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<rfc category="std" docName=" draft-ietf-lime-yang-oam-model-07"
     ipr="trust200902">
  <?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>

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  <front>
    <title abbrev="Connection-Oriented OAM YANG model">Generic YANG Data Model
    for Connection Oriented Operations, Administration, and Maintenance(OAM)
    protocols</title>

    <author fullname="Deepak Kumar" initials="D." surname="Kumar">
      <organization abbrev="Cisco">CISCO Systems</organization>

      <address>
        <postal>
          <street>510 McCarthy Blvd</street>

          <street/>

          <city>Milpitas</city>

          <region>CA</region>

          <code>95035</code>

          <country>USA</country>
        </postal>

        <email>dekumar@cisco.com</email>
      </address>
    </author>

    <author fullname="Qin Wu" initials="Q." surname="Wu">
      <organization>Huawei</organization>

      <address>
        <postal>
          <street>101 Software Avenue, Yuhua District</street>

          <city>Nanjing</city>

          <region>Jiangsu</region>

          <code>210012</code>

          <country>China</country>
        </postal>

        <email>bill.wu@huawei.com</email>
      </address>
    </author>

    <author fullname="Michael Wang" initials="M." surname="Wang">
      <organization abbrev="Huawei">Huawei Technologies,Co.,Ltd</organization>

      <address>
        <postal>
          <street>101 Software Avenue, Yuhua District</street>

          <street/>

          <city>Nanjing</city>

          <region/>

          <code>210012</code>

          <country>China</country>
        </postal>

        <email>wangzitao@huawei.com</email>
      </address>
    </author>

    <date year="2016"/>

    <area>OPS Area</area>

    <workgroup/>

    <abstract>
      <t>This document presents a base YANG Data model for connection oriented OAM protocols. It provides a technology-independent abstraction of key OAM constructs for such protocols. The model presented here can be extended to include technology specific details. This guarantees uniformity in the management of OAM protocols and provides support for nested OAM workflows (i.e., performing OAM functions at different levels through a unified interface)
</t>
    </abstract>
  </front>

  <middle>
    <section title="Introduction">
      <t>Operations, Administration, and Maintenance (OAM) are important
      networking functions that allow operators to: <list style="numbers">
          <t>Monitor networks connections (Connectivity Verification,
          Continuity Check).</t>

          <t>Troubleshoot failures (Fault verification and localization).</t>

          <t>Monitor Performance</t>
        </list></t>

      <t>An overview of OAM tools is presented in [RFC7276]<xref target="RFC7276"/>.  Over the years, many technologies have developed similar tools for fault and performance management.</t>

      <t>[IEEE802.1Q] Connectivity Fault Management is a well-established OAM
      standard that is widely adopted for Ethernet networks. ITU-T
      [G.8013]<xref target="G.8013"/>, MEF Service OAM, MPLS-TP [RFC6371],
      TRILL [RFC7455]<xref target="RFC7455"/> all define OAM mechanisms based on the 
      manageability frame work of [IEEE802.1Q] <xref
      target="IEEE802.1Q"/>CFM.</t>

      <t>Given the wide adoption of the underlying OAM concepts defined in
      [IEEE802.1Q]<xref target="IEEE802.1Q"/> CFM, it is a reasonable choice
      to develop the unified management framework for connection oriented OAM
      based on those concepts. In this document, we take the [IEEE802.1Q]<xref
      target="IEEE802.1Q"/> CFM model and extend it to a technology
      independent framework and define the corresponding YANG model
      accordingly. The YANG model presented in this document is the base model
      for connection oriented OAM protocols and supports generic continuity
      check, connectivity verification (Loopback) and path discovery (traceroute). The generic YANG
      model for connection oriented OAM is designed to be extensible to other connection oriented technologies. Technology
      dependent nodes and remote process call (RPC) commands are defined in
      technology specific YANG models, which use and extend the base model
      defined here. As an example, VXLAN uses source UDP port number for flow
      entropy, while TRILL uses either MAC addresses, the VLAN tag or fine
      grain label, and/or IP addresses for flow entropy in the hashing for
      multipath selection. To capture this variation, corresponding YANG
      models would define the applicable structures as augmentation to the
      generic base model presented here. This accomplishes three goals:
      First it keeps each YANG model smaller and more manageable. Second, it allows
      independent development of corresponding YANG models. Third,
      implementations can limit support to only the applicable set of YANG
      models. (e.g. TRILL RBridge may only need to implement Generic model and
      the TRILL YANG model).</t>

      <t>All implementations that follow the YANG framework presented in this
      document MUST implement the generic connection oriented YANG model
      presented here.</t>

      <t>The YANG data model presented in this document is generated at the
      management layer. Encapsulations and state machines may differ according
      to each OAM protocol. A user who wishes to issues a Continuity Check
      command or a Loopback or initiate a performance monitoring session can
      do so in the same manner regardless of the underlying protocol or
      technology or specific vendor implementation.</t>

      <t>As an example, consider a scenario where Loopback from device A to Device B fails. Between device A and B there are IEEE 802.1 bridges a, b and c. Let's assume a,b and c are using [IEEE802.1Q] CFM. Upon detecting the Loopback failures, a user may decide to drill down to the lower level at different segments of the path and issue the corresponding fault verification (LBM) and fault isolation (LTM) tools, using the same API. This ability to drill down to a lower layer of the protocol stack at a specific segment within a path for fault localization and troubleshooting is referred to as "nested OAM workflow". It is a useful concept that leads to efficient network troubleshooting and maintenance workflows.  The connection oriented OAM YANG model presented in this document facilitates that without needing changes to the underlying protocols.</t>
    </section>

    <section title="Conventions used in this document">
      <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"/>. Lower case uses of these words are not to be interpreted as carrying <xref target="RFC2119"/> significance.</t>

      <t>The following notations are used within the data tree and carry the
      meaning as below.</t>

      <t>Each node is printed as:<figure>
          <artwork>
&lt;status&gt; &lt;flags&gt; &lt;name&gt; &lt;opts&gt; &lt;type&gt;

&lt;status&gt; is one of:
     +  for current
     x  for deprecated
     o  for obsolete


&lt;flags&gt; is one of:

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


&lt;name&gt; is the name of the node</artwork>
        </figure></t>

      <t>If the node is augmented into the tree from another module, its name
      is printed as &lt;prefix&gt;:&lt;name&gt;. <figure>
          <artwork>&lt;opts&gt; is one of:

     ?  for an optional leaf or choice
     !  for a presence container
     *  for a leaf-list or list
     [&lt;keys&gt;] for a list's keys
     (choice)/:(case) Parentheses enclose choice and case nodes, 
	 and case nodes are also marked with a colon (":")
&lt;type&gt; is the name of the type for leafs and leaf-lists</artwork>
        </figure></t>

      <t>In this document, these words will appear with that interpretation
      only when in ALL CAPS.</t>

      <section title="Terminology">
        <t><list hangIndent="6" style="hanging">
            <t hangText="CCM">- Continuity Check Message [IEEE802.1Q].</t>

            <t hangText="ECMP">- Equal Cost Multipath.</t>

            <t hangText="LBM">- Loopback Message [IEEE802.1Q].</t>

            <t hangText="MP">- Maintenance Point [IEEE802.1Q].</t>

            <t hangText="MEP">- Maintenance End Point [RFC7174]
			(Maintenance association End Point [IEEE802.1Q], MEG End Points [RFC6371]).</t>

            <t hangText="MIP">- Maintenance Intermediate Point [RFC7174]
            (Maintenance domain Intermediate Point[IEEE802.1Q], MEG Intermediate Point [RFC6371]).</t>

            <t hangText="MA">- Maintenance Association [IEEE802.1Q]
            [RFC7174].</t>

            <t hangText="MD">- Maintenance Domain [IEEE802.1Q]</t>

			<t hangText='MEG'>- Maintenance Entity Group [RFC6371]</t>
			
            <t hangText="MTV">- Multi-destination Tree Verification
            Message.</t>

            <t hangText="OAM">- Operations, Administration, and Maintenance
            [RFC6291].</t>

            <t hangText="TRILL">- Transparent Interconnection of Lots of Links
            [RFC6325].</t>

            <t hangText="CFM">- Connectivity Fault Management [RFC7174]
            [IEEE802.1Q].</t>

            <t hangText="RPC">- Remote Process Call.</t>

            <t hangText="CC">- Continuity Check [RFC7276]. Continuity Checks
            are used to verify that a destination is reachable and therefore
            also referred to as reachability verification.</t>

            <t hangText="CV">- Connectivity Verification
            [RFC7276].Connectivity Verification are used to verify that a destination is connected. It are also referred to as path
            verification and used to verify not only that the two MPs are
            connected, but also that they are connected through the expected
            path, allowing detection of unexpected topology changes.</t>
          </list></t>
      </section>
    </section>

    <section title="Architecture of Generic YANG Model for OAM">
      <t>In this document we define a generic YANG model for connection
   oriented OAM protocols. The YANG model defined here is generic in a sense
   that other technologies can extend it for technology specific needs.
   The Generic YANG model acts as the root for other OAM YANG models.
   This allows users to traverse between different OAM protocols with ease
   through a uniform API set.  This also enables a nested OAM
   workflow. Figure 1 depicts the relationship of different OAM YANG
   models to the Generic YANG Model for connection oriented OAM.  The
   Generic YANG model for OAM provides a framework where technology-
   specific YANG models can inherit constructs from the base YANG models
   without needing to redefine them within the sub-technology.</t>

      <t>Figure 1 depicts relationship of different YANG modules.</t>

      <figure title="Relationship of OAM YANG model to generic (base) YANG model">
        <artwork>                         +----------+
                         |Connection|
                         | Oriented |
                         |  gen     |
                         |OAM YANG  |
                         +-+-+-+-+-++
                              |
                              |
                              |
      +------------------------------------------+
      |                       |                  |
  +-+-+-+-+-+          +-+-+-+-+-+          +-+-+-+-+-+
  | TRILL   |          | MPLS-TP |     . . .|  foo    |
  |OAM YANG |          |OAM YANG |          |OAM YANG |
  +-+-+-+-+-+          +-+-+-+-+-+          +-+-+-+-+-+
        |                    |                  |
        |                    |              +-+-+-+-+-+
        |                    |         . . .|  foo    |
        |                    |              |sub tech |
        |                    |              +-+-+-+-+-+
        |                    |                  |
        |                    |                  |
 +-------------------------------------------------------+
 |                      Uniform API                      |
 +-------------------------------------------------------+</artwork>
      </figure>
    </section>

    <section title="Overview of the OAM Model">
      <t>In this document we adopt the concepts of the [IEEE802.1Q] CFM model
      and structure it such that it can be adapted to different connection oriented OAM protocols.</t>

      <t>At the top of the Model is the Maintenance Domain. Each Maintenance
      Domain is associated with a Maintenance Name and a Domain Level.</t>

      <t>Under each Maintenance Domain there is one or more Maintenance
      Association (MA). In TRILL this can be per Fine-Grained Label or for
      VPLS this can be per VPLS instance.</t>

      <t>Under each MA, there can be two or more MEPs (Maintenance Association
      End Points). MEPs are addressed by their respective technology specific
      address identifiers. The YANG model presented here provides flexibility
      to accommodate different addressing schemes.</t>

      <t>In the vertical direction orthogonal to the Maintenance Domain,
      presented are the commands. Those, in YANG terms, are the rpc commands.
      These rpc commands provide uniform APIs for continuity
      check, connectivity verification(loopback), path discovery(traceroute) and their equivalents as
      well as other OAM commands.</t>

      <t>The generic YANG model defined here does not require explicit
   configuration of OAM entities prior to using any of the OAM tools.The
   OAM tools used here are limited to OAM toolset specified in section
   5.1 of [RFC7276]. In order to facilitate zero- touch experience,
   this document defines a default mode of OAM.  The default mode of OAM
   is referred to as the Base Mode and specifies default values for each
   of model parameters, such as Maintenance Domain Level, Name of the
   Maintenance Association, Addresses of MEPs and so on.  The default
   values of these depend on the technology.  Base Mode for TRILL is
   defined in [RFC7455]. Base mode for other technologies and future extensions developed in IETF will be defined in their corresponding
   documents.
</t>

      <t>It is important to note that, no specific enhancements are needed in
      the YANG model to support Base Mode. Implementations that comply with
      this document, by default implement the data nodes of the applicable
      technology. Data nodes of the Base Mode are read-only nodes.</t>

      <section title="Maintenance Domain (MD) configuration">
        <t>The container "domains" is the top level container within the
        gen-oam module. Within the container "domains", separate list is
        maintained per MD. The MD list uses the key MD-name-string for
        indexing. MD- name-string is a leaf and derived from type string.
        Additional name formats as defined in [IEEE802.1Q] or other standards
        can be included by association of the MD-name-format with an
        identity-ref. MD-name- format indicates the format of the augmented
        MD-names. MD-name is presented as choice/case construct. Thus, it is
        easily augmentable by derivative work.</t>

        <figure title="Snippet of data hierarchy related to OAM domains">
          <artwork>    module: ietf-conn-oam
   +--rw domains
      +--rw domain* [technology MD-name-string]
         +--rw technology        identityref
         +--rw MD-name-string    MD-name-string
         +--rw MD-name-format?   identityref
         +--rw (MD-name)?
         |  +--:(MD-name-null)
         |     +--rw MD-name-null?     empty
         +--rw md-level?         MD-level
</artwork>
        </figure>
      </section>

      <section title="Maintenance Association (MA) configuration">
        <t>Within a given Maintenance Domain there can be one or more
        Maintenance Associations (MA). MAs are represented as a list and
        indexed by the MA-name-string. Similar to MD-name defined previously,
        additional name formats can be added by augmenting the name-format
        identity-ref and adding applicable case statements to MA-name.</t>

        <figure title="Snippet of data hierarchy related to Maintenance Associations (MA) ">
          <artwork>   module: ietf-conn-oam
      +--rw domains
         +--rw domain* [technology MD-name-string]
            .
            .
            +--rw MAs
               +--rw MA* [MA-name-string]
                  +--rw MA-name-string       MA-name-string
                  +--rw MA-name-format?      identityref
                  +--rw (MA-name)?
                  |  +--:(MA-name-null)
                  |     +--rw MA-name-null?        empty</artwork>
        </figure>
      </section>

      <section title="Maintenance Endpoint (MEP) configuration">
        <t>Within a given Maintenance Association (MA), there can be one or
        more Maintenance End Points (MEP). MEPs are represented as a list
        within the data hierarchy and indexed by the key MEP-name.</t>

        <figure title="Snippet of data hierarchy related to Maintenance Endpoint (MEP) ">
          <artwork>   module: ietf-conn-oam
      +--rw domains
         +--rw domain* [technology MD-name-string]
            +--rw technology        identityref
            .
            .
            +--rw MAs
               +--rw MA* [MA-name-string]
                  +--rw MA-name-string       MA-name-string
                  .
                  .
                  +--rw MEP* [mep-name]
                  |  +--rw mep-name             MEP-name
                  |  +--rw (MEP-ID)?
                  |  |  +--:(MEP-ID-int)
                  |  |     +--rw MEP-ID-int?          int32
                  |  +--rw MEP-ID-format?       identityref
                  |  +--rw (mep-address)?
                  |  |  +--:(mac-address)
                  |  |  |  +--rw mac-address?   yang:mac-address
                  |  |  +--:(ipv4-address)
                  |  |  |  +--rw ipv4-address?  inet:ipv4-address
                  |  |  +--:(ipv6-address)
                  |  |     +--rw ipv6-address?  inet:ipv6-address
                  .          .
                  .          .
                  .          .</artwork>
        </figure>
      </section>

      <section title="rpc definitions">
        <t>The rpc model facilitates issuing commands to a NETCONF server (in
        this case to the device that need to execute the OAM command) and
        obtain a response. rpc model defined here abstracts OAM specific
        commands in a technology independent manner.</t>

        <t>There are several rpc commands defined for the purpose of OAM. In
        this section we present a snippet of the continuity check command for
        illustration purposes. Please refer to Section 4 for the complete data
        hierarchy and Section 5 for the YANG model.</t>

        <figure title="Snippet of data hierarchy related to rpc call continuity-check">
          <artwork>   module: ietf-conn-oam
      +--rw domains
            +--rw domain* [technology MD-name-string]
            +--rw technology        identityref
      .
      .
rpcs:
   +---x continuity-check {continuity-check}?
   |  +---w input
   |  |  +---w technology?             identityref
   |  |  +---w MD-name-string          -> /domains/domain/MD-name-string
   |  |  +---w MA-name-string          -> /domains/domain/MAs/MA/MA-name-string
   |  |  +---w cos-id?                 uint8
   |  |  +---w (ttl)?
   |  |  |  +--:(ip-ttl)
   |  |  |  |  +---w ip-ttl?                 uint8
   |  |  |  +--:(mpls-ttl)
   |  |  |     +---w mpls-ttl?               uint8
   |  |  +---w sub-type?               identityref
   |  |  +---w source-mep?             -> /domains/domain/MAs/MA/MEP/mep-name
   |  |  +---w destination-mep
   |  |  |  +---w (mep-address)?
   |  |  |  |  +--:(mac-address)
   |  |  |  |  |  +---w mac-address?     yang:mac-address
   |  |  |  |  +--:(ipv4-address)
   |  |  |  |  |  +---w ipv4-address?    inet:ipv4-address
   |  |  |  |  +--:(ipv6-address)
   |  |  |  |     +---w ipv6-address?    inet:ipv6-address
   |  |  |  +---w (MEP-ID)?
   |  |  |  |  +--:(MEP-ID-int)
   |  |  |  |     +---w MEP-ID-int?      int32
   |  |  |  +---w MEP-ID-format?   identityref
   |  |  +---w count?                  uint32
   |  |  +---w cc-transmit-interval?   Interval
   |  |  +---w packet-size?            uint32
   |  +--ro output
   |     +--ro (monitor-stats)?
   |        +--:(monitor-null)
   |           +--ro monitor-null?   empty
   +---x continuity-verification {connectivity-verification}?
   |  +---w input
   |  |  +---w MD-name-string     -> /domains/domain/MD-name-string
   |  |  +---w MA-name-string     -> /domains/domain/MAs/MA/MA-name-string
   |  |  +---w cos-id?            uint8
   |  |  +---w (ttl)?
   |  |  |  +--:(ip-ttl)
   |  |  |  |  +---w ip-ttl?            uint8
   |  |  |  +--:(mpls-ttl)
   |  |  |     +---w mpls-ttl?          uint8
   |  |  +---w sub-type?          identityref
   |  |  +---w source-mep?        -> /domains/domain/MAs/MA/MEP/mep-name
   |  |  +---w destination-mep
   |  |  |  +---w (mep-address)?
   |  |  |  |  +--:(mac-address)
   |  |  |  |  |  +---w mac-address?     yang:mac-address
   |  |  |  |  +--:(ipv4-address)
   |  |  |  |  |  +---w ipv4-address?    inet:ipv4-address
   |  |  |  |  +--:(ipv6-address)
   |  |  |  |     +---w ipv6-address?    inet:ipv6-address
   |  |  |  +---w (MEP-ID)?
   |  |  |  |  +--:(MEP-ID-int)
   |  |  |  |     +---w MEP-ID-int?      int32
   |  |  |  +---w MEP-ID-format?   identityref
   |  |  +---w count?             uint32
   |  |  +---w interval?          Interval
   |  |  +---w packet-size?       uint32
   |  +--ro output
   |     +--ro (monitor-stats)?
   |        +--:(monitor-null)
   |           +--ro monitor-null?   empty
   +---x traceroute {traceroute}?
      +---w input
      |  +---w MD-name-string      -> /domains/domain/MD-name-string
      |  +---w MA-name-string      -> /domains/domain/MAs/MA/MA-name-string
      |  +---w cos-id?             uint8
      |  +---w (ttl)?
      |  |  +--:(ip-ttl)
      |  |  |  +---w ip-ttl?             uint8
      |  |  +--:(mpls-ttl)
      |  |     +---w mpls-ttl?           uint8
      |  +---w command-sub-type?   identityref
      |  +---w source-mep?         -> /domains/domain/MAs/MA/MEP/mep-name
      |  +---w destination-mep
      |  |  +---w (mep-address)?
      |  |  |  +--:(mac-address)
      |  |  |  |  +---w mac-address?     yang:mac-address
      |  |  |  +--:(ipv4-address)
      |  |  |  |  +---w ipv4-address?    inet:ipv4-address
      |  |  |  +--:(ipv6-address)
      |  |  |     +---w ipv6-address?    inet:ipv6-address
      |  |  +---w (MEP-ID)?
      |  |  |  +--:(MEP-ID-int)
      |  |  |     +---w MEP-ID-int?      int32
      |  |  +---w MEP-ID-format?   identityref
      |  +---w count?              uint32
      |  +---w interval?           Interval
      +--ro output
         +--ro response* [response-index]
            +--ro response-index     uint8
            +--ro (ttl)?
            |  +--:(ip-ttl)
            |  |  +--ro ip-ttl?            uint8
            |  +--:(mpls-ttl)
            |     +--ro mpls-ttl?          uint8
            +--ro destination-mep
            |  +--ro (mep-address)?
            |  |  +--:(mac-address)
            |  |  |  +--ro mac-address?     yang:mac-address
            |  |  +--:(ipv4-address)
            |  |  |  +--ro ipv4-address?    inet:ipv4-address
            |  |  +--:(ipv6-address)
            |  |     +--ro ipv6-address?    inet:ipv6-address
            |  +--ro (MEP-ID)?
            |  |  +--:(MEP-ID-int)
            |  |     +--ro MEP-ID-int?      int32
            |  +--ro MEP-ID-format?   identityref
            +--ro (monitor-stats)?
               +--:(monitor-null)
                  +--ro monitor-null?      empty</artwork>
        </figure>
      </section>

      <section title="notifications">
        <t> Notification is sent on defect condition and defect clears with Maintenance Domain Name, MA Name, defect-type (The currently active defects), generating-mepid, and defect-message to indicate more details.</t>
      </section>

      <section title="monitor statistics">
        <t>Grouping for monitoring statistics is to be used by Yang modules
        which Augment Yang to provide statistics due to pro-active OAM like
        CCM Messages. For example CCM Transmit, CCM Receive, CCM Errors,
        etc.</t>
      </section>

      <section title="OAM data hierarchy">
        <t>The complete data hierarchy related to the connection oriented OAM
        YANG model is presented below.</t>

        <figure title="data hierarchy of OAM">
          <artwork>
module: ietf-conn-oam
   +--rw domains
      +--rw domain* [technology MD-name-string]
         +--rw technology        identityref
         +--rw MD-name-string    MD-name-string
         +--rw MD-name-format?   identityref
         +--rw (MD-name)?
         |  +--:(MD-name-null)
         |     +--rw MD-name-null?     empty
         +--rw md-level?         MD-level
         +--rw MAs
            +--rw MA* [MA-name-string]
               +--rw MA-name-string    MA-name-string
               +--rw MA-name-format?   identityref
               +--rw (MA-name)?
               |  +--:(MA-name-null)
               |     +--rw MA-name-null?     empty
               +--rw (MA-ID)?
               |  +--:(MA-id)
               |  |  +--rw MA-id?            uint32
               |  +--:(MEG-ID)
               |     +--rw meg-id?           string
               +--rw (connectivity-context)?
               |  +--:(context-null)
               |     +--rw context-null?     empty
               +--rw cos-id?           uint8
               +--rw cc-enable?        boolean
               +--rw MEP* [mep-name]
               |  +--rw mep-name         MEP-name
               |  +--rw (MEP-ID)?
               |  |  +--:(MEP-ID-int)
               |  |     +--rw MEP-ID-int?      int32
               |  +--rw MEP-ID-format?   identityref
               |  +--rw (mep-address)?
               |  |  +--:(mac-address)
               |  |  |  +--rw mac-address?     yang:mac-address
               |  |  +--:(ipv4-address)
               |  |  |  +--rw ipv4-address?    inet:ipv4-address
               |  |  +--:(ipv6-address)
               |  |     +--rw ipv6-address?    inet:ipv6-address
               |  +--rw cos-id?          uint8
               |  +--rw cc-enable?       boolean
               |  +--rw session* [session-cookie]
               |     +--rw session-cookie             uint32
               |     +--rw destination-mep
               |     |  +--rw (MEP-ID)?
               |     |  |  +--:(MEP-ID-int)
               |     |  |     +--rw MEP-ID-int?      int32
               |     |  +--rw MEP-ID-format?   identityref
               |     +--rw destination-mep-address
               |     |  +--rw (mep-address)?
               |     |     +--:(mac-address)
               |     |     |  +--rw mac-address?    yang:mac-address
               |     |     +--:(ipv4-address)
               |     |     |  +--rw ipv4-address?   inet:ipv4-address
               |     |     +--:(ipv6-address)
               |     |        +--rw ipv6-address?   inet:ipv6-address
               |     +--rw cos-id?                    uint8
               +--rw MIP* [interface]
                  +--rw interface    if:interface-ref
rpcs:
   +---x continuity-check {continuity-check}?
   |  +---w input
   |  |  +---w technology?             identityref
   |  |  +---w MD-name-string          -> /domains/domain/MD-name-string
   |  |  +---w MA-name-string          -> /domains/domain/MAs/MA/MA-name-string
   |  |  +---w cos-id?                 uint8
   |  |  +---w (ttl)?
   |  |  |  +--:(ip-ttl)
   |  |  |  |  +---w ip-ttl?                 uint8
   |  |  |  +--:(mpls-ttl)
   |  |  |     +---w mpls-ttl?               uint8
   |  |  +---w sub-type?               identityref
   |  |  +---w source-mep?             -> /domains/domain/MAs/MA/MEP/mep-name
   |  |  +---w destination-mep
   |  |  |  +---w (mep-address)?
   |  |  |  |  +--:(mac-address)
   |  |  |  |  |  +---w mac-address?     yang:mac-address
   |  |  |  |  +--:(ipv4-address)
   |  |  |  |  |  +---w ipv4-address?    inet:ipv4-address
   |  |  |  |  +--:(ipv6-address)
   |  |  |  |     +---w ipv6-address?    inet:ipv6-address
   |  |  |  +---w (MEP-ID)?
   |  |  |  |  +--:(MEP-ID-int)
   |  |  |  |     +---w MEP-ID-int?      int32
   |  |  |  +---w MEP-ID-format?   identityref
   |  |  +---w count?                  uint32
   |  |  +---w cc-transmit-interval?   Interval
   |  |  +---w packet-size?            uint32
   |  +--ro output
   |     +--ro (monitor-stats)?
   |        +--:(monitor-null)
   |           +--ro monitor-null?   empty
   +---x continuity-verification {connectivity-verification}?
   |  +---w input
   |  |  +---w MD-name-string     -> /domains/domain/MD-name-string
   |  |  +---w MA-name-string     -> /domains/domain/MAs/MA/MA-name-string
   |  |  +---w cos-id?            uint8
   |  |  +---w (ttl)?
   |  |  |  +--:(ip-ttl)
   |  |  |  |  +---w ip-ttl?            uint8
   |  |  |  +--:(mpls-ttl)
   |  |  |     +---w mpls-ttl?          uint8
   |  |  +---w sub-type?          identityref
   |  |  +---w source-mep?        -> /domains/domain/MAs/MA/MEP/mep-name
   |  |  +---w destination-mep
   |  |  |  +---w (mep-address)?
   |  |  |  |  +--:(mac-address)
   |  |  |  |  |  +---w mac-address?     yang:mac-address
   |  |  |  |  +--:(ipv4-address)
   |  |  |  |  |  +---w ipv4-address?    inet:ipv4-address
   |  |  |  |  +--:(ipv6-address)
   |  |  |  |     +---w ipv6-address?    inet:ipv6-address
   |  |  |  +---w (MEP-ID)?
   |  |  |  |  +--:(MEP-ID-int)
   |  |  |  |     +---w MEP-ID-int?      int32
   |  |  |  +---w MEP-ID-format?   identityref
   |  |  +---w count?             uint32
   |  |  +---w interval?          Interval
   |  |  +---w packet-size?       uint32
   |  +--ro output
   |     +--ro (monitor-stats)?
   |        +--:(monitor-null)
   |           +--ro monitor-null?   empty
   +---x traceroute {traceroute}?
      +---w input
      |  +---w MD-name-string      -> /domains/domain/MD-name-string
      |  +---w MA-name-string      -> /domains/domain/MAs/MA/MA-name-string
      |  +---w cos-id?             uint8
      |  +---w (ttl)?
      |  |  +--:(ip-ttl)
      |  |  |  +---w ip-ttl?             uint8
      |  |  +--:(mpls-ttl)
      |  |     +---w mpls-ttl?           uint8
      |  +---w command-sub-type?   identityref
      |  +---w source-mep?         -> /domains/domain/MAs/MA/MEP/mep-name
      |  +---w destination-mep
      |  |  +---w (mep-address)?
      |  |  |  +--:(mac-address)
      |  |  |  |  +---w mac-address?     yang:mac-address
      |  |  |  +--:(ipv4-address)
      |  |  |  |  +---w ipv4-address?    inet:ipv4-address
      |  |  |  +--:(ipv6-address)
      |  |  |     +---w ipv6-address?    inet:ipv6-address
      |  |  +---w (MEP-ID)?
      |  |  |  +--:(MEP-ID-int)
      |  |  |     +---w MEP-ID-int?      int32
      |  |  +---w MEP-ID-format?   identityref
      |  +---w count?              uint32
      |  +---w interval?           Interval
      +--ro output
         +--ro response* [response-index]
            +--ro response-index     uint8
            +--ro (ttl)?
            |  +--:(ip-ttl)
            |  |  +--ro ip-ttl?            uint8
            |  +--:(mpls-ttl)
            |     +--ro mpls-ttl?          uint8
            +--ro destination-mep
            |  +--ro (mep-address)?
            |  |  +--:(mac-address)
            |  |  |  +--ro mac-address?     yang:mac-address
            |  |  +--:(ipv4-address)
            |  |  |  +--ro ipv4-address?    inet:ipv4-address
            |  |  +--:(ipv6-address)
            |  |     +--ro ipv6-address?    inet:ipv6-address
            |  +--ro (MEP-ID)?
            |  |  +--:(MEP-ID-int)
            |  |     +--ro MEP-ID-int?      int32
            |  +--ro MEP-ID-format?   identityref
            +--ro (monitor-stats)?
               +--:(monitor-null)
                  +--ro monitor-null?      empty
notifications:
   +---n defect-condition-notification
   |  +--ro technology?         identityref
   |  +--ro MD-name-string      -> /domains/domain/MD-name-string
   |  +--ro MA-name-string      -> /domains/domain/MAs/MA/MA-name-string
   |  +--ro mep-name?           -> /domains/domain/MAs/MA/MEP/mep-name
   |  +--ro defect-type?        identityref
   |  +--ro generating-mepid
   |  |  +--ro (MEP-ID)?
   |  |  |  +--:(MEP-ID-int)
   |  |  |     +--ro MEP-ID-int?      int32
   |  |  +--ro MEP-ID-format?   identityref
   |  +--ro (defect)?
   |     +--:(defect-null)
   |     |  +--ro defect-null?        empty
   |     +--:(defect-code)
   |        +--ro defect-code?        int32
   +---n defect-cleared-notification
      +--ro technology?         identityref
      +--ro MD-name-string      -> /domains/domain/MD-name-string
      +--ro MA-name-string      -> /domains/domain/MAs/MA/MA-name-string
      +--ro mep-name?           -> /domains/domain/MAs/MA/MEP/mep-name
      +--ro defect-type?        identityref
      +--ro generating-mepid
      |  +--ro (MEP-ID)?
      |  |  +--:(MEP-ID-int)
      |  |     +--ro MEP-ID-int?      int32
      |  +--ro MEP-ID-format?   identityref
      +--ro (defect)?
         +--:(defect-null)
         |  +--ro defect-null?        empty
         +--:(defect-code)
            +--ro defect-code?        int32
</artwork>
        </figure>
      </section>
    </section>

    <section title="OAM YANG Module">
      <t>&lt;CODE BEGINS&gt; file "ietf-conn-oam.yang"</t>

      <figure title="YANG module of OAM">
        <artwork>   
module ietf-conn-oam {
  namespace "urn:ietf:params:xml:ns:yang:ietf-conn-oam";
  prefix goam;

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

  organization "IETF LIME Working Group";
  contact
    "WG Web:    http://tools.ietf.org/wg/lime
     WG List:   mailto:lime@ietf.org
     WG Chair:  Carlos Pignataro cpignata@cisco.com
     WG Chair:  Ron Bonica rbonica@juniper.net
     Editor:    Deepak Kumar dekumar@cisco.com
     Editor:    Qin Wu bill.wu@huawei.com
     Editor:    Zitao Wang wangzitao@huawei.com";
  description
    "This YANG module defines the generic configuration,
  statistics and rpc for connection oriented OAM
  to be used within IETF in a protocol indpendent manner.
  Functional level abstraction is indendent
  with YANG modeling. It is assumed that each protocol
  maps corresponding abstracts to its native format.
  Each protocol may extend the YANG model defined
  here to include protocol specific extensions";

  revision 2016-03-15 {
    description
      "Initial revision. - 05 version";
    reference "draft-ietf-lime-yang-oam-model";
  }

  /* features */
  feature connectivity-verification {
    description
      "This feature indicates that the server supports
    executing connectivity verification OAM command and
    returning a response. Servers that do not advertise
    this feature will not support executing
    connectivity verification command or rpc model for
    connectivity verification command.";
  }
  feature continuity-check{
    description
      "This feature indicates that the server supports
    executing continuity check OAM command and
    returning a response. Servers that do not advertise
    this feature will not support executing
    continuity check command or rpc model for
    continuity check command.";
  }
 
  feature traceroute{
    description
      "This feature indicates that the server supports
    executing traceroute OAM command and
    returning a response. Servers that do not advertise
    this feature will not support executing
    traceroute command or rpc model for
    traceroute command.";
   } 

  /* Identities */

  identity technology-types {
    description
      "this is the base identy of technology types which are
    TRILL,MPLS-TP,vpls etc";
  }

  identity command-sub-type {
    description
      "defines different rpc command subtypes, 
    e.g rfc6905 trill OAM, this is optional for most cases";
  }

  identity name-format {
    description
      "This defines the name format, IEEE 8021Q CFM defines varying
      styles of names. It is expected name format as an identity ref
      to be extended with new types.";
  }

  identity name-format-null {
    base name-format;
    description
      "defines name format as null";
  }

  identity identifier-format {
    description
      "identifier-format identity can be augmented to define other
     format identifiers used in MEP-ID etc";
  }

  identity identifier-format-integer {
    base identifier-format;
    description
      "defines identifier-format to be integer";

  }

  identity defect-types {
    description
      "defines different defect types, e.g. remote rdi,
       mis-connection defect, loss of continuity";
  }
  identity rdi {
    base defect-types;
    description
      "Indicates the aggregate health of the remote MEPs. ";
  }

  identity remote-mep-defect{
    base defect-types;
    description
      "Indicates that one or more of the remote MEPs is
       reporting a failure ";
  }

  identity loss-of-continuity{
    base defect-types;
    description
    "If no proactive CC-V OAM packets from the source
     MEP (and in the case of CV, this includes the
     requirement to have the expected globally unique
     Source MEP identifier) are received within the interval
     equal to 3.5 times the receiving MEP's
     configured CC-V reception period. ";
   }

  identity invalid-oam-defect{
    base defect-types;
    description
    "Indicates that one or more invalid OAM messages has been
    received and that 3.5 times that OAM message transmission
    interval has not yet expired.";
  }

  identity cross-connect-defect{
    base defect-types;
    description
    "Indicates that one or more cross-connect defect
    (for example, a service ID does not match the VLAN.)
     messages has been received and that 3.5 times that OAM message
     transmission interval has not yet expired.";
  }

  /* typedefs */


  typedef MEP-name {
    type string;
    description
      "Generic administrative name for a MEP";
  }

  typedef Interval{
    type decimal64{
    fraction-digits 2;
   }
   units "milliseconds";
    description
    "Interval between packets in milliseconds.
    0 means no packets are sent.";
  }

  typedef MD-name-string {
    type string;
    description
      "Generic administrative name for an MD";
  }

  typedef MA-name-string {
    type string;
    description
      "Generic administrative name for an MA";
  }

  typedef oam-counter32 {
    type yang:zero-based-counter32;
    description
      "defines 32 bit counter for OAM";
  }

  typedef MD-level {
    type uint32 {

      range "0..255";
    }
    description
      "Maintenance Domain level.  The level may be restricted in
       certain protocols (eg to 0-7)";
  }

  /* groupings */

  grouping MEG-ID{
    leaf meg-id{
      type string;
      description
       "concatenation of domain and ma, For example a co-routed
        bidirectional LSP, MEG_ID is A1-{Global_ID::Node_ID::
        Tunnel_Num}::Z9-{Global_ID::Node_ID::Tunnel_Num}::LSP_Num.";
    }
    description
      "MEG-ID grouping.";
  }
  
  grouping time-to-live {
    choice ttl{
      case ip-ttl{
        leaf ip-ttl{
        type uint8;
        default "255";
        description
          "time to live";
        }
      }
     case mpls-ttl{
       leaf mpls-ttl{
       type uint8;
       description
         "Time to live. When an IP packet is imposed with a label, 
	the IP TTL value is first decremented then copied into 
	the MPLS TTL. As each LSR the MPLS frame's TTL is 
	decremented.This behavior can be modified with no 
	mpls ip ttl. When a MPLS label is popped, the MPLS 
	TTL value is decremented then copied in the IP TTL 
	field. If the MPLS TTL value is great than IP TTL, 
	that values is not copied over. This is to prevent 
	a possible condition of forwarding loop and TTL 
	never reaching 0. When two MPLS labels are swapped,
	decrement by 1 and copy over the result into the new label.
	When a new MPLS labels is pushed, decrement by 1 and copy 
	over the result into the new label. When a new MPLS labels 
	is popped, decrement by 1 and copy over the result into 
	the label below.[RFC3443]";

       }
     }
     description
       "Time to Live.";
    }
    description
      "Time to Live grouping.";
  }
  grouping defect-message {
    choice defect {
      case defect-null {
        description

          "this is a placeholder when no defect status is needed";
        leaf defect-null {
           type empty;
           description
             "there is no defect define, it will be defined in
              technology specific model.";
        }
      }
      case defect-code {
        description
          "this is a placeholder to display defect code.";
        leaf defect-code {
           type int32;
           description
             "defect code is integer value specific to technology.";
        }
      }
      description
        "defect Message choices.";
    }

    description
      "defect Message.";
  }

  grouping mep-address {
    choice mep-address {
      case mac-address {
        leaf mac-address {
          type yang:mac-address;
          description
          "MAC Address";
        }
      description
      "MAC Address based MEP Addressing.";
      }
      case ipv4-address {
        leaf ipv4-address {
          type inet:ipv4-address;
          description
          "Ipv4 Address";
        }
      description
      "Ip Address based MEP Addressing.";
      }
      case ipv6-address {
        leaf ipv6-address {
          type inet:ipv6-address;
          description
          "Ipv6 Address";
        }
        description
        "ipv6 Address based MEP Addressing.";
      }
      description
       "MEP Addressing.";
    }
    description
     "MEP Address";
  }

  grouping maintenance-domain-id {
    description
      "Grouping containing leaves sufficient to identify an MD";
    leaf technology {
      type identityref {
        base technology-types;
      }
      mandatory true;

      description
        "Defines the technology";
    }
    leaf MD-name-string {
      type MD-name-string;
      mandatory true;
      description
        "Defines the generic administrative maintenance domain name";
    }
  }

  grouping MD-name {
    leaf MD-name-format {
      type identityref {
        base name-format;
      }
      description
        "Name format.";
    }
    choice MD-name {
      case MD-name-null {
        leaf MD-name-null {
        when "../../../MD-name-format = name-format-null" {
        description
        "MD name format is equal to null format.";
        }
        type empty;
        description
        "MD name Null.";
        }
      }
      description
        "MD name.";
    }
    description
      "MD name";
  }

  grouping ma-identifier {
    description
      "Grouping containing leaves sufficient to identify an MA";
    leaf MA-name-string {
      type MA-name-string;
      description

        "MA name string.";
    }
  }

  grouping MA-name {
    description
      "MA name";
    leaf MA-name-format {
      type identityref {
        base name-format;
      }
      description
        "Ma name format";
    }
    choice MA-name {
     case MA-name-null {
      leaf MA-name-null {
       when "../../../MA-name-format = name-format-null" {
       description
         "MA";
      }
        type empty;
        description
        "empty";
        }
      }
      description
        "MA name";
    }
  }

  grouping MEP-ID {
    choice MEP-ID {
      default "MEP-ID-int";
      case MEP-ID-int {
        leaf MEP-ID-int {
          type int32;
  description
    "MEP ID in integer format";
        }
      }
      description
        "MEP-ID";
    }

    leaf MEP-ID-format {
      type identityref {
        base identifier-format;
      }
      description
        "MEP ID format.";
    }
    description
      "MEP-ID";
  }

  grouping MEP {
    description
      "Defines elements within the MEP";
    leaf mep-name {
      type MEP-name;
      mandatory true;
      description
        "Generic administrative name of the MEP";
    }
    uses MEP-ID;
    uses mep-address;
  }

 grouping monitor-stats {
   description
    "grouping for monitoring statistics, this will be augmented
    by others who use this component";
    choice monitor-stats {

     default "monitor-null";
      case monitor-null {
       description
        "this is a place holder when
         no monitoring statistics is needed";
         leaf monitor-null {
          type empty;
          description
          "there is no monitoring statistics to be defined";
              }
            }
    description
    "define the monitor stats";
          }
        }

  grouping MIP {
    description
      "defines MIP";
    leaf interface {
      type if:interface-ref;
      description
         "Interface";
    }
  }

  grouping connectivity-context {
    description
      "Grouping defining the connectivity context for an MA; for
       example, a VRF for VPLS, or an LSP for MPLS-TP.  This will be
       augmented by each protocol who use this component";
    choice connectivity-context {
      default "context-null";
      case context-null {
        description
          "this is a place holder when no context is needed";
        leaf context-null {
          type empty;
          description
            "there is no context define";
        }
      }
      description
        "connectivity context";
    }
  }
  grouping cos {
    description

      "Priority used in transmitted packets; for example, in the
       EXP field in MPLS-TP.";
    leaf cos-id {
      type uint8;
      description
        "class of service";
    }
  }

  container domains {
    description
      "Contains configuration related data. Within the container
       is list of fault domains. Wihin each domian has List of MA.";
    list domain {
      key "technology MD-name-string";

      ordered-by system;
      description
        "Define the list of Domains within the IETF-OAM";
      uses maintenance-domain-id;
      uses MD-name;
      leaf md-level {
        type MD-level;
        description
          "Defines the MD-Level";
      }
      container MAs {
        description
          "This container defines MA, within that have multiple MA
           and within MA have MEP, MIP";
        list MA {
          key "MA-name-string";
          ordered-by system;
          uses ma-identifier;
          uses MA-name;
          choice MA-ID{
	       case MA-id{
	        leaf MA-id{
	        type uint32;
	        description
	        "MA Identifier";
	        }
	       description
	       "MA ID case";
          }
	       case MEG-ID{
	        uses MEG-ID;
	        description
            "In case MPLS-TP, the MA equivalent to MEG";
	      }
	      description
          "The MA/MEG identifier";
	     }
          uses connectivity-context;
          uses cos {
            description
              "Default class of service for this MA, which may be overridden
               for particular MEPs, sessions or operations.";
          }
	     leaf cc-enable{
	      type boolean;
	      description
	      "Indicate whether the CC enable.";
	     }
          list MEP {
            key "mep-name";
            ordered-by system;
            description
            "contain list of MEPS";
            uses MEP;
            uses cos;
		    leaf cc-enable{
		     type boolean;
		     description
		     "Indicate whether the CC enable.";
		    }
            list session {
              key "session-cookie";
              ordered-by user;
              description
                "Monitoring session to/from a particular remote MEP.
                 Depending on the protocol, this could represent CC
                 messages received from a single remote MEP (if the
                 protocol uses multicast CCs) or a target to which
                 unicast echo request CCs are sent and from which
                 responses are received (if the protocol uses a
                 unicast request/response mechanism).";
              leaf session-cookie {
                type uint32;
                description
                  "Cookie to identify different sessions, when there
                   are multiple remote MEPs or multiple sessions to
                   the same remote MEP.";
              }
              container destination-mep {
                uses MEP-ID;
                description
                "Destination MEP";
              }
              container destination-mep-address {
                uses mep-address;
                description
                "Destination MEP Address";
              }
              uses cos;
            }
          }
          list MIP {
            key "interface";
            uses MIP;
            description
            "Maintenance Intermediate Point";
          }
          description
          "Maintenance Association list";
        }
      }
    }
  }

  notification defect-condition-notification {
    description
      "When defect condition is met this notification is sent";
    leaf technology {
      type identityref {
        base technology-types;
      }
      description
        "the technology";
    }
    leaf MD-name-string {
      type leafref{
	   path "/domains/domain/MD-name-string";
	  }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
    }
    leaf MA-name-string{
	  type leafref{
	   path "/domains/domain/MAs/MA/MA-name-string";
	  }
      mandatory true;
      description
      "Indicate which MA is seeing the defect";	  
	}
    leaf mep-name {
      type leafref{
	   path "/domains/domain/MAs/MA/MEP/mep-name";
	  }
      description
        "Indicate which MEP is seeing the defect";
    }
    leaf defect-type {
      type identityref {
        base defect-types;
      }
      description

        "The currently active defects on the specific MEP.";
    }
    container generating-mepid {
      uses MEP-ID;
      description
        "Who is generating the defect (if known) if
         unknown make it 0.";
    }
    uses defect-message {
      description
         "defect message to indicate more details.";
    }
  }
 
  notification defect-cleared-notification {
    description
      "When defect cleared is met this notification is sent";
    leaf technology {
      type identityref {
        base technology-types;
      }
      description
        "the technology";
    }
    leaf MD-name-string {
      type leafref{
	   path "/domains/domain/MD-name-string";
	  }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
    }
    leaf MA-name-string{
	  type leafref{
	   path "/domains/domain/MAs/MA/MA-name-string";
	  }
      mandatory true;
      description
      "Indicate which MA is seeing the defect";	  
	}
    leaf mep-name {
      type leafref{
	   path "/domains/domain/MAs/MA/MEP/mep-name";
	  }
      description
        "Indicate which MEP is seeing the defect";
    }

    leaf defect-type {
      type identityref {
        base defect-types;
      }
      description

        "The currently active defects on the specific MEP.";
    }
    container generating-mepid {
      uses MEP-ID;
      description
        "Who is generating the defect (if known) if
         unknown make it 0.";
    }
    uses defect-message {
      description
         "defect message to indicate more details.";
    }
  }
 
  rpc continuity-check {
    if-feature continuity-check;
    description
      "Generates continuity-check as per RFC7276 Table 4.";
    input {
    leaf technology {
      type identityref {
        base technology-types;
      }
      description
        "the technology";
    }
    leaf MD-name-string {
      type leafref{
	   path "/domains/domain/MD-name-string";
	  }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
    }
    leaf MA-name-string{
	  type leafref{
	   path "/domains/domain/MAs/MA/MA-name-string";
	  }
      mandatory true;
      description
      "Indicate which MA is seeing the defect";	  
	}
      uses cos;
      uses time-to-live;
      leaf sub-type {
        type identityref {
          base command-sub-type;
        }
        description
          "defines different command types";
      }
      leaf source-mep {
       type leafref{
	   path "/domains/domain/MAs/MA/MEP/mep-name";
	   }
       description
       "Source MEP";
      }
      container destination-mep {
        uses mep-address;
        uses MEP-ID {
          description "Only applicable if the destination is a MEP";
        }
        description
        "Destination MEP";

      }
      leaf count {
        type uint32;
        default "3";
        description
         "Number of continuity-check message to send";
      }
      leaf cc-transmit-interval {
        type Interval;
        description

          "Interval between echo requests";
      }
      leaf packet-size {
        type uint32 {
          range "64..10000";
        }
        default "64";
        description
          "Size of continuity-check packets, in octets";
      }
    }
    output {
      uses monitor-stats {
        description
          "Stats of continuity check.";
      }
    }
  }

  rpc continuity-verification {
    if-feature connectivity-verification;
    description
      "Generates continuity-verification as per RFC7276 Table 4.";
    input {
     leaf MD-name-string {
      type leafref{
	   path "/domains/domain/MD-name-string";
	  }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
     }
     leaf MA-name-string{
	  type leafref{
	   path "/domains/domain/MAs/MA/MA-name-string";
	  }
      mandatory true;
      description
      "Indicate which MA is seeing the defect";	  
	 }
      uses cos;
      uses time-to-live;
      leaf sub-type {

        type identityref {
          base command-sub-type;
        }
        description
          "defines different command types";
      }
      leaf source-mep {
       type leafref{
	   path "/domains/domain/MAs/MA/MEP/mep-name";
	   }
       description
       "Source MEP";
      }
      container destination-mep {
        uses mep-address;
        uses MEP-ID {
          description "Only applicable if the destination is a MEP";
        }
        description
        "Destination MEP";
      }
      leaf count {
        type uint32;
        default "3";
        description
          "Number of continuity-verification message to send";
      }
      leaf interval {
        type Interval;
        description
          "Interval between echo requests";
      }
      leaf packet-size {
        type uint32 {
          range "64..10000";
        }
        default "64";
        description
          "Size of continuity-verification packets, in octets";
      }
    }
    output {
      uses monitor-stats {
        description
          "Stats of continuity check.";
      }
    }
  }
  rpc traceroute {
    if-feature traceroute;
    description
      "Generates Traceroute or Path Trace and return response.
       Referencing RFC7276 for common Toolset name, for
       MPLS-TP OAM it's Route Tracing, and for TRILL OAM It's
       Path Tracing tool. Starts with TTL of one and increment
       by one at each hop. Untill destination reached or TTL
       reach max value";
    input {
     leaf MD-name-string {
      type leafref{
	   path "/domains/domain/MD-name-string";
	  }
      mandatory true;
      description
      "Indicate which MD is seeing the defect";
     }
     leaf MA-name-string{
	  type leafref{
	   path "/domains/domain/MAs/MA/MA-name-string";
	  }
      mandatory true;
      description
      "Indicate which MA is seeing the defect";	  
	 }
      uses cos;
      uses time-to-live;
      leaf command-sub-type {
        type identityref {

          base command-sub-type;
        }
        description
          "defines different command types";
      }
      leaf source-mep {
       type leafref{
	   path "/domains/domain/MAs/MA/MEP/mep-name";
	   }
       description
       "Source MEP";
      }
      container destination-mep {
        uses mep-address;
        uses MEP-ID {
          description "Only applicable if the destination is a MEP";
        }
        description
        "Destination MEP";
      }
      leaf count {
        type uint32;
        default "1";
        description
          "Number of traceroute probes to send.  In protocols where a
           separate message is sent at each TTL, this is the number
           of packets to send at each TTL.";
      }
      leaf interval {
        type Interval;
        description
          "Interval between echo requests";
      }
    }
    output {
      list response {
        key "response-index";
        leaf response-index {
         type uint8;
          description
            "Arbitrary index for the response.  In protocols that
             guarantee there is only a single response at each TTL
             , the TTL can be used as the response
             index.";
        }
        uses time-to-live;
        container destination-mep {
          description "MEP from which the response has been received";
          uses mep-address;
          uses MEP-ID {
            description
              "Only applicable if the destination is a MEP";
          }
        }
        uses monitor-stats {
          description
            "Stats of traceroute.";
        }
      description
        "List of response.";
      }
    }
  }
}
</artwork>
      </figure>

      <t>&lt;CODE ENDS&gt;</t>
    </section>

    <section title="Base Mode">
      <t>The Base Mode defines default configuration that MUST be present in
      the devices that comply with this document. Base Mode allows users to
      have "zero-touch" experience. Several parameters require technology
      specific definition.</t>

      <section title="MEP Address">
        <t>In the Base Mode of operation, the MEP Address is by default the IP
        address of the interface on which the MEP is located.</t>
      </section>

      <section title="MEP ID for Base Mode">
        <t>In the Base Mode of operation, each device creates a single UP MEP
        associated with a virtual OAM port with no physical layer (NULL PHY).
        The MEPID associated with this MEP is zero (0). The choice of MEP-ID
        zero is explained below.</t>

        <t>MEPID is 2 octet field by default. It is never used on the wire
        except when using CCM. It is important to have method that can derive
        MEP ID of base mode in an automatic manner with no user intervention.
        IP address cannot be directly used for this purpose as the MEP ID is
        much smaller field. For Base Mode of operation we propose to use MEP
        ID zero (0) as the default MEP-ID.</t>

        <t>CCM packet use MEP-ID on the payload. CCM MUST NOT be used in the
        Base Mode. Hence CCM MUST be disabled on the Maintenance Association
        of the Base Mode.</t>

        <t>If CCM is required, users MUST configure a separate Maintenance
        association and assign unique value for the corresponding MEP IDs.</t>

        <t>[IEEE802.1Q] CFM defines MEP ID as an unsigned integer in the range
        1 to 8191. In this document we propose to extend the range to 0 to
        65535. Value 0 is reserved for MEP ID of Base Mode operation and MUST
        NOT be used for other purposes.</t>
      </section>

      <section title="Maintenance Association">
        <t>MAID [IEEE802.1Q] has a flexible format and includes two parts:
        Maintenance Domain Name and Short MA name. In the Based Mode of
        operation, the value of the Maintenance Domain Name must be the
        character string "GenericBaseMode" (excluding the quotes "). In Base
        Mode operation Short MA Name format is set to 2-octet integer format
        (value 3 in Short MA Format field [IEEE802.1Q]) and Short MA name set
        to 65532 (0xFFFC).</t>
      </section>
    </section>

    <section title="connection-oriented oam yang model applicability">
      <t>ietf-conn-oam model defined in this document provides
      technology-independent abstraction of key OAM constructs for connection
      oriented protocols. This model can be further extended to include
      technology specific details, e.g., adding new data nodes with technology
      specific functions and parameters into proper anchor points of the base
      model, so as to develop a technology-specific connection-oriented OAM
      model.</t>

      <t>This section demonstrates the usability of the connection-oriented
      YANG OAM data model to various connection-oriented OAM technologies,
      e.g., TRILL and MPLS-TP. Note that, in this section, we only present
      several snippets of technology-specific model extensions for
      illustrative purposes. The complete model extensions should be worked on
      in respective protocol working groups.</t>

      <section title="Generic YANG Model extension for TRILL OAM">
        <t>The TRILL YANG module is augmenting connection oriented OAM module
        for both configuration and RPC commands.</t>

        <t>The TRILL YANG module requires the base TRILL module
        ([I-D.ietf-trill-yang]) to be supported as there is a strong
        relationship between those modules.</t>

        <t>The configuration extensions for connection oriented OAM include MD
        configuration extension, Technology type extension, MA configuration
        extension, Connectivity-Context Extension, MEP Configuration
        Extension, ECMP extension. In the RPC extension, the continuity-check
        and path-discovery RPC are extended with TRILL specific.</t>

        <section title="MD Configuration Extension">
          <t>MD level configuration parameters are management information
          which can be inherited in the TRILL OAM model and set by connection
          oriented base model as default values. For example domain name can
          be set to area-ID in the TRILL OAM case. In addition, at the
          Maintenance Domain level, domain data node at root level can be
          augmented with technology type.</t>

          <t>Note that MD level configuration parameters provides context
          information for management system to correlate faults, defects,
          network failures with location information, which helps quickly
          identify root causes of network failures.</t>

          <section title="Technology Type Extension">
            <t>No TRILL technology type has been defined in the connection
            oriented base model. Therefore a technology type extension is
            required in the TRILL OAM model. The technology type "trill" is
            defined as an identity that augments the base "technology-types"
            defined in the connection oriented base model:</t>

            <figure>
              <artwork>   identity trill{
    base goam:technology-types;
    description
     "trill type";
   }
</artwork>
            </figure>
          </section>
        </section>

        <section title="MA Configuration Extension">
          <t>MA level configuration parameters are management information
          which can be inherited in the TRILL OAM model and set by connection
          oriented base model as default values. In addition, at the
          Maintenance Association(MA) level, MA data node at the second level
          can be augmented with connectivity-context extension.</t>

          <t>Note that MA level configuration parameters provides context
          information for management system to correlate faults, defects,
          network failures with location information, which helps quickly
          identify root causes of network failures.</t>

          <section title="Connectivity-Context Extension">
            <t>In TRILL OAM, one example of connectivity-context is either a
            12 bit VLAN ID or a 24 bit Fine Grain Label. The connection
            oriented base model defines a placeholder for context-id. 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 either VLAN
            ID or Fine Grain Label.</t>

            <figure>
              <artwork>   augment /goam:domains/goam:domain/goam:MAs
   /goam:MA /goam:connectivity-context:
         +--:(connectivity-context-vlan)
         |  +--rw connectivity-context-vlan?   vlan
         +--:(connectivity-context-fgl)
            +--rw connectivity-context-fgl?    fgl
</artwork>
            </figure>
          </section>
        </section>

        <section title="MEP Configuration Extension">
          <t>The MEP configuration definition in the connection oriented base
          model already supports configuring the interface of MEP with either
          MAC address or IP address. In addition, the MEP address can be
          represented using a 2 octet RBridge Nickname in TRILL OAM . Hence,
          the TRILL OAM model augments the MEP configuration in base model to
          add a nickname case into the MEP address choice node as follows:</t>

          <figure>
            <artwork>augment /goam:domains/goam:domain/goam:MAs
   /goam:MA/ goam:MEP/goam:mep-address:
         +--:( mep-address-trill)
         |  +--rw mep-address-trill?  tril-rb-nickname</artwork>
          </figure>

          <t>In addition, at the Maintenance Association Endpoint(MEP) level,
          MEP data node at the third level can be augmented with ECMP
          extension.</t>

          <section title="ECMP Extension">
            <t>Since TRILL supports ECMP path selection, flow-entropy in TRILL
            is defined as a 96 octet field in the LIME model extension for
            TRILL OAM. The snippet below illustrates its extension.</t>

            <figure>
              <artwork> augment /goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP:
            +--rw flow-entropy-trill?   flow-entropy-trill
   augment /goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP
   /goam:session:
            +--rw flow-entropy-trill?   flow-entropy-trill</artwork>
            </figure>
          </section>
        </section>

        <section title="RPC extension">
          <t>In the TRILL OAM YANG model, the continuity-check and
          path-discovery RPC commands are extended with TRILL specific
          requirements. The snippet below depicts an example of illustrates
          the TRILL OAM RPC extension.</t>

          <figure>
            <artwork>   augment /goam:continuity-check/goam:input:
         +--ro (out-of-band)?
         |  +--:(ipv4-address)
         |  |  +--ro ipv4-address?      inet:ipv4-address
         |  +--:(ipv6-address)
         |  |  +--ro ipv6-address?      inet:ipv6-address
         |  +--:(trill-nickname)
         |     +--ro trill-nickname?    tril-rb-nickname
         +--ro diagnostic-vlan?   boolean
   augment /goam:continuity-check/goam:input:
            +--ro flow-entropy-trill?   flow-entropy-trill
   augment /goam:continuity-check/goam:output:
         +--ro upstream-rbridge?   tril-rb-nickname
         +--ro next-hop-rbridge*   tril-rb-nickname
   augment /goam:path-discovery/goam:input:
         +--ro (out-of-band)?
         |  +--:(ipv4-address)
         |  |  +--ro ipv4-address?      inet:ipv4-address
         |  +--:(ipv6-address)
         |  |  +--ro ipv6-address?      inet:ipv6-address
         |  +--:(trill-nickname)
         |     +--ro trill-nickname?    tril-rb-nickname
         +--ro diagnostic-vlan?   boolean
   augment /goam:path-discovery/goam:input:
            +--ro flow-entropy-trill?   flow-entropy-trill
   augment /goam:path-discovery/goam:output/goam:response:
         +--ro upstream-rbridge?   tril-rb-nickname
         +--ro next-hop-rbridge*   tril-rb-nickname
</artwork>
          </figure>
        </section>
      </section>

      <section title="Generic YANG Model extension for MPLS-TP OAM">
        <t>The MPLS-TP OAM YANG module can augment connection oriented OAM Module with some technology-specific details. And the [mpls-tp-oam-yang] presents the YANG Data model for MPLS-TP OAM.</t>

        <t>The configuration extensions for connection oriented OAM include MD
        configuration extension, Technology type extension, Sub Technology
        Type Extension ,MA configuration extension, MEP Configuration Extension. </t>

        <section title="MD Configuration Extension">
          <t>MD level configuration parameters are management information
          which can be inherited in the MPLS-TP OAM model and set by LIME base
          model as default values. For example domain name can be set to
          area-ID or the provider's Autonomous System Number(ASN) [RFC6370] in
          the MPLS-TP OAM case. In addition, at the Maintenance Domain level,
          domain data node at root level can be augmented with technology type
          and sub-technology type.</t>

          <t>Note that MD level configuration parameters provides context
          information for management system to correlate faults, defects,
          network failures with location information, which helps quickly
          identify root causes of network failures</t>

          <section title="Technology Type Extension">
            <t>No MPLS-TP technology type has been defined in the connection
            oriented base model, hence it is required in the MPLS OAM model.
            The technology type "mpls-tp" is defined as an identity that
            augments the base "technology-types" defined in the connection
            oriented base model:</t>

            <figure>
              <artwork>    identity mpls-tp{
          base goam:technology-types;
          description
           "mpls-tp type";
         }
</artwork>
            </figure>
          </section>

          <section title="Sub Technology Type Extension">
            <t>In MPLS-TP, since different encapsulation types such as IP/UDP
            Encapsulation, PW-ACH encapsulation can be employed, the
            "technology- sub-type" data node is defined and added into the
            MPLS OAM model to further identify the encapsulation types within
            the MPLS-TP OAM model. Based on it, we also define a technology
            sub-type for IP/UDP encapsulation and PW-ACH encapsulation. Other
            Encapsulation types can be defined in the same way. The snippet
            below depicts an example of several encapsulation types.</t>

            <figure>
              <artwork>identity technology-sub-type {
      description
      "certain implementations can have different
       encapsulation types such as ip/udp, pw-ach and so on.
       Instead of defining separate models for each
       encapsulation, we define a technology sub-type to 
    further identify different encapsulations. 
    Technology sub-type is associated at the MA level"; }

           identity technology-sub-type-udp {
             base technology-sub-type;
             description
               "technology sub-type is IP/UDP encapsulation";
           }

           identity technology-sub-type-ach {
             base technology-sub-type;
             description
               "technology sub-type is PW-ACH encapsulation";
           }
           }

      augment "/goam:domains/goam:domain/goam:MAs/goam:MA" {
             leaf technology-sub-type {
               type identityref {
                 base technology-sub-type;
               }
             }
           }
  </artwork>
            </figure>
          </section>
        </section>

        <section title="MA Configuration Extension">
          <t>MA level configuration parameters are management information
          which can be inherited in the MPLS-TP OAM model and set by
          Connection Oriented base model as default values. Meg-Id parameter
          under MA data node will be selected for MPLT-TP OAM model. Therefore
          one example of MA Name could be MEG LSP ID or MEG Section ID or MEG
          PW ID[RFC6370].</t>

          <t>Note that MA level configuration parameters provides context
          information for management system to correlate faults, defects,
          network failures with location information, which helps quickly
          identify root causes of network failures.</t>

        </section>

        <section title="MEP Configuration Extension">
          <t>In MPLS-TP, MEP-ID is either a variable length label value in
          case of G-ACH encapsulation or a 2 octet unsigned integer value in
          case of IP/UDP encapsulation. One example of MEP-ID is MPLS-TP
          LSP_MEP_ID [RFC6370]. In the connection-oriented base model, MEP-ID
          is defined as a choice/case node which can supports an int32 value,
          and the same definition can be used for MPLS-TP with no further
          modification. In addition, at the Maintenance Association
          Endpoint(MEP) level, MEP data node at the third level can be
          augmented with Session extension and interface extension.</t>
        </section>

      </section>
    </section>



    <section title="Security Considerations">
      <t>The YANG module defined in this memo is designed to be accessed via
      the NETCONF protocol [RFC6241] <xref target="RFC6241"/>. The lowest
      NETCONF layer is the secure transport layer and the
      mandatory-to-implement secure transport is SSH [RFC6242] <xref
      target="RFC6242"/>. The NETCONF access control model [RFC6536] <xref
      target="RFC6536"/> provides the means to restrict access for particular
      NETCONF users to a pre-configured subset of all available NETCONF
      protocol operations and content.</t>

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

      <t>The vulnerable "config true" subtrees and data nodes are the
      following:<figure>
          <artwork>/goam:domains/goam:domain/

/goam:domains/goam:domain/goam:MAs/goam:MA/

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

/goam:domains/goam:domain/goam:MAs/goam:MA/goam:MEP/goam:session/</artwork>
        </figure></t>

      <t>Unauthorized access to any of these lists can adversely affect OAM
      management system handling of end-to-end OAM and coordination of OAM
      within underlying network layers This may lead to inconsistent
      configuration, reporting, and presentation for the OAM mechanisms used
      to manage the network.</t>
    </section>

    <section title="IANA Considerations">
      <t>This document registers a URI in the IETF XML registry [RFC3688]
      [RFC3688]. Following the format in RFC 3688, the following registration
      is requested to be made:</t>

      <figure>
        <artwork>URI: urn:ietf:params:xml:ns:yang:ietf-gen-oam

Registrant Contact: The IESG.

XML: N/A, the requested URI is an XML namespace.</artwork>
      </figure>

      <t>This document registers a YANG module in the YANG Module Names
      registry [RFC6020].</t>

      <figure>
        <artwork>name: ietf-gen-oam namespace: urn:ietf:params:xml:ns:yang:ietf-gen-oam
   prefix: goam reference: RFC XXXX</artwork>
      </figure>
    </section>

    <section title="Acknowledgments">
      <t>Giles Heron came up with the idea of developing a YANG model as a way
      of creating a unified OAM API set (interface), work in this document is
      largely an inspiration of that. Alexander Clemm provided many valuable
      tips, comments and remarks that helped to refine the YANG model
      presented in this document.</t>

      <t>Carlos Pignataro, David Ball,Mahesh Jethanandani,Benoit
      Claise,Ladislav Lhotka,GUBALLA JENS,Yuji Tochio,Gregory Mirsky, Huub van
      Helvoort, Tom Taylor, Dapeng Liu,Mishael Wexler, Adi Molkho participated
      and contributed to this document.</t>
    </section>
  </middle>

  <back>
    <references title="Normative References">
      <?rfc include='reference.RFC.2119'?>
	  
      <?rfc include='reference.RFC.6241'?>

      <?rfc include='reference.RFC.6242'?>
	  
	  <?rfc include='reference.RFC.6370'?>

      <?rfc include='reference.RFC.6536'?>

      <?rfc include='reference.RFC.3688'?>

      <?rfc include='reference.RFC.6020'?>
    </references>

    <references title="Informative References">
      <reference anchor="IEEE802.1Q">
        <front>
          <title>Media Access Control (MAC) Bridges and Virtual Bridged Local
          Area Networks</title>

          <author>
            <organization/>
          </author>

          <date month="August" year="2011"/>
        </front>

        <seriesInfo name="IEEE" value="Std 802.1Q-2011"/>
      </reference>

      <reference anchor="G.8013">
        <front>
          <title>OAM functions and mechanisms for Ethernet based
          networks</title>

          <author>
            <organization/>
          </author>

          <date year="2013"/>
        </front>

        <seriesInfo name="ITU-T" value="Recommendation G.8013/Y.1731"/>
      </reference>

      <?rfc include='reference.RFC.7455'?>

      <?rfc include='reference.RFC.7276'?>

      <?rfc include='reference.RFC.7174'?>

      <?rfc include='reference.RFC.6291'?>

      <?rfc include='reference.RFC.6325'?>

      <?rfc include='reference.RFC.6371'?>
	  
	  
	  <reference anchor="mpls-tp-oam-yang">
        <front>
          <title>YANG Data Model for MPLS-TP Operations, Administration, and Maintenance</title>

          <author fullname="Li Zhang" initials="L." surname="Zhang">
            <organization/>
          </author>

		  <author fullname="Lianshu Zheng" initials="L." surname="Zheng">
            <organization/>
          </author>
		  
		  <author fullname="Sam K. Aldrin" initials="S." surname="Aldrin">
            <organization/>
          </author>	

		  <author fullname="Greg Mirsky" initials="G." surname="Mirsky">
            <organization/>
          </author>	
		  
          <date year="2016"/>
        </front>

        <seriesInfo name="Internet-Draft" value="draft-zhang-mpls-tp-yang-oam"/>
      </reference>
	  
    </references>

    <section title="Contributors' Addresses">
      <figure>
        <artwork>   Tissa Senevirathne
   Consultant

   Email: tsenevir@gmail.com


   Norman Finn
   CISCO Systems
   510 McCarthy Blvd
   Milpitas, CA  95035
   USA

   Email: nfinn@cisco.com

   Samer Salam
   CISCO Systems
   595 Burrard St. Suite 2123
   Vancouver, BC  V7X 1J1
   Canada

   Email: ssalam@cisco.com</artwork>
      </figure>
    </section>
  </back>
</rfc>
