PCE Working Group R. Pobbathi
Internet-Draft V. KumarS
Intended status: Standards Track D. Dhody, Ed.
Expires: April 28, 2015 Huawei Technologies
J. Hardwick
Metaswitch
October 25, 2014

A YANG Data Model for Path Computation Element Communications Protocol (PCEP)
draft-pkd-pce-pcep-yang-01

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 data and state data (status information and counters for the collection of statistics).

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 http://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 April 28, 2015.

Copyright Notice

Copyright (c) 2014 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 (http://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).

This document defines a YANG [RFC6020] 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 (status information and counters for the collection of statistics).

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

[Editor's Note: Further modules augmenting the data model with advanced features maybe handled in a future revision or a separate document.]

2. Requirements Language

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

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 term defined in [I-D.ietf-pce-pcep-mib]:

3.1. Tree Diagrams

A graphical representation of the complete data tree is presented in Section 5. The meaning of the symbols in these diagrams is as follows and as per [I-D.ietf-netmod-rfc6087bis]:

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]

4. Objectives

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

5. The Design of PCEP Data Model

    
module: ietf-pcep
   +--rw pcep
   |  +--rw entity* [addr-type addr]
   |     +--rw addr-type                     inet:ip-version
   |     +--rw addr                          inet:ip-address
   |     +--rw enabled?                      boolean
   |     +--rw role                          pcep-role
   |     +--rw description?                  string
   |     +--rw connect-timer?                uint32
   |     +--rw connect-max-retry?            uint32
   |     +--rw init-backoff-timer?           uint32
   |     +--rw max-backoff-timer?            uint32
   |     +--rw open-wait-timer?              uint32
   |     +--rw keep-wait-timer?              uint32
   |     +--rw keep-alive-timer?             uint32
   |     +--rw dead-timer?                   uint32
   |     +--rw allow-negotiation?            boolean
   |     +--rw max-keep-alive-timer?         uint32
   |     +--rw max-dead-timer?               uint32
   |     +--rw min-keep-alive-timer?         uint32
   |     +--rw min-dead-timer?               uint32
   |     +--rw sync-timer?                   uint32
   |     +--rw request-timer?                uint32
   |     +--rw max-sessions?                 uint32
   |     +--rw max-unknown-reqs?             uint32
   |     +--rw max-unknown-msgs?             uint32
   |     +--rw pcep-notification-max-rate    uint32
   |     +--rw peers
   |        +--rw peer* [addr-type addr]
   |           +--rw addr-type      inet:ip-version
   |           +--rw addr           inet:ip-address
   |           +--rw description?   string
   +--ro pcep-state
      +--ro entity* [addr-type addr]
         +--ro index?                  uint32
         +--ro addr-type               inet:ip-version
         +--ro addr                    inet:ip-address
         +--ro admin-status?           pcep-admin-status
         +--ro oper-status?            pcep-admin-status
         +--ro role?                   pcep-role
         +--ro connect-timer?          uint32
         +--ro connect-max-retry?      uint32
         +--ro init-backoff-timer?     uint32
         +--ro max-backoff-timer?      uint32
         +--ro open-wait-timer?        uint32
         +--ro keep-wait-timer?        uint32
         +--ro keep-alive-timer?       uint32
         +--ro dead-timer?             uint32
         +--ro allow-negotiation?      boolean
         +--ro max-keep-alive-timer?   uint32
         +--ro max-dead-timer?         uint32
         +--ro min-keep-alive-timer?   uint32
         +--ro min-dead-timer?         uint32
         +--ro sync-timer?             uint32
         +--ro request-timer?          uint32
         +--ro max-sessions?           uint32
         +--ro max-unknown-reqs?       uint32
         +--ro max-unknown-msgs?       uint32
         +--ro peers
            +--ro peer* [addr-type addr]
               +--ro addr-type                   inet:ip-version
               +--ro addr                        inet:ip-address
               +--ro role?                       pcep-role
               +--ro discontinuity-time?         yang:timestamp
               +--ro initiate-session?           boolean
               +--ro session-exists?             boolean
               +--ro num-sess-setup-ok?          yang:counter32
               +--ro num-sess-setup-fail?        yang:counter32
               +--ro session-up-time?            yang:timestamp
               +--ro session-fail-time?          yang:timestamp
               +--ro session-fail-up-time?       yang:timestamp
               +--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-svec-sent?              yang:counter32
               +--ro num-svec-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-svec-rcvd?              yang:counter32
               +--ro num-svec-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-cancel-rcvd?   yang:counter32
               +--ro num-rep-rcvd-unknown?       yang:counter32
               +--ro num-req-rcvd-unknown?       yang:counter32
               +--ro num-req-sent-closed?        yang:counter32
               +--ro num-req-rcvd-closed?        yang:counter32
               +--ro sessions
                  +--ro session* [initiator]
                     +--ro initiator                   pcep-initiator
                     +--ro state-last-change?          yang:timestamp
                     +--ro state?                      pcep-sess-state
                     +--ro connect-retry?              yang:counter32
                     +--ro local-id?                   uint32
                     +--ro remote-id?                  uint32
                     +--ro keepalive-timer?            uint32
                     +--ro peer-keepalive-timer?       uint32
                     +--ro dead-timer?                 uint32
                     +--ro peer-dead-timer?            uint32
                     +--ro ka-hold-time-rem?           uint32
                     +--ro overloaded?                 boolean
                     +--ro overload-time?              uint32
                     +--ro peer-overloaded?            boolean
                     +--ro peer-overload-time?         uint32
                     +--ro discontinuity-time?         yang:timestamp
                     +--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-svec-sent?              yang:counter32
                     +--ro num-svec-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-svec-rcvd?              yang:counter32
                     +--ro num-svec-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-cancel-rcvd?   yang:counter32
                     +--ro num-rep-rcvd-unknown?       yang:counter32
                     +--ro num-req-rcvd-unknown?       yang:counter32
notifications:
   +---n pcep-session-up
   |  +--ro entity-addr?         leafref
   |  +--ro entity-addr-type?    leafref
   |  +--ro peer-addr?           leafref
   |  +--ro peer-addr-type?      leafref
   |  +--ro session-initiator?   leafref
   |  +--ro state-last-change?   yang:timestamp
   |  +--ro state?               pcep-sess-state
   +---n pcep-session-down
   |  +--ro entity-addr?         leafref
   |  +--ro entity-addr-type?    leafref
   |  +--ro peer-addr?           leafref
   |  +--ro peer-addr-type?      leafref
   |  +--ro session-initiator?   leafref
   |  +--ro state-last-change?   yang:timestamp
   |  +--ro state?               pcep-sess-state
   +---n pcep-session-local-overload
   |  +--ro entity-addr?         leafref
   |  +--ro entity-addr-type?    leafref
   |  +--ro peer-addr?           leafref
   |  +--ro peer-addr-type?      leafref
   |  +--ro session-initiator?   leafref
   |  +--ro overloaded?          boolean
   |  +--ro overload-time?       uint32
   +---n pcep-session-local-overload-clear
   |  +--ro entity-addr?        leafref
   |  +--ro entity-addr-type?   leafref
   |  +--ro peer-addr?          leafref
   |  +--ro peer-addr-type?     leafref
   |  +--ro overloaded?         boolean
   +---n pcep-session-peer-overload
   |  +--ro entity-addr?          leafref
   |  +--ro entity-addr-type?     leafref
   |  +--ro peer-addr?            leafref
   |  +--ro peer-addr-type?       leafref
   |  +--ro session-initiator?    leafref
   |  +--ro peer-overloaded?      boolean
   |  +--ro peer-overload-time?   uint32
   +---n pcep-session-peer-overload-clear
      +--ro entity-addr?        leafref
      +--ro entity-addr-type?   leafref
      +--ro peer-addr?          leafref
      +--ro peer-addr-type?     leafref
      +--ro peer-overloaded?    boolean
                  

The module, "ietf-pcep", defines the basic components of a PCE speaker.

5.1. The Entity Lists

The PCEP yang module may contain status information for multiple logical local PCEP entities. There are several scenarios in which there may be more than one local PCEP entity, it is listed in [I-D.ietf-pce-pcep-mib].

The data model for PCEP presented in this document uses a flat list of entities. Each entity in the list is identified by its IP address (addr-type, addr). Furthermore, each entity has a mandatory "role" leaf (the local entity PCEP role). The ietf-inet-types [RFC6991] is used.

There is one list for configuration ("/pcep/entity"), and a separate list for the operational state of all entities ("/pcep-state/entity").

The PCEP MIB module [I-D.ietf-pce-pcep-mib] uses 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.

5.2. The Peer Lists

The peer list contains peer 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 one list for static peer configuration ("/pcep/entity/peers"), and a separate list for the operational state of all peers (i.e. static as well as discovered)("/pcep-state/entity/peers").

5.3. 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 apply to the current session only, whereas the latter are the aggregate for all sessions that have existed to that peer.

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

There is only one list for the operational state of all sessions ("/pcep-state/entity/peers/peer/sessions/session").

5.4. 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.

6. Advanced PCE Features

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

A means and procedure to handle to following PCE features needs to be decided:

7. PCEP YANG 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@2014-10-25.yang"    


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

    import ietf-inet-types {
        prefix inet;
    }

    import ietf-yang-types {
        prefix yang;
    }

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

    contact
        "WG Web:   <http://tools.ietf.org/wg/pce/>
         WG List:  <mailto:pce@ietf.org>

         WG Chair: JP Vasseur
                   <mailto:jpv@cisco.com>

         WG Chair: Julien Meuric
                   <mailto:julien.meuric@orange.com>

         Editor:   Dhruv Dhody
                   <mailto:dhruv.ietf@gmail.com>";

    description
        "The YANG module defines a generic configuration and
         operational model for PCEP common across all of the
         vendor implementations.";


    revision 2014-10-25 {
        description "Initial revision.";
        reference
            "RFC XXXX:  A YANG Data Model for Path Computation
                        Element Communications Protocol
                        (PCEP)";
    }

    /*
     * Identities
     */

    identity pcep {
        description "Identity for the PCEP protocol.";
    }

    /*
     * 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-admin-status {
        type enumeration {
                enum admin-status-up {
                value "1";
                description
                "Admin Status is Up";
            }
            enum admin-status-down {
                value "2";
                description
                "Admin Status is Down";
            }
        }

        description
        "The Admin Status of the PCEP entity.
         Takes one of the following values
             - admin-status-up(1): Admin Status is Up.
             - admin-status-down(2): Admin Status is Down";
    }

    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";
    }

    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";
    }


    /*
     * Features - TBD
     */

    /*
     * Groupings
     */
    grouping  pcep-entity-identifier{
        description
            "This grouping defines the identifier for PCEP entity.";
        leaf addr-type {
            type inet:ip-version;
            description
                "The type of the PCEP entity's Internet address.
                 This object specifies how the value of the
                 addr leaf should be interpreted.";
        }

        leaf addr {
            type inet:ip-address;
            description
                "The local Internet address of this PCEP entity.
                 The type is given by addr-type.

                 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.";
        }
    }

    grouping  pcep-peer-identifier{
        description
            "This grouping defines the identifier for PCEP peer.";
        leaf addr-type {
            type inet:ip-version;
            description
                "The type of the PCEP peer's Internet address.
                 This object specifies how the value of the
                 addr leaf should be interpreted.";
        }

        leaf addr {
            type inet:ip-address;
            description
                "The local Internet address of this PCEP peer.
                 The type is given by addr-type.";
        }
    }


    grouping pcep-entity-info{
        description
            "This grouping defines the attributes for PCEP entity.";
        leaf connect-timer {
            type uint32 {
                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 uint32 {
                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.";
        }

        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.";
        }

        leaf open-wait-timer {
            type uint32 {
                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 uint32 {
                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 uint32 {
                range "0..255";
            }
            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 uint32 {
                range "0..255";
            }
            units "seconds";
            must ". >= ../keep-alive-timer" {
                error-message "The dead timer must be "
                       + "larger than the keep alive timer";
                description
                    "This value MUST be greater than
                     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 uint32 {
                range "0..255";
            }
            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 uint32 {
                range "0..255";
            }
            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 uint32 {
                range "0..255";
            }
            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 uint32 {
                range "0..255";
            }
            units "seconds";
            description
                 "In PCEP session parameter negotiationin 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{
            type uint32 {
                range "0..65535";
            }
            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 uint32 {
                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)";
        }
    }//pcep-entity-info

    grouping  pcep-stats{
        description
            "This grouping defines statistics for PCEP. It is used
             for both peer and current session.";
        leaf avg-rsp-time{
            type uint32;
            units "milliseconds";
            must "(/pcep-state/entity/peers/peer/role != 'pcc'" +
                 " or " +
                 "(/pcep-state/entity/peers/peer/role = 'pcc'" +
                 " and avg-rsp-time = 0))" {
                error-message
                    "Invalid average response time";
                description
                    "If role is pcc then this leaf is meaningless 
                     and is set to zero.";                
            }
            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{
            type uint32;
            units "milliseconds";
            must "(/pcep-state/entity/peers/peer/role != 'pcc'" +
                 " or " +
                 "(/pcep-state/entity/peers/peer/role = 'pcc'" +
                 " and lwm-rsp-time = 0))" {
                error-message
                    "Invalid smallest (low-water mark) 
                     response time";
                description
                    "If role is pcc then this leaf is meaningless 
                     and is set to zero.";                
            }
            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{
            type uint32;
            units "milliseconds";
            must "(/pcep-state/entity/peers/peer/role != 'pcc'" +
                 " or " +
                 "(/pcep-state/entity/peers/peer/role = 'pcc'" +
                 " and hwm-rsp-time = 0))" {
                error-message
                    "Invalid greatest (high-water mark) 
                     response time seen";
                description
                    "If role is pcc then this field is     
                     meaningless and is set to zero.";
            } 
            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{
            type yang:counter32;
            description
             "The number of PCReq messages sent.";
        }

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

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

        leaf num-pcrep-rcvd{
            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{
            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-svec-sent{
            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{
            type yang:counter32;
            description
              "The number of requests sent that appeared in one
               or more SVEC objects.";
        }

        leaf num-req-sent-pend-rep{
            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{
            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{
            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{
            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{
            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{
            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{
            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{
            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-svec-rcvd{
            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{
            type yang:counter32;
            description
              "The number of requests received that appeared in one
               or more SVEC objects.";
        }

        leaf num-req-rcvd-pend-rep{
            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{
            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{
            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{
            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-cancel-rcvd{
            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{
            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{
            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.";
        }

    }//pcep-stats

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

        leaf entity-addr {
            type leafref {
                path "/pcep-state/entity/addr";
            }
            description
                "Reference to local entity address";
        }

        leaf entity-addr-type {
            type leafref {
                path "/pcep-state/entity/addr-type";
            }
            description
                "Reference to local entity address type";
        }

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

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

    /*
     * Configuration data nodes
     */
    container pcep{

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

        list entity{
            key "addr-type addr";

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

            uses  pcep-entity-identifier {
                description
                    "The configured PCEP entity Identifier.";
            }

            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";
            }

            uses pcep-entity-info {
                description
                    "The configuration related to the PCEP
                     entity.";
            }

            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 peers{
                description
                        "The list of configured peers for the
                         entity";

                list peer{
                    key "addr-type addr";

                    description
                        "The peer configured for the entity.";

                     uses pcep-peer-identifier{
                        description
                            "The configured PCEP peer's
                             Identifier.";
                     }

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

    /*
     * Operational data nodes
     */

    container pcep-state{
        config false;
        description
            "The list of operational PCEP entities on the
             device.";

        list entity{
            key "addr-type addr";
            unique "index";

            description
                "The operational PCEP entity on the device.";

            leaf index{
                type uint32;
                description
                    "The index of the PECP operational
                     entity";
            }

            uses  pcep-entity-identifier {
                description
                    "The PCEP entity Identifier.";
            }

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

            leaf oper-status {
                type pcep-admin-status;
                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.";
            }

            leaf role {
                type pcep-role;
                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.";
            }


            uses pcep-entity-info{
                description
                    "The operational information related to the
                     PCEP entity.";
            }

            container peers{
                description
                        "The list of peers for the entity";

                list peer{
                    key "addr-type addr";

                    description
                        "The peer for the entity.";

                     uses pcep-peer-identifier{
                        description
                            "The PCEP peer's Identifier.";
                     }

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

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

                    leaf num-sess-setup-ok{
                        type yang:counter32;
                        description
                            "The number of PCEP sessions successfully
                             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;
                        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.";
                    }

                    leaf session-up-time{
                        type yang:timestamp;
                        must "(../num-sess-setup-ok != 0  or " +
                            "(../num-sess-setup-ok = 0  and "  +
                            "session-up-time = 0))" {
                                error-message
                                    "Invalid Session Up timestamp";
                                description
                                    "If num-sess-setup-ok is zero,
                                     then this leaf contains zero.";
                            }
                        description
                           "The timestamp value of the last time a
                            session with this peer was successfully
                            established.";
                    }

                    leaf session-fail-time{
                        type yang:timestamp;
                        must "(../num-sess-setup-fail != 0  or " +
                            "(../num-sess-setup-fail = 0  and "  +
                            "session-fail-time = 0))" {
                                error-message
                                    "Invalid Session Fail timestamp";
                                description
                                    "If num-sess-setup-fail is zero,
                                     then this leaf contains zero.";
                            }
                        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;
                        must "(../num-sess-setup-ok != 0  or "     +
                            "(../num-sess-setup-ok = 0  and "     +
                            "session-fail-up-time = 0))" {
                                error-message
                                    "Invalid Session Fail from 
                                     Up timestamp";
                                description     
                                    "If num-sess-setup-ok is zero, 
                                     then this leaf contains zero.";
                            }
                        description
                          "The timestamp value of the last time a
                           session with this peer failed from 
                           active.";
                    }

                    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{
                        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{
                        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.";
                    }

                    container sessions {
                        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 MIB
                                     module. The sessions are
                                     distinguished by who initiated
                                     them, and so this field is the
                                     key.";
                            }

                            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 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 uint32 {
                                  range "0..255";
                                }
                                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.";
                            }

                            leaf remote-id {
                                type uint32 {
                                    range "0..255";
                                }
                                must "((../state != 'tcp-pending'" +
                                     "and " +
                                     "../state != 'open-wait' )" +
                                     "or " +
                                     "((../state = 'tcp-pending'" +
                                     " or " +
                                     "../state = 'open-wait' )" +
                                     "and remote-id = 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.";
                            }

                            leaf keepalive-timer {
                                type uint32 {
                                  range "0..255";
                                }
                                units "seconds";
                                must "(../state = 'session-up'" + 
                                     "or " +
                                     "(../state != 'session-up'" +
                                     "and keepalive-timer = 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.";
                            }

                            leaf peer-keepalive-timer {
                                type uint32 {
                                  range "0..255";
                                }
                                units "seconds";
                                must "(../state = 'session-up'" +
                                     "or "   +
                                     "(../state != 'session-up'" +
                                     "and " +
                                     "peer-keepalive-timer = 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.";
                            }

                            leaf dead-timer {
                                type uint32 {
                                  range "0..255";
                                }
                                units "seconds";
                                description
                                     "The dead timer interval for
                                      this PCEP session.";
                            }

                            leaf peer-dead-timer {
                                type uint32 {
                                  range "0..255";
                                }
                                units "seconds";
                                must "((../state != 'tcp-pending'" + 
                                     "and " +
                                     "../state != 'open-wait' )" + 
                                     "or " +
                                     "((../state = 'tcp-pending'" + 
                                     " or " +
                                     "../state = 'open-wait' )" +
                                     "and " +
                                     "peer-dead-timer = 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.";
                            }

                            leaf ka-hold-time-rem {
                                type uint32 {
                                  range "0..255";
                                }
                                units "seconds";
                                must "((../state != 'tcp-pending'" +
                                     "and " +
                                     "../state != 'open-wait' ) " +
                                     "or " +
                                     "((../state = 'tcp-pending'" +
                                     "or " +
                                     "../state = 'open-wait' )" +
                                     "and " +
                                     "ka-hold-time-rem = 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.";
                            }

                            leaf overload-time {
                                type uint32;
                                units "seconds";
                                must "(../overloaded = true or" +
                                    "(../overloaded != true and" +
                                    " overload-time = 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.";
                            }

                            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";
                                must "(../peer-overloaded = true" +
                                     " or " +
                                     "(../peer-overloaded != true" +
                                     " and " +
                                     "peer-overload-time = 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.";
                            }

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

                            uses pcep-stats{
                                description
                                    "The statistics contained are
                                     for the current sessions to that
                                     peer. These are lost when the
                                     session goes down.";

                            }

                        } // session
                    } // sessions
                }//peer
            }//peers
        }//entity
    }//pcep-state

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

    notification pcep-session-down {
        description
            "This notification is sent when the value of
             '/pcep/pcep-state/peers/peer/sessions/session/state'
             leaves 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.";
        }
    } //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";
            must "(../overloaded = true or "    +
                "(../overloaded != true  and "  +
                "overload-time = 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.";
        }
    } //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.";
        }
    } //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";
            must "(../peer-overloaded = true or "    +
                "(../peer-overloaded != true  and "  +
                "peer-overload-time = 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.";
        }
    } //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.";
        }
    } //notification
}//module

<CODE ENDS>          
                     

8. Security Considerations

This document does not add any new security concerns beyond those discussed in [RFC5440].

9. Manageability Considerations

9.1. Control of Function and Policy

9.2. Information and Data Models

9.3. Liveness Detection and Monitoring

9.4. Verify Correct Operations

9.5. Requirements On Other Protocols

9.6. Impact On Network Operations

10. IANA Considerations

11. Acknowledgements

The initial document is based on the PCEP MIB [I-D.ietf-pce-pcep-mib]. Further this document structure is based on Routing Yang Module [I-D.ietf-netmod-routing-cfg]. We would like to thank the authors of aforementioned documents.

12. References

12.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, July 2013.

12.2. Informative References

[RFC4655] Farrel, A., Vasseur, J. and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006.
[I-D.ietf-pce-pcep-mib] Sreenivasa, K., Emile, S., Zhao, Q., King, D. and J. Hardwick, "Path Computation Element Communications Protocol (PCEP) Management Information Base (MIB) Module", Internet-Draft draft-ietf-pce-pcep-mib-11, October 2014.
[I-D.ietf-netmod-routing-cfg] Lhotka, L., "A YANG Data Model for Routing Management", Internet-Draft draft-ietf-netmod-routing-cfg-15, May 2014.
[I-D.ietf-netmod-rfc6087bis] Bierman, A., "Guidelines for Authors and Reviewers of YANG Data Model Documents", Internet-Draft draft-ietf-netmod-rfc6087bis-01, October 2014.

Appendix A. Contributor Addresses

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
Leela Palace
Bangalore, Karnataka  560008
India

EMail: udayasree.palle@huawei.com      

Vishnu Pavan Beeram
Juniper Networks
USA

EMail: vbeeram@juniper.net    
        

Authors' Addresses

Rohit Pobbathi Huawei Technologies Leela Palace Bangalore, Karnataka 560008 India EMail: rohit.pobbathi@huawei.com
Vinod KumarS Huawei Technologies Leela Palace Bangalore, Karnataka 560008 India EMail: vinods.kumar@huawei.com
Dhruv Dhody (editor) Huawei Technologies Leela Palace Bangalore, Karnataka 560008 India EMail: dhruv.ietf@gmail.com
Jonathan Hardwick Metaswitch 100 Church Street Enfield, EN2 6BQ UK EMail: jonathan.hardwick@metaswitch.com