YANG Logical Network Elements
draft-ietf-rtgwg-lne-model-05

Network Working Group                                          L. Berger
Internet-Draft                                   LabN Consulting, L.L.C.
Intended status: Standards Track                                C. Hopps
Expires: March 30, 2018                                 Deutsche Telekom
                                                               A. Lindem
                                                           Cisco Systems
                                                           D. Bogdanovic

                                                                  X. Liu
                                                                   Jabil
                                                      September 26, 2017


                     YANG Logical Network Elements
                     draft-ietf-rtgwg-lne-model-04

Abstract

   This document defines a logical network element module.  This module
   can be used to manage the logical resource partitioning that may be
   present on a network device.  Examples of common industry terms for
   logical resource partitioning are Logical Systems or Logical Routers.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 30, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Logical Network Elements  . . . . . . . . . . . . . . . . . .   5
     3.1.  LNE Instantiation and Resource Assignment . . . . . . . .   6
     3.2.  LNE Management - LNE View . . . . . . . . . . . . . . . .   7
     3.3.  LNE Management - Host Network Device View . . . . . . . .   7
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   6.  Logical Network Element Model . . . . . . . . . . . . . . . .   9
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  14
   Appendix B.  Examples . . . . . . . . . . . . . . . . . . . . . .  15
     B.1.  Example: Host Device Managed LNE  . . . . . . . . . . . .  15
       B.1.1.  Configuration Data  . . . . . . . . . . . . . . . . .  19
       B.1.2.  State Data  . . . . . . . . . . . . . . . . . . . . .  23
     B.2.  Example: Self Managed LNE . . . . . . . . . . . . . . . .  32
       B.2.1.  Configuration Data  . . . . . . . . . . . . . . . . .  35
       B.2.2.  State Data  . . . . . . . . . . . . . . . . . . . . .  38
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  47

1.  Introduction

   This document defines a YANG [RFC6020] module to support the creation
   of logical network elements on a network device.  A logical network
   element (LNE) is an independently managed virtual device made up of
   resources allocated to it from the host or parent network device.  An
   LNE running on a host network device conceptually parallels a virtual
   machine running on a host system.  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.

   This document also defines the necessary augmentations for allocating
   host resources to a given LNE.  As the interface management model
   [RFC7223] is the only a module that currently defines host resources,



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   this document currently defines only a single augmentation to cover
   the assignment of interfaces to an LNE.  Future modules that define
   support for the control of host device resources are expected to,
   where appropriate, provide parallel support for the assignment of
   controlled resources to LNEs.

   As each LNE is an independently managed device, each will have its
   own set of YANG modeled data that is independent of the host device
   and other LNEs.  For example, multiple LNEs may all have their own
   "Tunnel0" interface defined which will not conflict with each other
   and will not exist in the host's interface model.  An LNE will have
   its own management interfaces possibly including independent
   instances of netconf/restconf/etc servers to support configuration of
   their YANG models.  As an example of this independence, an
   implementation may choose to completely rename assigned interfaces,
   so on the host the assigned interface might be called "Ethernet0/1"
   while within the LNE it might be called "eth1".

   In addition to standard management interfaces, a host device
   implementation may support accessing LNE configuration and
   operational YANG models directly from the host system.  When
   supported, such access is accomplished through a yang-schema-mount
   mount point [I-D.ietf-netmod-schema-mount] under which the root level
   LNE YANG models may be accessed.

   Examples of vendor terminology for an LNE include logical system or
   logical router, and virtual switch, chassis, or fabric.

1.1.  Terminology

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

   Readers are expected to be familiar with terms and concepts of YANG
   [RFC7950] and YANG Schema Mount [I-D.ietf-netmod-schema-mount].

   This document uses the graphical representation of data models
   defined in [I-D.ietf-netmod-yang-tree-diagrams].

2.  Overview

   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



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   network elements (LNEs), each of which provides a managed logical
   device.  Examples of vendor terminology for an LNE include logical
   system or logical 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.


              ,'''''''''''''''''''''''''''''''''''''''''''''''.
              |      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

   Figure 1: Module Element Relationships

   A model for LNEs is described in Section 3 and the model for NIs is
   covered in [I-D.ietf-rtgwg-ni-model].

   The interface management model [RFC7223] is an existing model that is
   impacted by the definition of LNEs and network instances.  This
   document and [I-D.ietf-rtgwg-ni-model] define 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.

   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
   [RFC7223].  The logical-network-element module augments existing
   interface management model by adding an identifier which is used on
   physical interface types to identify an associated LNE.



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   The interface related augmentation is as follows:

       module: ietf-logical-network-element
           augment /if:interfaces/if:interface:
             +--rw bind-lne-name?   ->
                  /logical-network-elements/logical-network-element/name

   The interface model defined in [RFC7223] is structured to include all
   interfaces in a flat list, without regard to logical assignment of
   resources supported on the device.  The bind-lne-name and leaf
   provides the association between an interface and its associated LNE.
   Note that as currently defined, to assign an interface to both an LNE
   and NI, the interface would first be assigned to the LNE and then
   within that LNE's interface module, the LNE's representation of that
   interface would be assigned to an NI using the mechanisms defined in
   [I-D.ietf-rtgwg-ni-model].

3.  Logical Network Elements

   Logical network elements support the ability 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 logical
   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.

   The LNE model can be represented using the tree format defined in
   [I-D.ietf-netmod-yang-tree-diagrams] as:
















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   module: ietf-logical-network-element
       +--rw logical-network-elements
          +--rw logical-network-element* [name]
             +--rw name           string
             +--rw managed?       boolean
             +--rw description?   string
             +--mp root
     augment /if:interfaces/if:interface:
       +--rw bind-lne-name?
               -> /logical-network-elements/logical-network-element/name

     notifications:
       +---n bind-lne-name-failed
          +--ro name             -> /if:interfaces/interface/name
          +--ro bind-lne-name
          |       -> /if:interfaces/interface/lne:bind-lne-name
          +--ro error-info?      string

   'name' identifies the logical network element.  'managed' indicates
   if the server providing the host network device will provide the
   client LNE information via the 'root' structure.  The root of an
   LNE's specific data is the schema mount point 'root'. bind-lne-name
   is used to associated an interface with an LNE and bind-lne-name-
   failed is used in certain failure cases.

   An LNE root MUST contain at least the YANG library [RFC7895] and
   Interfaces [RFC7223] modules.

3.1.  LNE Instantiation and Resource Assignment

   Logical network elements may be controlled by clients using existing
   list operations.  When list entries are created, a new LNE is
   instantiated.  The models mounted under an LNE root are expected to
   be dependent on the server implementation.  When a list entry is
   deleted, an existing LNE is destroyed.  For more information, see
   [RFC7950] Section 7.8.6.

   Once instantiated, host network device resources can be associated
   with the new LNE.  As previously mentioned, this document augments
   ietf-interfaces with the bind-lne-name leaf to support such
   associations for interfaces.  When an bind-lne-name is set to a valid
   LNE name, an implementation MUST take whatever steps are internally
   necessary to assign the interface to the LNE or provide an error
   message (defined below) with an indication of why the assignment
   failed.  It is possible for the assignment to fail while processing
   the set, or after asynchronous processing.  Error notification in the
   latter case is supported via a notification.




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   On a successful interface assignment to an LNE, an implementation
   MUST also make the resource available to the LNE by providing a
   system created interface to the LNE.  The name of the system created
   interface is a local matter and may be identical or completely
   different, and mapped from and to, the name used in the context of
   the host device.  The system created interface SHOULD be exposed via
   the LNE-specific instance of the interfaces module [RFC7223].

3.2.  LNE Management - LNE View

   Each LNE instance is expected to support management functions from
   within the context of the LNE root, via a server that provides
   information with the LNE's root exposed as device root.  Management
   functions operating within the context of an LNE are accessed through
   the LNE's standard management interfaces, e.g., NETCONF and SNMP.
   Initial configuration, much like the initial configuration of the
   host device, is a local implementation matter.

   When accessing an LNE via the 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 the required YANG library [RFC7895] instance, 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 a physical network device.

3.3.  LNE Management - Host Network Device View

   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
   operational 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.

   Independent of the method selected by an implementation, the
   'managed' boolean mentioned above is used to indicate when LNE
   management from the network device context is possible.  When the
   'managed' boolean 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 previous section, Section 3.2.  Attempts to access
   information below a root node whose associated 'managed' boolean is
   set to 'false' MUST result in the error message indicated below.  In
   some implementations, it may not be possible to change this value.



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   For example, when an LNE is implemented using virtual machine and
   traditional hypervisor technologies, it is likely that this value
   will be restricted to a 'false' value.

   It is an implementation choice if the information can be accessed and
   modified from within the context of the LNE, or even the context of
   the host device.  When the 'managed' boolean is 'true', LNE
   information SHALL be accessible from the context of the host device.
   When the associated schema-mount definition has the 'config' leaf set
   to 'true', then LNE information SHALL also be modifiable from the
   context of the host device.  When LNE information is available from
   both the host device and from within the context of the LNE, the same
   information MUST be made available via the 'root' element, with paths
   modified as described in [I-D.ietf-netmod-schema-mount].

   An implementation MAY represent an LNE's schema using either the
   'inline' or 'use-schema' approaches defined in
   [I-D.ietf-netmod-schema-mount].  The choice of which to use is
   completely an implementation choice.  The inline case is anticipated
   to be generally used in the cases where the 'managed' will always be
   'false'.  The 'use-schema' approach is expected to be be most useful
   in the case where all LNEs share the same schema.  When 'use-schema'
   is used with an LNE mount point, the YANG library rooted in the LNE's
   mount point MUST match the associated schema defined within the ietf-
   yang-schema-mount module.

   Beyond the two modules that will always be present for an LNE, 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.  The
   list of available modules is expected to be implementation dependent.
   As is the method used by an implementation to support LNEs.
   Appendix B provide example uses of LNEs.

4.  Security Considerations

   LNE information represents device and network configuration
   information.  As such, the security of this information is important,
   but it is fundamentally no different than any other interface or
   device configuration information that has already been covered in
   other documents such as [RFC7223], [RFC7317] and [RFC8022].

   The vulnerable "config true" parameters and subtrees are the
   following:

   /logical-network-elements/logical-network-element:  This list
      specifies the logical network element and the related logical
      device configuration.




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   /logical-network-elements/logical-network-element/managed:  While
      this leaf is contained in the previous list, it is worth
      particular attention as it controls whether information under the
      LNE mount point is accessible by both the host device and within
      the LNE context.  There may be extra sensitivity to this leaf in
      environments where an LNE is managed by a different party than the
      host device, and that party does not wish to share LNE information
      with the operator of the host device.

   /if:interfaces/if:interface/bind-lne-name:  This leaf indicates the
      LNE instance to which an interface is assigned.

   Unauthorized access to any of these lists can adversely affect the
   security of both the local device and the network.  This may lead to
   network malfunctions, delivery of packets to inappropriate
   destinations, and other problems.

5.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688].
   Following the format in RFC 3688, the following registration is
   requested to be made.

        URI: urn:ietf:params:xml:ns:yang:ietf-logical-network-element

        Registrant Contact: The IESG.

        XML: N/A, the requested URI is an XML namespace.

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

   name:        ietf-logical-network-element
   namespace:   urn:ietf:params:xml:ns:yang:ietf-logical-network-element
   prefix:      lne
   reference:   RFC XXXX

6.  Logical Network Element Model

   The structure of the model defined in this document is described by
   the YANG module below.

 <CODE BEGINS> file "ietf-logical-network-element@2017-09-27.yang"
 module ietf-logical-network-element {
   yang-version 1.1;

   // namespace




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

   // import some basic types

   import ietf-interfaces {
     prefix if;
     reference "RFC 7223: A YANG Data Model for Interface Management";
   }
   import ietf-yang-schema-mount {
     prefix yangmnt;
     reference "draft-ietf-netmod-schema-mount: YANG Schema Mount";
     // RFC Ed.: Please replace this draft name with the corresponding
     // RFC number
   }

   organization
     "IETF Routing Area (rtgwg) Working Group";
   contact
     "WG Web:   <http://tools.ietf.org/wg/rtgwg/>
      WG List:  <mailto:rtgwg@ietf.org>

      Author:   Lou Berger
                <mailto:lberger@labn.net>
      Author:   Christan Hopps
                <mailto:chopps@chopps.org>
      Author:   Acee Lindem
                <mailto:acee@cisco.com>
      Author:   Dean Bogdanovic
                <mailto:ivandean@gmail.com>";
   description
     "This module is used to support multiple logical network
      elements on a single physical or virtual system.

      Copyright (c) 2017 IETF Trust and the persons
      identified as authors of the code.  All rights reserved.

      Redistribution and use in source and binary forms, with or
      without modification, is permitted pursuant to, and subject
      to the license terms contained in, the Simplified BSD License
      set forth in Section 4.c of the IETF Trust's Legal Provisions
      Relating to IETF Documents
      (http://trustee.ietf.org/license-info).

      This version of this YANG module is part of RFC XXXX; see
      the RFC itself for full legal notices.";

   // RFC Ed.: replace XXXX with actual RFC number and remove



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   // this note
   // RFC Ed.: please update TBD

   revision 2017-09-27 {
     description
       "Initial revision.";
     reference "RFC TBD";
   }

   // top level device definition statements

   container logical-network-elements {
     description
       "Allows a network device to support multiple logical
        network element (device) instances.";
     list logical-network-element {
       key "name";
       description
         "List of logical network elements.";
       leaf name {
         type string;
         description
           "Device-wide unique identifier for the
            logical network element.";
       }
       leaf managed {
         type boolean;
         default "true";
         description
           "True if the host can access LNE information
            using the root mount point.  This value
            my not be modifiable in all implementations.";
       }
       leaf description {
         type string;
         description
           "Description of the logical network element.";
       }
       container "root" {
         description
           "Container for mount point.";
         yangmnt:mount-point "root" {
           description
             "Root for models supported per logical
              network element.  This mount point will
              may or may not be inline based on the server
              implementation.  It SHALL always contain a YANG
              library and interfaces instance.



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              When the associated 'managed' leaf is 'false' any
              operation that attempts to access information below
              the root SHALL fail with an error-tag of
              'access-denied' and an error-app-tag of
              'lne-not-managed'.";
         }
       }
     }
   }

   // 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.

        Note that a standard error will be returned if the
        identified leafref isn't present.  If an interfaces cannot
        be assigned for any other reason, the operation SHALL fail
        with an error-tag of 'operation-failed' and an error-app-tag
        of 'lne-assignment-failed'.  A meaningful error-info that
        indicates the source of the assignment failure SHOULD also
        be provided.";
     leaf bind-lne-name {
       type leafref {
         path "/logical-network-elements/logical-network-element/name";
       }
       description
         "Logical network element ID to which interface is bound.";
     }
   }

   // notification statements

   notification bind-lne-name-failed {
     description
       "Indicates an error in the association of an interface to an
        LNE. Only generated after success is initially returned when
        bind-lne-name is set.";
     leaf name {
       type leafref {
         path "/if:interfaces/if:interface/if:name";
       }
       mandatory true;
       description
         "Contains the interface name associated with the



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          failure.";
     }
     leaf bind-lne-name {
       type leafref {
         path "/if:interfaces/if:interface/lne:bind-lne-name";
       }
       mandatory true;
       description
         "Contains the bind-lne-name associated with the
          failure.";
     }
     leaf error-info {
       type string;
       description
         "Optionally, indicates the source of the assignment
          failure.";
     }
   }
 }
 <CODE ENDS>

7.  References

7.1.  Normative References

   [I-D.ietf-netmod-schema-mount]
              Bjorklund, M. and L. Lhotka, "YANG Schema Mount", draft-
              ietf-netmod-schema-mount-06 (work in progress), July 2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC7223]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
              <https://www.rfc-editor.org/info/rfc7223>.





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7.2.  Informative References

   [I-D.ietf-netmod-yang-tree-diagrams]
              Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft-
              ietf-netmod-yang-tree-diagrams-01 (work in progress), June
              2017.

   [I-D.ietf-rtgwg-device-model]
              Lindem, A., Berger, L., Bogdanovic, D., and C. Hopps,
              "Network Device YANG Logical Organization", draft-ietf-
              rtgwg-device-model-02 (work in progress), March 2017.

   [I-D.ietf-rtgwg-ni-model]
              Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X.
              Liu, "YANG Network Instances", draft-ietf-rtgwg-ni-
              model-03 (work in progress), July 2017.

   [RFC7317]  Bierman, A. and M. Bjorklund, "A YANG Data Model for
              System Management", RFC 7317, DOI 10.17487/RFC7317, August
              2014, <https://www.rfc-editor.org/info/rfc7317>.

   [RFC7895]  Bierman, A., Bjorklund, M., and K. Watsen, "YANG Module
              Library", RFC 7895, DOI 10.17487/RFC7895, June 2016,
              <https://www.rfc-editor.org/info/rfc7895>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8022]  Lhotka, L. and A. Lindem, "A YANG Data Model for Routing
              Management", RFC 8022, DOI 10.17487/RFC8022, November
              2016, <https://www.rfc-editor.org/info/rfc8022>.

Appendix A.  Acknowledgments

   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.  Useful review
   comments were also received by Martin Bjorklund and John Scudder.

   This document was motivated by, and derived from,
   [I-D.ietf-rtgwg-device-model].

   The RFC text was produced using Marshall Rose's xml2rfc tool.







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Appendix B.  Examples

   The following subsections provide example uses of LNEs.

B.1.  Example: Host Device Managed LNE

   This section describes an example of the LNE model using schema mount
   to achieve the parent management.  An example device supports
   multiple instances of LNEs (logical routers), each of which supports
   features of layer 2 and layer 3 interfaces [RFC7223], routing
   information base [RFC8022], and OSPF protocol.  Each of these
   features is specified by a YANG model, and they are combined using
   YANG Schema Mount as follows:

   module: ietf-logical-network-element
      +--rw logical-network-elements
         +--rw logical-network-element* [name]
            +--rw name           string
            +--mp root
               +--ro yanglib:modules-state/
               |  +--ro module-set-id    string
               |  +--ro module* [name revision]
               |     +--ro name                yang:yang-identifier
               +--rw sys:system/
               |  +--rw contact?          string
               |  +--rw hostname?         inet:domain-name
               |  +--rw authentication {authentication}?
               |     +--rw user-authentication-order*   identityref
               |     +--rw user* [name] {local-users}?
               |        +--rw name              string
               |        +--rw password?         ianach:crypt-hash
               |        +--rw authorized-key* [name]
               |           +--rw name         string
               |           +--rw algorithm    string
               |           +--rw key-data     binary
               +--ro sys:system-state/
               |     ...
               +--ro rt:routing-state/
               |  +--ro router-id?                 yang:dotted-quad
               |  +--ro control-plane-protocols
               |     +--ro control-plane-protocol* [type name]
               |        +--ro ospf:ospf/
               |           +--ro instance* [af]
               |           ...
               +--rw rt:routing/
               |  +--rw router-id?                 yang:dotted-quad
               |  +--rw control-plane-protocols
               |     +--rw control-plane-protocol* [type name]



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               |        +--rw ospf:ospf/
               |           +--rw instance* [af]
               |              +--rw areas
               |                 +--rw area* [area-id]
               |                    +--rw interfaces
               |                       +--rw interface* [name]
               |                          +--rw name if:interface-ref
               |                          +--rw cost?   uint16
               +--rw if:interfaces/
               |  +--rw interface* [name]
               |     +--rw name            string
               |     +--rw ip:ipv4!/
               |     |  +--rw address* [ip]
               |     |  ...
               +--ro if:interfaces-state/
                  +--ro interface* [name]
                     +--ro name               string
                     +--ro ip:ipv4!/
                     |  +--ro address* [ip]
                     |  ...

   module: ietf-interfaces
      +--rw interfaces
      |  +--rw interface* [name]
      |     +--rw name                        string
      |     +--rw lne:bind-lne-name?          string
      +--ro interfaces-state
         +--ro interface* [name]
            +--ro name               string
            +--ro oper-status        enumeration

   module: ietf-yang-library
      +--ro modules-state
         +--ro module-set-id    string
         +--ro module* [name revision]
            +--ro name                yang:yang-identifier

   module: ietf-system
      +--rw system
      |  +--rw contact?          string
      |  +--rw hostname?         inet:domain-name
      |  +--rw authentication {authentication}?
      |     +--rw user-authentication-order*   identityref
      |     +--rw user* [name] {local-users}?
      |        +--rw name              string
      |        +--rw password?         ianach:crypt-hash
      |        +--rw authorized-key* [name]
      |           +--rw name         string



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      |           +--rw algorithm    string
      |           +--rw key-data     binary
      +--ro system-state
         +--ro platform
         |  +--ro os-name?      string
         |  +--ro os-release?   string

   To realize the above schema, the example device implements the
   following schema mount instance:

   "ietf-yang-schema-mount:schema-mounts": {
     "mount-point": [
       {
         "module": "ietf-logical-network-element",
         "name": "root",
         "use-schema": [
           {
             "name": "lne-schema"
           }
         ]
       }
     ],
     "schema": [
       {
         "name": "lne-schema",
         "module": [
           {
             "name": "ietf-yang-library",
             "revision": "2016-06-21",
             "namespace":
               "urn:ietf:params:xml:ns:yang:ietf-yang-library",
             "conformance-type": "implement"
           },
           {
             "name": "ietf-system",
             "revision": "2014-08-06",
             "namespace":
               "urn:ietf:params:xml:ns:yang:ietf-system",
             "conformance-type": "implement"
           },
           {
             "name": "ietf-routing",
             "revision": "2016-11-04",
             "namespace":
               "urn:ietf:params:xml:ns:yang:ietf-routing",
             "conformance-type": "implement"
           },
           {



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             "name": "ietf-ospf",
             "revision": "2017-03-12",
             "namespace":
               "urn:ietf:params:xml:ns:yang:ietf-ospf",
             "conformance-type": "implement"
           },
           {
             "name": "ietf-interfaces",
             "revision": "2014-05-08",
             "namespace":
               "urn:ietf:params:xml:ns:yang:ietf-interfaces",
             "conformance-type": "implement"
           },
           {
             "name": "ietf-ip",
             "revision": "2014-06-16",
             "namespace":
               "urn:ietf:params:xml:ns:yang:ietf-ip",
             "conformance-type": "implement"
           }
         ]
       }
     ]
   }

   By using the implementation of the YANG schema mount, an operator can
   create instances of logical routers.  An interface can be assigned to
   a logical router, so that the logical router has the permission to
   access this interface.  The OSPF protocol can then be enabled on this
   assigned interface.

   For this implementation, a parent management session has access to
   the schemas of both the parent hosting system and the child logical
   routers.  In addition, each child logical router can grant its own
   management sessions, which have the following schema:

   module: ietf-yang-library
      +--ro modules-state
         +--ro module-set-id    string
         +--ro module* [name revision]
            +--ro name                yang:yang-identifier

   module: ietf-system
      +--rw system
      |  +--rw contact?          string
      |  +--rw hostname?         inet:domain-name
      |  +--rw authentication {authentication}?
      |     +--rw user-authentication-order*   identityref



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      |     +--rw user* [name] {local-users}?
      |        +--rw name              string
      |        +--rw password?         ianach:crypt-hash
      |        +--rw authorized-key* [name]
      |           +--rw name         string
      |           +--rw algorithm    string
      |           +--rw key-data     binary
      +--ro system-state
         +--ro platform
         |  +--ro os-name?      string
         |  +--ro os-release?   string

   module: ietf-routing
      +--ro routing-state
      |  +--ro router-id?                 yang:dotted-quad
      |  +--ro control-plane-protocols
      |  |  +--ro control-plane-protocol* [type name]
      |  |     +--ro ospf:ospf/
      |  |        +--ro instance* [af]
      +--rw routing
         +--rw router-id?                 yang:dotted-quad
         +--rw control-plane-protocols
            +--rw control-plane-protocol* [type name]
               +--rw ospf:ospf/
                  +--rw instance* [af]
                     +--rw areas
                        +--rw area* [area-id]
                           +--rw interfaces
                              +--rw interface* [name]
                                 +--rw name    if:interface-ref
                                 +--rw cost?   uint16

   module: ietf-interfaces
      +--rw interfaces
      |  +--rw interface* [name]
      |     +--rw name                        string
      +--ro interfaces-state
         +--ro interface* [name]
         +--ro name               string
         +--ro oper-status        enumeration

B.1.1.  Configuration Data

   The following shows an example where two customer specific LNEs are
   configured:

   {
     "ietf-logical-network-element:logical-network-elements": {



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       "logical-network-element": [
         {
           "name": "cust1",
           "root": {
             "ietf-system:system": {
               "authentication": {
                 "user": [
                   {
                     "name": "john",
                     "password": "$0$password"
                   }
                 ]
               }
             },
             "ietf-routing:routing": {
               "router-id": "192.0.2.1",
               "control-plane-protocols": {
                 "control-plane-protocol": [
                   {
                     "type": "ietf-routing:ospf",
                     "name": "1",
                     "ietf-ospf:ospf": {
                       "instance": [
                         {
                         "af": "ipv4",
                           "areas": {
                             "area": [
                               {
                                 "area-id": "203.0.113.1",
                                 "interfaces": {
                                   "interface": [
                                     {
                                       "name": "eth1",
                                       "cost": 10
                                     }
                                   ]
                                 }
                               }
                             ]
                           }
                         }
                       ]
                     }
                   }
                 ]
               }
             },
             "ietf-interfaces:interfaces": {



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               "interfaces": {
                 "interface": [
                   {
                     "name": "eth1",
                     "ip:ipv4": {
                       "address": [
                         {
                           "ip": "192.0.2.11",
                           "prefix-length": 24,
                         }
                       ]
                     }
                   }
                 ]
               }
             }
           }
         },
         {
           "name": "cust2",
           "root": {
             "ietf-system:system": {
               "authentication": {
                 "user": [
                   {
                     "name": "john",
                     "password": "$0$password"
                   }
                 ]
               }
             }
             "ietf-routing:routing": {
               "router-id": "192.0.2.2",
               "control-plane-protocols": {
                 "control-plane-protocol": [
                   {
                     "type": "ietf-routing:ospf",
                     "name": "1",
                     "ietf-ospf:ospf": {
                       "instance": [
                         {
                           "af": "ipv4",
                           "areas": {
                             "area": [
                               {
                                 "area-id": "203.0.113.1",
                                 "interfaces": {
                                   "interface": [



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                                     {
                                       "name": "eth1",
                                       "cost": 10
                                     }
                                   ]
                                 }
                               }
                             ]
                           }
                         }
                       ]
                     }
                   }
                 ]
               }
             }
             "ietf-interfaces:interfaces": {
               "interfaces": {
                 {
                   "name": "eth1",
                   "ip:ipv4": {
                     "address": [
                       {
                         "ip": "192.0.2.11",
                         "prefix-length": 24,
                       }
                     ]
                   }
                 }
               ]
             }
           }
         }
       ]
     },

     "ietf-interfaces:interfaces": {
       "interfaces": {
         "interface": [
           {
             "name": "eth0",
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.10",
                   "prefix-length": 24,
                 }
               ]



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             }
           },
           {
             "name": "cust1:eth1",
             "lne:bind-lne-name": "cust1"
           },
           {
             "name": "cust2:eth1",
             "lne:bind-lne-name": "cust2"
           }
         ]
       }
     },

     "ietf-system:system": {
       "authentication": {
         "user": [
           {
             "name": "root",
             "password": "$0$password"
           }
         ]
       }
     }
   }

B.1.2.  State Data

   The following shows possible state data associated the above
   configuration data:

   {
     "ietf-logical-network-element:logical-network-elements": {
       "logical-network-element": [
         {
           "name": "cust1",
           "root": {
             "ietf-yang-library:modules-state": {
               "module-set-id": "123e4567-e89b-12d3-a456-426655440000",
               "module": [
                 {
                   "name": "iana-if-type",
                   "revision": "2014-05-08",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:iana-if-type",
                   "conformance-type": "import"
                 },
                 {



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                   "name": "ietf-inet-types",
                   "revision": "2013-07-15",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-inet-types",
                   "conformance-type": "import"
                 },
                 {
                   "name": "ietf-interfaces",
                   "revision": "2014-05-08",
                   "feature": [
                     "arbitrary-names",
                     "pre-provisioning"
                   ],
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-interfaces",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-ip",
                   "revision": "2014-06-16",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-ip",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-ospf",
                   "revision": "2017-03-12",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-ospf",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-routing",
                   "revision": "2016-11-04",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-routing",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-system",
                   "revision": "2014-08-06",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-system",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-yang-library",
                   "revision": "2016-06-21",



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                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-yang-library",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-yang-types",
                   "revision": "2013-07-15",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-yang-types",
                   "conformance-type": "import"
                 }
               ]
             }
             "ietf-system:system-state": {
               "ietf-system:system-state": {
                 "platform": {
                   "os-name": "NetworkOS"
                 }
               }
             },
             "ietf-routing:routing-state": {
               "router-id": "192.0.2.1",
               "control-plane-protocols": {
                 "control-plane-protocol": [
                   {
                     "type": "ietf-routing:ospf",
                     "name": "1",
                     "ietf-ospf:ospf": {
                       "instance": [
                         {
                         "af": "ipv4",
                           "areas": {
                             "area": [
                               {
                                 "area-id": "203.0.113.1",
                                 "interfaces": {
                                   "interface": [
                                     {
                                       "name": "eth1",
                                       "cost": 10
                                     }
                                   ]
                                 }
                               }
                             ]
                           }
                         }
                       ]



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                     }
                   }
                 ]
               }
             },
             "ietf-interfaces:interfaces-state": {
               "interfaces": {
                 "interface": [
                   {
                     "name": "eth1",
                     "type": "iana-if-type:ethernetCsmacd",
                     "oper-status": "up",
                     "phys-address": "00:01:02:A1:B1:C1",
                     "statistics": {
                       "discontinuity-time": "2017-06-26T12:34:56-05:00"
                     },
                     "ip:ipv4": {
                       "address": [
                         {
                           "ip": "192.0.2.11",
                           "prefix-length": 24,
                         }
                       ]
                     }
                   }
                 ]
               }
             }
           }
         },
         {
           "name": "cust2",
           "root": {
             "ietf-yang-library:modules-state": {
               "module-set-id": "123e4567-e89b-12d3-a456-426655440000",
               "module": [
                 {
                   "name": "iana-if-type",
                   "revision": "2014-05-08",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:iana-if-type",
                   "conformance-type": "import"
                 },
                 {
                   "name": "ietf-inet-types",
                   "revision": "2013-07-15",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-inet-types",



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                   "conformance-type": "import"
                 },
                 {
                   "name": "ietf-interfaces",
                   "revision": "2014-05-08",
                   "feature": [
                     "arbitrary-names",
                     "pre-provisioning"
                   ],
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-interfaces",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-ip",
                   "revision": "2014-06-16",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-ip",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-ospf",
                   "revision": "2017-03-12",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-ospf",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-routing",
                   "revision": "2016-11-04",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-routing",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-system",
                   "revision": "2014-08-06",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-system",
                   "conformance-type": "implement"
                 },
                 {
                   "name": "ietf-yang-library",
                   "revision": "2016-06-21",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-yang-library",
                   "conformance-type": "implement"
                 },



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                 {
                   "name": "ietf-yang-types",
                   "revision": "2013-07-15",
                   "namespace":
                   "urn:ietf:params:xml:ns:yang:ietf-yang-types",
                   "conformance-type": "import"
                 }
               ]
             }
             "ietf-system:system-state": {
               "ietf-system:system-state": {
                 "platform": {
                   "os-name": "NetworkOS"
                 }
               }
             },
             "ietf-routing:routing-state": {
               "router-id": "192.0.2.2",
               "control-plane-protocols": {
                 "control-plane-protocol": [
                   {
                     "type": "ietf-routing:ospf",
                     "name": "1",
                     "ietf-ospf:ospf": {
                       "instance": [
                         {
                           "af": "ipv4",
                           "areas": {
                             "area": [
                               {
                                 "area-id": "203.0.113.1",
                                 "interfaces": {
                                   "interface": [
                                     {
                                       "name": "eth1",
                                       "cost": 10
                                     }
                                   ]
                                 }
                               }
                             ]
                           }
                         }
                       ]
                     }
                   }
                 ]
               }



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             }
             "ietf-interfaces:interfaces-state": {
               "interfaces": {
                 {
                   "name": "eth1",
                   "type": "iana-if-type:ethernetCsmacd",
                   "oper-status": "up",
                   "phys-address": "00:01:02:A1:B1:C2",
                   "statistics": {
                     "discontinuity-time": "2017-06-26T12:34:56-05:00"
                   },
                   "ip:ipv4": {
                     "address": [
                       {
                         "ip": "192.0.2.11",
                         "prefix-length": 24,
                       }
                     ]
                   }
                 }
               ]
             }
           }
         }
       ]
     },

     "ietf-interfaces:interfaces-state": {
       "interfaces": {
         "interface": [
           {
             "name": "eth0",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",
             "phys-address": "00:01:02:A1:B1:C0",
             "statistics": {
                "discontinuity-time": "2017-06-26T12:34:56-05:00"
             },
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.10",
                   "prefix-length": 24,
                 }
               ]
             }
           },
           {



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             "name": "cust1:eth1",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",
             "phys-address": "00:01:02:A1:B1:C1",
             "statistics": {
                "discontinuity-time": "2017-06-26T12:34:56-05:00"
             }
           },
           {
             "name": "cust2:eth1",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",
             "phys-address": "00:01:02:A1:B1:C2",
             "statistics": {
                "discontinuity-time": "2017-06-26T12:34:56-05:00"
             }
           }
         ]
       }
     },

     "ietf-yang-library:modules-state": {
       "module-set-id": "123e4567-e89b-12d3-a456-426655440000",
       "module": [
         {
           "name": "iana-if-type",
           "revision": "2014-05-08",
           "namespace":
           "urn:ietf:params:xml:ns:yang:iana-if-type",
           "conformance-type": "import"
         },
         {
           "name": "ietf-inet-types",
           "revision": "2013-07-15",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-inet-types",
           "conformance-type": "import"
         },
         {
           "name": "ietf-interfaces",
           "revision": "2014-05-08",
           "feature": [
             "arbitrary-names",
             "pre-provisioning"
           ],
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-interfaces",
           "conformance-type": "implement"



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         },
         {
           "name": "ietf-ip",
           "revision": "2014-06-16",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-ip",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-logical-network-element",
           "revision": "2017-03-13",
           "feature": [
             "bind-lne-name"
           ],
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-logical-network-element",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-ospf",
           "revision": "2017-03-12",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-ospf",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-routing",
           "revision": "2016-11-04",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-routing",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-system",
           "revision": "2014-08-06",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-system",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-yang-library",
           "revision": "2016-06-21",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-library",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-yang-schema-mount",



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           "revision": "2017-05-16",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-schema-mount",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-yang-types",
           "revision": "2013-07-15",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-types",
           "conformance-type": "import"
         }
       ]
     },

     "ietf-system:system-state": {
       "platform": {
         "os-name": "NetworkOS"
       }
     }
   }

B.2.  Example: Self Managed LNE

   This section describes an example of the LNE model using schema mount
   to achieve child independent management.  An example device supports
   multiple instances of LNEs (logical routers), each of them has the
   features of layer 2 and layer 3 interfaces [RFC7223], routing
   information base [RFC8022], and the OSPF protocol.  Each of these
   features is specified by a YANG model, and they are put together by
   the YANG Schema Mount as following:




















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         module: ietf-logical-network-element
      +--rw logical-network-elements
         +--rw logical-network-element* [name]
            +--rw name           string
            +--mp root
               // The internal modules of the LNE are not visible to
               // the parament management.
               // The child manages its modules, including ietf-routing
               // and ietf-interfaces

   module: ietf-interfaces
      +--rw interfaces
      |  +--rw interface* [name]
      |     +--rw name                        string
      |     +--rw lne:bind-lne-name?          string
      +--ro interfaces-state
         +--ro interface* [name]
            +--ro name               string
            +--ro oper-status        enumeration

   module: ietf-yang-library
      +--ro modules-state
         +--ro module-set-id    string
         +--ro module* [name revision]
            +--ro name                yang:yang-identifier

   module: ietf-system
      +--rw system
      |  +--rw contact?          string
      |  +--rw hostname?         inet:domain-name
      |  +--rw authentication {authentication}?
      |     +--rw user-authentication-order*   identityref
      |     +--rw user* [name] {local-users}?
      |        +--rw name              string
      |        +--rw password?         ianach:crypt-hash
      |        +--rw authorized-key* [name]
      |           +--rw name         string
      |           +--rw algorithm    string
      |           +--rw key-data     binary
      +--ro system-state
         +--ro platform
         |  +--ro os-name?      string
         |  +--ro os-release?   string

   To realize the above schema, the device implements the following
   schema mount instance:





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   "ietf-yang-schema-mount:schema-mounts": {
     "mount-point": [
       {
         "module": "ietf-logical-network-element",
         "name": "root",
         "inline": [null]
       }
     ]
   }

   By using the implementation of the YANG schema mount, an operator can
   create instances of logical routers, each with their logical router
   specific in-line modules.  An interface can be assigned to a logical
   router, so that the logical router has the permission to access this
   interface.  The OSPF protocol can then be enabled on this assigned
   interface.  Each logical router independently manages its own set of
   modules, which may or may not be the same as other logical routers.
   The following is an example of schema set implemented on one
   particular logical router:

   module: ietf-yang-library
      +--ro modules-state
         +--ro module-set-id    string
         +--ro module* [name revision]
            +--ro name                yang:yang-identifier

   module: ietf-system
      +--rw system
      |  +--rw contact?          string
      |  +--rw hostname?         inet:domain-name
      |  +--rw authentication {authentication}?
      |     +--rw user-authentication-order*   identityref
      |     +--rw user* [name] {local-users}?
      |        +--rw name              string
      |        +--rw password?         ianach:crypt-hash
      |        +--rw authorized-key* [name]
      |           +--rw name         string
      |           +--rw algorithm    string
      |           +--rw key-data     binary
      +--ro system-state
         +--ro platform
         |  +--ro os-name?      string
         |  +--ro os-release?   string

   module: ietf-routing
      +--ro routing-state
      |  +--ro router-id?                 yang:dotted-quad
      |  +--ro control-plane-protocols



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      |  |  +--ro control-plane-protocol* [type name]
      |  |     +--ro ospf:ospf/
      |  |        +--ro instance* [af]
      +--rw routing
         +--rw router-id?                 yang:dotted-quad
         +--rw control-plane-protocols
            +--rw control-plane-protocol* [type name]
               +--rw ospf:ospf/
                  +--rw instance* [af]
                     +--rw areas
                        +--rw area* [area-id]
                           +--rw interfaces
                              +--rw interface* [name]
                                 +--rw name    if:interface-ref
                                 +--rw cost?   uint16

   module: ietf-interfaces
      +--rw interfaces
      |  +--rw interface* [name]
      |     +--rw name                        string
      +--ro interfaces-state
         +--ro interface* [name]
         +--ro name               string
         +--ro oper-status        enumeration

B.2.1.  Configuration Data

   Each of the child virtual routers is managed through its own sessions
   and configuration data.

B.2.1.1.  Logical Network Element 'vnf1'

   The following shows an example configuration data for the LNE name
   "vnf1":

   {
     "ietf-system:system": {
       "authentication": {
         "user": [
           {
             "name": "john",
             "password": "$0$password"
           }
         ]
       }
     },
     "ietf-routing:routing": {
       "router-id": "192.0.2.1",



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       "control-plane-protocols": {
         "control-plane-protocol": [
           {
             "type": "ietf-routing:ospf",
             "name": "1",
             "ietf-ospf:ospf": {
               "instance": [
                 {
                   "af": "ipv4",
                   "areas": {
                     "area": [
                       {
                         "area-id": "203.0.113.1",
                         "interfaces": {
                           "interface": [
                             {
                               "name": "eth1",
                               "cost": 10
                             }
                           ]
                         }
                       }
                     ]
                   }
                 }
               ]
             }
           }
         ]
       }
     },
     "ietf-interfaces:interfaces": {
       "interfaces": {
         "interface": [
           {
             "name": "eth1",
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.11",
                   "prefix-length": 24,
                 }
               ]
             }
           }
         ]
       }
     }



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   }

B.2.1.2.  Logical Network Element 'vnf2'

   The following shows an example configuration data for the LNE name
   "vnf2":

   {
     "ietf-system:system": {
       "authentication": {
         "user": [
           {
             "name": "john",
             "password": "$0$password"
           }
         ]
       }
     },
     "ietf-routing:routing": {
       "router-id": "192.0.2.2",
       "control-plane-protocols": {
         "control-plane-protocol": [
           {
             "type": "ietf-routing:ospf",
             "name": "1",
             "ietf-ospf:ospf": {
               "instance": [
                 {
                   "af": "ipv4",
                   "areas": {
                     "area": [
                       {
                         "area-id": "203.0.113.1",
                         "interfaces": {
                           "interface": [
                             {
                               "name": "eth1",
                               "cost": 10
                             }
                           ]
                         }
                       }
                     ]
                   }
                 }
               ]
             }
           }



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         ]
       }
     },
     "ietf-interfaces:interfaces": {
   "interfaces": {
         "interface": [
           {
             "name": "eth1",
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.11",
                   "prefix-length": 24,
                 }
               ]
             }
           }
         ]
       }
     }
   }

B.2.2.  State Data

   The following sections shows possible state data associated the above
   configuration data.  Note that there are three views: the host
   device's, and each LNE's.

B.2.2.1.  Host Device

   The following shows state data for the device hosting the example
   LNEs:

   {
     "ietf-logical-network-element:logical-network-elements": {
       "logical-network-element": [
         {
           "name": "vnf1",
           "root": {
           }
         },
         {
           "name": "vnf2",
           "root": {
           }
         }
       ]
     },



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     "ietf-interfaces:interfaces-state": {
       "interfaces": {
         "interface": [
           {
             "name": "eth0",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",
             "phys-address": "00:01:02:A1:B1:C0",
             "statistics": {
                "discontinuity-time": "2017-06-26T12:34:56-05:00"
             },
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.10",
                   "prefix-length": 24,
                 }
               ]
             }
           },
           {
             "name": "vnf1:eth1",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",
             "phys-address": "00:01:02:A1:B1:C1",
             "statistics": {
                "discontinuity-time": "2017-06-26T12:34:56-05:00"
             }
           },
           {
             "name": "vnf2:eth2",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",
             "phys-address": "00:01:02:A1:B1:C2",
             "statistics": {
                "discontinuity-time": "2017-06-26T12:34:56-05:00"
             }
           }
         ]
       }
     },

     "ietf-yang-library:modules-state": {
       "module-set-id": "123e4567-e89b-12d3-a456-426655440000",
       "module": [
         {
           "name": "iana-if-type",
           "revision": "2014-05-08",



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           "namespace":
           "urn:ietf:params:xml:ns:yang:iana-if-type",
           "conformance-type": "import"
         },
         {
           "name": "ietf-inet-types",
           "revision": "2013-07-15",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-inet-types",
           "conformance-type": "import"
         },
         {
           "name": "ietf-interfaces",
           "revision": "2014-05-08",
           "feature": [
             "arbitrary-names",
             "pre-provisioning"
           ],
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-interfaces",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-ip",
           "revision": "2014-06-16",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-ip",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-logical-network-element",
           "revision": "2017-03-13",
           "feature": [
             "bind-lne-name"
           ],
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-logical-network-element",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-system",
           "revision": "2014-08-06",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-system",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-yang-library",



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           "revision": "2016-06-21",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-library",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-yang-schema-mount",
           "revision": "2017-05-16",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-schema-mount",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-yang-types",
           "revision": "2013-07-15",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-types",
           "conformance-type": "import"
         }
       ]
     },

     "ietf-system:system-state": {
       "platform": {
         "os-name": "NetworkOS"
       }
     }
   }

B.2.2.2.  Logical Network Element 'vnf1'

   The following shows state data for the example LNE with name "vnf1":

   {
     "ietf-yang-library:modules-state": {
       "module-set-id": "123e4567-e89b-12d3-a456-426655440000",
       "module": [
         {
           "name": "iana-if-type",
           "revision": "2014-05-08",
           "namespace":
           "urn:ietf:params:xml:ns:yang:iana-if-type",
           "conformance-type": "import"
         },
         {
           "name": "ietf-inet-types",
           "revision": "2013-07-15",
           "namespace":



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           "urn:ietf:params:xml:ns:yang:ietf-inet-types",
           "conformance-type": "import"
         },
         {
           "name": "ietf-interfaces",
           "revision": "2014-05-08",
           "feature": [
             "arbitrary-names",
             "pre-provisioning"
           ],
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-interfaces",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-ip",
           "revision": "2014-06-16",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-ip",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-ospf",
           "revision": "2017-03-12",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-ospf",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-routing",
           "revision": "2016-11-04",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-routing",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-system",
           "revision": "2014-08-06",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-system",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-yang-library",
           "revision": "2016-06-21",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-library",
           "conformance-type": "implement"



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         },
         {
           "name": "ietf-yang-types",
           "revision": "2013-07-15",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-types",
           "conformance-type": "import"
         }
       ]
     },

     "ietf-system:system-state": {
       "platform": {
         "os-name": "NetworkOS"
       }
     },

     "ietf-routing:routing-state": {
       "router-id": "192.0.2.1",
       "control-plane-protocols": {
         "control-plane-protocol": [
           {
             "type": "ietf-routing:ospf",
             "name": "1",
             "ietf-ospf:ospf": {
               "instance": [
                 {
                   "af": "ipv4",
                   "areas": {
                     "area": [
                       {
                         "area-id": "203.0.113.1",
                         "interfaces": {
                           "interface": [
                             {
                               "name": "eth1",
                               "cost": 10
                             }
                           ]
                         }
                       }
                     ]
                   }
                 }
               ]
             }
           }
         ]



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       }
     },

     "ietf-interfaces:interfaces-state": {
       "interfaces": {
         "interface": [
           {
             "name": "eth1",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",
             "phys-address": "00:01:02:A1:B1:C1",
             "statistics": {
               "discontinuity-time": "2017-06-26T12:34:56-05:00"
             },
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.11",
                   "prefix-length": 24,
                 }
               ]
             }
           }
         ]
       }
     }
   }

B.2.2.3.  Logical Network Element 'vnf2'

   The following shows state data for the example LNE with name "vnf2":

   {
     "ietf-yang-library:modules-state": {
       "module-set-id": "123e4567-e89b-12d3-a456-426655440000",
       "module": [
         {
           "name": "iana-if-type",
           "revision": "2014-05-08",
           "namespace":
           "urn:ietf:params:xml:ns:yang:iana-if-type",
           "conformance-type": "import"
         },
         {
           "name": "ietf-inet-types",
           "revision": "2013-07-15",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-inet-types",



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           "conformance-type": "import"
         },
         {
           "name": "ietf-interfaces",
           "revision": "2014-05-08",
           "feature": [
             "arbitrary-names",
             "pre-provisioning"
           ],
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-interfaces",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-ip",
           "revision": "2014-06-16",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-ip",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-ospf",
           "revision": "2017-03-12",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-ospf",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-routing",
           "revision": "2016-11-04",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-routing",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-system",
           "revision": "2014-08-06",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-system",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-yang-library",
           "revision": "2016-06-21",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-library",
           "conformance-type": "implement"
         },



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         {
           "name": "ietf-yang-types",
           "revision": "2013-07-15",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-types",
           "conformance-type": "import"
         }
       ]
     },

     "ietf-system:system-state": {
       "platform": {
         "os-name": "NetworkOS"
       }
     },

     "ietf-routing:routing-state": {
       "router-id": "192.0.2.2",
       "control-plane-protocols": {
         "control-plane-protocol": [
           {
             "type": "ietf-routing:ospf",
             "name": "1",
             "ietf-ospf:ospf": {
               "instance": [
                 {
                   "af": "ipv4",
                   "areas": {
                     "area": [
                       {
                         "area-id": "203.0.113.1",
                         "interfaces": {
                           "interface": [
                             {
                               "name": "eth1",
                               "cost": 10
                             }
                           ]
                         }
                       }
                     ]
                   }
                 }
               ]
             }
           }
         ]
       }



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     },

     "ietf-interfaces:interfaces-state": {
       "interfaces": {
         "interface": [
           {
             "name": "eth1",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",
             "phys-address": "00:01:02:A1:B1:C2",
             "statistics": {
               "discontinuity-time": "2017-06-26T12:34:56-05:00"
             },
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.11",
                   "prefix-length": 24,
                 }
               ]
             }
           }
         ]
       }
     }
   }

Authors' Addresses

   Lou Berger
   LabN Consulting, L.L.C.

   Email: lberger@labn.net


   Christan Hopps
   Deutsche Telekom

   Email: chopps@chopps.org


   Acee Lindem
   Cisco Systems
   301 Midenhall Way
   Cary, NC  27513
   USA

   Email: acee@cisco.com



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   Dean Bogdanovic

   Email: ivandean@gmail.com


   Xufeng Liu
   Jabil

   Email: Xufeng_Liu@jabil.com










































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