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<rfc ipr="trust200902" category="std" docName="draft-pkd-pce-pcep-yang-00" obsoletes="" updates="" submissionType="IETF" xml:lang="en">
  <front>
    <title abbrev="PCE-YANG">A YANG Data Model for Path Computation Element Communications Protocol (PCEP)</title>
    <author initials="R" surname="Pobbathi" fullname="Rohit Pobbathi">
      <organization>Huawei Technologies</organization>
      <address>
        <postal>
          <street>Leela Palace</street>
          <city>Bangalore</city>
          <region>Karnataka</region>
          <code>560008</code>
          <country>India</country>
        </postal>
        <email>rohit.pobbathi@huawei.com</email>
      </address>
    </author>    
    <author initials="V" surname="KumarS" fullname="Vinod KumarS">
      <organization>Huawei Technologies</organization>
      <address>
        <postal>
          <street>Leela Palace</street>
          <city>Bangalore</city>
          <region>Karnataka</region>
          <code>560008</code>
          <country>India</country>
        </postal>
        <email>vinods.kumar@huawei.com</email>
      </address>
    </author>    
    <author initials="D" surname="Dhody" fullname="Dhruv Dhody" role="editor">
      <organization>Huawei Technologies</organization>
      <address>
        <postal>
          <street>Leela Palace</street>
          <city>Bangalore</city>
          <region>Karnataka</region>
          <code>560008</code>
          <country>India</country>
        </postal>
        <email>dhruv.ietf@gmail.com</email>
      </address>
    </author>
    <author fullname="Jonathan Hardwick" initials="J." surname="Hardwick">
      <organization>Metaswitch</organization>
      <address>
        <postal>
          <street>100 Church Street</street>
          <city>Enfield</city>
          <code>EN2 6BQ</code>
          <country>UK</country>
        </postal>
        <email> jonathan.hardwick@metaswitch.com </email>
      </address>
    </author>
    <date month="October" year="2014" />
    <area>Routing</area>
    <workgroup>PCE Working Group</workgroup>
    <abstract>
    <t>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).</t>
    </abstract>
  </front>
  <middle>
    <section title="Introduction" toc="default">
    <t>The Path Computation Element (PCE) defined in <xref target="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.</t>

   <t>PCEP is the communication protocol between a PCC and PCE and is
   defined in <xref target="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).</t>
   
   <t>This document defines a YANG <xref target="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).</t>
   
   <t>This document contains a specification of the base PCEP YANG module, 
   "ietf-pcep" which provides the basic PCEP <xref target="RFC5440"/> data
   model.</t>
   <t>[Editor's Note: Further modules augmenting the data model with advanced 
   features maybe handled in a future revision or a separate document.]</t>
     
      
    </section>
<section title="Requirements Language" toc="default">
        <t>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 <xref target="RFC2119"/>.</t>
      </section>    
    <section title="Terminology and Notation" toc="default">
<t>
          This document uses the terminology defined in <xref target="RFC4655"/>
          and <xref target="RFC5440"/>.  In particular, it uses the following
          acronyms.
          <list style='symbols'>
            <t>
              Path Computation Request message (PCReq).
            </t>
            <t>
              Path Computation Reply message (PCRep).
            </t>
            <t>
              Notification message (PCNtf).
            </t>
            <t>
              Error message (PCErr).
            </t>
            <t>
              Request Parameters object (RP).
            </t>
            <t>
              Synchronization Vector object (SVEC).
            </t>
            <t>
              Explicit Route object (ERO).
            </t>
          </list>
        </t>
        <t>
          This document also uses the following term defined in 
          <xref target="I-D.ietf-pce-pcep-mib"/>: 
          <list style='symbols'>
            <t>          
            PCEP entity: a local PCEP speaker.
            </t>
            <t>
            PCEP peer: to refer to a remote PCEP speaker.
            </t>
            <t>PCEP speaker: where it is not necessary to distinguish between local
          and remote.
        </t>      
        </list>
        </t>
      
      
    <section anchor="sec.tree-symbols" title="Tree Diagrams" toc="default">
      <t>A graphical representation of the complete data
      tree is presented in <xref target="sec.data-tree" pageno="false" format="default"/>. The
      meaning of the symbols in these diagrams is as follows and as per
      <xref target="I-D.ietf-netmod-rfc6087bis"/>:
      <list style="symbols">
        <t>Brackets "[" and "]" enclose list keys.</t>
        <t>Curly braces "{" and "}" contain names of optional features
        that make the corresponding node conditional.</t>
        <t>Abbreviations before data node names: "rw" means
        configuration (read-write), and "ro" state data
        (read-only).</t>
        <t>Symbols after data node names: "?" means an optional node and "*"
        denotes a "list" or "leaf-list".</t>
        <t>Parentheses enclose choice and case nodes, and case nodes
        are also marked with a colon (":").</t>
        <t>Ellipsis ("...") stands for contents of subtrees that are
        not shown.</t>
      </list></t>
    </section>    
    <section title="Prefixes in Data Node Names" toc="default">
      <t>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 <xref target="tab.prefixes" pageno="false" format="default"/>.</t>

      <texttable anchor="tab.prefixes" title="Prefixes and corresponding YANG modules" suppress-title="false" align="center" style="full">
        <ttcol align="left">Prefix</ttcol>
        <ttcol align="left">YANG module</ttcol>
        <ttcol align="left">Reference</ttcol>
        <c>yang</c><c>ietf-yang-types</c><c><xref target="RFC6991" pageno="false" format="default"/></c>
        <c>inet</c><c>ietf-inet-types</c><c><xref target="RFC6991" pageno="false" format="default"/></c>
      </texttable>
    </section>
    </section>
    
    <section title="Objectives" toc="default">
    <t>This section describes some of the design objectives for the model:
    <list style="symbols">
    <t>In case of existing implementations, it needs to map
      the data model defined in this document to their proprietary
      native data model.  To facilitate such mappings, the data model
      should be simple.</t>
    <t>The data model should be suitable for new implementations to use
      as is.</t>
    <t>Mapping to the PCEP MIB Module should be clear.</t>
    <t>The data model should allow for static configurations of peers.</t>
    <t>The data model should include read-only counters in order to
      gather statistics for sent and received PCEP messages,
      received messages with errors, and messages that could not be sent
      due to errors.</t>    
    <t>It should be fairly straight forward to augment the base data model
    for advanced PCE features.</t>  
    </list>
    </t>
    </section>

    <section title="The Design of PCEP Data Model" toc="default" anchor="sec.data-tree">
    <t> The module, "ietf-pcep", defines the basic components of a PCE speaker.
    <figure title="" suppress-title="false" align="left" alt="" width="" height="">
          <artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[    
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 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 
                   ]]></artwork>
        </figure>
      </t>     
    
    <section title="The Entity Lists" toc="default">
    <t>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 
    <xref target="I-D.ietf-pce-pcep-mib"/>.</t>
    <t>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 <xref target="RFC6991"/> 
   is used.</t>
   <t> There is one list for configuration ("/pcep/entity"),
   and a separate list for the operational state of all entities
   ("/pcep-state/entity").
    </t>
    <t>The PCEP MIB module <xref target="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.</t>
    </section>
    <section title="The Peer Lists" toc="default">
        <t>
          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.
        </t>
        <t>
          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.
        </t>
        <t>
          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.
        </t>
   
   <t>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).</t>
   <t> 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").
    </t>   
    </section>
    <section title="The Session Lists" toc="default">
 <t>
          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.
        </t>
        <t>
          Although <xref target="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.
        </t>
<t>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.</t>
   <t> There is only one list for the operational state of all sessions
   ("/pcep-state/entity/peers/peer/sessions/session").
    </t>           
    </section>
    </section>
    
    <section title="Advanced PCE Features" toc="default">
    <t>This document contains a specification of the base PCEP YANG module, 
   "ietf-pcep" which provides the basic PCEP <xref target="RFC5440"/> data
   model.</t>
   <t>A means and procedure to handle to following PCE features needs to be
   decided:
   <list style="symbols">
   <t>Capability and Scope</t>
   <t>Domain information (local/neighbour) </t>
   <t>Path-Key</t>
   <t>OF</t>
   <t>GCO</t>
   <t>P2MP</t>
   <t>GMPLS</t>
   <t>Inter-Layer</t>
   <t>Stateful PCE</t>
   </list>
   </t>
    </section>
    
  
    
    <section title="PCEP YANG Module" toc="default">
    <t>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).</t>
    <figure title="" suppress-title="false" align="left" alt="" width="" height="">
          <artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height="">
          <![CDATA[ 
<CODE BEGINS> file "ietf-pcep@2014-10-09.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 2014-10-09 {
        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" {
                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";
            description
              "The average response time.

               If an average response time has not been  
               calculated then this leaf has the value zero.

               If role is pcc then this leaf is meaningless 
               and is set to zero.";
        }

        leaf lwm-rsp-time{
            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.

              If role is pcc then this leaf is meaningless 
              and is set to zero.";
        }

        leaf hwm-rsp-time{
            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.

              If role is pcc then this field is meaningless and   
              is set to 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

    /*
     * 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.";
            }

            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;
                        description
                           "The timestamp value of the last time a
                            session with this peer was successfully
                            established.

                            If num-sess-setup-ok is zero, then this
                            leaf contains zero.";
                    }

                    leaf session-fail-time{
                        type yang:timestamp;
                        description
                          "The timestamp value of the last time a
                           session with this peer failed to be
                           established.

                           If num-sess-setup-fail is zero, then 
                           this leaf contains zero.";
                    }

                    leaf session-fail-up-time{
                        type yang:timestamp;
                        description
                          "The timestamp value of the last time a
                          session with this peer failed from active.

                          If num-sess-setup-ok is zero, then this
                          leaf contains zero.";
                    }

                    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";
                                }
                                description
                                     "The value of the PCEP session 
                                      ID
 used by the peer in its 
                                      Open message for this session.

                                      If state is tcp-pending or
                                      open-wait then this leaf is not
                                      used and MUST be set to zero.";
                            }

                            leaf keepalive-timer {
                                type uint32 {
                                  range "0..255";
                                }
                                units "seconds";
                                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.

                                      This field is used if and only 
                                      if state is session-up. 
                                      Otherwise, it is not used and 
                                      MUST be set to zero.";
                            }

                            leaf peer-keepalive-timer {
                                type uint32 {
                                  range "0..255";
                                }
                                units "seconds";
                                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.

                                      This field is used if and only 
                                      if state is session-up. 
                                      Otherwise, it is not used and
                                      MUST be set to zero.";
                            }

                            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";
                                description
                                     "The peer's dead-timer interval
                                      for this PCEP session.

                                      If state is tcp-pending or
                                      open-wait then this leaf is 
                                      not used and MUST be set to
                                      zero.";
                            }

                            leaf ka-hold-time-rem {
                                type uint32 {
                                  range "0..255";
                                }
                                units "seconds";
                                description
                                     "The keep alive hold time
                                      remaining for this session.

                                      If state is tcp-pending or
                                      open-wait then this field is
                                      not used and MUST be set to 
                                      zero.";
                            }

                            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.

                                      This field is only used if
                                      overloaded is set to true.
                                      Otherwise, it is not used and
                                      MUST be set to zero.";
                            }

                            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.

                                      This field is only used if
                                      peer-overloaded is set to true.
                                      Otherwise, it is not used and
                                      MUST be 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
}//module
<CODE ENDS>          
/* To Do - Notifications, rpc (if any) */
                     ]]></artwork>
        </figure>
    </section>     
    
    
    
    <section title="Security Considerations" toc="default">
      <t>This document does not add any new 
      security concerns beyond those discussed in <xref target="RFC5440"/>.</t>
    </section>
    
    <section title="Manageability Considerations" toc="default">
      <section title="Control of Function and Policy" toc="default">
        <t></t>
      </section>
      <section title="Information and Data Models" toc="default">
        <t></t>
      </section>
      <section title="Liveness Detection and Monitoring" toc="default">
        <t></t>
      </section>
      <section title="Verify Correct Operations" toc="default">
        <t></t>
      </section>
      <section title="Requirements On Other Protocols" toc="default">
        <t></t>
      </section>
      <section title="Impact On Network Operations" toc="default">
        <t></t>
      </section>
    </section>    
    <section title="IANA Considerations" toc="default">
    <t></t>
    </section>
    
    <section title="Acknowledgements" toc="default">
      <t>The initial document is based on the PCEP MIB 
      <xref target="I-D.ietf-pce-pcep-mib"/>. Further this document 
      structure is based on Routing Yang Module 
      <xref target="I-D.ietf-netmod-routing-cfg"/>. We would
      like to thank the authors of aforementioned documents.</t>
    </section>    
  </middle>
  <back>
    <references title="Normative References">
    <?rfc include="reference.RFC.2119.xml" ?>
    <?rfc include="reference.RFC.5440.xml" ?>
    <?rfc include="reference.RFC.6020.xml" ?>
    <?rfc include="reference.RFC.6991.xml" ?>
    </references>
    <references title="Informative References">
      <?rfc include="reference.RFC.4655.xml" ?>
      <?rfc include="reference.I-D.ietf-pce-pcep-mib.xml" ?>
      <?rfc include="reference.I-D.ietf-netmod-routing-cfg.xml" ?>
      <?rfc include="reference.I-D.ietf-netmod-rfc6087bis.xml" ?>
      
    </references>
<section title="Contributor Addresses" toc="default">
    <t>
    <figure title="" suppress-title="false" align="left" alt="" width="" height="">
          <artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
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    
        ]]></artwork>
        </figure>
      </t>
    </section>    
      
  </back>
</rfc>
