinitiate-sent{
             when "../../../../p:role = 'pcc'" +
                  "or " +
                  "../../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of PCInitiate messages sent.";
           }




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           leaf num-pcinitiate-rcvd{
             when "../../../../p:role = 'pce'" +
                  "or " +
                  "../../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of PCInitiate messages received.";
           }

           leaf num-initiate-sent{
             when "../../../../p:role = 'pcc'" +
                  "or " +
                  "../../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of LSP Initiation sent via PCE.
               A LSP initiation corresponds 1:1 with an LSP
               object in a PCInitiate message. This might be
               greater than num-pcinitiate-sent because
               multiple initiations can be batched into a
               single PCInitiate message.";
           }

           leaf num-initiate-rcvd{
             when "../../../../p:role = 'pce'" +
                  "or " +
                  "../../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of LSP Initiation received from
               PCE.  A LSP initiation corresponds 1:1 with
               an LSP object in a PCInitiate message. This
               might be greater than num-pcinitiate-rcvd
               because multiple initiations can be batched
               into a single PCInitiate message.";
           }



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           leaf num-initiate-rcvd-error-sent{
             when "../../../../p:role = 'pce'" +
                  "or " +
                  "../../../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of initiations of LSPs received
               that were responded by the local PCEP entity
               by sending a PCErr message.";
           }
         }//initiation
       }//stateful

       container path-key {
         when "../../p:role = 'pcc'" +
              "or " +
              "../../p:role = 'pcc-and-pce'"
         {
           description
             "Valid for PCEP Peer as PCC";
         }
         if-feature p:path-key;
         description
           "If Path-Key is supported";
         leaf num-unknown-path-key{
           type yang:counter32;
           description
             "The number of attempts to expand an unknown
             path-key.";
         }
         leaf num-exp-path-key{
           type yang:counter32;
           description
             "The number of attempts to expand an expired
             path-key.";
         }
         leaf num-dup-path-key{
           type yang:counter32;
           description
             "The number of duplicate attempts to expand same
             path-key.";
         }
         leaf num-path-key-no-attempt{
           type yang:counter32;



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           description
             "The number of expired path-keys with no attempt to
             expand it.";
         }
       }//path-key
     }//pcep-stats

     /*
      * Augment modules to add statistics
      */

     augment "/p:pcep/p:entity/p:peers/p:peer" {
       description
         "Augmenting the statistics";

         leaf num-sess-setup-ok{
           type yang:counter32;
           config false;
           description
             "The number of PCEP sessions successfully established with
             the peer, including any current session.  This counter is
             incremented each time a session with this peer is
             successfully established.";
         }

         leaf num-sess-setup-fail{
             type yang:counter32;
             config false;
             description
                "The number of PCEP sessions with the peer
                 that have been attempted but failed
                 before being fully established. This
                 counter is incremented each time a
                 session retry to this peer fails.";
         }

         container pcep-stats {
           config false;
           description
             "The container for all statistics at peer level.";
           uses pcep-stats{
             description
             "Since PCEP sessions can be ephemeral, the peer statistics
             tracks a peer even when no PCEP session currently exists
             to that peer. The statistics contained are an aggregate of
             the statistics for all successive sessions to that peer.";
           }




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           leaf num-req-sent-closed{
             when "../../p:role = 'pce'" +
                  "or " +
                  "../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCE";
             }
             type yang:counter32;
             description
               "The number of requests that were sent to the peer and
               implicitly cancelled when the session they were sent
               over was closed.";
           }

           leaf num-req-rcvd-closed{
             when "../../p:role = 'pcc'" +
                  "or " +
                  "../../p:role = 'pcc-and-pce'"
             {
               description
                 "Valid for PCEP Peer as PCC";
             }
             type yang:counter32;
             description
               "The number of requests that were received from the peer
               and implicitly cancelled when the session they were
               received over was closed.";
           }
         }//pcep-stats
     }//augment

     augment "/p:pcep/p:entity/p:peers/p:peer/" +
             "p:sessions/p:session" {
       description
         "Augmenting the statistics";

       container pcep-stats {
         description
           "The container for all statistics at session level.";
         uses pcep-stats{
         description
           "The statistics contained are for the current sessions to
           that peer. These are lost when the session goes down.";
         }
       }//pcep-stats
     }//augment
   }//module



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   <CODE ENDS>

11.  Security Considerations

   The YANG module defined in this document is designed to be accessed
   via network management protocol such as NETCONF [RFC6241] or RESTCONF
   [RFC8040].  The lowest NETCONF layer is the secure transport layer
   and the mandatory-to-implement secure transport is SSH [RFC6242].
   The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement
   secure transport is TLS [RFC8446]

   The NETCONF access control model [RFC8341] provides the means to
   restrict access for particular NETCONF or RESTCONF users to a pre-
   configured subset of all available NETCONF or RESTCONF protocol
   operations and content.

   There are a number of data nodes defined in the YANG module which are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., <edit-config>)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

      /pcep/entity/ - configure local parameters, capabilities etc.

      /pcep/entity/peers - configure remote peers to setup PCEP session.

   Unauthorized access to above list can adversely affect the PCEP
   session between the local entity and the peers.  This may lead to
   inability to compute new paths, stateful operations on the delegated
   as well as PCE-initiated LSPs.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

      /pcep/lsp-db - All the LSPs in the network.  Unauthorized access
      to this could provide the all path and network usage information.

      /pcep/path-keys/ - The Confidential Path Segments (CPS) are hidden
      using path-keys.  Unauthorized access to this could leak
      confidential path information.

   Some of the RPC operations in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus



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   important to control access to these operations.  These are the
   operations and their sensitivity/vulnerability:

      trigger-resync - trigger resynchronization with the PCE.
      Unauthorized access to this could force a PCEP session into
      continuous state synchronization.

12.  IANA Considerations

   This document registers a URI in the "IETF XML Registry" [RFC3688].
   Following the format in RFC 3688, the following registration has been
   made.

   URI:  urn:ietf:params:xml:ns:yang:ietf-pcep

   Registrant Contact:  The PCE WG of the IETF.

   XML:  N/A; the requested URI is an XML namespace.

   This document registers a YANG module in the "YANG Module Names"
   registry [RFC6020].

       Name:         ietf-pcep
       Namespace:    urn:ietf:params:xml:ns:yang:ietf-pcep
       Prefix:       pcep
       Reference:    This I-D

13.  Acknowledgements

   The initial document is based on the PCEP MIB [RFC7420].  We would
   like to thank the authors of aforementioned documents.

14.  References

14.1.  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>.






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   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC5088]  Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
              Zhang, "OSPF Protocol Extensions for Path Computation
              Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088,
              January 2008, <https://www.rfc-editor.org/info/rfc5088>.

   [RFC5089]  Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
              Zhang, "IS-IS Protocol Extensions for Path Computation
              Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089,
              January 2008, <https://www.rfc-editor.org/info/rfc5089>.

   [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>.

   [RFC5520]  Bradford, R., Ed., Vasseur, JP., and A. Farrel,
              "Preserving Topology Confidentiality in Inter-Domain Path
              Computation Using a Path-Key-Based Mechanism", RFC 5520,
              DOI 10.17487/RFC5520, April 2009,
              <https://www.rfc-editor.org/info/rfc5520>.

   [RFC5541]  Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
              Objective Functions in the Path Computation Element
              Communication Protocol (PCEP)", RFC 5541,
              DOI 10.17487/RFC5541, June 2009,
              <https://www.rfc-editor.org/info/rfc5541>.

   [RFC5557]  Lee, Y., Le Roux, JL., King, D., and E. Oki, "Path
              Computation Element Communication Protocol (PCEP)
              Requirements and Protocol Extensions in Support of Global
              Concurrent Optimization", RFC 5557, DOI 10.17487/RFC5557,
              July 2009, <https://www.rfc-editor.org/info/rfc5557>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.





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   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8177]  Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
              Zhang, "YANG Data Model for Key Chains", RFC 8177,
              DOI 10.17487/RFC8177, June 2017,
              <https://www.rfc-editor.org/info/rfc8177>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [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>.

   [RFC8232]  Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X.,
              and D. Dhody, "Optimizations of Label Switched Path State
              Synchronization Procedures for a Stateful PCE", RFC 8232,
              DOI 10.17487/RFC8232, September 2017,
              <https://www.rfc-editor.org/info/rfc8232>.

   [RFC8253]  Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
              "PCEPS: Usage of TLS to Provide a Secure Transport for the
              Path Computation Element Communication Protocol (PCEP)",
              RFC 8253, DOI 10.17487/RFC8253, October 2017,
              <https://www.rfc-editor.org/info/rfc8253>.

   [RFC8281]  Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
              Computation Element Communication Protocol (PCEP)
              Extensions for PCE-Initiated LSP Setup in a Stateful PCE
              Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
              <https://www.rfc-editor.org/info/rfc8281>.



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   [RFC8306]  Zhao, Q., Dhody, D., Ed., Palleti, R., and D. King,
              "Extensions to the Path Computation Element Communication
              Protocol (PCEP) for Point-to-Multipoint Traffic
              Engineering Label Switched Paths", RFC 8306,
              DOI 10.17487/RFC8306, November 2017,
              <https://www.rfc-editor.org/info/rfc8306>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8408]  Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
              Hardwick, "Conveying Path Setup Type in PCE Communication
              Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408,
              July 2018, <https://www.rfc-editor.org/info/rfc8408>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [I-D.ietf-teas-yang-te]
              Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin,
              "A YANG Data Model for Traffic Engineering Tunnels and
              Interfaces", draft-ietf-teas-yang-te-19 (work in
              progress), February 2019.

   [I-D.ietf-teas-yang-te-types]
              Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin,
              "Traffic Engineering Common YANG Types", draft-ietf-teas-
              yang-te-types-06 (work in progress), February 2019.

   [I-D.ietf-netconf-tls-client-server]
              Watsen, K., Wu, G., and L. Xia, "YANG Groupings for TLS
              Clients and TLS Servers", draft-ietf-netconf-tls-client-
              server-10 (work in progress), March 2019.

   [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-08 (work in progress), March
              2019.




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   [I-D.ietf-pce-segment-routing]
              Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
              and J. Hardwick, "PCEP Extensions for Segment Routing",
              draft-ietf-pce-segment-routing-16 (work in progress),
              March 2019.

   [I-D.ietf-isis-yang-isis-cfg]
              Litkowski, S., Yeung, D., Lindem, A., Zhang, Z., and L.
              Lhotka, "YANG Data Model for IS-IS Protocol", draft-ietf-
              isis-yang-isis-cfg-35 (work in progress), March 2019.

   [I-D.ietf-ospf-yang]
              Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem,
              "YANG Data Model for OSPF Protocol", draft-ietf-ospf-
              yang-21 (work in progress), January 2019.

   [I-D.ietf-pce-gmpls-pcep-extensions]
              Margaria, C., Dios, O., and F. Zhang, "PCEP extensions for
              GMPLS", draft-ietf-pce-gmpls-pcep-extensions-13 (work in
              progress), January 2019.

14.2.  Informative 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>.

   [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>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.













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Appendix A.  Example

   The example below provide an overview of PCEP peer session
   informations and LSP-DB in the Yang Module.



          +-------+                  +-------+
          |       |                  |       |
          | PCC1  |<---------------->|       |
          |       |                  |       |
          +-------+                  |       |
         IP:192.0.2.1                |       |
                                     |  PCE  |
                                     |       |
          +-------+                  |       |
          |       |                  |       |
          | PCC2  |<---------------->|       |
          |       |                  |       |
          +-------+                  |       |
         IP:192.0.2.2                |       |
                                     |       |
                                     |       |
          +-------+                  |       |
          |       |                  |       |
          | PCC4  |<---------------->|       |
          |       |                  |       |
          +-------+                  |       |
         IP:2001:DB8::4              |       |
                                     +-------+
                                   IP:192.0.2.3
                                      2001:DB8::3

   at PCE:
   {
      "entity": [
      {
           "addr": "192.0.2.3",
           "oper-status": "oper-status-up",
           "role":"pce",
           "capability" : {
               "stateful": {
                    "enabled": true
               }
           }
           "lsp-db" : [
              "lsp" : {
                   "plsp-id": 3,



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                   "pcc-id" :"192.0.2.1",
                   "lsp-ref" : {
                     "source": "192.0.2.1",
                     "destination": "192.0.2.4"
                     "tunnel-id": 16,
                     "lsp-id": 3,
                     "extended-tunnel-id": 0
                   },
                   "oper-status": "oper-status-up",
                   "delegated": true,
                   "symbolic-path-name": "iewauh",
                   },
              "lsp" : {
                   "plsp-id": 4,
                   "pcc-id" :"192.0.2.2",
                   "lsp-ref" : {
                     "source": "192.0.2.2",
                     "destination": "192.0.2.5"
                     "tunnel-id": 17,
                     "lsp-id": 4
                     "extended-tunnel-id": 0
                   },
                   "oper-status": "oper-status-up",
                   "delegated": true,
                   "symbolic-path-name": "iewauhiewauh",
                   "extended-tunnel-id": 0
                   }
           ]
           "peers":[
               {
                   "peer": {
                        "addr":"192.0.2.1",
                        "role": "pcc",

                        "capability": {
                            "stateful" : {
                                 "enabled": true,
                                 "active": yes,
                            }
                        }
                        "sessions": [
                            {
                                "session": {
                                    "initiator": "remote",
                                    "role": "pcc",
                                }
                            }
                        ]



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                    }
               },
               {
                   "peer": {
                        "addr":"192.0.2.2",
                        "role": "pcc",

                        "capability": {
                            "stateful" : {
                                 "enabled": true,
                                 "active": true,
                            }
                        }
                        "sessions": [
                            {
                                "session": {
                                    "initiator": "remote",
                                    "role": "pcc",
                                }
                            }
                        ]
                    }
               }
           ]
       },

      {
           "addr": "2001:DB8::3",
           "oper-status": "oper-status-up",
           "role":"pce",
           "peers":[
               {
                   "peer": {
                        "addr":"2001:DB8::4",
                        "role": "pcc",
                        "sessions": [
                            {
                                "session": {
                                    "initiator": "remote",
                                    "role": "pcc",
                                }
                            }
                        ]
                    }
               }
           ]
       }
   }



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Appendix B.  Contributor Addresses

   Rohit Pobbathi
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: rohit.pobbathi@huawei.com

   Vinod KumarS
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: vinods.kumar@huawei.com

   Zafar Ali
   Cisco Systems
   Canada

   EMail: zali@cisco.com

   Xufeng Liu
   Jabil
   8281 Greensboro Drive, Suite 200
   McLean  VA 22102
   USA

   EMail: Xufeng_Liu@jabil.com

   Young Lee
   Huawei Technologies
   5340 Legacy Drive, Building 3
   Plano, TX 75023, USA

   Phone: (469) 277-5838
   EMail: leeyoung@huawei.com

   Udayasree Palle
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: udayasreereddy@gmail.com




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   Xian Zhang
   Huawei Technologies
   Bantian, Longgang District
   Shenzhen  518129
   P.R.China

   EMail: zhang.xian@huawei.com

   Avantika
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: s.avantika.avantika@gmail.com

   Shashikanth
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: shashikanth.vh@huawei.com


Authors' Addresses

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

   EMail: dhruv.ietf@gmail.com


   Jonathan Hardwick
   Metaswitch
   100 Church Street
   Enfield  EN2 6BQ
   UK

   EMail: jonathan.hardwick@metaswitch.com








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   Vishnu Pavan Beeram
   Juniper Networks
   USA

   EMail: vbeeram@juniper.net


   Jeff Tantsura
   USA

   EMail: jefftant@gmail.com








































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