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Versions: 00 01 02 03 04 05 06                                          
Network Working Group                                            Z. Wang
Internet-Draft                                                    L. Xia
Intended status: Standards Track                                  Huawei
Expires: September 5, 2015                                      D. Kumar
                                                                   Cisco
                                                                   Q. Wu
                                                                  Huawei
                                                           March 4, 2015


          A Layer Independent Operations, Administration, and
  Maintenance(OAM)Management YANG Data Model Extension for BFD Support
                       draft-wang-yang-bfd-oam-01

Abstract

   This document presents a YANG Data model for BFD support.  The YANG
   Model presented in this document extends the YANG model for Layer
   independent OAM Management with BFD technology specifics.

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 September 5, 2015.

Copyright Notice

   Copyright (c) 2015 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



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   2
     2.1.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Architecture of OAM YANG Model and Relationship to BFD OAM  .   4
   4.  Generic YANG Model extension for BFD  . . . . . . . . . . . .   4
     4.1.  BFD-session grouping  . . . . . . . . . . . . . . . . . .   5
     4.2.  BFD-session-stats grouping  . . . . . . . . . . . . . . .   9
     4.3.  Identity technology-sub-type  . . . . . . . . . . . . . .  10
     4.4.  connectivity-context  . . . . . . . . . . . . . . . . . .  11
     4.5.  rpc definitions . . . . . . . . . . . . . . . . . . . . .  13
     4.6.  Notification definitions  . . . . . . . . . . . . . . . .  16
   5.  OAM Data Hierarchy  . . . . . . . . . . . . . . . . . . . . .  16
   6.  OAM YANG Module . . . . . . . . . . . . . . . . . . . . . . .  18
   7.  Default Mode for BFD OAM  . . . . . . . . . . . . . . . . . .  29
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  29
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  29
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  29
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  30

1.  Introduction

   This document presents a YANG Data model for BFD [RFC5880] support.
   The YANG Model presented in this document extends the YANG model for
   Layer Independent OAM Management defined in [I-D.tissa-lime-yang-oam-
   model] and [I-D.wang-lime-rpc-yang-oam-management].

2.  Conventions and Terminology

   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].

   The following terms are defined in [RFC6241] and are not redefined
   here:

   o  client

   o  configuration data

   o  server

   o  state data



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   The following terms are defined in [RFC6020] and are not redefined
   here:

   o  augment

   o  data model

   o  data node

   The terminology for describing YANG data models is found in
   [RFC6020].

2.1.  Tree Diagrams

   A simplified graphical representation of the data model is used in
   this document.  The meaning of the symbols in these diagrams is as
   follows:

   Each node is printed as:

   <status> <flags> <name> <opts> <type>

   <status> is one of:
        +  for current
        x  for deprecated
        o  for obsolete


   <flags> is one of:

       rw for configuration data
       ro for non-configuration data
       -x for rpcs
       -n for notifications


   <name> is the name of the node

   If the node is augmented into the tree from another module, its name
   is printed as <prefix>:<name>.











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   <opts> is one of:

        ?  for an optional leaf or choice
        !  for a presence container
        *  for a leaf-list or list
        [<keys>] for a list's keys

   <type> is the name of the type for leafs and leaf-lists

3.  Architecture of OAM YANG Model and Relationship to BFD OAM

   Layer independent OAM YANG model[I-D.tissa-lime-yang-oam-model] and
   [I-D.wang-lime-rpc-yang-oam-management] is used as the basis for all
   the other OAM YANG models.  This allows users to span across OAM
   tools of different technologies through a uniform API.  The following
   Figure depicts the relationship of BFD OAM YANG model to the Layer
   Independent OAM YANG Model.

                          +-+-+-+-+-+
                          |  Layer  |
                          |independent
                          |OAM YANG |
                          +-+-+-+-+-+
                               |
                               O
                               |
       +--------------------------------------------------+
       |               |                    |             |
   +-+-+-+-+-+    +-+-+-+-+-+          +-+-+-+-+-+   +-+-+-+-+-+
   | TRILL   |    | NVO3    |          | BFD     |. .|  foo    |
   |OAM YANG |    |OAM YANG |          |OAM YANG |   |OAM YANG |
   +-+-+-+-+-+    +-+-+-+-+-+          +-+-+-+-+-+   +-+-+-+-+-+
         |              |                    |            |
         |              |                    |            |
         |              |                    |            |
       +----------------------------------------------------+
       |             Uniform API                            |
       +----------------------------------------------------+

     Relationship of BFD OAM YANG model to Layer independent OAM YANG
                                   model

4.  Generic YANG Model extension for BFD

   The Technology parameter is defined in the [I-D.tissa-lime-yang-oam-
   model] and [I-D.wang-lime-rpc-yang-oam-management] as an identity.
   This allows easy extension of the YANG model by other technologies.
   Technology specific extensions are applied only when the technology



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   is set to the specific type. "bfd" is defined as an identity that
   augments the base technology-types identity.

         identity bfd {
             base goam:technology-types;
             description
               "bfd type";
           }

4.1.  BFD-session grouping

   In BFD session, there are some useful parameters be used to indicate
   some specific type or operation mode.  This document define a bfd-
   session grouping which include all of these parameters.  Using this
   bfd-session grouping, we can augment the basic gen-oam model as
   follows:

grouping bfd-session{
leaf bfdsess-version-num{
type uint32;
default "1";
        description
         " The version number of the BFD protocol that this session
          is running in.  Write access is available for this object
          to provide the ability to set the desired version for this
          BFD session ";}

leaf bfdsess-type{
type enumeration{
    enum singleHop{value 1;}
    enum multiHopTotallyArbitraryPaths{value 2;}
    enum multiHopOutOfBandSignaling{value 3;}
    enum multiHopUnidirectionalLinks{value 4;}
}
        description
         " This leaf specifies the type of this BFD session ";
}
leaf bfdsess-oper-mode {
type enumeration{
    enum asynchModeWEchoFunction{value 1;}
    enum asynchModeWOEchoFunction{value 2;}
    enum demandModeWEchoFunction{value 3;}
    enum demandModeWOEchoFunction{value 4;}
}
        description
         " This object specifies the operational mode of this
          BFD session ";
         }



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leaf bfdsess-demandmode-desired {
        type boolean;
        description
         " This leaf indicates the local system's
          desire to use Demand mode.  Specifically, it is set
          to true if the local system wishes to use
          Demand mode or false if not ";
         }


leaf bfdsess-controlplanel-indep {
        type boolean;
        description
         " This leaf indicates the local system's
          ability to continue to function through a disruption of
          the control plane.  Specifically, it is set
          to true if the local system BFD implementation is
          independent of the control plane.  Otherwise, the
          value is set to false ";
         }

leaf bfdsess-multi-point {
        type boolean;
        description
         " This leaf indicates the Multipoint (M) bit for this
          session.  It is set to true if the Multipoint (M) bit is
          set to 1.  Otherwise, the value is set to false ";
         }

leaf bfdsess-detect-mult {
          type uint32;
        description
         " This leaf specifies the Detect time multiplier ";
         }

leaf bfdsess-authpres {
          type boolean;
        description
         " This leaf indicates the local system's
          desire to use authentication.  Specifically, it is set
          to true if the local system wishes the session
          to be authenticated or false if not";
         }

leaf bfdsess-authentication-type {
        type enumeration{
   enum noAuthentication;
        enum reserved;



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        enum simplePassword;
        enum keyedMD5;
        enum meticulousKeyedMD5;
        enum keyedSHA1;
        enum meticulousKeyedSHA1;
}
description
         " The authentication type used for this BFD session.
          This field is valid only when the Authentication
          Present bit is set ";


leaf bfdsess-authentication-key {
        type uint32;
        description
         "This leaf specifies the authentication key in use for this session.";
         }
bfdSess-authentication-keyID{
        type uint32;
        description
         " The authentication key ID in use for this session.  This
          leaf permits multiple keys to be active simultaneously.";
}
leaf bfdSess-DesiredMinTx-Interval{

          description
         " This leaf specifies the minimum interval, in
          microseconds, that the local system would like to use
          when transmitting BFD Control packets.  The value of
          zero(0) is reserved in this case and should not be
          used.";
             type uint32;
}
leaf bfdSess-ReqMinRx-Interval {
          description
         " This leaf specifies the minimum interval, in
          microseconds, between received BFD Control packets the
          local system is capable of supporting.  The value of
          zero(0) can be specified when the transmitting system
          does not want the remote system to send any periodic BFD
          Control packets ";
             type uint32;
           }
leaf bfdSess-ReqMinEchoRx-Interval {
          description
         " This leaf specifies the minimum interval, in
          microseconds, between received BFD Echo packets that this
          system is capable of supporting.  The value must be zero(0) if



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          this is a multihop BFD session ";
             type uint32;
           }
leaf bfdSess-Negotiated-Interval {
          description
         " This leaf specifies the negotiated interval, in
          microseconds, that the local system is transmitting
          BFD Control packets ";
             type uint32;
           }
leaf bfdSess-NegotiatedEcho-Interval {
          description
         " This leaf specifies the negotiated interval, in
          microseconds, that the local system is transmitting
          BFD Echo packets.  The value is expected to be zero if
          the sessions are not running in Echo mode ";
             type uint32;
           }
leaf bfdSess-Source-UdpPort {
          description
         " This leaf specifies the source UDP port number used
          for this BFD session's Control packets.  The value may be
          0 if the session is in adminDown state.  Upon
          creation of a new BFD session via this, the value of
          0 specified would permit the implementation to
          choose its own source port number ";
           }
leaf bfdSess-echoSrc-Udp{
          type uint32;
description
         " This leaf specifies the source UDP port number used for
          this BFD session's Echo packets.  The value may be 0
          if the session is not running in the Echo mode, or the
          session is in adminDown state.  Upon creation of a new
          BFD session via this, the value of 0 would
          permit the implementation to choose its own source port
          number ";
           }

leaf bfdSess-Destination-UdpPort {
         type uint32;
description
         " This leaf specifies the destination UDP port number
          used for this BFD session's Control packets.
3784 represents single-hop BFD session.
4784 represents multi-hop BFD session.
6784 represents BFD on Link Aggregation Group (LAG) session.
The value may be zero(0) if the session is in adminDown(1) state";



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           }
}

 augment "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session"
{uses BFD-session;}

4.2.  BFD-session-stats grouping

   In BFD session, there are some useful parameters be used to indicate
   bfd session stats.  This document define a bfd-session-status
   grouping which include these parameters.  Using this bfd-session-
   status grouping, we can augment the basic gen-oam model as follows:

grouping bfd-session-stats{
        leaf bfdsess-status {
        type uint32;
        description
         " Configured BFD session state ";
         }
         leaf bfd-Sess-Diag{
type enumeration{
        enum noDiagnostic{value 0;}
        enum controlDetectionTimeExpired{value 1;}
        enum echoFunctionFailed{value 2;}
        enum neighborSignaledSessionDown{value 3;}
        enum forwardingPlaneReset{value 4;}
        enum pathDown{value 5;}
        enum concatenatedPathDown{value 6;}
        enum administrativelyDown{value 7;}
        enum reverseConcatenatedPathDown{value 8;}
        enum misConnectivityDefect{value 9;}
}
description
"A diagnostic code specifying the local system's reason
 for the last transition of the session from up
to some other state."
}
         leaf bfdsess-admin-stats {
           type enumeration{
           enum enabled{value 1;}
           enum disabled{value 2;}
           enum adminDown{value 3;}
           enum down{value 4;}
           }
       description
         " Denotes the desired operational status of the BFD session.
          A transition to enabled will start the BFD state machine
          for the session.  The state machine will have an initial



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          state of down.
          A transition to disabled will stop the BFD state machine
          for the session.  The state machine may first transition to
          adminDown prior to stopping.
          A transition to adminDown will cause the BFD state
          machine to transition to adminDown and will cause the
          session to remain in this state.
          A transition to down will cause the BFD state machine
          to transition to down and will cause the session to
          remain in this state";
         }
         leaf bfdsess-oper-status {
           type enumeration{
           enum up{value 1;}
           enum down{value 2;}
           enum adminDown{value 3;}
        };
        description
         " Denotes the actual operational status of the BFD session.
          If the value of bfdOperStatus is down, this value MUST
          eventually be down as well.  If the value of
          bfdOperStatus is adminDown, this value MUST eventually
          be adminDown as well ";
         }
        leaf bfdsess-remote-heard {
           type boolean;
        description
         " This leaf specifies the status of BFD packet reception from
          the remote system.  Specifically, it is set to true if
          the local system is actively receiving BFD packets from the
          remote system and is set to false if the local system
          has not received BFD packets recently (within the detection
          time) or if the local system is attempting to tear down
          the BFD session ";
         }
}
augment "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session"
{uses BFD-session-stats;}

4.3.  Identity technology-sub-type

   In BFD, different encapsulation types such as MPLS[RFC5884] OSPFv2
   [RFC5882], OSPFv3 [RFC5882], IS-IS [RFC5882], BGP [RFC5882], RIP
   [RFC5882] can be employed. "technology-sub-type" identifies the
   encapsulation type within the BFD.  Technology sub-type is defined as
   an identity type.  This allows different encapsulation types to
   augment BFD OAM YANG model to include encapsulation type specific
   extensions without redefining common BFD definitions



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augment "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session" {
identity technology-sub-type{
description
 "this is the base identity of sub-technology.
It can be used to identify the encapsulation type
such as MPLS, OSPFv2, OSPFv3, IS-IS, BGP, RIP, etc";
  }
}

4.4.  connectivity-context

   In BFD, connectivity-context is a pair of 32 bit Discriminators
   (SessDiscriminator,remotSessDiscriminator).  This allows other
   technologies to easily augment that to include technology specific
   extensions.  The snippet below depicts an example of augmenting
   connectivity-context to include Discriminator.



































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   augment
    "/goam:domains/goam:domain/goam:MAs/gam:MA/goam:MEP
    /goam:session/goam: connectivity-context"
   {
   case context-bfdsess {
   leaf bfdsess-discriminator {
   type uint32;
   description
   "This leaf specifies the local discriminator for this BFD
   session, which is used to uniquely identify it ";
               }
   leaf bfdsess-remotediscr {
    type uint32;
    description
   "This leaf specifies the session discriminator chosen
   by the remote system for this BFD session.  The value may
   be zero(0) if the remote discriminator is not yet known
   or if the session is in the down or adminDown(1) state ";
   }
   leaf Interface{
   type leafref{
    path
   "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP"
   +"/goam:Interface";
   }
   }
   leaf source-mep{
   type leafref{
    path
   "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP"
   +"/goam:session/goam:source-mep";
   }
   }
    leaf destination-mep{
   type leafref{
   path
   "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP"
   +"/goam:session/goam:destination-mep"
   +"/goam:destination-mep/goam:MEP-ID/goam:MEP-ID-int"
   +"/goam:MEP-ID-int";
   }
   }

             }
           }






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4.5.  rpc definitions

   The rpc model facilitates issuing commands to a NETCONF server (in
   this case to the device that need to execute the OAM command) and
   obtaining a response.

   CC extension:

    augment "/goam:cc/goam:output/goam: maintenance-stats" {
    case session-ccperform-bfd {
    leaf bfdSess-PerfCtrlPkt-In {
            type uint32;
            description
            "The total number of BFD control messages received for this
             BFD session";
             }
    leaf bfdSess-PerfCtrlPkt-Out {
            type uint32;
            description
            "The total number of BFD control messages sent for this BFD
             session";
             }
    leaf bfdSess-PerfCtrlPkt-Drop {
            type uint32;
            description
            "The total number of BFD control messages received for this
             session yet dropped for being invalid";
             }
    leaf bfdSess-PerfCtrlPktDrop-LastTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at
             which received the BFD control message for this session was
             dropped. If no such up event exists, this object contains
             a zero value";
             }
    leaf bfdSess-PerfEchoPkt-In {
            type uint32;
            description
            "The total number of BFD Echo messages received for this
             BFD session";
             }
    leaf bfdSess-PerfEchoPkt-Out {
            type uint32;
            description
            "The total number of BFD Echo messages sent for this BFD
             session";
             }



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    leaf bfdSess-PerfEchoPkt-Drop {
            type uint32;
            description
            "The total number of BFD Echo messages received for this
             session yet dropped for being invalid";
             }
    leaf bfdSess-PerfEchoPktDrop-LastTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at
             which received the BFD Echo message for this session was
             dropped. If no such up event has been issued, this
             object contains a zero value";
             }
    leaf bfdSess-UpTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at which
             the session came up. If no such event has been issued,
             this object contains a zero value";
             }
    leaf bfdSess-PerfLastSessDownTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at
             which the last time communication was lost with the
             neighbor. If no down event has been issued, this object
             contains a zero value ";
             }
    leaf bfdSess-PerfLastCommLostDiag {
            type uint32;
            description
            "The BFD diag code for the last time communication was lost
             with the neighbor. If such an event has not been issued,
             this object contains a zero value";
             }
    leaf bfdSess-PerfSess-UpCount {
            type uint32;
            description
            "The number of times this session has gone into the Up
             state since the system last rebooted";
             }
    leaf bfdSess-Perf-DiscTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at
             which any one or more of the session counters suffered
             a discontinuity ";



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             }
           }
         }

   CV extension:

 augment "/goam:cv/goam:output/goam: maintenance-stats"{
    case session-cvperform-bfdctr {
    leaf bfdSess-PerfCtrlPkt-In {
            type uint32;
            description
            "The total number of BFD control messages received for this
             BFD session";
             }
    leaf bfdSess-PerfCtrlPkt-Out {
            type uint32;
            description
            "The total number of BFD control messages sent for this BFD
             session";
             }
    leaf bfdSess-PerfCtrlPkt-Drop {
            type uint32;
            description
            "The total number of BFD control messages received for this
             session yet dropped for being invalid";
             }
    leaf bfdSess-PerfCtrlPktDrop-LastTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at
             which received the BFD control message for this session was
             dropped. If no such up event exists, this object contains
             a zero value";
             }
    leaf bfdSess-UpTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at which
             the session came up. If no such event has been issued,
             this object contains a zero value";
             }
    leaf bfdSess-PerfLastSessDownTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at
             which the last time communication was lost with the
             neighbor. If no down event has been issued, this object
             contains a zero value";



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             }
    leaf bfdSess-PerfLastCommLostDiag {
            type uint32;
            description
            "The BFD diag code for the last time communication was lost
             with the neighbor. If such an event has not been issued,
             this object contains a zero value";
             }
    leaf bfdSess-PerfSess-UpCount {
            type uint32;
            description
            "The number of times this session has gone into the Up
             state since the system last rebooted";
             }
    leaf bfdSess-Perf-DiscTime {
            type uint32;
            description
            "The value of sysUpTime on the most recent occasion at
             which any one or more of the session counters suffered
             a discontinuity";
             }
           }
         }

4.6.  Notification definitions

   In BFD, the bfdsess-admin-status, bfdsess-oper-status, bfdsess-status
   and the bfdsess-remote-heard are used to indicate the session status.
   i.e. the bfdsess-admin-status denotes the desired operational status
   of the BFD session.  And the bfdsess-oper-status denotes the actual
   operational status of the BFD session.  The bfdsess-status is used to
   indicate the BFD session state.  And the bfdsess-oper-status
   specifies the status of BFD packet reception from the remote system.

   augment "/moam:notifications/moam:defect-condition-notification"{
   uses bfd-session-stats;
   }

5.  OAM Data Hierarchy

   The complete data hierarchy related to the OAM YANG model is
   presented below.

augment
/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session

      +--rw technology-sub-type           identityref
      +--rw bfdsess-version-num?           uint32



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      +--rw bfdsess-type?                  uint32
      +--rw bfdsess-oper-mode?             uint32
      +--rw bfdsess-demandmode-desired?    boolean
      +--rw bfdsess-controlplanel-indep?   boolean
      +--rw bfdsess-multi-point?           boolean
      +--rw bfdsess-detect-mult?           uint32
      +--rw bfdsess-authpres?              boolean
      +--rw bfdsess-authentication-type    uint32
      +--rw bfdsess-authentication-key?      uint32
      +--rw bfdSess-DesiredMinTx-Interval uint32
      +--rw bfdSess-ReqMinRx-Interval?           uint32
      +--rw bfdSess-ReqMinEchoRx-Interval?       unit32
      +--ro bfdSess-Negotiated-Interval?         uint32
      +--ro bfdSess-NegotiatedEcho-Interval?     uint32
      +--rw bfdSess-Source-UdpPort?  uint32
      +--rw bfdSess-echoSrc-UdpPort? uint32
      +--rw bfdSess-Destination-UdpPort  uint32
      +--ro bfdsess-status?                uint32
      +--ro bfdsess-bfd-Sess-Diag?         enumeration
      +--rw bfdsess-admin-status?          enumeration
      +--ro bfdsess-oper-status?           enumeration
      +--ro bfdsess-remote-heard?          boolean

augment
/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session/goam:connective-context
   +--:(context-bfdsess)
       +--rw bfdsess-discriminator?           uint32
       +--rw bfdsess-remotediscr?             uint32
       +--rw Interface?                       leafref
       +--rw source-mep?                      leafref
       +--rw destination-mep?                 leafref

   augment
   /goam:cc/goam:output/goam:maintenance-stats:
   +--:(session-ccperform-bfd)
      +--ro bfdSess-PerfCtrlPkt-In?           uint32
      +--ro bfdSess-PerfCtrlPkt-Out?          uint32
      +--ro bfdSess-PerfCtrlPkt-Drop?         unit32
      +--ro bfdSess-PerfCtrlPktDrop-LastTime? uint32
      +--ro bfdSess-PerfEchoPkt-In?           uint32
      +--ro bfdSess-PerfEchoPkt-Out?          uint32
      +--ro bfdSess-PerfEchoPkt-Drop?         unit32
      +--ro bfdSess-PerfEchoPktDrop-LastTime? uint32
      +--ro bfdSess-UpTime?                   uint32
      +--ro bfdSess-PerfLastSessDownTime?     uint32
      +--ro bfdSess-PerfLastCommLostDiag?     uint32
      +--ro bfdSess-PerfSess-UpCount?         uint32
      +--ro bfdSess-Perf-DiscTime?            uint32



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   augment
   /goam:cv/goam:output/goam:maintenance-stats:
   +--:(session-cvperform-bfd)
      +--ro bfdSess-PerfCtrlPkt-In?           uint32
      +--ro bfdSess-PerfCtrlPkt-Out?          uint32
      +--ro bfdSess-PerfCtrlPkt-Drop?         unit32
      +--ro bfdSess-PerfCtrlPktDrop-LastTime? uint32
      +--ro bfdSess-UpTime?                   uint32
      +--ro bfdSess-PerfLastSessDownTime?     uint32
      +--ro bfdSess-PerfLastCommLostDiag?     uint32
      +--ro bfdSess-PerfSess-UpCount?         uint32
      +--ro bfdSess-Perf-DiscTime?            uint32

   augment
   /moam: notifications/moam: defect-condition-notification:
      +--ro bfdsess-status?                uint32
      +--ro bfdsess-bfd-Sess-Diag?         enumeration
      +--ro bfdsess-admin-status?          enumeration
      +--ro bfdsess-oper-status?           enumeration
      +--ro bfdsess-remote-heard?          boolean

                         Data hierarchy of BFD OAM

6.  OAM YANG Module

   <CODE BEGINS> file "xxx.yang"

<CODE BEGINS> file "xxx.yang"

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

     import gen-oam  {
       prefix goam;
     }
     import ietf-inet-types {
       prefix inet;
     }
     import ietf-interfaces {
       prefix if;
     }
     import ietf-yang-types {
       prefix yang;
     }

     revision 2014-08-30 {
       description



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         "Initial revision.";
     }

     identity bfd {
       base bfd:technology-types;
       description
         "bfd type";
     }

     identity bfd-contiuity-check {
       base goam:command-sub-type;
     }

     identity bfd-connectity-verification {
       base goam:command-sub-type;
     }

grouping bfd-session{
leaf bfdsess-version-num{
type uint32;
default "1";
        description
         " The version number of the BFD protocol that this session
          is running in.  Write access is available for this object
          to provide the ability to set the desired version for this
          BFD session ";}

leaf bfdsess-type{
type enumeration{
    enum singleHop{value 1;}
    enum multiHopTotallyArbitraryPaths{value 2;}
    enum multiHopOutOfBandSignaling{value 3;}
    enum multiHopUnidirectionalLinks{value 4;}
}
        description
         " This leaf specifies the type of this BFD session ";
}
leaf bfdsess-oper-mode {
type enumeration{
    enum asynchModeWEchoFunction{value 1;}
    enum asynchModeWOEchoFunction{value 2;}
    enum demandModeWEchoFunction{value 3;}
    enum demandModeWOEchoFunction{value 4;}
}
        description
         " This object specifies the operational mode of this
          BFD session ";
         }



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leaf bfdsess-demandmode-desired {
        type boolean;
        description
         " This leaf indicates the local system's
          desire to use Demand mode.  Specifically, it is set
          to true if the local system wishes to use
          Demand mode or false if not ";
         }


leaf bfdsess-controlplanel-indep {
        type boolean;
        description
         " This leaf indicates the local system's
          ability to continue to function through a disruption of
          the control plane.  Specifically, it is set
          to true if the local system BFD implementation is
          independent of the control plane.  Otherwise, the
          value is set to false ";
         }

leaf bfdsess-multi-point {
        type boolean;
        description
         " This leaf indicates the Multipoint (M) bit for this
          session.  It is set to true if the Multipoint (M) bit is
          set to 1.  Otherwise, the value is set to false ";
         }

leaf bfdsess-detect-mult {
          type uint32;
        description
         " This leaf specifies the Detect time multiplier ";
         }

leaf bfdsess-authpres {
          type boolean;
        description
         " This leaf indicates the local system's
          desire to use authentication.  Specifically, it is set
          to true if the local system wishes the session
          to be authenticated or false if not";
         }

leaf bfdsess-authentication-type {
        type enumeration{
   enum noAuthentication;
        enum reserved;



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        enum simplePassword;
        enum keyedMD5;
        enum meticulousKeyedMD5;
        enum keyedSHA1;
        enum meticulousKeyedSHA1;
}
description
         " The authentication type used for this BFD session.
          This field is valid only when the Authentication
          Present bit is set ";


leaf bfdsess-authentication-key {
        type uint32;
        description
         "This leaf specifies the authentication key in use for this session.";
         }
bfdSess-authentication-keyID{
        type uint32;
        description
         " The authentication key ID in use for this session.  This
          leaf permits multiple keys to be active simultaneously.";
}
leaf bfdSess-DesiredMinTx-Interval{

          description
         " This leaf specifies the minimum interval, in
          microseconds, that the local system would like to use
          when transmitting BFD Control packets.  The value of
          zero(0) is reserved in this case and should not be
          used.";
             type uint32;
}
leaf bfdSess-ReqMinRx-Interval {
          description
         " This leaf specifies the minimum interval, in
          microseconds, between received BFD Control packets the
          local system is capable of supporting.  The value of
          zero(0) can be specified when the transmitting system
          does not want the remote system to send any periodic BFD
          Control packets ";
             type uint32;
           }
leaf bfdSess-ReqMinEchoRx-Interval {
          description
         " This leaf specifies the minimum interval, in
          microseconds, between received BFD Echo packets that this
          system is capable of supporting.  The value must be zero(0) if



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          this is a multihop BFD session ";
             type uint32;
           }
leaf bfdSess-Negotiated-Interval {
          description
         " This leaf specifies the negotiated interval, in
          microseconds, that the local system is transmitting
          BFD Control packets ";
             type uint32;
           }
leaf bfdSess-NegotiatedEcho-Interval {
          description
         " This leaf specifies the negotiated interval, in
          microseconds, that the local system is transmitting
          BFD Echo packets.  The value is expected to be zero if
          the sessions are not running in Echo mode ";
             type uint32;
           }
leaf bfdSess-Source-UdpPort {
          description
         " This leaf specifies the source UDP port number used
          for this BFD session's Control packets.  The value may be
          0 if the session is in adminDown state.  Upon
          creation of a new BFD session via this, the value of
          0 specified would permit the implementation to
          choose its own source port number ";
           }
leaf bfdSess-echoSrc-Udp{
          type uint32;
description
         " This leaf specifies the source UDP port number used for
          this BFD session's Echo packets.  The value may be 0
          if the session is not running in the Echo mode, or the
          session is in adminDown state.  Upon creation of a new
          BFD session via this, the value of 0 would
          permit the implementation to choose its own source port
          number ";
           }

leaf bfdSess-Destination-UdpPort {
         type uint32;
description
         " This leaf specifies the destination UDP port number
          used for this BFD session's Control packets.
3784 represents single-hop BFD session.
4784 represents multi-hop BFD session.
6784 represents BFD on Link Aggregation Group (LAG) session.
The value may be zero(0) if the session is in adminDown(1) state";



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           }
}

grouping bfd-session-stats{
        leaf bfdsess-status {
        type uint32;
        description
         " Configured BFD session state ";
         }
         leaf bfd-Sess-Diag{
type enumeration{
        enum noDiagnostic{value 0;}
        enum controlDetectionTimeExpired{value 1;}
        enum echoFunctionFailed{value 2;}
        enum neighborSignaledSessionDown{value 3;}
        enum forwardingPlaneReset{value 4;}
        enum pathDown{value 5;}
        enum concatenatedPathDown{value 6;}
        enum administrativelyDown{value 7;}
        enum reverseConcatenatedPathDown{value 8;}
        enum misConnectivityDefect{value 9;}
}
description
"A diagnostic code specifying the local system's reason
 for the last transition of the session from up
to some other state."
}
         leaf bfdsess-admin-stats {
           type enumeration{
           enum enabled{value 1;}
           enum disabled{value 2;}
           enum adminDown{value 3;}
           enum down{value 4;}
           }

       description
         " Denotes the desired operational status of the BFD session.
          A transition to enabled will start the BFD state machine
          for the session.  The state machine will have an initial
          state of down.
          A transition to disabled will stop the BFD state machine
          for the session.  The state machine may first transition to
          adminDown prior to stopping.
          A transition to adminDown will cause the BFD state
          machine to transition to adminDown and will cause the
          session to remain in this state.
          A transition to down will cause the BFD state machine
          to transition to down and will cause the session to



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          remain in this state";
         }
         leaf bfdsess-oper-status {
           type enumeration{
           enum up{value 1;}
           enum down{value 2;}
           enum adminDown{value 3;}
        };
        description
         " Denotes the actual operational status of the BFD session.
          If the value of bfdOperStatus is down, this value MUST
          eventually be down as well.  If the value of
          bfdOperStatus is adminDown, this value MUST eventually
          be adminDown as well ";
         }
        leaf bfdsess-remote-heard {
           type boolean;
        description
         " This leaf specifies the status of BFD packet reception from
          the remote system.  Specifically, it is set to true if
          the local system is actively receiving BFD packets from the
          remote system and is set to false if the local system
          has not received BFD packets recently (within the detection
          time) or if the local system is attempting to tear down
          the BFD session ";
         }
}

augment "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session" {
identity technology-sub-type{
description
 "this is the base identity of sub-technology.
It can be used to identify the encapsulation type
such as MPLS, OSPFv2, OSPFv3, IS-IS, BGP, RIP, etc";
 }
}

augment "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session"
{using bfd-session;}
augment "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session"
{using bfd-session-stats;}

augment
   "/goam:domains/goam:domain/goam:MAs/gam:MA/goam:MEP
   /goam:session/goam: connectivity-context"
      {
          case context-bfdsess {
            leaf bfdsess-discriminator {



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             type uint32;
           description
            "This leaf specifies the local discriminator for this BFD
             session, which is used to uniquely identify it ";
            }
            leaf bfdsess-remotediscr {
             type uint32;
           description
            "This leaf specifies the session discriminator chosen
             by the remote system for this BFD session.  The value may
             be zero(0) if the remote discriminator is not yet known
             or if the session is in the down or adminDown(1) state ";
            }
            leaf Interface{
             type leafref{
             path
            "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP"
           +"/goam:Interface";
            }
            }
            leaf source-mep{
             type leafref{
            path
            "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP"
            +"/goam:session/goam:source-mep";
            }
            }
            leaf destination-mep{
            type leafref{
            path
            "/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP"
            +"/goam:session/goam:destination-mep"
            +"/goam:destination-mep/goam:MEP-ID/goam:MEP-ID-int"
            +"/goam:MEP-ID-int";
            }
            }
          }
        }

augment "/moam:cc/moam:output/moam: maintenance-stats " {
case session-ccperform-bfd {
         leaf bfdSess-PerfCtrlPkt-In {
          type uint32;
        description
         " The total number of BFD control messages received for this
          BFD session";
         }
leaf bfdSess-PerfCtrlPkt-Out {



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          type uint32;
        description
         " The total number of BFD control messages sent for this BFD
          session";
         }
leaf bfdSess-PerfCtrlPkt-Drop {
          type uint32;
        description
         " The total number of BFD control messages received for this
          session yet dropped for being invalid ";
         }
leaf bfdSess-PerfCtrlPktDrop-LastTime {
          type uint32;
        description
         " The value of sysUpTime on the most recent occasion at
          which received the BFD control message for this session was
          dropped.  If no such up event exists, this object contains
          a zero value ";
         }
leaf bfdSess-PerfEchoPkt-In {
          type uint32;
        description
         " The total number of BFD Echo messages received for this
          BFD session ";
         }
leaf bfdSess-PerfEchoPkt-Out {
          type uint32;
        description
         " The total number of BFD Echo messages sent for this BFD
          session ";
         }
leaf bfdSess-PerfEchoPkt-Drop {
          type uint32;
        description
         " The total number of BFD Echo messages received for this
          session yet dropped for being invalid ";
         }
leaf bfdSess-PerfEchoPktDrop-LastTime {
          type uint32;
        description
         " The value of sysUpTime on the most recent occasion at
          which received the BFD Echo message for this session was
          dropped.  If no such up event has been issued, this
          object contains a zero value ";
         }
leaf bfdSess-UpTime {
          type uint32;
        description



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         "The value of sysUpTime on the most recent occasion at which
          the session came up.  If no such event has been issued,
          this object contains a zero value";
         }
leaf bfdSess-PerfLastSessDownTime {
          type uint32;
        description
         " The value of sysUpTime on the most recent occasion at
          which the last time communication was lost with the
          neighbor.  If no down event has been issued, this object
          contains a zero value ";

         }
leaf bfdSess-PerfLastCommLostDiag {
          type uint32;
        description
         " The BFD diag code for the last time communication was lost
          with the neighbor.  If such an event has not been issued,
          this object contains a zero value";
         }
leaf bfdSess-PerfSess-UpCount {
          type uint32;
        description
         " The number of times this session has gone into the Up
          state since the system last rebooted ";
         }
leaf bfdSess-Perf-DiscTime {
          type uint32;
        description
         " The value of sysUpTime on the most recent occasion at
          which any one or more of the session counters suffered
          a discontinuity ";
         }
       }
     }

augment "/moam: cv /moam:output/moam: maintenance-stats " {
case session-cvperform-bfdctr {
         leaf bfdSess-PerfCtrlPkt-In {
          type uint32;
        description
         " The total number of BFD control messages received for this
          BFD session";
         }
leaf bfdSess-PerfCtrlPkt-Out {
          type uint32;
        description
         " The total number of BFD control messages sent for this BFD



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          session";
         }
leaf bfdSess-PerfCtrlPkt-Drop {
          type uint32;
        description
         " The total number of BFD control messages received for this
          session yet dropped for being invalid ";
         }
leaf bfdSess-PerfCtrlPktDrop-LastTime {
          type uint32;
        description
         " The value of sysUpTime on the most recent occasion at
          which received the BFD control message for this session was
          dropped.  If no such up event exists, this object contains
          a zero value ";
         }
         }
leaf bfdSess-UpTime {
          type uint32;
        description
         "The value of sysUpTime on the most recent occasion at which
          the session came up.  If no such event has been issued,
          this object contains a zero value";
         }
leaf bfdSess-PerfLastSessDownTime {
          type uint32;
        description
         " The value of sysUpTime on the most recent occasion at
          which the last time communication was lost with the
          neighbor.  If no down event has been issued, this object
          contains a zero value ";
         }
leaf bfdSess-PerfLastCommLostDiag {
        type uint32;
        description
         " The BFD diag code for the last time communication was lost
          with the neighbor.  If such an event has not been issued,
          this object contains a zero value";
         }
leaf bfdSess-PerfSess-UpCount {
          type uint32;
        description
         " The number of times this session has gone into the Up
          state since the system last rebooted ";
         }
leaf bfdSess-Perf-DiscTime {
          type uint32;
        description



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         " The value of sysUpTime on the most recent occasion at
          which any one or more of the session counters suffered
          a discontinuity ";
         }
       }
     }

augment "/moam:notifications/moam:defect-condition-notification
 " { uses bfd-session-stats;}

   <CODE ENDS>

7.  Default Mode for BFD OAM

   This document defines default configuration that MUST be present in
   the devices that comply with this document.  Base Mode allows users
   to have zero-touch experience.

8.  Security Considerations

   TBD.

9.  IANA Considerations

   TBD.

10.  Normative References

   [I-D.tissa-lime-yang-oam-model]
              Senevirathne, T., Finn, N., Kumar, D., Salam, S., and Q.
              Wu, "Generic YANG Data Model for Operations,
              Administration, and Maintenance (OAM)", draft-tissa-lime-
              yang-oam-model-03 (work in progress), November 2014.

   [I-D.wang-lime-rpc-yang-oam-management]
              Wang, Z. and Q. Wu, "Additional RPC definitions to Generic
              YANG Data Model for layer Independent OAM Management",
              draft-wang-lime-rpc-yang-oam-management-00 (work in
              progress), October 2014.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", March 1997.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, June 2010.






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   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)", RFC
              6241, June 2011.

   [RFC7331]  Nadeau, T., Ali, Z., and N. Akiya, "Bidirectional
              Forwarding Detection (BFD) Management Information Base",
              RFC 7331, August 2014.

Authors' Addresses

   Zitao Wang
   Huawei Technologies,Co.,Ltd
   101 Software Avenue, Yuhua District
   Nanjing  210012
   China

   Email: wangzitao@huawei.com


   Liang Xia
   Huawei Technologies,Co.,Ltd
   101 Software Avenue, Yuhua District
   Nanjing  210012
   China

   Email: frank.xialiang@huawei.com


   Deepak Kumar
   Cisco Systems
   510 McCarthy Blvd Milpitas,
   CA   95035
   USA

   Email: dekumar@cisco.com


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: bill.wu@huawei.com



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