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Versions: (draft-rtgyangdt-rtgwg-ni-model) 00 01 02 03

Network Working Group                                          L. Berger
Internet-Draft                                   LabN Consulting, L.L.C.
Intended status: Standards Track                                C. Hopps
Expires: January 4, 2018                                Deutsche Telekom
                                                               A. Lindem
                                                           Cisco Systems
                                                           D. Bogdanovic

                                                                  X. Liu
                                                                   Jabil
                                                            July 3, 2017


                         YANG Network Instances
                      draft-ietf-rtgwg-ni-model-03

Abstract

   This document defines a network instance module.  This module can be
   used to manage the virtual resource partitioning that may be present
   on a network device.  Examples of common industry terms for virtual
   resource partitioning are Virtual Routing and Forwarding (VRF)
   instances and Virtual Switch Instances (VSIs).

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 January 4, 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



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   (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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Status of Work and Open Issues  . . . . . . . . . . . . .   3
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Network Instances . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  NI Types and Mount Points . . . . . . . . . . . . . . . .   6
       3.1.1.  Well Known Mount Points . . . . . . . . . . . . . . .   7
       3.1.2.  NI Type Example . . . . . . . . . . . . . . . . . . .   8
     3.2.  NIs and Interfaces  . . . . . . . . . . . . . . . . . . .   9
     3.3.  Network Instance Management . . . . . . . . . . . . . . .  11
     3.4.  Network Instance Instantiation  . . . . . . . . . . . . .  13
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   6.  Network Instance Model  . . . . . . . . . . . . . . . . . . .  14
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  20
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  21
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  22
   Appendix B.  Example NI usage . . . . . . . . . . . . . . . . . .  22
     B.1.  Configuration Data  . . . . . . . . . . . . . . . . . . .  22
     B.2.  State Data  . . . . . . . . . . . . . . . . . . . . . . .  25
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  30

1.  Introduction

   This document defines the second of two new modules that are defined
   to support the configuration and operation of network-devices that
   allow for the partitioning of resources from both, or either,
   management and networking perspectives.  Both leverage the YANG
   functionality enabled by YANG Schema Mount
   [I-D.ietf-netmod-schema-mount].

   The first form of resource partitioning provides a logical
   partitioning of a network device where each partition is separately
   managed as essentially an independent network element which is
   'hosted' by the base network device.  These hosted network elements
   are referred to as logical network elements, or LNEs, and are
   supported by the logical-network-element module defined in



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   [I-D.ietf-rtgwg-lne-model].  That module is used to identify LNEs and
   associate resources from the network-device with each LNE.  LNEs
   themselves are represented in YANG as independent network devices;
   each accessed independently.  Examples of vendor terminology for an
   LNE include logical system or logical router, and virtual switch,
   chassis, or fabric.

   The second form, which is defined in this document, provides support
   for what is commonly referred to as Virtual Routing and Forwarding
   (VRF) instances as well as Virtual Switch Instances (VSI), see
   [RFC4026] and [RFC4664].  In this form of resource partitioning,
   multiple control plane and forwarding/bridging instances are provided
   by and managed via a single (physical or logical) network device.
   This form of resource partitioning is referred to as a Network
   Instance and is supported by the network-instance module defined
   below.  Configuration and operation of each network-instance is
   always via the network device and the network-instance module.

   One notable difference between the LNE model and the NI model is that
   the NI model provides a framework for VRF and VSI management.  This
   document envisions the separate definition of VRF and VSI, i.e., L3
   and L2 VPN, technology specific models.  An example of such can be
   found in the emerging L3VPN model defined in
   [I-D.ietf-bess-l3vpn-yang] and the examples discussed below.

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].

1.2.  Status of Work and Open Issues

   The top open issues are:

   1.  Schema mount currently doesn't allow parent-reference filtering
       on the instance of the mount point, but rather just the schema.
       This means it is not possible to filter based on actual data,
       e.g., bind-network-instance-name="green".  In the schema mount
       definition, the text and examples should be updated to cover this
       case.




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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
   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 [I-D.ietf-rtgwg-lne-model] and the
   model for NIs is covered in this document in Section 3.

   The current interface management model [RFC7223] is impacted by the
   definition of LNEs and NIs.  This document and
   [I-D.ietf-rtgwg-lne-model] define augmentations to the interface
   module to support LNEs and NIs.

   The network instance model supports the configuration of VRFs and
   VSIs.  Each instance is supported by information that relates to the
   device, for example the route target used when advertising VRF routes
   via the mechanisms defined in [RFC4364], and information that relates
   to the internal operation of the NI, for example for routing



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   protocols [RFC8022] and OSPF [I-D.ietf-ospf-yang].  This document
   defines the network-instance module that provides a basis for the
   management of both types of information.

   NI information that relates to the device, including the assignment
   of interfaces to NIs, is defined as part of this document.  The
   defined module also provides a placeholder for the definition of NI-
   technology specific information both at the device level and for NI
   internal operation.  Information related to NI internal operation is
   supported via schema mount [I-D.ietf-netmod-schema-mount] and
   mounting appropriate modules under the mount point.  Well known mount
   points are defined for L3VPN, L2VPN, and L2+L3VPN NI types.

3.  Network Instances

   The network instance container is used to represent virtual routing
   and forwarding instances (VRFs) and virtual switching instances
   (VSIs).  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 supports both core/provider and virtual instances.  Core/
   provider instance information is accessible at the top level of the
   server, while virtual instance information is accessible under the
   root schema mount points.

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
























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   module: ietf-network-instance
     +--rw network-instances
        +--rw network-instance* [name]
           +--rw name           string
           +--rw enabled?       boolean
           +--rw description?   string
           +--rw (ni-type)?
           +--rw (root-type)?
              +--:(vrf-root)
              |  +--mp vrf-root?
              +--:(vsi-root)
              |  +--mp vsi-root?
              +--:(vv-root)
                 +--mp vv-root?
   augment /if:interfaces/if:interface:
     +--rw bind-ni-name?   -> /network-instances/network-instance/name
   augment /if:interfaces/if:interface/ip:ipv4:
     +--rw bind-ni-name?   -> /network-instances/network-instance/name
   augment /if:interfaces/if:interface/ip:ipv6:
     +--rw bind-ni-name?   -> /network-instances/network-instance/name

   notifications:
     +---n bind-ni-name-failed
        +--ro name          -> /if:interfaces/interface/name
        +--ro interface
        |  +--ro bind-ni-name?
        |                  -> /if:interfaces/interface/ni:bind-ni-name
        +--ro ipv4
        |  +--ro bind-ni-name?
        |          -> /if:interfaces/interface/ip:ipv4/ni:bind-ni-name
        +--ro ipv6
        |  +--ro bind-ni-name?
        |          -> /if:interfaces/interface/ip:ipv6/ni:bind-ni-name
        +--ro error-info?   string

   A network instance is identified by a 'name' string.  This string is
   used both as an index within the network-instance module and to
   associate resources with a network instance as shown above in the
   interface augmentation.  The ni-type and root-type choice statements
   are used to support different types of L2 and L3 VPN technologies.
   The bind-ni-name-failed notification is used in certain failure
   cases.

3.1.  NI Types and Mount Points

   The network-instance module is structured to facilitate the
   definition of information models for specific types of VRFs and VSIs
   using augmentations.  For example, the information needed to support



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   VPLS, VxLAN and EVPN based L2VPNs are likely to be quite different.
   Example models under development that could be restructured to take
   advantage on NIs include, for L3VPNs [I-D.ietf-bess-l3vpn-yang] and
   for L2VPNs [I-D.ietf-bess-l2vpn-yang].

   Documents defining new YANG models for the support of specific types
   of network instances should augment the network instance module.  The
   basic structure that should be used for such augmentations include a
   case statement, with containers for configuration and state data and
   finally, when needed, a type specific mount point.  Generally ni
   types, are expected to not need to define type specific mount points,
   but rather reuse one of the well known mount point, as defined in the
   next section.  The following is an example type specific
   augmentation:

    augment "/ni:network-instances/ni:network-instance/ni:ni-type" {
      case l3vpn {
        container l3vpn {
            ...
        }
        container l3vpn-state {
            ...
        }
      }
    }

3.1.1.  Well Known Mount Points

   YANG Schema Mount, [I-D.ietf-netmod-schema-mount], identifies mount
   points by name within a module.  This definition allows for the
   definition of mount points whose schema can be shared across ni-
   types.  As discussed above, ni-types largely differ in the
   configuration information needed in the core/top level instance to
   support the NI, rather than in the information represented within an
   NI.  This allows the use of shared mount points across certain NI
   types.

   The expectation is that there are actually very few different schema
   that need to be defined to support NIs on an implementation.  In
   particular, it is expected that the following three forms of NI
   schema are needed, and each can be defined with a well known mount
   point that can be reused by future modules defining ni-types.

   The three well known mount points are:

   vrf-root
      vrf-root is intended for use with L3VPN type ni-types.




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   vsi-root
      vsi-root is intended for use with L2VPN type ni-types.

   vv-root
      vv-root is intended for use with ni-types that simultaneously
      support L2VPN bridging and L3VPN routing capabilities.

   Future model definitions should use the above mount points whenever
   possible.  When a well known mount point isn't appropriate, a model
   may define a type specific mount point via augmentation.

3.1.2.  NI Type Example

   The following is an example of an L3VPN VRF using a hypothetical
   augmentation to the networking instance schema defined in
   [I-D.ietf-bess-l3vpn-yang].  More detailed examples can be found in
   Appendix B.


































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   module: ietf-network-instance
     +--rw network-instances
        +--rw network-instance* [name]
           +--rw name           string
           +--rw enabled?       boolean
           +--rw description?   string
           +--rw (ni-type)?
           |  +--:(l3vpn)
           |     +--rw l3vpn:l3vpn
           |     |  ... // config data
           |     +--ro l3vpn:l3vpn-state
           |     |  ... // state data
           +--rw (root-type)?
              +--:(vrf-root)
                 +--mp vrf-root
                    +--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]
                    |     +--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
                    +--ro if:interfaces@
                    |  ...
                    +--ro if:interfaces-state@
                    |  ...

   This shows YANG Routing Management [RFC8022] and YANG OSPF
   [I-D.ietf-ospf-yang] as mounted modules.  The mounted modules can
   reference interface information via a parent-reference to the
   containers defined in [RFC7223].

3.2.  NIs and Interfaces

   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,



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   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].

   As shown below, the network-instance module augments the existing
   interface management model by adding a name which is used on
   interface or sub-interface types to identify an associated network
   instance.  Similarly, this name is also added for IPv4 and IPv6
   types, as defined in [RFC7277].

   The following is an example of envisioned usage.  The interfaces
   container includes a number of commonly used components as examples:

   module: ietf-interfaces
      +--rw interfaces
      |  +--rw interface* [name]
      |     +--rw name                        string
      |     +--rw ip:ipv4!
      |     |  +--rw ip:enabled?                      boolean
      |     |  +--rw ip:forwarding?                   boolean
      |     |  +--rw ip:mtu?                          uint16
      |     |  +--rw ip:address* [ip]
      |     |  |  +--rw ip:ip               inet:ipv4-address-no-zone
      |     |  |  +--rw (ip:subnet)
      |     |  |     +--:(ip:prefix-length)
      |     |  |     |  +--rw ip:prefix-length?   uint8
      |     |  |     +--:(ip:netmask)
      |     |  |        +--rw ip:netmask?         yang:dotted-quad
      |     |  +--rw ip:neighbor* [ip]
      |     |  |  +--rw ip:ip                  inet:ipv4-address-no-zone
      |     |  |  +--rw ip:link-layer-address  yang:phys-address
      |     |  +--rw ni:bind-network-instance-name?   string
      |     +--rw ni:bind-network-instance-name?   string

   The [RFC7223] defined interface model is structured to include all
   interfaces in a flat list, without regard to virtual instances (e.g.,
   VRFs) supported on the device.  The bind-network-instance-name leaf
   provides the association between an interface and its associated NI
   (e.g., VRF or VSI).  Note that as currently defined, to assign an
   interface to both an LNE and NI, the interface would first be
   assigned to the LNE using the mechanisms defined in
   [I-D.ietf-rtgwg-lne-model] and then within that LNE's interface
   module, the LNE's representation of that interface would be assigned
   to an NI.




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3.3.  Network Instance Management

   Modules that may be used to represent network instance information
   will be available under the ni-type specific 'root' mount point.  The
   use-schema mechanism defined as part of the Schema Mount module
   [I-D.ietf-netmod-schema-mount] MUST be used with the module defined
   in this document to identify accessible modules.  A future version of
   this document could relax this requirement.  Mounted modules in the
   non-inline case SHOULD be defined with access, via the appropriate
   schema mount parent-references [I-D.ietf-netmod-schema-mount], to
   device resources such as interfaces.

   All modules that represent control-plane and data-plane information
   may be present at the 'root' mount point, and be accessible via paths
   modified per [I-D.ietf-netmod-schema-mount].  The list of available
   modules is expected to be implementation dependent, as is the method
   used by an implementation to support NIs.

   For example, the following could be used to define the data
   organization of the example NI shown in Section 3.1.2:































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     "ietf-yang-schema-mount:schema-mounts": {
       "mount-point": [
         {
           "module": "ietf-network-instance",
           "name": "vrf-root",
           "use-schema": [
             {
               "name": "ni-schema",
               "parent-reference": [
                 "/*[namespace-uri() = 'urn:ietf:...:ietf-interfaces']"
               ]
             }
           ]
         }
       ],
       "schema": [
         {
           "name": "ni-schema",
           "module": [
             {
                "name": "ietf-routing",
                "revision": "2016-11-04",
                "namespace":
                  "urn:ietf:params:xml:ns:yang:ietf-routing",
                "conformance-type": "implement"
              },
             {
                "name": "ietf-ospf",
                "revision": "2017-03-12",
                "namespace":
                  "urn:ietf:params:xml:ns:yang:ietf-ospf",
                "conformance-type": "implement"
             }
           ]
         }
       ]
     }

   Module data identified under "schema" will be instantiated under the
   mount point identified under "mount-point".  These modules will be
   able to reference information for nodes belonging to top-level
   modules that are identified under "parent-reference".  Parent
   referenced information is available to clients via their top level
   paths only, and not under the associated mount point.







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3.4.  Network Instance Instantiation

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

   Once instantiated, host network device resources can be associated
   with the new NI.  As previously mentioned, this document augments
   ietf-interfaces with the bind-ni-name leaf to support such
   associations for interfaces.  When a bind-ni-name is set to a valid
   NI name, an implementation MUST take whatever steps are internally
   necessary to assign the interface to the NI 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 operation, or after asynchronous processing.  Error
   notification in the latter case is supported via a notification.

4.  Security Considerations

   There are two different sets of security considerations to consider
   in the context of this document.  One set is security related to
   information contained within mounted modules.  The security
   considerations for mounted modules are not substantively changed
   based on the information being accessible within the context of an
   NI.  For example, when considering the modules defined in [RFC8022],
   the security considerations identified in that document are equally
   applicable, whether those modules are accessed at a server's root or
   under an NI instance's root node.

   The second area for consideration is information contained in the NI
   module itself.  NI information represents network configuration and
   route distribution policy information.  As such, the security of this
   information is important, but it is fundamentally no different than
   any other interface or routing configuration information that has
   already been covered in [RFC7223] and [RFC8022].

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

   /network-instances/network-instance:  This list specifies the network
      instances and the related control plane protocols configured on a
      device.

   /if:interfaces/if:interface/*/bind-network-instance-name:  This leaf
      indicates the NI instance to which an interface is assigned.



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   Unauthorized access to any of these lists can adversely affect the
   routing subsystem 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-network-instance

        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-network-instance
     namespace:   urn:ietf:params:xml:ns:yang:ietf-network-instance
     prefix:      ni
     reference:   RFC XXXX

6.  Network Instance Model

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

   <CODE BEGINS> file "ietf-network-instance@2017-07-03.yang"
   module ietf-network-instance {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-network-instance";
     prefix ni;

     // import some basic types

     import ietf-interfaces {
       prefix if;
       reference "RFC 7223: A YANG Data Model for Interface
                  Management";
     }
     import ietf-ip {
       prefix ip;
       reference "RFC 7277: A YANG Data Model for IP Management";
     }
     import ietf-yang-schema-mount {



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       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 network instances
        within a single physical or virtual device.  Network
        instances are commonly known as VRFs (virtual routing
        and forwarding) and VSIs (virtual switching instances).

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

     revision 2017-07-02 {
       description
         "Initial revision.";
       reference "RFC TBD";
     }



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     // top level device definition statements

     container network-instances {
       description
         "Network instances each of which consists of a
          VRFs (virtual routing and forwarding) and/or
          VSIs (virtual switching instances).";
       reference "RFC 8022 - A YANG Data Model for Routing
                  Management";
       list network-instance {
         key "name";
         description
           "List of network-instances.";
         leaf name {
           type string;
           description
             "device scoped identifier for the network
              instance.";
         }
         leaf enabled {
           type boolean;
           default "true";
           description
             "Flag indicating whether or not the network
              instance is enabled.";
         }
         leaf description {
           type string;
           description
             "Description of the network instance
              and its intended purpose.";
         }
         choice ni-type {
           description
             "This node serves as an anchor point for different types
              of network instances.  Each 'case' is expected to
              differ in terms of the information needed in the
              parent/core to support the NI, and may differ in their
              mounted schema definition. When the mounted schema is
              not expected to be the same for a specific type of NI
              a mount point should be defined.";
         }
         choice root-type {
           description
             "Well known mount points.";
           yangmnt:mount-point "vrf-root" {
             description
               "Root for L3VPN type models. This will typically



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                not be an inline type mount point.";
           }
           yangmnt:mount-point "vsi-root" {
             description
               "Root for L2VPN type models. This will typically
                not be an inline type mount point.";
           }
           yangmnt:mount-point "vv-root" {
             description
               "Root models that support both L2VPN type bridging
                and L3VPN type routing. This will typically
                not be an inline type mount point.";
           }
         }
       }
     }

     // augment statements

     augment "/if:interfaces/if:interface" {
       description
         "Add a node for the identification of the network
          instance associated with the information configured
          on a interface.

          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 'ni-assignment-failed'.  A meaningful
          error-info that indicates the source of the assignment
          failure SHOULD also be provided.";
       leaf bind-ni-name {
         type leafref {
           path "/network-instances/network-instance/name";
         }
         description
           "Network Instance to which an interface is bound.";
       }
     }
     augment "/if:interfaces/if:interface/ip:ipv4" {
       description
         "Add a node for the identification of the network
          instance associated with the information configured
          on an IPv4 interface.

          Note that a standard error will be returned if the
          identified leafref isn't present.  If an interfaces cannot



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          be assigned for any other reason, the operation SHALL fail
          with an error-tag of 'operation-failed' and an
          error-app-tag of 'ni-assignment-failed'.  A meaningful
          error-info that indicates the source of the assignment
          failure SHOULD also be provided.";
       leaf bind-ni-name {
         type leafref {
           path "/network-instances/network-instance/name";
         }
         description
           "Network Instance to which IPv4 interface is bound.";
       }
     }
     augment "/if:interfaces/if:interface/ip:ipv6" {
       description
         "Add a node for the identification of the network
          instance associated with the information configured
          on an IPv6 interface.

          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 'ni-assignment-failed'.  A meaningful
          error-info that indicates the source of the assignment
          failure SHOULD also be provided.";
       leaf bind-ni-name {
         type leafref {
           path "/network-instances/network-instance/name";
         }
         description
           "Network Instance to which IPv6 interface is bound.";
       }
     }

     // notification statements

     notification bind-ni-name-failed {
       description
         "Indicates an error in the association of an interface to an
          NI. Only generated after success is initially returned when
          bind-ni-name is set.

          Note: some errors may need to be reported for multiple
          associations, e.g., a single error may need to be reported
          for an IPv4 and an IPv6 bind-ni-name.

          At least one container with a bind-ni-name leaf MUST be



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          included in this notification.";
       leaf name {
         type leafref {
           path "/if:interfaces/if:interface/if:name";
         }
         mandatory true;
         description
           "Contains the interface name associated with the
           failure.";
       }
       container interface {
         description
           "Generic interface type.";
         leaf bind-ni-name {
           type leafref {
             path "/if:interfaces/if:interface/ni:bind-ni-name";
           }
           description
             "Contains the bind-ni-name associated with the
              failure.";
         }
       }
       container ipv4 {
         description
           "IPv4 interface type.";
         leaf bind-ni-name {
           type leafref {
             path "/if:interfaces/if:interface"
               + "/ip:ipv4/ni:bind-ni-name";
           }
           description
             "Contains the bind-ni-name associated with the
              failure.";
         }
       }
       container ipv6 {
         description
           "IPv6 interface type.";
         leaf bind-ni-name {
           type leafref {
             path "/if:interfaces/if:interface"
               + "/ip:ipv6/ni:bind-ni-name";
           }
           description
             "Contains the bind-ni-name associated with the
              failure.";
         }
       }



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       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-05 (work in progress), May 2017.

   [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.

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

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <http://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,
              <http://www.rfc-editor.org/info/rfc6020>.

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

   [RFC7277]  Bjorklund, M., "A YANG Data Model for IP Management",
              RFC 7277, DOI 10.17487/RFC7277, June 2014,
              <http://www.rfc-editor.org/info/rfc7277>.







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7.2.  Informative References

   [I-D.ietf-bess-l2vpn-yang]
              Shah, H., Brissette, P., Chen, I., Hussain, I., Wen, B.,
              and K. Tiruveedhula, "YANG Data Model for MPLS-based
              L2VPN", draft-ietf-bess-l2vpn-yang-05 (work in progress),
              March 2017.

   [I-D.ietf-bess-l3vpn-yang]
              Jain, D., Patel, K., Brissette, P., Li, Z., Zhuang, S.,
              Liu, X., Haas, J., Esale, S., and B. Wen, "Yang Data Model
              for BGP/MPLS L3 VPNs", draft-ietf-bess-l3vpn-yang-01 (work
              in progress), April 2017.

   [I-D.ietf-ospf-yang]
              Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem,
              "Yang Data Model for OSPF Protocol", draft-ietf-ospf-
              yang-08 (work in progress), July 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-lne-model]
              Berger, L., Hopps, C., Lindem, A., and D. Bogdanovic,
              "YANG Logical Network Elements", draft-ietf-rtgwg-lne-
              model-02 (work in progress), March 2017.

   [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
              Private Network (VPN) Terminology", RFC 4026,
              DOI 10.17487/RFC4026, March 2005,
              <http://www.rfc-editor.org/info/rfc4026>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <http://www.rfc-editor.org/info/rfc4364>.

   [RFC4664]  Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer
              2 Virtual Private Networks (L2VPNs)", RFC 4664,
              DOI 10.17487/RFC4664, September 2006,
              <http://www.rfc-editor.org/info/rfc4664>.

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





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   [RFC8022]  Lhotka, L. and A. Lindem, "A YANG Data Model for Routing
              Management", RFC 8022, DOI 10.17487/RFC8022, November
              2016, <http://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.

Appendix B.  Example NI usage

   The following subsections provide example uses of NIs.

B.1.  Configuration Data

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

   {
     "ietf-network-instance:network-instances": {
       "network-instance": [
         {
           "name": "vrf-red",
           "vrf-root": {
             "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": [



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                                     {
                                       "name": "eth1",
                                       "cost": 10
                                     }
                                   ]
                                 }
                               }
                             ]
                           }
                         }
                       ]
                     }
                   }
                 ]
               }
             }
           }
         },
         {
           "name": "vrf-blue",
           "vrf-root": {
             "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": "eth2",
                                       "cost": 10
                                     }
                                   ]
                                 }
                               }
                             ]
                           }
                         }



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                       ]
                     }
                   }
                 ]
               }
             }
           }
         }
       ]
     },

     "ietf-interfaces:interfaces": {
       "interfaces": {
         "interface": [
           {
             "name": "eth0",
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.10",
                   "prefix-length": 24,
                 }
               ]
             }
           },
           {
             "name": "eth1",
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.11",
                   "prefix-length": 24,
                 }
               ]
             },
             "ni:bind-network-instance-name": "vrf-red"
           },
           {
             "name": "eth2",
             "ip:ipv4": {
               "address": [
                 {
                   "ip": "192.0.2.11",
                   "prefix-length": 24,
                 }
               ]
             },
             "ni:bind-network-instance-name": "vrf-blue"



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           }
         ]
       }
     },

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

B.2.  State Data

   The following shows state data for the example above.

   {
     "ietf-network-instance:network-instances": {
       "network-instance": [
         {
           "name": "vrf-red",
           "vrf-root": {
             "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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                                   ]
                                 }
                               }
                             ]
                           }
                         }
                       ]
                     }
                   }
                 ]
               }
             }
           }
         },
         {
           "name": "vrf-blue",
           "vrf-root": {
             "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": "eth2",
                                       "cost": 10
                                     }
                                   ]
                                 }
                               }
                             ]
                           }
                         }
                       ]
                     }
                   }
                 ]



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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": "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": "eth2",
             "type": "iana-if-type:ethernetCsmacd",
             "oper-status": "up",



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             "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-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"
         },
         {
           "name": "ietf-ip",
           "revision": "2014-06-16",



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           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-ip",
           "conformance-type": "implement"
         },
         {
           "name": "ietf-network-instance",
           "revision": "2017-03-13",
           "feature": [
             "bind-network-instance-name"
           ],
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-network-instance",
           "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",
           "revision": "2017-05-16",
           "namespace":
           "urn:ietf:params:xml:ns:yang:ietf-yang-schema-mount",
           "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"
       }
     }
   }

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


   Dean Bogdanovic

   Email: ivandean@gmail.com








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   Xufeng Liu
   Jabil

   Email: Xufeng_Liu@jabil.com















































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