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Versions: 00 01 02 03 04 05 draft-ietf-rtgwg-device-model

Network Working Group                                          A. Lindem
Internet-Draft                                                     Cisco
Intended status: Informational                            L. Berger, Ed.
Expires: January 7, 2016                                            LabN
                                                           D. Bogdanovic

                                                                C. Hopps
                                                        Deustche Telekom
                                                            July 6, 2015


                Network Device YANG Organizational Model
                 draft-rtgyangdt-rtgwg-device-model-00

Abstract

   This document presents an approach for organizing YANG models in a
   comprehensive structure that defines how individual models may be
   composed to configure and operate network infrastructure and
   services.  The structure is itself represented as a YANG model rooted
   at a device, with all of the related component models logically
   organized in a way that is operationally intuitive. 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.

Status of This Memo

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

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

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

   This Internet-Draft will expire on September 10, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   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.

Contents

   1.       Introduction
   1.1.     Status of Work and Open Issues
   2.       Model Overview
   2.1.     Interface Model Components
   2.2.     Logical Network Elements
   2.2.1.   System Management
   2.2.2.   Network Instances
   2.2.2.1. OAM Protocols
   2.2.2.2. Network Instance Policy
   2.2.2.3. Control Plane Protocols
   2.2.2.4. RIBs
   2.2.2.5. MPLS
   2.2.2.6. Networking Services
   2.3.     Device View vs Logical Network Element (LNE) View Management
   3.       Populating the structural model
   3.1.     Constructing the device model
   3.2.     "Pull" approach for model composition
   3.3.     "Push" approach for model composition
   4.       Security Considerations
   5.       IANA Considerations
   6.       YANG module
   6.1.     Model structure
   7.       References
   7.1.     Normative references
   7.2.     Informative references














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1.  Introduction

   "Operational Structure and Organization of YANG Models" [OC-STRUCT],
   highlights the value of organizing individual, self-standing YANG
   [RFC6020] models into a more comprehensive device-level model.  This
   document builds on that work and presents a derivative structure for
   use in representing the networking infrastructure aspects of physical
   and virtual devices.

   This document aims to provide an extensible structure that can be
   used to tie together other models. It allows for existing, emerging,
   and future models. The overall structure can be constructed using
   YANG augmentation and imports.

   Additional motivation for this work can be found in [OC-STRUCT].

   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, nor does
   it specify details of how hardware-related data should be organized.
   We focus on the set of models that are commonly used by network
   operators, and suggest a corresponding organization.

   A significant portion of the text and model contained in this
   document was taken from the -00 of that document.

1.1.  Status of Work and Open Issues

   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.  Disagreement and open issues
   remain, even within the design team.  Major open issues are as
   follows:

   1. The structure related to L2VPNs, Ethernet services, and virtual
      switching instances has not yet received sufficient discussion
      and is likely to change.

   2. Additional discussion and text is need to ensure that the
      interpretation of different policy containers is clear.

   3. Configuration information related to network-instance
      interconnection (over a "core" network) is currently commingled
      with configuration related to operation within the instance.


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   4. The representation of operational state is currently missing.  The
      model will be updated once the "opstate" requirements are
      addressed.

2.  Model Overview

   The model organization can itself be thought of as a "meta-model",
   in that it describes the relationships between individual models.  We
   choose to represent it also as simple YANG model consisting of lists
   and containers to serve as anchor points for the corresponding
   individual models.

   As shown below, our model is rooted at a "device", which represents a
   network router, switch, or similar network element.  The model is
   applicable to both physical, hardware-based devices, as well as
   software-based devices such as virtual network functions (VNFs).  It
   does 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.

     +--rw device
          +--rw info
          |  +--rw device-type?   enumeration
          +--rw hardware
          +--rw interfaces
          |  +--rw interface* [name]
          |     ...
          +--rw qos
          +--rw logical-network-elements
          |     ...

   The key subsystems are represented at the top level of the device,
   including, system-wide configuration, interfaces, and routing
   instances.  The info section can be used for basic device information
   such as its type (e.g., physical or virtual), vendor, and model.  For
   physical devices, the hardware container is intended to be a
   placeholder for platform-specific configuration and operational state
   data.  For example, a common structure for the hardware model might
   include chassis, line cards, and ports, but we leave this
   unspecified.

2.1.  Interface Model Components

   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


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   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 model is taken from [RFC7223] and includes possible
   technology-specific augmentations using example technologies defined
   in [RFC7277]. Also included are examples of envisioned models
   in order to provide future guidance.

   The interfaces container includes a number of commonly used
   components as examples:

          +--rw interfaces
          |  +--rw interface* [name]
          |     +--rw name                       string
          |     +--rw bind-network-element-id?   uint8
          |     +--rw ethernet
          |     |  +--rw bind-networking-instance-name?   string
          |     |  +--rw aggregates
          |     |  +--rw rstp
          |     |  +--rw lldp
          |     |  +--rw ptp
          |     +--rw vlans
          |     +--rw tunnels
          |     +--rw ipv4
          |     |  +--rw bind-networking-instance-name?   string
          |     |  +--rw arp
          |     |  +--rw icmp
          |     |  +--rw vrrp
          |     |  +--rw dhcp-client
          |     +--rw ipv6
          |        +--rw bind-networking-instance-name?   string
          |        +--rw vrrp
          |        +--rw icmpv6
          |        +--rw nd
          |        +--rw dhcpv6-client

   The bind-networking-instance-name leaf is an explicit and notable
   addition.  The [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-networking-instance-name leaf provides the association between
   an interface and the networking instance (e.g., VRF or virtual switch
   instance) that is configured to use it.

2.2.  Logical Network Elements



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   Logical network elements represent the capability on 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 will have
   just a single container.  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:

     +--rw device
          +--rw logical-network-elements
             +--rw logical-network-element* [network-element-id]
                +--rw network-element-id                  uint8
                +--rw network-element-name?               string
                +--rw default-networking-instance-name?   string
                +--rw system-management
                |  ...
                +--rw ietf-acl
                +--rw ietf-key-chain
                +--rw networking-instances
                |  ...

   Network-element-id and network-element-name identify the logical
   network element.

   Default-networking-instance-name identifies the networking instance
   to use for system management connectivity.  Other instances may
   access system management function through appropriate inter-instance
   configuration.

2.2.1.  System Management

   The model supports the potentially independent system management
   functions and configuration per logical network element. This
   permits, for example, different users to manage either the whole
   device or just the associated logical network element.  System
   management is supported by the system-management container which is
   expected to reuse and augment [RFC7317] and is shown below:

     +--rw device
          +--rw logical-network-elements
                +--rw system-management
                |  +--rw device-view?                      boolean


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                |  +--rw syslog
                |  +--rw dns
                |  +--rw ntp
                |  +--rw statistics-collection
                |  +--rw ssh
                |  +--rw tacacs
                |  +--rw snmp
                |  +--rw netconf

   The device-view leaf is used to indicate if the system management
   functions associated with the logical network element are restricted
   to the logical network element or can manage the whole device.  The
   leaf may have a fixed value.  For example, some implementations may
   only support management on a device-wide basis.  Additional
   information on the implications of this leaf can be found in Section
   2.3.

2.2.2.  Network Instances

   The network instance container is used to represent virtual routing
   and forwarding instances (VRFs) and virtual switching instances
   (VSIs), [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 [RTG-CFG] and are
   shown below:

     +--rw device
          +--rw logical-network-elements
                +--rw networking-instances
                   +--rw networking-instance* [networking-instance-name]
                      +--rw networking-instance-name    string
                      +--rw type?                       identityref
                      +--rw enabled?                    boolean
                      +--rw router-id?                  uint32
                      +--rw description?                string
                      +--rw oam-protocols
                      |  ...
                      +--rw networking-instance-policy
                      |  ...
                      +--rw control-plane-protocols
                      |  ...
                      +--rw ribs
                      |  ...
                      +--rw mpls
                      |  ...
                      +--rw networking-services


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                          ...

  [Editor's note: L2/MAC forwarding table is TBD]

2.2.2.1.  OAM Protocols

   OAM protocols that may run within the context of a network instance
   are grouped.  Examples shown below include Bi-directional Forwarding
   Detection (BFD), Ethernet Connectivity Fault Management (CFM), and
   Two-Way Active Measurement Protocol (TWAMP):

     +--rw device
          +--rw logical-network-elements
                +--rw networking-instances
                   +--rw networking-instance* [networking-instance-name]
                      +--rw oam-protocols
                      |  +--rw bfd
                      |  +--rw cfm
                      |  +--rw twamp

2.2.2.2.  Network Instance Policy

   Network instance policies are used to control provider instances, VRF
   routing policies, and VRF/VSI identifiers. Examples include BGP route
   targets (RTs) and route distinguishers (RDs), if the instances is a
   core/provider instance, virtual network identifiers(VN-IDs), VPLS
   neighbors, etc. The structure is:

     +--rw device
          +--rw logical-network-elements
                +--rw networking-instances
                   +--rw networking-instance* [networking-instance-name]
                      +--rw networking-instance-policy
                        (TBD)

2.2.2.3.  Control Plane Protocols

   Control plane protocols that may run within the context of a network
   instance are grouped. Each protocol is expected to have its own
   model.  Note that protocol specific policy is included with the
   protocol rather than being combined in a separate generic policy
   grouping. The rationale behind this is that this ensures that only
   protocol relevant policies may be configured.  A reusable or common
   approach may still be leveraged in creating these policy groupings,
   perhaps based on [RTG-POLICY].




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     +--rw device
          +--rw logical-network-elements
                +--rw networking-instances
                   +--rw networking-instance* [networking-instance-name]
                      +--rw control-plane-protocols
                      |  +--rw bgp
                      |  |  +--rw policy
                      |  +--rw is-is
                      |  |  +--rw policy
                      |  +--rw ospf
                      |  |  +--rw policy
                      |  +--rw rsvp
                      |  +--rw segment-routing
                      |  +--rw ldp
                      |  +--rw pim
                      |  +--rw igmp
                      |  +--rw mld
                      |  +--rw static-routes

2.2.2.4.  RIBs

   Every routing instance manages one or more routing information bases
   (RIB).  A RIB is a list of routes complemented with administrative
   data. RIBs reuse and build on [RTG-CFG] and are shown below:

     +--rw device
          +--rw logical-network-elements
                +--rw networking-instances
                   +--rw networking-instance* [networking-instance-name]
                      +--rw ribs
                      |  +--rw rib* [name]
                      |     +--rw name           string
                      |     +--rw description?   string
                      |     +--rw policy

2.2.2.5.  MPLS

    MPLS data plane related information is grouped together. MPLS
    control plane protocols are included above.  MPLS may reuse and
    build on [OC-MPLS] or other emerging models and is shown below:

     +--rw device
          +--rw logical-network-elements
                +--rw networking-instances
                   +--rw networking-instance* [networking-instance-name]
                      +--rw mpls
                      |  +--rw global
                      |  +--rw label-switched-paths


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                      |  +--rw constrained-path
                      |  +--rw igp-congruent
                      |  +--rw static

2.2.2.6.  Networking Services

  A device may provide services to other devices within the scope of a
  networking instance. 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:

     +--rw device
          +--rw logical-network-elements
                +--rw networking-instances
                   +--rw networking-instance* [networking-instance-name]
                      +--rw networking-services
                           +--rw ntp-server
                           +--rw dns-server
                           +--rw dhcp-server

2.3.  Device View vs Logical Network Element (LNE) View Management

   On some devices it is possible to limit control and management to a
   scoped set of system resources.  As stated above in Section 2.2., the
   documented approach supports this capability using logical network
   elements and the system management device-view leaf.

   When the device-view leaf is set to true, information accessible via
   a logical network element's system management functions represents
   the complete device.  This applies to all system management
   functions, not just those represented in the YANG model.   When
   viewing information represented in a YANG model, the device model
   will cover the full device and allow management across all logical
   network elements.

   The case when a logical network element's system management functions
   do not have a device wide view is more complex.  In this case, there
   are two perspectives: one from functions that are operating within a
   context of a logical network element that has a device wide view (or
   more simply have a "device view"); and the other from functions that
   are operating within a context of a logical network element that has
   only a logical network element view (or more simply have an "LNE
   view").

   From a management function operating with a device view, the
   limited logical network element's system management device-view
   leaf is simply set to false.



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   Management functions operating with an LNE view can only see
   information (e.g., resources, interfaces, configuration, operational
   state, etc.) associated with in the logical network element.  When
   viewing information represented in a YANG model, a full device model
   (as defined in this document) is available from within the view, but
   it includes only those elements associated with the LNE.  For
   information contained with the logical-network-element container
   entry, this is the same information as available in a device wide
   view.  Information outside the logical-network-elements container is
   made available within an LNE view as is appropriated based on device
   wide configuration.  For example, interfaces assigned to the logical
   network element can be managed from within the LNE view.  Note: some
   information that can be modified from a device view may be read-only
   from within the LNE view.

   Multiple implementation approaches are possible to provide LNE views,
   and these are outside the scope of this document.

3.  Populating the structural model

   The structural model in this document describes how individual YANG
   models may be used together to represent the configuration and
   operational state for all parts of a physical or virtual device.  It
   does not, however, document the actual model in its entirety.  In
   this section, we outline an option for creating the full model and
   also describe how it may be used.

3.1.  Constructing the device model

   One of the challenges in assembling existing YANG models is that they
   are generally written with the assumption that each model is at the
   root of the configuration or state tree.  Combining models then
   results in a multi-rooted tree that does not follow any logical
   construction and makes it difficult to work with operationally.  In
   some cases, models explicitly reference other models (e.g., via
   augmentation) to define a relationship, but this is the case for only
   a few existing models.

   Some examples include the interfaces [RFC7223] and IP management
   [RFC7277] models, and proposed IS-IS [RTG-ISIS], OSPF [RTG-OSPF] and
   routing configuration [RTG-CFG] models.

3.2.  "Pull" approach for model composition

   To enable model composition, one possible approach is to avoid using
   root-level containers in individual component models.  Instead, the
   top level container (and all other data definitions) can be enclosed
   in a YANG 'grouping' statement so that when the model is imported by


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   another model, its location in the configuration tree can be
   controlled by the importing YANG module with the 'uses' statement.
   One advantage of this approach is that the importing module has the
   flexibility to readily use the data definitions where the author
   deems appropriate.

   One obvious drawback is that individual models no longer contain any
   of their own data definitions and must be used by a higher-level
   model for their data nodes to become active.  Some judgment as to
   which models are more suited for inclusion in higher level models is
   also necessary to decide when the corresponding YANG module should
   contain only groupings.  Another potential drawback is that this
   approach does not define a common structure for models to fit
   together, limiting interoperability due to implementations using
   different structures.  To address this, a top-level standard model
   structure could be defined and updated to import new models into the
   hierarchy as they are defined.

3.3.  "Push" approach for model composition

   An alternative approach is to develop a top level model which defines
   the overall structure of the models, similar to the structure
   described in Section 2.  Individual models may augment the top level
   model with their data nodes in the appropriate locations.  The
   drawback is the need for a pre-defined top level model structure.  On
   the other hand, when this top level model is standardized, it can
   become the basis for a vendor-neutral way to manage devices, assuming
   that the component models are supported by a given implementation.

   One question in both approaches is what the root of the top-level
   model should be.  In this document we selected to base the model at a
   device because this layer should be common across many use cases and
   implementations.  Starting at a higher layer (e.g., services) makes
   defining and agreeing on a common organization more challenging as
   discussed in Section 1.1.

   Ideally, one could consider a hybrid construction mechanism that
   supports both styles of model composition.  For example, a YANG
   compiler or preprocessing directive could be used to indicate whether
   an individual model should assume it is at the root, or whether it is
   meant for inclusion in other higher-level models.

4.  Security Considerations

   The model structure described in this document does not define actual
   configuration and state data, hence it is not directly responsible
   for security risks.



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   However, 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.

5.  IANA Considerations

   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"
   [RFC3688].  The YANG structure modules will be registered in the
   "YANG Module Names" registry [RFC6020].

6.  YANG module

   The model structure is described by the YANG module below.

6.1.  Model structure

   <CODE BEGINS> file "model-structure.yang"
   module model-structure {

     yang-version "1";

     // namespace
     namespace "urn:ietf:params:xml:ns:yang:model-structure";

     prefix "struct";

     // import some basic types


     // meta
     organization "OpenConfig working group/IETF RTG YANG Design Team";

     contact
       "OpenConfig working group netopenconfig@googlegroups.com
        Routing Area YANG Architecture DT 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 "2015-07-09" {


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       description
         "First Pass of IETF Routing YANG Design Team";
       reference "draft-rtgyangdt-rtgwg-device-model-00.txt";
     }

     // extension statements

     // feature statements

     // identity statements

     // typedef statements

     // grouping statements

     grouping info {
       description
         "Base system information";

       container info {
         description
           "This container is for base system information, including
           device type (e.g., physical or virtual), model, serial no.,
           location, etc.";

         leaf device-type {
           //TODO: consider changing to an identity if finer grained
           // device type classification is envisioned
           type enumeration {
             enum PHYSICAL {
               description "physical or hardware device";
             }
             enum VIRTUAL {
               description "virtual or software device";
             }
           }
           description
             "Type of the device, e.g., physical or virtual.  This node
             may be used to activate other containers in the model";
         }

       }
     }

     grouping hardware {
       description
         "hardware / vendor -specific data relevant to the platform";


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       container hardware {
         description
           "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";
       }
     }

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

     }

     grouping interfaces {
       description "interface-related models";
       container interfaces {
         description "Various interface models";
         reference "RFC 7223 - A Yang Model for Interface Management";
         list interface {
           key "name";
           description "List of interfaces keyed by name";
           leaf name {
               type string;
               description "Interface name";
           }
           leaf bind-network-element-id {
             type uint8;
             description "Logical network element ID to which
                          interface is bound";
           }
           container ethernet {
             description "Ethernet interface config, e.g., 10, 40,
                          100GB Ethernet";
             leaf bind-networking-instance-name {
                 type string;
                 description "Networking Instance to which
                              the Ethernet instance is bound";
             }
             container aggregates {
                 description
                     "LAGs, LACP, etc. for Ethernet interfaces";
                 reference "IEEE 802.1ad, 802.1AX";
             }
             container rstp {
                 description "Rapid Spanning Tree Protocol";

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                 reference "IEEE 802.1D-2004";
             }
             container lldp {
                 description "link layer discovery protocol";
                 reference "IEEE 802.1AB";
             }
             container ptp {
                 description
                     "Precision Time Protocol (PTP) for time
                      synchronization services. PTP typically requires
                      per-interface configuration";
                 reference "IEEE 1588-2008";
             }
           }
           container vlans {
               description "VLANs, 802.1q, q-in-q, etc.";
               reference "IEEE 802.1Q";
           }
           container tunnels {
               description
                   "Logical tunnel interfaces incl. GRE, VxLAN,
                     L2TP etc.";
           }

           container ipv4 {
             description "IPv4 interface";
             reference "RFC 7277 - A Yang Model for IP Management";
             leaf bind-networking-instance-name {
                 type string;
                 description "Networking Instance to which
                              IPv4 interface is bound";
             }
             container arp {
               description "Address resolution protocol";
               reference "STD 37 - An Ethernet Address Resolution
                          Protocol";
             }
            container icmp {
              description "Internet Control Message Protocol";
              reference "RFC 792 - Internet Control Message Protocol";
            }
            container vrrp {
              description "virtual router redundancy protocol";
              reference
                "RFC 5798 - Virtual Router Redundancy Protocol
                 (VRRP) Version 3 for IPv4 and IPv6";
             }
            container dhcp-client {
              description "Dynamic Host Configuration Protocol";


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               reference
                 "RFC 2131 - Dynamic Host Configuration Protocol";
            }
           }
           container ipv6 {
             description "IPv6 interface";
               reference "RFC 7277 - A Yang Model for IP Management";
               leaf bind-networking-instance-name {
                   type string;
                   description "Networking Instance to which
                                IPv4 interface is bound";
               }
             container vrrp {
                 description "virtual router redundancy protocol";
                 reference
                     "RFC 5798 - Virtual Router Redundancy Protocol
                      (VRRP) Version 3 for IPv4 and IPv6";
             }
             container icmpv6 {
               description "Internet Control Message Protocol";
               reference
                 "RFC 2463 - Internet Control Message Protocol
                  (ICMPv6) for Internet Protocol Version 6 (IPv6)";
             }
             container nd {
               description "IPv6 Neighbor Discovery";
                 reference "RFC 4861 - Neighbor Discovery for IP
                            version 6 (IPv6)";
             }
            container dhcpv6-client {
              description
                  "Dynamic Host Configuration Protocol Version 6";
               reference
                   "RFC 3315 - Dynamic Host Configuration Protocol
                    for IPv6 (DHCPv6)";
            }
           }
         }
       }
     }

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

     grouping router-id {
         description

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             "This grouping provides router ID.";
         leaf router-id {
             type uint32;  // yang:dotted-quad
             description
               "A 32-bit number in the form of a dotted quad that is
                used by some routing protocols identifying a router.";
             reference
                 "RFC 2328: OSPF Version 2.";
         }
     }

     grouping oam-protocols {
      description
         "Definitions for OAM protocols within a networking-instance";
      container oam-protocols {
          description
              "OAM protocols";
        container bfd {
            description "Bi-directional Forwarding Detection (BFD)
                      configuration";

        }
        container cfm {
            description
               "Ethernet connectivity fault management.  Also includes
                options that are associated with specific interfaces,
                such as maintenance endpoint domains.";
           reference "IEEE 802.1ag";
        }
        container twamp {
            description
                "Two-way active measurement protocol for measuring
                round-trip IP layer performance.";
            reference "RFC 5357 A Two-Way Active Measurement Protocol
                      (TWAMP)";
        }
      }
     }

     grouping mpls {
       description "MPLS and TE configuration";
       container mpls {
         description "MPLS and TE configuration";
         container global {
             description "global MPLS configuration";
         }
        container label-switched-paths {
          description "Models for different types of LSPs";
        }

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        container constrained-path {
          description "traffic-engineered or constrained path LSPs";
        }
        container igp-congruent {
          description "LSPs that follow the IGP-computed path";
        }
        container static {
           description "Statically configured LSPs";
        }
       }
     }

     grouping networking-instance-policy {
       description
           "Networking 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 networking-instance-policy {
           description "Networking Instance Policy -- details TBD";
       }
     }

     grouping control-plane-protocols {
       description "control protocol models";

       container control-plane-protocols {
         description "Control plane protocols and features";

         container bgp {
             description "BGP-4 protocol configuration";
             reference "RFC 4271 - Border Gateway Protocol 4 (BGP-4)";
             container policy {
                 description "Policy specific to BGP";
             }
         }
         container is-is {
             description "ISO IS-IS protocol configuration";
             reference "RFC 1195 - Use of OSI IS-IS for Routing in
                        TCP/IP and Dual Environments";
             container policy {
                 description "Policy specific to IS-IS";
             }
         }


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         container ospf {
             description "Open Shortest Path First (OSPF) protocol
                          configuration";
             reference "RFC 2328 - OSPFv2 Protocol
                        RFC 5340 - OSPF for IPv6";
             container policy {
                 description "Policy specific to OSPF";
             }
         }
         container rsvp {
             description "Resource Reservation Protocol (RSVP)
                          protocol configuration";
             reference "RFC 2205 - Resource ReSerVation Protocol (RSVP)
                        RFC 3209 - RSVP-TE: Extensions to RSVP for LSP
                        Tunnels";
         }
         container segment-routing {
             description "Segment Routing configuration for networking
                          instance";
             reference "draft-likowski-spring-sr-yang";
         }
         container ldp {
             description "Label Distribution Protocol (LDP)
                          configuration";
             reference "RFC 5036 - LDP Specification";
         }
         container pim {
             description "Protocol Independent Multicast (PIM)
                          configuration";
             reference "RFC 4601 - Protocol Independent Multicast -
                        Sparse Mode (PIM-SM) Protocol Specification";
         }
         container igmp {
             description "Internet Group Management Protocol
                          configuration";
             reference "RFC 3376 - Internet Group Management Protocol,
                        Version 3";
         }
         container mld {
             description "Multicast Listener Discovery Protocol
                          configuration";
             reference "RFC 3810 - Multicast Listener Discovery
                        Version 2 (MLDv2 for IPv6)";
         }
         container static-routes {
             description "Static route configuration";
             reference "draft-ietf-netmod-routing-cfg";
         }
       }


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     }

     grouping ribs {
       description
         "Routing Information Bases (RIBs) supported by a
          networking-instance";
       container ribs {
           description
               "RIBs supported by a networking-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";
               }
           }
       }
     }

     grouping networking-services {
       description
         "Networking services provided by the device in the scope of
          the networking-instance";
        container networking-services {
          description "Networking services";
          container ntp-server {
            description "Network Time Protocol (NTP) Server";
            reference "RFC 5905 - Network Time Protocol Version 4:
                       Protocol and Algorithms Specification";

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          }
          container dns-server {
            description "Domain Name System (DNS) Server";
            reference "RFC 1035 - DOMAIN NAMES - IMPLEMENTATION
                      AND SPECIFICATION";
          }
          container dhcp-server {
            description "Dynamic Host Configuration Protocol (DHCP)
                         Server";
            reference "RFC 2131 - Dynamic Host Configuration Protocol";
          }
        }
     }

     grouping system-management {
         description "System management for device or logical network
                      element";
         container system-management {
             description "System management - logical device
                          management with reuse of RFC 7317";
             leaf device-view {
                 type boolean;
                 default "true";
                 description "Flag indicating whether or not the
                              logical network element is able to view
                              and manage the entire device";
             }
             container syslog {
                 description "Syslog configuration";
             }
             container dns {
                 description "Domain Name Service (DNS) and resolver
                              configuration";
             }
             container ntp {
                 description "network time protocol configuration";
             }
             container statistics-collection {
                 description
                     "Mechanisms for data collection from devices,
                      including packet and flow-level sampling";
             }
             container ssh {
                 description "SSH server configuration";
             }
             container tacacs {
                 description "TACACS+ configuration";
             }
             container snmp {


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                 description "System Network Management Protocol
                              (SNMP) configuration";
             }
             container netconf {
                 description "Network Configuration Protocol(NETCONF)";
                 reference "RFC 6020 - YANG - A Data Modeling Language
                            for the Network Configuration Protocol
                            (NETCONF)";
             }
         }
     }

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

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

     grouping qos {
       description "QoS features";

       container qos {
         description "QoS, including policing, shaping, etc.";
       }
     }

     // data definition statements

     container device {
       description "Top-level anchor point for models. Device is a
                    generic L2/L3 network element";
       uses info;
       uses hardware;
       uses interfaces;
       uses qos;
       container logical-network-elements {
         description "Network devices may support multiple logical
         network instances";


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         list logical-network-element {
           key network-element-id;
           description "List of logical network elements";
           leaf network-element-id {
             type uint8; // expect a small number of logical routers
             description "Device-wide unique identifier for the
                          logical network element";
           }
           leaf network-element-name {
             type string;
             description "Descriptive name for the logical network
                          element";
           }
           leaf default-networking-instance-name {
             type string;
             description "Specification of the networking instance to
                          use for management connectivity";
           }
           uses system-management;
           uses ietf-acl;
           uses ietf-key-chain;
           container networking-instances {
               description "Networking 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 networking-instance {
                   key networking-instance-name;
                   description "List of networking-instances";
                   leaf networking-instance-name {
                       type string;
                       description "logical network element scoped
                                    identifier for the networking
                                    instance";
                   }
                   leaf type {
                       type identityref {
                           base networking-instance;
                       }
                       description
                           "The networking instance type -- details TBD
                            Likely types include core, L3-VRF, VPLS,
                            L2-cross-connect, L2-VSI, etc.";
                   }
                   leaf enabled {
                       type boolean;


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                       default "true";
                       description
                         "Flag indicating whether or not the networking
                          instance is enabled.";
                   }
                   uses router-id {
                       description
                           "Router ID for networking instances";
                   }
                   leaf description {
                       type string;
                       description
                         "Description of the networking instance
                         and its intended purpose";
                   }
                   // Note that there is no list of interfaces within
                   // the networking-instance
                   uses oam-protocols;
                   uses networking-instance-policy;
                   uses control-plane-protocols;
                   uses ribs;
                   uses mpls;
                   uses networking-services;
               }
           }
         }
       }

     }

     // augment statements

     // rpc statements

     // notification statements

   }
   <CODE ENDS>












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7.  References

7.1.  Normative references

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2014.

   [RFC7223]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 7223, May 2014.

   [RFC7277]  Bjorklund, M., "A YANG Data Model for IP Management", RFC
              7277, June 2014.

   [RFC7317]  Bierman, A. and M. Bjorklund, "A YANG Data Model for
              System Management", RFC 7317, August 2014.

   [RFC3688]  Mealling, M., "The IETF XML Registry", RFC 3688, January
              2004.

7.2.  Informative references

   [OC-MPLS]  George, J., Fang, L., Osborne, E., Shakir, R., "MPLS TE
              Model for Service Provider Networks",
              draft-openconfig-mpls-consolidated-model-00 (work in
              progress).

   [OC-STRUCT] Shaikh, A., Shakir, R., D'Souza, K., Fang, L.,
              "Operational Structure and Organization of YANG Models",
              draft-openconfig-netmod-model-structure-00 (work in
              progress).

   [RFC4026]  Andersson, L., Madsen, T., "Provider Provisioned Virtual
              Private Network (VPN) Terminology", RFC 4026, March 2005.

   [RFC7277]  Bjorklund, M., "A YANG Data Model for IP Management",
              RFC 7277, June 2014.

   [RTG-CFG]  Lhotka, L., "A YANG Data Model for Routing Management",
              draft-ietf-netmod-routing-cfg-19 (work in progress),
              October 2014.

   [RTG-POLICY]
              Shaikh, A., Shakir, R., D'Souza, K., and C. Chase,
              "Routing Policy Configuration Model for Service Provider
              Networks", draft-shaikh-rtgwg-policy-model-01 (work in
              progress), July 2015.


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   [RTG-OSPF] Yeung, D., Qu, Y., Zhang, J., and D. Bogdanovic, "Yang
              Data Model for OSPF Protocol", draft-yeung-netmod-ospf-02
              (work in progress), October 2014.

   [RTG-ISIS] Litkowski, S., Yeung, D., Lindem, A., Zhang, J., and L.
              Lhotka, "YANG Data Model for ISIS protocol", draft-ietf-
              isis-yang-isis-cfg-04 (work in progress), October 2014.


Appendix A.  Acknowledgments

   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.

   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.

   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.

Contributors

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

   Rob Shakir
   BT
   pp. C3L, BT Centre
   81, Newgate Street
   London  EC1A 7AJ
   UK
   Email: rob.shakir@bt.com
   URI:   http://www.bt.com/

   Kevin D'Souza
   AT&T
   200 S. Laurel Ave
   Middletown, NJ

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   US
   Email: kd6913@att.com

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

   Qin Wu
   Email: bill.wu@huawei.com

   Stephane Litkowski
   Email: stephane.litkowski@orange.com

   Yan Gang
   Email: yangang@huawei.com

Authors' Addresses

   Acee Lindem
   Cisco Systems
   301 Midenhall Way
   Cary, NC  27513
   USA
   Email: acee@cisco.com

   Lou Berger (editor)
   LabN Consulting, L.L.C.
   Email: lberger@labn.net

   Dean Bogdanovic
   Email: ivandean@gmail.com

   Christian Hopps
   Deustche Telekom
   Email: chopps@chopps.org













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