<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd" [
  ]>
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>
<?rfc toc="yes" ?>
<?rfc symrefs="yes" ?>
<?rfc sortrefs="yes"?>
<?rfc iprnotified="no" ?>
<?rfc strict="yes" ?>
<rfc category="info" ipr="trust200902" docName="draft-rtgyangdt-rtgwg-device-model-03" >

<front>
<title abbrev="RTG YANG Device Model">Network Device YANG Organizational Models</title>
   <author initials='A.' surname="Lindem" fullname='Acee Lindem' role='editor'>
    <organization>Cisco Systems</organization>
    <address>
      <postal>
        <street>301 Midenhall Way</street>
        <city>Cary</city> <region>NC</region>
        <country>USA</country>
        <code>27513</code>
       </postal>
       <email>acee@cisco.com</email>
    </address>
    </author>
    <author initials='L.' surname="Berger" fullname='Lou Berger' role='editor'>
     <organization>LabN Consulting, L.L.C.</organization>
     <address>
       <email>lberger@labn.net</email>
    </address>
    </author>
   <author initials='D.' surname="Bogdanovic" fullname='Dean Bogdanovic'>
    <organization></organization>
     <address>
       <email>ivandean@gmail.com</email>
    </address>
    </author>
   <author initials='C.' surname="Hopps" fullname='Christan Hopps'>
    <organization>Deutsche Telekom</organization>
     <address>
       <email>chopps@chopps.org</email>
    </address>
    </author>

  <date/>
  <abstract>
<t>
   This document presents an approach for organizing YANG models
   in a comprehensive structure that may be used to configure and
   operate network devices.  The structure is itself represented
   as a YANG model, with all of the related component models
   logically organized in a way that is operationally intuitive,
   but this model is not expected to be implemented. The
   identified component modules are expected to be defined and
   implemented on common network devices.
</t>
<t>
   This document also defines two modules that can be used to
   model the logical and virtual resource representations that may
   be present on a network device. Examples of common industry
   terms for logical resource representations are Logical Systems
   or Routers.  Examples of of common industry
   terms for virtual resource representations are Virtual
   Routing and Forwarding (VRF) instances and Virtual Switch
   Instances (VSIs).
</t>
<t>
   This document is derived from work submitted to the IETF by
   members of the informal OpenConfig working group of network
   operators and is a product of the Routing Area YANG
   Architecture design team.
</t>
</abstract>
</front>

<middle>
<section anchor="sec-1" title="Introduction">
<t>
   "Operational Structure and Organization of YANG Models"
   <xref target="OC-STRUCT"/>, highlights the value of organizing
   individual, self-standing YANG <xref target="RFC6020"/> models
   into a more comprehensive structure.  This document builds on
   that work and presents a derivative structure for use in
   representing the networking infrastructure aspects of physical
   and virtual devices. <xref target="OC-STRUCT"/> and earlier
   versions of this document presented a single device-centric
   model root, this document no longer contains this element.
   Such an element would have translated to a single device
   management model that would be the root of all other models and
   was judged to be overly restrictive in terms of definition,
   implementation, and operation.
</t>
<t>
   The document first presents a notional network device YANG
   organizational structure that provides a conceptual framework
   for the models that may be used to configure and operate
   network devices.  The structure is itself presented as a YANG
   module, with all of the related component modules logically
   organized in a way that is operationally intuitive.  This
   network device model is not expected to be implemented, but
   rather provide as context for the identified representative
   component modules with are expected to be defined, and
   supported on typical network devices.
</t>
<t>
   This document also defines two new modules that are expected to
   be implemented.  These models are defined to support the
   configuration and operation of network-devices that allow for
   the partitioning of resources from both, or either, management
   and networking perspectives.  Both make use of emerging YANG
   functionality supported by either structural mount
   <xref target="STRUCTURAL-MOUNT"/>  or YANG Schema Dispatching
   Language (YSDL) <xref target="YANG-YSDL"/>.  The function
   provided by these documents are collectively refered to as
   "Schema Mount".  This document is expected to use whatever
   Schema Mount solution is adopted by the Netmod Working Group.
</t>
<t>
   Two forms of resource partitioning are supported:
</t>
<t>
   The first form provides a logical partitioning of a network
   device where each partition is separately managed as
   essentially an independent network element which is 'hosted' by
   the base network device.  These hosted network elements are
   referred to as logical network elements, or LNEs, and are
   supported by the logical-network-element module defined below.
   The module is used to identify LNEs and associate resources
   from the network-device with each LNE.  LNEs themselves are
   represented in YANG as independent network devices; each
   accessed independently.  Optionally, and when supported by the
   implementation, they may also be accessed from the host system.
   Examples of vendor terminology for an LNE include logical
   system or router, and virtual switch, chassis, or fabric.
</t>
<t>
   The second form provides support what is commonly referred to
   as Virtual Routing and Forwarding (VRF) instances as well as
   Virtual Switch Instances (VSI), see <xref target="RFC4026"/>.
   In this form of resource partitioning multiple control plane
   and forwarding/bridging instances are provided by and managed
   via a single (physical or logical) network device.  This form
   of resource partitioning is referred to as Network Instances
   and are supported by the network-instance module defined
   below.  Configuration and operation of each network-instance is
   always via the network device and the network-instance
   module.
</t>
<t>
   This document was motivated by, and derived from,
   <xref target="OC-STRUCT"/>.  The requirements from that
   document have been combined with the requirements from
   "Consistent Modeling of Operational State Data in YANG",
   <xref target="OC-OPSTATE"/>, into "NETMOD Operational State
   Requirements", <xref target="NETMOD-OPSTATE"/>.  This document
   is aimed at the requirement related to a common
   model-structure, currently Requirement 7, and also aims to
   provide a modeling base for Operational State representation.
</t>
<t>
   The approach taken in this (and the original) document is to
   organize the models describing various aspects of network
   infrastructure, focusing on devices, their subsystems, and
   relevant protocols operating at the link and network layers.
   The proposal does not consider a common model for higher level
   network services.  We focus on the set of models that are
   commonly used by network operators, and suggest a corresponding
   organization.
</t>
<t>
   A significant portion of the text and model contained in this
   document was taken from the -00 of <xref target="OC-STRUCT"/>.
</t>
<t>
</t>
<section anchor="sec-1.1" title="Status of Work and Open Issues">
<t>
   This version of the document and structure are a product of the
   Routing Area YANG Architecture design team and is very much a work in
   progress rather than a final proposal.  This version is a major
   change from the prior version and this change was enabled by
   the work on the previously mentioned Schema Mount.
</t>
<t>
   Schema Mount enables a dramatic simplification of the
   presented device model, particularly for "lower-end" devices
   which are unlikely to support multiple network instances or
   logical network elements.  Should structural-mount/YSDL not be
   available, the more explicit tree structure presented in
   earlier versions of this document will need to be utilized.
</t>
<t>
The top open issues are:
  <list style="numbers">
   <t>The use of YSDL vs Structural Mount, i.e., a Netmod
      defined Schema Mount solution, needs to be resolved as does
      ensuring that the selected approach has the needed capabilities.</t>
   <t>This document will need to match the evolution and
   standardization of  <xref target="OC-OPSTATE"/> or
   <xref target="NETMOD-OPSTATE"/> by the Netmod WG.
   </t>
   <t>Interpretation of different policy containers requires clarification.</t>
   <t>It may make sense to use the identityref structuring with
     hardware and QoS model.</t>
   <t>Which document(s) define the base System management,
   network services, and oam protocols modules is TBD.  This
   includes the possibility of simply using RFC7317 in place of
   the presented System management module.</t>
   <t>The model will be updated once the "opstate" requirements are
      addressed.</t>
<t>
      It may make sense to publish the network-instance and
      logical-network-element modules separately, as different
      devices may not implement both, and network providers may
      only require one or the other.
   </t>
   </list>
 </t>
</section>
</section>
<section anchor="sec-2" title="Module Overview">
<t>
   In this document, we consider network devices that support protocols
   and functions defined within the IETF Routing Area, e.g, routers,
   firewalls and hosts. Such devices may be physical or virtual, e.g., a
   classic router with custom hardware or one residing within a
   server-based virtual machine implementing a virtual network function
   (VNF). Each device may sub-divide their resources into logical
   network elements (LNEs) each of which provides a managed logical
   device.  Examples of vendor terminology for an LNE include logical
   system or router, and virtual switch, chassis, or fabric. Each LNE
   may also support virtual routing and forwarding (VRF) and virtual
   switching instance (VSI) functions, which are referred to below as a
   network instances (NIs). This breakdown is represented in
   Figure 1.
</t>
<t>
<figure>
<artwork>

           ,''''''''''''''''''''''''''''''''''''''''''''''`.
           |      Network Device (Physical or Virtual)     |
           | .....................   ..................... |
           | :  Logical Network  :   :  Logical Network  : |
           | :      Element      :   :      Element      : |
           | :+-----+-----+-----+:   :+-----+-----+-----+: |
           | :| Net | Net | Net |:   :| Net | Net | Net |: |
           | :|Inst.|Inst.|Inst.|:   :|Inst.|Inst.|Inst.|: |
           | :+-----+-----+-----+:   :+-----+-----+-----+: |
           | :  | |   | |   | |  :   :  | |   | |   | |  : |
           | :..|.|...|.|...|.|..:   :..|.|...|.|...|.|..: |
           |    | |   | |   | |         | |   | |   | |    |
            `'''|'|'''|'|'''|'|'''''''''|'|'''|'|'''|'|'''''
                | |   | |   | |         | |   | |   | |
                   Interfaces              Interfaces
</artwork>
</figure>
</t>
<t>
                 Figure 1: Module Element Relationships
</t>
<t>
   A model for LNEs is described in <xref target="sec-LNE"/> and
   the model for network instances is covered in
   <xref target="sec-NI"/>.
</t>
<t>
   The presented notional network device module can itself be
   thought of as a "meta-model" as it describes the relationships
   between individual models.  We choose to represent it also as a
   simple YANG module consisting of other models, which are in
   fact independent top level individual models. Although it is
   never expected to be implemented.
</t>
<t>
   The presented modules do not follow the hierarchy of any
   particular implementation, and hence is vendor-neutral.
   Nevertheless, the structure should be familiar to network
   operators and also readily mapped to vendor implementations.
</t>
<t>
   The overall structure is:
<figure>
<artwork>
    module: network-device
       +--rw ietf-yang-library
       |
       +--rw interfaces
       +--rw hardware
       +--rw qos
       |
       +--rw system-management
       +--rw network-services
       +--rw oam-protocols
       |
       +--rw routing
       +--rw mpls
       +--rw ieee-dot1Q
       |
       +--rw ietf-acl
       +--rw ietf-key-chain
       |
       +--rw logical-network-element
       +--rw network-instance
</artwork>
</figure>
</t>
<t>
   The network device is composed of top level modules that can be
   used to configure and operate a network device. (This is a
   significant difference from earlier versions of this document
   where there was a strict model hierarchy.)  Importantly the
   network device structure is the same for a physical network
   device or a logical network device, such as those instantiated
   via the logical-network-element model.  Extra spacing is
   included to denote different types of modules included.
</t>
<t>
   YANG library <xref target="YANG-LIBRARY"/> is included as it
   used to identify details of the top level modules supported by
   the (physical or logical) network device.  Th ability to
   identify supported modules is particularly important for LNEs
   which may have a set of supported modules which differs from
   the set supported by the host network device.
</t>
<t>
   The interface management model <xref target="RFC7223"/> is
   included at the top level. The hardware module is a placeholder
   for a future device-specific configuration and operational
   state data model.  For example, a common structure for the
   hardware model might include chassis, line cards, and ports,
   but we leave this unspecified.  The quality of service (QoS)
   section is also a placeholder module for device configuration
   and operational state data which relates to the treatment of
   traffic across the device. This document defines augmentations
   to the interface module to support LNEs and NIs.  Similar
   elements, although perhaps only for LNEs, may also need to be
   included as part of the definition of the future hardware and
   QoS modules.
</t>
<t>
   System management, network services, and oam protocols
   represent new top level modules that are used to organize data
   models of similar functions.  Additional information on each
   is provided below.
</t>
<t>
   The routing and MPLS modules provide core support for the
   configuration and operation of a devices control plane and data plane
   functions. IEEE dot1Q <xref target="IEEE-8021Q"/> is an example of
   another module that provides similar functions for VLAN bridging,
   and other similar modules are also possible.  Each of these modules is
   expected to be LNE and NI unaware, and to be instantiated as needed
   as part of the LNE and NI configuration and operation supported by
   the logical-network-element and network-instance modules.  (Note
   that this is a change from <xref target="RTG-CFG"/> which is
   currently defined with VRF/NI semantics.)
</t>
<t>
   The access control list (ACL) and key chain modules are
   included as examples of other top level modules that may
   be supported by a network device.
</t>
<t>
  The logical network element and network instance modules
  enable LNEs and NIs respectively and are defined below.
</t>
<section anchor="sec-2.1" title="  Interface Model Components">
<t>
   Interfaces are a crucial part of any network device's configuration
   and operational state.  They generally include a combination of raw
   physical interfaces, link-layer interfaces, addressing configuration,
   and logical interfaces that may not be tied to any physical
   interface.  Several system services, and layer 2 and layer 3
   protocols may also associate configuration or operational state data
   with different types of interfaces (these relationships are not shown
   for simplicity).  The interface management model is defined by
   <xref target="RFC7223"/>.
</t>
<t>
   The logical-network-element and network-instance modules
   defined in this document augment the existing interface
   management model in two ways: The first, by the
   logical-network-element module, adds an identifier which is
   used on physical interface types to identify an associated LNE.
   The second, by the network-instance module, adds a name
   which is used on sub-interface types to identify an associated
   network instance.  Similarly, this name is also added for
   IPv4 and IPv6 types, as defined in <xref target="RFC7277"/>.
</t>
<t>
   The interface related augmentations are as follows:
<figure>
<artwork>
    augment /if:interfaces/if:interface:
       +--rw bind-lne-name?   string

    augment /if:interfaces/if:interface:
       +--rw bind-network-instance-name?   string
    augment /if:interfaces/if:interface/ip:ipv4:
       +--rw bind-network-instance-name?   string
    augment /if:interfaces/if:interface/ip:ipv6:
       +--rw bind-network-instance-name?   string
</artwork>
</figure>
</t>
<t>
   The following is an example of envisioned combined usage.  The
   interfaces container includes a number of commonly used
   components as examples:
</t>
<t>
<figure>
<artwork>
          +--rw interfaces
          |  +--rw interface* [name]
          |     +--rw name                       string
          |     +--rw bind-lne-name?             string
          |     +--rw ethernet
          |     |  +--rw bind-network-instance-name?   string
          |     |  +--rw aggregates
          |     |  +--rw rstp
          |     |  +--rw lldp
          |     |  +--rw ptp
          |     +--rw vlans
          |     +--rw tunnels
          |     +--rw ipv4
          |     |  +--rw bind-network-instance-name?   string
          |     |  +--rw arp
          |     |  +--rw icmp
          |     |  +--rw vrrp
          |     |  +--rw dhcp-client
          |     +--rw ipv6
          |        +--rw bind-network-instance-name?   string
          |        +--rw vrrp
          |        +--rw icmpv6
          |        +--rw nd
          |        +--rw dhcpv6-client
</artwork>
</figure>
</t>
<t>
   The <xref target="RFC7223"/> defined interface model is
   structured to include all interfaces in a flat list, without
   regard to logical or virtual instances (e.g., VRFs) supported
   on the device.  The bind-lne-name and
   bind-network-instance-name leaves provide the association
   between an interface and its associated LNE and NI (e.g., VRF
   or VSI).
</t>
</section>
<section anchor="sec-2.2" title="  System Management">
<t>
   [Editor's note: need to discuss and resolve relationship
   between this structure and RFC7317 and determine if 7317 is
   close enough to simply use as is.]
</t>
<t>
   System management is expected to reuse definitions contained in
   <xref target="RFC7317"/>.  It is expected to be instantiated per
   device and LNE.  Its structure is shown below:
</t>
<t>
<figure>
<artwork>
    module: network-device
       +--rw system-management
       |  +--rw system-management-global
       |  +--rw system-management-protocol* [type]
       |     +--rw type    identityref
</artwork>
</figure>
</t>
<t>
   System-management-global is used for configuration information and
   state that is independent of a particular management protocol.
   System-management-protocol is a list of management protocol specific
   elements.  The type-specific sub-modules are expected to be defined.
</t>
<t>
   The following is an example of envisioned usage:
</t>
<t>
<figure>
<artwork>
    module: network-device
       +--rw system-management
          +--rw system-management-global
          |  +--rw statistics-collection
          |  ...
          +--rw system-management-protocol* [type]
          |  +--rw type=syslog
          |  +--rw type=dns
          |  +--rw type=ntp
          |  +--rw type=ssh
          |  +--rw type=tacacs
          |  +--rw type=snmp
          |  +--rw type=netconf

</artwork>
</figure>
</t>
<t>
</t>
</section>
<section anchor="sec-2.3" title="  Network Services">
<t>
  A device may provide different network services to other devices, for
  example a device my act as a DHCP server.  The model may be
  instantiated per device, LNE, and NI. An identityref is used
  to identify the type of specific service being provided and its
  associated configuration and state information. The defined structure
  is as follows:
</t>
<t>
<figure>
<artwork>
    module: network-device
       +--rw network-services
       |  +--rw network-service* [type]
       |     +--rw type    identityref
</artwork>
</figure>
</t>
<t>
  The following is an example of envisioned usage: Examples shown below
  include a device-based Network Time Protocol (NTP) server, a Domain
  Name System (DNS) server, and a Dynamic Host Configuration Protocol
  (DHCP) server:
</t>
<t>
<figure>
<artwork>
    module: network-device
       +--rw network-services
          +--rw network-service* [type]
             +--rw type=ntp-server
             +--rw type=dns-server
             +--rw type=dhcp-server
</artwork>
</figure>
</t>
<t>
</t>
</section>
<section anchor="sec-2.4" title="  OAM Protocols">
<t>
   OAM protocols that may run within the context of a device are
   grouped within the oam-protocols model.  The model may be
   instantiated per device, LNE, and NI. An identifyref is used to
   identify the information and state that may relate to a
   specific OAM protocol. The defined structure is as follows:
</t>
<t>
<figure>
<artwork>
    module: network-device
       +--rw oam-protocols
          +--rw oam-protocol* [type]
             +--rw type    identityref

</artwork>
</figure>
</t>
<t>
   The following is an example of envisioned usage.  Examples shown
   below include Bi-directional Forwarding Detection (BFD), Ethernet
   Connectivity Fault Management (CFM), and Two-Way Active Measurement
   Protocol (TWAMP):
</t>
<t>
<figure>
<artwork>
    module: network-device
       +--rw oam-protocols
          +--rw oam-protocol* [type]
             +--rw type=bfd
             +--rw type=cfm
             +--rw type=twamp
</artwork>
</figure>
</t>
<t>
</t>
</section>
<section anchor="sec-2.RTG" title="  Routing">
<t>
    Routing protocol and IP forwarding configuration and operation
    information is modeled via a routing model, such as the one
    defined in <xref target="RTG-CFG"/>.  Although, the defined
    routing module includes support for NIs, which it refers to as
    Routing Instances, while the approach presented in this
    document presumes that the routing module is unaware of LNEs
    and NIs. 
</t>
<t>
    The routing module is expected to include all IETF
    defined control plane protocols, such as BGP, OSPF, LDP and
    RSVP-TE.  It is also expected to support configuration and
    operation of or more routing information bases (RIB).  A RIB
    is a list of routes complemented with administrative
    data. Finally, policy is expected to be represented within
    each control plane protocol and RIB.
</t>
<t>
    The anticipated structure is as follows:
</t>
<t>
<figure>
<artwork>
   module: network-device
       +--rw routing
          +--rw control-plane-protocols
          |  +--rw control-plane-protocol* [type]
          |     +--rw type      identityref
          |     +--rw policy
          +--rw ribs
             +--rw rib* [name]
                +--rw name           string
                +--rw description?   string
                +--rw policy
</artwork>
</figure>
</t>
</section>
<section anchor="sec-2.MPLS" title="  MPLS">
<t>
    MPLS data plane related information is grouped together, as
    with the previously discussed modules, is unaware of
    VRFs/NIs. The model may be instantiated per device, LNE, and
    NI.  MPLS control plane protocols are expected to be included
    in <xref target="sec-2.RTG"/>.  MPLS may reuse and build on
    <xref target="OC-MPLS"/> or other emerging models and has an
    anticipated structure as follows:
</t>
<t>
<figure>
<artwork>
  module: network-device
       +--rw mpls
          +--rw global
          +--rw lsps* [type]
             +--rw type    identityref
</artwork>
</figure>
</t>
<t>
Type refers to LSP type,  such as static, traffic engineered or
routing congruent.  The following is an example of such usage:
</t>
<t>
<figure>
<artwork>
  module: network-device
       +--rw mpls
          +--rw global
          +--rw lsps* [type]
              +--rw type=static
              +--rw type=constrained-paths
              +--rw type=igp-congruent
</artwork>
</figure>
</t>
</section>
</section>

<section anchor="sec-LNE" title="  Logical Network Elements">
<t>
   A logical network element is a network-device which is contained
   within another network-device. Using host-virtualization
   terminology one could refer to an LNE as a "Guest", and the
   containing network-device as the "Host". While LNEs may be
   implemented via host-virtualization technologies this is not a
   requirement.
</t>
<t>
   Logical network elements represent the capability of some
   devices to partition resources into independent logical routers
   and/or switches.  Device support for multiple logical network
   elements is implementation specific.  Systems without such
   capabilities need not include support for the
   logical-network-element module.  In physical devices, some
   hardware features are shared across partitions, but control
   plane (e.g., routing) protocol instances, tables, and
   configuration are managed separately.  For example, in virtual
   routers or VNFs, this may correspond to establishing multiple
   logical instances using a single software installation.  The
   model supports configuration of multiple instances on a single
   device by creating a list of logical network elements, each
   with their own configuration and operational state related to
   routing and switching protocols, as shown below:
</t>
<t>
<figure>
<artwork>
    module: logical-network-element
       +--rw logical-network-inventory
          +--rw logical-network-element* [name]
             +--rw name?   string
             +--rw description? string
             +--rw managed?     boolean
             +--rw root?        schema-mount
    augment /if:interfaces/if:interface:
       +--rw bind-lne-name?     string
</artwork>
</figure>
</t>
<t>
  `name` identifies the logical network element.
  `managed` indicates if the host network device is able
  to manage the LNE via the `root` structure.
</t>

<section anchor="sec-LNE.HOST"
  title="  LNE Management - Host Network Device View">
<t>
   There are multiple implementation approaches possible to enable
   a network device to support the logical-network-element
   module and multiple LNEs.  Some approaches will allow the
   management functions operating at network device level to
   access LNE configuration and operation information, while
   others will not.  Similarly, even when LNE management from the
   network device is supported by the implementation, it may be
   prohibited by user policy.
</t>
<t>
   The `managed` boolean mentioned above is used to
   indicate when LNE management from the network device context is
   possible. When the `managed` is
   `false`, the LNE cannot be managed by the host
   system and can only be managed from within the context of the LNE
   as described in the next section, <xref target="sec-LNE.LNE"/>.
</t>
<t>
   When `managed` is `true`, the LNE can be managed from both the
   context of the LNE and the host network device. In this case,
   the same information that is available from within the LNE
   context is made available via the `root` element, with paths
   modified as described in <xref target="STRUCTURAL-MOUNT"/>.
</t>
<t>
   As an example, consider the case where an LNE with a
   `name` of "one" is defined on a network device.
   In this case  the following structure might be made available:
</t>
<t>
<figure>
<artwork>
 .................................................................
                                          [ network-device state ]
    module: logical-network-element
       +--rw logical-network-inventory
          +--rw logical-network-element* [name]
             +--rw name="one"          string
             +--rw manged=true         boolean
             +--rw root                schema-mount

 .................................................................
                            [ LNE state exposed to network-device]

                +--rw ietf-yang-library
                +--rw interfaces
                +--rw hardware
                +--rw qos
                +--rw system-management
                +--rw network-services
                +--rw oam-protocols
                +--rw routing
                +--rw mpls
                +--rw ieee-dot1Q
                +--rw network-instance
 .................................................................
</artwork>
</figure>
</t>
<t>
    As an LNE is a network device itself, all modules that may be present at
    the top level network device may also be present for the LNE, be made
    available under `root`, and be accessible via paths
    modified per <xref target="STRUCTURAL-MOUNT"/>. The list of available
    modules is expected to be implementation dependent. As is the method used
    by an implementation to support LNEs.
</t>
<t>
    Resources assigned to the LNE will be represented in that LNE's resource
    modules. e.g., an LNE's interfaces module will contain the interfaces
    assigned to that LNE from the containing network-device.
</t>
</section>

<section anchor="sec-LNE.LNE"
 title="  LNE Management - LNE View">
<t>
   Management functions operating with the context of an LNE are
   accessed through standard LNE's management interfaces, e.g.,
   NETCONF and SNMP.  When accessing an LNE via an LNE's management
   interface, a network-device representation will be presented,
   but its scope will be limited to the specific LNE.
   Normal YANG/NETCONF mechanisms, together with
   ietf-yang-library, can be used to identify the available
   modules.  Each supported module will be presented as a top level
   module. Only LNE associated resources will be reflected in
   resource related modules, e.g., interfaces, hardware and
   perhaps QoS. From the management perspective, there will be no
   difference between the available LNE view (information) and an
   a physical network device.
</t>
<t>
   Multiple implementation approaches are possible to provide LNE
   views, and these are outside the scope of this document.
</t>
</section>

<section anchor="sec-LNE.MOUNT"
  title="  LNE Instantiation">
<t>
  TBD -- need to resolve if instantiation is based on new list entry
  creation per the pending Schema Mount solution definition.
</t>
</section>

</section>

<section anchor="sec-NI" title="  Network Instances">
<t>
   The network instance container is used to represent virtual routing
   and forwarding instances (VRFs) and virtual switching instances
   (VSIs), <xref target="RFC4026"/>.  VRFs and VSIs are commonly used to isolate
   routing and switching domains, for example to create virtual private
   networks, each with their own active protocols and routing/switching
   policies.  The model represents both core/provider and virtual
   instances.  Network instances reuse and build on <xref target="RTG-CFG"/>
   and are shown below:
</t>
<t>
<figure>
<artwork>
    module: network-instance
       +--rw network-instances
          +--rw network-instance* [name]
             +--rw name                         string
             +--rw type?                        identityref
             +--rw enabled?                     boolean
             +--rw description?                 string
             +--rw network-instance-policy
             |  ...
             +--rw root?                      schema-mount
             |  ...
    augment /if:interfaces/if:interface:
       +--rw bind-network-instance-name?   string
    augment /if:interfaces/if:interface/ip:ipv4:
       +--rw bind-network-instance-name?   string
    augment /if:interfaces/if:interface/ip:ipv6:
       +--rw bind-network-instance-name?   string
</artwork>
</figure>
</t>
<t>
   A network instance is identified by a
   `name` string.  This string is used both as
   an index within the network-instance module and to associate
   resources with a network instance is shown above in the
   interface augmentation. Type is used to indicate the type NI,
   such as L3-VRF, VPLS, L2-VSI, etc. Network instance policy
   and root are discussed in greater detail below.
</t>
<section anchor="sec-NI.1" title="  Network Instance Policy">
<t>
   Network instance policies are used to control how NI
   information is represented at the device level, VRF routing
   policies, and VRF/VSI identifiers. Examples include BGP route
   targets (RTs) and route distinguishers (RDs), virtual network
   identifiers (VN-IDs), VPLS neighbors, etc. The structure is
   expected to be:
</t>
<t>
<figure>
<artwork>
    module: network-instance
       +--rw network-instances
          +--rw network-instance* [name]
             +--rw network-instance-policy
                (TBD)
</artwork>
</figure>
</t>
</section>

<section anchor="sec-NI.2" title="  Network Instance Management">
<t>
   Modules that may be used to represent network instance
   specific information will be available under
   `root`.  As with LNEs, actual module
   availability is expected to be implementation dependent. The
   ietf-yang-library module is expected to be the primary method
   used to identify supported modules.  Resource related control
   and assignment is expected to be managed at the network-device
   level, not the network instance level, based on the
   `bind-network-instance-name` augmentation
   mentioned above.
</t>
<t>
   As an example, consider the case where a network instance with
   a `name` of "green" is defined on a network
   device.  In this case the following structure might be made
   available:
</t>
<t>
<figure>
<artwork>
    module: network-instance
       +--rw ietf-yang-library
       +--rw interfaces
       |  +--rw bind-network-instance-name="green"  string
       +--rw system-management
       +--rw network-instances
          +--rw network-instance* [name]
             +--rw name="green"    string
             +--rw type?                               identityref
             +--rw enabled=true                        boolean
             +--rw description="The Green VRF"         string
             +--rw network-instance-policy
             |  ... (RT=1000:1, RD=1.2.3.4)
             +--rw root?                               schema-mount
                +--rw ietf-yang-library
                +--rw network-services
                +--rw oam-protocols
                +--rw routing
                +--rw mpls
</artwork>
</figure>
</t>
<t>
    All modules that represent control-plane and data-plane
    information may be present at the `root`,
    and be accessible via paths modified per
    <xref target="STRUCTURAL-MOUNT"/>.  The list of available
    modules is expected to be implementation dependent.  As is the
    method used by an implementation to support NIs.
</t>
</section>

<section anchor="sec-NI.3" title="  Network Instance Instantiation">
<t>
  TBD -- need to resolve if instantiation is based on new list entry
  creation per the pending Schema Mount solution definition.
</t>
</section>
</section>
<section anchor="sec-4" title="  Security Considerations">
<t>
   The network-device model structure described in this document
   does not define actual configuration and state data, hence it
   is not directly responsible for security risks.
</t>
<t>
   Each of the component models that provide the corresponding
   configuration and state data should be considered sensitive from a
   security standpoint since they generally manipulate aspects of
   network configurations.  Each component model should be carefully
   evaluated to determine its security risks, along with mitigations to
   reduce such risks.
</t>
<t>
  LNE portion is TBD
</t>
<t>
  NI portion is TBD
</t>
</section>
<section anchor="sec-5" title="  IANA Considerations">
<t>
   This YANG model currently uses a temporary ad-hoc namespace.  If it
   is placed or redirected for the standards track, an appropriate
   namespace URI will be registered in the "IETF XML Registry"
   <xref target="RFC3688"/>.  The YANG structure modules will be registered in the
   "YANG Module Names" registry <xref target="RFC6020"/>.
</t>
<t>
</t>
</section>
<section anchor="sec-6" title="  YANG Modules">
<t>
   The structure of the models defined in this document are  described
   by the YANG module below.
</t>
<t>
</t>
<section anchor="sec-6.1" title="  Network Device Model Structure">
<t>
<figure>
<artwork><![CDATA[
<CODE BEGINS> file "network-device@2016-02-22.yang"
module network-device {

  yang-version "1";

  // namespace
  namespace "urn:ietf:params:xml:ns:yang:network-device";

  prefix "struct";

  // import some basic types

  // meta
  organization "IETF RTG YANG Design Team Collaboration
                with OpenConfig";

  contact
      "Routing Area YANG Architecture Design Team -
       <rtg-dt-yang-arch@ietf.org>";

  description
    "This module describes a model structure for YANG
     configuration and operational state data models. Its intent is
     to describe how individual device protocol and feature models
     fit together and interact.";

  revision "2016-02-22" {
    description
      "IETF Routing YANG Design Team Meta-Model";
    reference "TBD"; 
  }

  // extension statements

  // identity statements

  identity oam-protocol-type {
      description
          "Base identity for derivation of OAM protocols";
  }

  identity network-service-type {
      description
          "Base identity for derivation of network services";
  }

   identity system-management-protocol-type {
      description
          "Base identity for derivation of system management
           protocols";
   }

   identity oam-service-type {
      description
          "Base identity for derivation of Operations,
           Administration, and Maintenance (OAM) services.";
   }

   identity control-plane-protocol-type {
      description
          "Base identity for derivation of control-plane protocols";
   }

   identity mpls-lsp-type {
      description
          "Base identity for derivation of MPLS LSP typs";
   }

  // typedef statements

  // grouping statements

  grouping control-plane-protocols {
      description
          "Grouping for control plane protocols configured for
           a network-instance";
      container control-plane-protocols {
          description
              "Container for control plane protocols configured for
               a network instance.";
          list control-plane-protocol {
              key "type";
              description
                  "List of control plane protocols configured for
                   a network instance.";
              leaf type {
                  type identityref {
                      base control-plane-protocol-type;
                  }
                  mandatory true;
                  description
                      "The control plane protocol type, e.g., BGP,
                       OSPF IS-IS, etc";
              }
              container policy {
                  description
                      "Protocol specific policy,
                      reusing [RTG-POLICY]";
              }
          }
      }
  }

  grouping ribs {
    description
      "Routing Information Bases (RIBs) supported by a
       network-instance";
    container ribs {
        description
            "RIBs supported by a network-instance";
        list rib {
            key "name";
            min-elements "1";
            description
                "Each entry represents a RIB identified by the
               'name' key. All routes in a RIB must belong to the
                same address family.

                For each routing instance, an implementation should
                provide one system-controlled default RIB for each
                supported address family.";
            leaf name {
                type string;
                description
                    "The name of the RIB.";
            }
            reference "draft-ietf-netmod-routing-cfg";
            leaf description {
                type string;
                description
                    "Description of the RIB";
            }
            // Note that there is no list of interfaces within
            container policy {
                description "Policy specific to RIB";
            }
        }
    }
  }

  // top level device definition statements
  container ietf-yang-library {
    description 
      "YANG Module Library as defined in
       draft-ietf-netconf-yang-library";
  }

  container interfaces {
    description
     "Interface list as defined by RFC7223/RFC7224";
  }

  container hardware {
    description
      "Hardware / vendor-specific data relevant to the platform.
      This container is an anchor point for platform-specific
      configuration and operational state data.  It may be further
      organized into chassis, line cards, ports, etc.  It is
      expected that vendor or platform-specific augmentations
      would be used to populate this part of the device model";
  }

  container qos {
    description "QoS features, for example policing, shaping, etc.";
  }

  container system-management {
      description 
        "System management for physical or virtual device.";
      container system-management-global {
          description "System management - with reuse of RFC 7317";
      }
      list system-management-protocol {
          key "type";
          leaf type {
              type identityref {
                  base system-management-protocol-type;
              }
              mandatory true;
              description
                  "Syslog, ssh, TACAC+, SNMP, NETCONF, etc.";
          }
          description "List of system management protocol
                       configured for a logical network
                       element.";
      }
  }

  container network-services {
      description
          "Container for list of configured network 
           services.";
      list network-service {
          key "type";
          description
              "List of network services configured for a
               network instance.";
          leaf type {
              type identityref {
                  base network-service-type;
              }
              mandatory true;
              description
                  "The network service type supported within
                   a network instance, e.g., NTP server, DNS
                   server, DHCP server, etc.";
          }
      }
  }

  container oam-protocols {
      description
          "Container for configured OAM protocols.";
      list oam-protocol {
          key "type";
          leaf type {
              type identityref {
                  base oam-protocol-type;
              }
              mandatory true;
              description
                  "The Operations, Administration, and
                   Maintenance (OAM) protocol type, e.g., BFD,
                   TWAMP, CFM, etc.";
          }
          description
              "List of configured OAM protocols.";
      }
  }

  container routing {
    description 
      "The YANG Data Model for Routing Management revised to be
       Network Instance / VRF independent. ";
    // Note that there is no routing or network instance
    uses control-plane-protocols;
    uses ribs;
  }

  container mpls {
      description "MPLS and TE configuration";
      container global {
          description "Global MPLS configuration";
      }
      list lsps {
          key "type";
          description
              "List of LSP types.";
          leaf type {
              type identityref {
                  base mpls-lsp-type;
              }
              mandatory true;
              description
                  "MPLS and Traffic Engineering protocol LSP types,
                   static, LDP/SR (igp-congruent), 
                   RSVP TE (constrained-paths) , etc.";
          }
      }
  }

  container ieee-dot1Q {
    description 
      "The YANG Data Model for VLAN bridges as defined by the IEEE";
  }

  container ietf-acl {
    description "Packet Access Control Lists (ACLs) as specified
                   in draft-ietf-netmod-acl-model";
  }

  container ietf-key-chain {
    description "Key chains as specified in
                 draft-ietf-rtgwg-yang-key-chain;";
  }

  container logical-network-element {
    description 
      "This module is used to support multiple logical network 
       elements on a single physical or virtual system.";
  }

  container network-instance {
    description 
      "This module is used to support multiple network instances 
       within a single physical or virtual device.  Network 
       instances are commonly know as VRFs (virtual routing 
       and forwarding) and VSIs (virtual switching instances).";
  }
  // rpc statements

  // notification statements

}
<CODE ENDS>
]]></artwork>
</figure>
</t>
</section>
<section anchor="sec-6.2" title="  Logical Network Element Model">
<t>
<figure>
<artwork><![CDATA[
<CODE BEGINS> file "logical-network-element@2016-01-19.yang"
module logical-network-element {

  yang-version "1";

  // namespace
  namespace "urn:ietf:params:xml:ns:yang:logical-network-element";

  prefix "struct";

  // import some basic types
  import ietf-interfaces {
    prefix if;
  }

  // meta
  organization "IETF RTG YANG Design Team Collaboration
                with OpenConfig";

  contact
      "Routing Area YANG Architecture Design Team -
       <rtg-dt-yang-arch@ietf.org>";

  description
    "This module is used to support multiple logical network
     elements on a single physical or virtual system.";

  revision "2016-01-19" {
    description
      "IETF Routing YANG Design Team Meta-Model";
    reference "TBD";
  }

  // extension statements

  // feature statements
  feature bind-network-element-id {
    description
      "Logical network element ID to which an interface is bound";
  }

  // identity statements

  identity logical-network-element-type {
    description
     "Identify type of logical-network-element";
  }

  identity lne-managed {
    base logical-network-element-type;
    description
      "A Logical Network Element that can
       be managed by the host system";
  }

  identity lne-unmanaged {
    base logical-network-element-type;
    description
      "A Logical Network Element that cannot
       be managed by the host system";
  }

  // typedef statements

  // grouping statements

  // top level device definition statements
  container logical-network-inventory {
    description "Allows a network device to support multiple logical
                 network element (device) instances";
    list logical-network-element {
      key lne-id;
      description "List of logical network elements";
      leaf lne-id {
        type uint16; // expect a small number of logical routers
        description "Device-wide unique identifier for the
                     logical network element";
      }
      leaf lne-name {
        type string;
        description "Descriptive name for the logical network
                     element";
      }
      leaf lne-type {
        type identityref {
          base logical-network-element-type;
        }
        description "Type of logical-network-element";
      }
      leaf lne-root {
        type schema-mount;
        description "Root for models supported per logical
                     network element";
      }
    }
  }

  // augment statements
  augment "/if:interfaces/if:interface" {
    description
        "Add a node for the identification of the logical network
        element associated with an interface. Applies to interfaces
        that can be assigned on a per logical network element basis.
        A <TBD> error is returned when the interface type cannot be
        assigned.";

    leaf bind-lne-id {
      type uint16;
      description
        "Logical network element ID to which interface is bound";
    }
  }

  // rpc statements

  // notification statements

}
<CODE ENDS>
]]></artwork>
</figure>
</t>
</section>
<section anchor="sec-6.3" title="  Network Instance Model">
<t>
<figure>
<artwork><![CDATA[
<CODE BEGINS> file "network-instance@2016-02-22.yang"
module network-instance {

  yang-version "1";

  // namespace
  namespace "urn:ietf:params:xml:ns:yang:network-instance";

  prefix "struct";

  // import some basic types
  import ietf-interfaces {
    prefix if;
  }

  import ietf-ip {
    prefix ip;
  }

  // meta
  organization "IETF RTG YANG Design Team Collaboration
                with OpenConfig";

  contact
      "Routing Area YANG Architecture Design Team -
       <rtg-dt-yang-arch@ietf.org>";

  description
    "This module is used to support multiple network instances
     within a single physical or virtual device.  Network
     instances are commonly know as VRFs (virtual routing
     and forwarding) and VSIs (virtual switching instances).";

  revision "2016-02-22" {
    description
      "IETF Routing YANG Design Team Meta-Model";
    reference "TBD";
  }

  // extension statements

  feature bind-network-instance-name {
    description
      "Network Instance to which an interface instance is bound";
  }

  // identity statements

  identity network-instance-type {
      description
         "Base identity from which identities describing
          network instance types are derived.";
  }

   identity ipv4-interface-protocol-type {
      description
          "Base identity for derivation of IPv4 interface
           protocols";
   }

   identity ipv6-interface-protocol-type {
      description
          "Base identity for derivation of IPv6 interface
           protocols";
   }

  // typedef statements

  // grouping statements

  grouping interface-ip-common {
    description
      "interface-specific configuration for IP interfaces, IPv4 and
      IPv6";

  }

  grouping ipv4-interface-protocols {
      container ipv4-interface-protocols {
          list ipv4-interface-protocol {
              key "type";
              leaf type {
                  type identityref {
                      base ipv4-interface-protocol-type;
                  }
                  mandatory true;
                  description
                      "ARP, ICMP, VRRP, DHCP Client, etc.";
              }
              description
                  "List of IPv4 protocols configured
                   on an interface";
          }
          description
              "Container for list of IPv4 protocols configured
                on an interface";
      }
      description
          "Grouping for IPv4 protocols configured on an interface";
  }

  grouping ipv6-interface-protocols {
      description
          "Grouping for IPv6 protocols configured on
           an interface.";
      container ipv6-interface-protocols {
          description
              "Container for list of IPv6 protocols configured
                on an interface.";
          list ipv6-interface-protocol {
              key "type";
              description
                  "List of IPv6 protocols configured
                   on an interface";
              leaf type {
                  type identityref {
                      base ipv6-interface-protocol-type;
                  }
                  mandatory true;
                  description
                      "ND, ICMPv6, VRRP, DHCPv6 Client, etc.";
              }
          }
      }
  }

  grouping network-instance-policy {
    description
        "Network instance policies such as route
         distinguisher, route targets, VPLS ID and neighbor,
         Ethernet ID, etc. ";
    reference
        "RFC 4364 - BGP/MPLS Virtual Private Networks (VPNs)
         RFC 6074 - Provisioning, Auto-Discovery, and Signaling
              in Layer 2 Virtual Private Networks (L2VPNs)
         RFC 7432 - BGP MPLS-Based Ethernet VPN";
    container network-instance-policy {
        description "Network Instance Policy -- details TBD";
    }
  }

  // top level device definition statements
  container network-instances {
      description "Network instances each of which have
                   an independent IP/IPv6 addressing space
                   and protocol instantiations. For layer 3,
                   this consistent with the routing-instance
                   definition in ietf-routing";
      reference "draft-ietf-netmod-routing-cfg";
      list network-instance {
          key name;
          description "List of network-instances";
          leaf name {
              type string;
              description "device scoped
                           identifier for the network
                           instance";
          }
          leaf type {
              type identityref {
                  base network-instance-type;
              }
              description
                  "The network instance type -- details TBD
                   Likely types include core, L3-VRF, VPLS,
                   L2-cross-connect, L2-VSI, etc.";
          }
          leaf enabled {
              type boolean;
              default "true";
              description
                "Flag indicating whether or not the network
                 instance is enabled.";
          }
          leaf description {
              type string;
              description
                "Description of the network instance
                and its intended purpose";
          }
          uses network-instance-policy;
          leaf root {
            type schema-mount;
            description "Root for models supported per
                         network instance";
          }
      }
  }

  // augment statements

  augment "/if:interfaces/if:interface" {
    description
        "Add a node for the identification of the logical network
        instance (which is within the interface's identified logical
        network element) associated with the IP information
        configured on an interface";

    leaf bind-network-instance-name {
      type string;
      description
        "Network Instance to which an interface is bound";
    }
  }

  augment "/if:interfaces/if:interface/ip:ipv4" {
    description
        "Add a node for the identification of the logical
        network instance (which is within the interface's
        identified physical or virtual device) associated with
        the IP information configured on an interface";

    leaf bind-network-instance-name {
      type string;
      description
        "Network Instance to which IPv4 interface is bound";

    }
  }

  augment "/if:interfaces/if:interface/ip:ipv6" {
    description
        "Add a node for the identification of the logical
        network instance (which is within the interface's
        identified physical or virtual device) associated with
        the IP information configured on an interface";

    leaf bind-network-instance-name {
      type string;
      description
        "Network Instance to which IPv6 interface is bound";

    }
  }

  // rpc statements

  // notification statements

}
<CODE ENDS>
]]></artwork>
</figure>
</t>
</section>
</section>
</middle>

<?rfc needLines="20"?>
<back>
<references title="Normative References">

<reference anchor="STRUCTURAL-MOUNT">
<front>
<title>YANG Structural Mount</title>
<author initials="M." surname="Bjorklund" fullname="Martin Bjorklund">
<organization>Tail-F Systems</organization>
</author>
<date month="December" year="2015" />
</front>
<seriesInfo name="Internet-Draft" value="draft-bjorklund-netmod-structural-mount-00.txt"/>
</reference>

<reference anchor="RFC6020">
<front>
<title>YANG - A Data Modeling Language for  the Network Configuration Protocol (NETCONF)</title>
<author initials="M." surname="Bjorklund" fullname="Martin Bjorklund">
<organization>Tail-F Systems</organization>
</author>
<date month="October" year="2010" />
</front>
<seriesInfo name="RFC" value="6020" />
</reference>

<reference anchor="RFC7223">
<front>
<title>A YANG Data Model for Interface Management</title>
<author initials="M." surname="Bjorklund" fullname="Martin Bjorklund">
<organization>Tail-F Systems</organization>
</author>
<date month="May" year="2014" />
</front>
<seriesInfo name="RFC" value="7223" />
</reference>

<reference anchor="RFC7277">
<front>
<title>A YANG Data Model for IP Management</title>
<author initials="M." surname="Bjorklund" fullname="Martin Bjorklund">
<organization>Tail-F Systems</organization>
</author>
<date month="June" year="2014" />
</front>
<seriesInfo name="RFC" value="7277" />
</reference>

<reference anchor="RFC7317">
<front>
<title>A YANG Data Model for System Management</title>
<author initials="A." surname="Bierman" fullname="Andy Bierman">
<organization>YumaWorks</organization>
</author>
<author initials="M." surname="Bjorklund" fullname="Martin Bjorklund">
<organization>Tail-F Systems</organization>
</author>
<date month="August" year="2014" />
</front>
<seriesInfo name="RFC" value="7317" />
</reference>

<reference anchor="RFC3688">
<front>
<title>The IETF XML Registry</title>
<author initials="M." surname="Mealling" fullname="Michael Mealling">
<organization>Verisign, Inc</organization>
</author>
<date month="January" year="2004" />
</front>
<seriesInfo name="BCP" value="81" />
<seriesInfo name="RFC" value="3688" />
</reference>

<reference anchor="RFC4026">
<front>
<title>Provider Provisioned Virtual Private Network (VPN) Terminology</title>
<author initials="L." surname="Andersson" fullname="Loa Andersson">
<organization>Acreo AB</organization>
</author>
<author initials="T." surname="Madsen" fullname="Tove Madsen">
<organization>Acreo AB</organization>
</author>
<date month="March" year="2005" />
</front>
<seriesInfo name="RFC" value="4026" />
</reference>

<reference anchor="YANG-YSDL">
<front>
<title>YANG Schema Dispatching Language</title>
<author initials="L." surname="Lhotha" fullname="Ladislav Lhotha">
<organization>CZ.NIC</organization>
</author>
<date month="November" year="2015" />
</front>
<seriesInfo name="Internet-Draft" value="draft-lhotka-netmod-ysdl-00.txt"/>
</reference>

</references>

<references title="Informative References">

<reference anchor="OC-OPSTATE">
<front>
<title>Consistent Modeling of Operational State Data in YANG</title>
<author initials="R." surname="Shakir" fullname="Rob Shakir">
<organization>Jive</organization>
</author>
<author initials="A." surname="Shaikh" fullname="Anees Shaikh">
<organization>Google</organization>
</author>
<author initials="M." surname="Hines" fullname="Marcus Hines">
<organization>Google</organization>
</author>
<date month="July" year="2015" />
</front>
<seriesInfo name="Internet-Draft" value="draft-openconfig-netmod-opstate-01.txt"/>
</reference>

<reference anchor="OC-STRUCT">
<front>
<title>Consistent Modeling of Operational State Data in YANG</title>
<author initials="A." surname="Shaikh" fullname="Anees Shaikh">
<organization>Google</organization>
</author>
<author initials="R." surname="Shakir" fullname="Rob Shakir">
<organization>Jive Communications, Inc</organization>
</author>
<author initials="K." surname="D'Souza" fullname="Kevin D'Souza">
<organization>AT&amp;T</organization>
</author>
<author initials="L" surname="Fang" fullname="Luyuan Fang">
<organization>Microsoft</organization>
</author>
<date month="March" year="2015" />
</front>
<seriesInfo name="Internet-Draft" value="draft-openconfig-netmod-model-structure-00.txt"/>
</reference>

<reference anchor="IEEE-8021Q">
<front>
<title>IEEE 802.1Q YANG Module Specifications</title>
<author initials="M." surname="Holness" fullname="Marc Holness">
<organization>IEEE</organization>
</author>
<date month="May" year="2015" />
</front>
<seriesInfo name="IEEE-Draft" value="http://www.ieee802.org/1/files/public/docs2015/new-mholness-yang-8021Q-0515-v04.pdf"/>
</reference>

<reference anchor="RTG-CFG">
<front>
<title>A YANG Data Model for Routing Management</title>
<author initials="L." surname="Lhotha" fullname="Ladislav Lhotha">
<organization>CZ.NIC</organization>
</author>
<author initials="A." surname="Lindem" fullname="Acee Lindem">
<organization>Cisco Systems</organization>
</author>
<date month="October" year="2015" />
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-netmod-routing-cfg-20.txt"/>
</reference>

<reference anchor="NETMOD-OPSTATE">
<front>
<title>NETMOD Operational State Requirements</title>
<author initials="K." surname="Watsen" fullname="Kent Watsen">
<organization>Juniper Networks</organization>
</author>
<author initials="T." surname="Nadeau" fullname="Thomas Nadeau">
<organization>Brocade</organization>
</author>
<date month="January" year="2016" />
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-netmod-opstate-reqs-03.txt"/>
</reference>

<reference anchor="OC-MPLS">
<front>
<title>MPLS / TE Model for Service Provider Networks</title>
<author initials="J" surname="George" fullname="Joshua George">
<organization>Google</organization>
</author>
<author initials="L" surname="Fang" fullname="Luyuan Fang">
<organization>Microsoft</organization>
</author>
<author initials="E" surname="Osborne" fullname="Eric Osborne">
<organization>Level 3</organization>
</author>
<author initials="R." surname="Shakir" fullname="Rob Shakir">
<organization>Jive Communications, Inc</organization>
</author>
<date month="October" year="2015" />
</front>
<seriesInfo name="Internet-Draft" value="draft-openconfig-mpls-consolidated-model-02.txt"/>
</reference>

<reference anchor="YANG-LIBRARY">
<front>
<title>YANG Module Library</title>
<author initials="A." surname="Bierman" fullname="Andy Bierman">
<organization>YumaWorks</organization>
</author>
<author initials="M." surname="Bjorklund" fullname="Martin Bjorklund">
<organization>Tail-F Systems</organization>
</author>
<author initials="K." surname="Watsen" fullname="Kent Watsen">
<organization>Juniper Networks</organization>
</author>
<date month="December" year="2015" />
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-netconf-yang-library-03.txt"/>
</reference>

</references>

<?rfc needLines="100"?>
<section title="Acknowledgments">
   <t>This document is derived from
   draft-openconfig-netmod-model-structure-00. The Authors of that
   document who are not also authors of this document are listed as
   Contributors to this work.</t>

   <t>The original stated: The authors are grateful for valuable
   contributions to this document and the associated models from: Deepak
   Bansal, Paul Borman, Chris Chase, Josh George, Marcus Hines, and Jim
   Uttaro.</t>

   <t>The Routing Area Yang Architecture design team members included Acee
   Lindem, Anees Shaikh, Christian Hopps, Dean Bogdanovic, Lou Berger,
   Qin Wu, Rob Shakir, Stephane Litkowski, and Yan Gang.</t>

  <t>The identityref approach was proposed by Mahesh Jethanandani.</t>
  <t>The RFC text was produced using Marshall Rose's xml2rfc tool.
   <vspace blankLines="100"/></t>
</section>
<section title="Contributors">
<figure>
<artwork>
Contributors' Addresses

   Anees Shaikh
   Google
   1600 Amphitheatre Pkwy
   Mountain View, CA  94043
   United States
   Email: aashaikh@google.com


   Rob Shakir
   Jive Communications, Inc.
   1275 W 1600 N, Suite 100
   Orem, UT  84057
   United States
   Email: rjs@rob.sh


   Kevin D'Souza
   AT&amp;T
   200 S. Laurel Ave
   Middletown, NJ
   United States
   Email: kd6913@att.com

   Luyuan Fang
   Microsoft
   205 108th Ave. NE, Suite 400
   Bellevue, WA
   United States
   Email: lufang@microsoft.com

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

   Email: bill.wu@huawei.com







   Stephane Litkowski
   Orange
   9 rue du chene germain
   Cesson Sevigne  35512
   France

   Email: stephane.litkowski@orange.com


   Gang Yan
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing  100095
   China

   Email: yangang@huawei.com

</artwork>
</figure>
</section>
</back>

</rfc>
