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 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

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 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.

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

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

[RFC8281] :

[RFC8408] :

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

[RFC6241] :

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].

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.

Prefixes and corresponding YANG modules
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-acm [RFC8341]
tls-server ietf-tls-server [I-D.ietf-netconf-tls-client-server]
tls-client ietf-tls-client [I-D.ietf-netconf-tls-client-server]
ospf ietf-ospf [I-D.ietf-ospf-yang]
isis ietf-isis [I-D.ietf-isis-yang-isis-cfg]

3.3. Refrences in the Model

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

Refrences in the YANG modules
Documents Reference
RSVP-TE: Extensions to RSVP for LSP Tunnels [RFC3209]
OSPF Protocol Extensions for Path Computation Element (PCE) Discovery [RFC5088]
IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery [RFC5089]
Path Computation Element (PCE) Communication Protocol (PCEP) [RFC5440]
Preserving Topology Confidentiality in Inter-Domain Path Computation Using a Path-Key-Based Mechanism [RFC5520]
Encoding of Objective Functions in the Path Computation Element Communication Protocol (PCEP) [RFC5541]
Path Computation Element Communication Protocol (PCEP) Requirements and Protocol Extensions in Support of Global Concurrent Optimization [RFC5557]
Common YANG Data Types [RFC6991]
YANG Data Model for Key Chains [RFC8177]
Path Computation Element Communication Protocol (PCEP) Extensions for Stateful PCE [RFC8231]
Optimizations of Label Switched Path State Synchronization Procedures for a Stateful PCE [RFC8232]
PCEPS: Usage of TLS to Provide a Secure Transport for the Path Computation Element Communication Protocol (PCEP) [RFC8253]
Path Computation Element Communication Protocol (PCEP) Extensions for PCE-Initiated LSP Setup in a Stateful PCE Model [RFC8281]
Extensions to the Path Computation Element Communication Protocol (PCEP) for Point-to-Multipoint Traffic Engineering Label Switched Paths [RFC8306]
Network Configuration Access Control Model [RFC8341]
Conveying Path Setup Type in PCE Communication Protocol (PCEP) Messages [RFC8408]
Traffic Engineering Common YANG Types [I-D.ietf-teas-yang-te-types]
A YANG Data Model for Traffic Engineering Tunnels and Interfaces [I-D.ietf-teas-yang-te]
YANG Groupings for TLS Clients and TLS Servers [I-D.ietf-netconf-tls-client-server]
PCEP Extensions for Segment Routing [I-D.ietf-pce-segment-routing]
PCEP Extensions for Establishing Relationships Between Sets of LSPs [I-D.ietf-pce-association-group]
YANG Data Model for OSPF Protocol [I-D.ietf-ospf-yang]
YANG Data Model for IS-IS Protocol [I-D.ietf-isis-yang-isis-cfg]
PCEP extensions for GMPLS [I-D.ietf-pce-gmpls-pcep-extensions]

4. Objectives

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

5. The Design of PCEP Data Model

5.1. The Overview of PCEP Data Model

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
                   +--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
       ...
                  

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

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.

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.

5.7. The Full PCEP Data Model

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}?
          |     +--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?
          |     |  |       -> /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
          |     |        |     +--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
                |  |  +--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
                      +--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
    +---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

                

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

6. The Design of PCEP Statistics Data Model


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
       +--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
       +--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}?
          +--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


            

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

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 -

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.

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 {
    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 
        "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)";
  }

  /*
   * 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";
      }
      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";
      }
      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";
    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.";
  }

  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";    
  }

  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";
  }

  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 
      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 
      "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
      "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
   */


  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{
      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
        "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.";
          }
          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{
            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
          "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";
        }
        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.";
          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 {
        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 {
        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
          "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";
          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
          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
          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)";
      }

      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.";
      }

      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)  
          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
          "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
            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'"
            {
              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 {
              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 {
                  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 {
                  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
                  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{
              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{
                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 {
                  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
                "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";
            }
            
            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
                      "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
                        "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
              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 {
                  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
                  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 
                  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 " +
                     "../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.
                  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";
                    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'" +
                     "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
                      "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
        }//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;
      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.";
    }
    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
        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.";
      }
    }//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.

    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
          "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";
      }
      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;
        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
          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.";
      }

      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
          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.";
      }

      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,
          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
          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
            "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.";
        }

        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";
          }
          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'"
          {
            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{
          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.";
        }

        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.";
        }

        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;
        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.";
        }

        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


<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:

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:

Some of the RPC operations in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control access to these operations. These are the operations and their sensitivity/vulnerability:

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.

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

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

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.
[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.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004.
[RFC5088] Le Roux, JL., Vasseur, JP., Ikejiri, Y. and R. Zhang, "OSPF Protocol Extensions for Path Computation Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088, January 2008.
[RFC5089] Le Roux, JL., Vasseur, JP., Ikejiri, Y. and R. Zhang, "IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089, January 2008.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, March 2009.
[RFC5520] Bradford, R., 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.
[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.
[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.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013.
[RFC7950] Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016.
[RFC8177] Lindem, A., Qu, Y., Yeung, D., Chen, I. and J. Zhang, "YANG Data Model for Key Chains", RFC 8177, DOI 10.17487/RFC8177, June 2017.
[RFC8040] Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.
[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.
[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.
[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.
[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.
[RFC8306] Zhao, Q., Dhody, D., 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.
[RFC8340] Bjorklund, M. and L. Berger, "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018.
[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.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018.
[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", Internet-Draft draft-ietf-teas-yang-te-19, 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", Internet-Draft draft-ietf-teas-yang-te-types-06, February 2019.
[I-D.ietf-netconf-tls-client-server] Watsen, K., Wu, G. and L. Xia, "YANG Groupings for TLS Clients and TLS Servers", Internet-Draft draft-ietf-netconf-tls-client-server-10, 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", Internet-Draft draft-ietf-pce-association-group-08, March 2019.
[I-D.ietf-pce-segment-routing] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W. and J. Hardwick, "PCEP Extensions for Segment Routing", Internet-Draft draft-ietf-pce-segment-routing-16, 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", Internet-Draft draft-ietf-isis-yang-isis-cfg-35, March 2019.
[I-D.ietf-ospf-yang] Yeung, D., Qu, Y., Zhang, Z., Chen, I. and A. Lindem, "YANG Data Model for OSPF Protocol", Internet-Draft draft-ietf-ospf-yang-21, January 2019.
[I-D.ietf-pce-gmpls-pcep-extensions] Margaria, C., Dios, O. and F. Zhang, "PCEP extensions for GMPLS", Internet-Draft draft-ietf-pce-gmpls-pcep-extensions-13, 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.
[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.
[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.

Appendix A. Example

   

       +-------+                  +-------+ 
       |       |                  |       |  
       | 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,
                "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",  
                             }
                         }
                     ]
                 }
            }, 
            {
                "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",  
                             }
                         }
                     ]
                 }
            }
        ]        
    }
}

        

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

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

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
Vishnu Pavan Beeram Juniper Networks USA EMail: vbeeram@juniper.net
Jeff Tantsura USA EMail: jefftant@gmail.com