path: root/doc/rfc/rfc8695.txt

Internet Engineering Task Force (IETF)                            X. Liu
Request for Comments: 8695                                Volta Networks
Category: Standards Track                                       P. Sarda
ISSN: 2070-1721                                                 Ericsson
                                                            V. Choudhary
                                                              Individual
                                                           February 2020


      A YANG Data Model for the Routing Information Protocol (RIP)

Abstract

   This document describes a data model for the management of the
   Routing Information Protocol (RIP).  Both RIP version 2 and RIPng are
   covered.  The data model includes definitions for configuration,
   operational state, and Remote Procedure Calls (RPCs).

   The YANG data model in this document conforms to the Network
   Management Datastore Architecture (NMDA).

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8695.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   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
     1.1.  Terminology
     1.2.  Tree Diagrams
     1.3.  Prefixes in Data Node Names
   2.  Design of the Data Model
     2.1.  Scope of the Data Model
     2.2.  Relation to the Core Routing Framework
     2.3.  Protocol Configuration
     2.4.  Protocol States
     2.5.  RPC Operations
     2.6.  Notifications
     2.7.  Optional Features
   3.  Tree Structure
   4.  YANG Module
   5.  IANA Considerations
   6.  Security Considerations
   7.  References
     7.1.  Normative References
     7.2.  Informative References
   Appendix A.  Data Tree Example
   Authors' Addresses

1.  Introduction

   This document introduces a YANG [RFC7950] data model for the Routing
   Information Protocol (RIP) [RFC2453][RFC2080].  RIP was designed to
   work as an Interior Gateway Protocol (IGP) in moderate-size
   Autonomous Systems (AS).

   This YANG data model supports both RIP version 2 and RIPng.  RIP
   version 2 (defined in [RFC2453]) supports IPv4.  RIPng (defined in
   [RFC2080]) supports IPv6.

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   The following terms are defined in [RFC7950] and are not redefined
   here:

   *  augment

   *  data model

   *  data node

1.2.  Tree Diagrams

   A simplified graphical representation of the data model is used in
   this document.  The meaning of the symbols in these diagrams is
   defined in [RFC8340].

1.3.  Prefixes in Data Node Names

   In this document, names of data nodes, actions, and other data model
   objects are often used without a prefix, as long as it is clear from
   the context in which YANG module each name is defined.  Otherwise,
   names are prefixed using the standard prefix associated with the
   corresponding YANG module, as shown in Table 1.

               +-----------+-----------------+-------------+
               | Prefix    | YANG module     | Reference   |
               +===========+=================+=============+
               | yang      | ietf-yang-types | [RFC6991]   |
               +-----------+-----------------+-------------+
               | inet      | ietf-inet-types | [RFC6991]   |
               +-----------+-----------------+-------------+
               | if        | ietf-interfaces | [RFC8343]   |
               +-----------+-----------------+-------------+
               | ip        | ietf-ip         | [RFC8344]   |
               +-----------+-----------------+-------------+
               | rt        | ietf-routing    | [RFC8349]   |
               +-----------+-----------------+-------------+
               | bfd-types | ietf-bfd-types  | [YANG-BFD]  |
               +-----------+-----------------+-------------+
               | isis      | ietf-isis       | [YANG-ISIS] |
               +-----------+-----------------+-------------+
               | key-chain | ietf-key-chain  | [RFC8177]   |
               +-----------+-----------------+-------------+
               | ospf      | ietf-ospf       | [YANG-OSPF] |
               +-----------+-----------------+-------------+

                  Table 1: Prefixes and Corresponding YANG
                                  Modules

2.  Design of the Data Model

2.1.  Scope of the Data Model

   The data model covers RIP version 2 [RFC2453] and RIPng [RFC2080]
   protocols.  The model is designed to be implemented on a device where
   RIP version 2 or RIPng is implemented, and can be used to:

   *  Configure the RIP version 2 or RIPng protocol.

   *  Manage the protocol operational behaviors.

   *  Retrieve the protocol operational status.

   The capabilities described in [RFC1724] are covered.

2.2.  Relation to the Core Routing Framework

   This data model augments the core routing data model "ietf-routing"
   specified in [RFC8349].

     +--rw routing
        +--rw router-id?
        +--rw control-plane-protocols
        |  +--rw control-plane-protocol* [type name]
        |     +--rw type
        |     +--rw name
        |     +--rw rip     <= Augmented by this Model
                    ...

   The "rip" container instantiates a RIP entity that supports RIP
   version 2 or RIPng.  Depending on the implementation of "ietf-
   routing", a RIP instance MAY belong to a logical router or network
   instance.

2.3.  Protocol Configuration

   The data model structure for the protocol configuration is as shown
   below:

     augment /rt:routing/rt:control-plane-protocols/
     rt:control-plane-protocol:
       +--rw rip
          +--rw <per instance configuration>
          +--rw interface* [interface]
             +--rw interface                  if:interface-ref
             +--rw <per interface configuration>
             +--rw neighbors {explicit-neighbors}?
             |  +--rw neighbor* [address]
             |     +--rw address    inet:ip-address
             |     +--rw <per neighbor configuration>

   The data model allows the configuration of the following protocol
   entities:

   *  Protocol instance (RIP version 2 or RIPng)

   *  Interface

   *  Neighbor

2.4.  Protocol States

   The data model structure for the protocol states is as shown below:

     augment /rt:routing/rt:control-plane-protocols/
     rt:control-plane-protocol:
       +--rw rip
          +--ro <per instance operational states>
          +--rw interface* [interface]
          |  +--rw interface                  if:interface-ref
          |  +--ro <per instance operational states>
          |  +--ro statistics {interface-statistics}?
          |     +--ro <per instance statistics>
          +--ro ipv4
          |  +--ro neighbors
          |  |  +--ro neighbor* [ipv4-address]
          |  |     +--ro <per neighbor IPv4 operational states>
          |  +--ro routes
          |     +--ro route* [ipv4-prefix]
          |        +--ro <IPv4 RIP route states>
          +--ro ipv6
          |  +--ro neighbors
          |  |  +--ro neighbor* [ipv6-address]
          |  |     +--ro <per neighbor IPv6 operational states>
          |  +--ro routes
          |     +--ro route* [ipv6-prefix]
          |        +--ro ipv6-prefix                    inet:ipv6-prefix
          |        +--ro <IPv4 RIP route states>
          +--ro statistics {global-statistics}?
             +--ro <per instance statistics>

   This model conforms to the Network Management Datastore Architecture
   (NMDA) [RFC8342].  The operational state data is combined with the
   associated configuration data in the same hierarchy [RFC8407].  When
   protocol states are retrieved from the NMDA operational state
   datastore, the returned states cover all "config true" (rw) and
   "config false" (ro) nodes defined in the schema.

   The model allows the retrieval of protocol states at the following
   levels:

   *  Protocol instance (RIP version 2 or RIPng)

   *  Interface

   *  Neighbor

   *  Route

2.5.  RPC Operations

   This model defines one RPC "clear-rip-route" that can be used to
   clear RIP routes from the routing table.

2.6.  Notifications

   This model does not define RIP-specific notifications.  To enable
   notifications, the mechanisms defined in [RFC8639] and [RFC8641] can
   be used.  This mechanism currently allows the user to do the
   following:

   *  Subscribe to notifications on a per-client basis.

   *  Specify subtree filters or XML Path Language (XPath) filters so
      that only interested contents will be sent.

   *  Specify either periodic or on-demand notifications.

2.7.  Optional Features

   This model defines several features that are beyond the basic RIP
   configuration, and it is the responsibility of each vendor to decide
   whether to support a given feature on a device.

3.  Tree Structure

   This document defines the YANG module "ietf-rip", which has the
   following tree structure:

   module: ietf-rip
     augment /rt:routing/rt:control-plane-protocols
   /rt:control-plane-protocol:
       +--rw rip
          +--rw originate-default-route
          |  +--rw enabled?        boolean
          |  +--rw route-policy?   route-policy-ref
          +--rw default-metric?               uint8
          +--rw distance?                     uint8
          +--rw triggered-update-threshold?   uint8
          +--rw maximum-paths?                uint8
          +--rw output-delay?                 uint8
          +--rw distribute-list* [prefix-set-name direction]
          |  +--rw prefix-set-name    prefix-set-ref
          |  +--rw direction          enumeration
          |  +--rw if-name?           if:interface-ref
          +--rw redistribute
          |  +--rw bgp* [asn]
          |  |  +--rw asn             inet:as-number
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw cg-nat!
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw connected!
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw ipsec!
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw isis* [instance]
          |  |  +--rw instance
          |  |  |       -> ../../../../../rt:control-plane-protocol/name
          |  |  +--rw level?          enumeration
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw nat!
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw ospfv2* [instance]
          |  |  +--rw instance
          |  |  |       -> ../../../../../rt:control-plane-protocol/name
          |  |  +--rw route-type?     ospf:route-type
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw ospfv3* [instance]
          |  |  +--rw instance
          |  |  |       -> ../../../../../rt:control-plane-protocol/name
          |  |  +--rw route-type?     ospf:route-type
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw ripv2* [instance]
          |  |  +--rw instance
          |  |  |       -> ../../../../../rt:control-plane-protocol/name
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw ripng* [instance]
          |  |  +--rw instance
          |  |  |       -> ../../../../../rt:control-plane-protocol/name
          |  |  +--rw metric?         uint8
          |  |  +--rw route-policy?   route-policy-ref
          |  +--rw static!
          |     +--rw metric?         uint8
          |     +--rw route-policy?   route-policy-ref
          +--rw timers
          |  +--rw update-interval?     uint16
          |  +--rw invalid-interval?    uint16
          |  +--rw holddown-interval?   uint16
          |  +--rw flush-interval?      uint16
          +--rw interfaces
          |  +--rw interface* [interface]
          |     +--rw interface                  if:interface-ref
          |     +--rw authentication
          |     |  +--rw (auth-type-selection)?
          |     |     +--:(auth-key-chain)
          |     |     |  +--rw key-chain?
    key-chain:key-chain-ref
          |     |     +--:(auth-key)
          |     |        +--rw key?                string
          |     |        +--rw crypto-algorithm?   identityref
          |     +--rw bfd {bfd}?
          |     |  +--rw enable?                     boolean
          |     |  +--rw local-multiplier?           multiplier
          |     |  +--rw (interval-config-type)?
          |     |     +--:(tx-rx-intervals)
          |     |     |  +--rw desired-min-tx-interval?    uint32
          |     |     |  +--rw required-min-rx-interval?   uint32
          |     |     +--:(single-interval)
          |     |        +--rw min-interval?               uint32
          |     +--rw cost?                      uint8
          |     +--rw neighbors {explicit-neighbors}?
          |     |  +--rw neighbor* [address]
          |     |     +--rw address    inet:ip-address
          |     +--rw no-listen?                 empty
          |     +--rw originate-default-route
          |     |  +--rw enabled?        boolean
          |     |  +--rw route-policy?   route-policy-ref
          |     +--rw passive?                   empty
          |     +--rw split-horizon?             enumeration
          |     +--rw summary-address
          |     |  +--rw address?   inet:ip-prefix
          |     |  +--rw metric?    uint8
          |     +--rw timers
          |     |  +--rw update-interval?     uint16
          |     |  +--rw invalid-interval?    uint16
          |     |  +--rw holddown-interval?   uint16
          |     |  +--rw flush-interval?      uint16
          |     +--ro oper-status?               enumeration
          |     +--ro next-full-update?          uint32
          |     +--ro valid-address?             boolean
          |     +--ro statistics {interface-statistics}?
          |        +--ro discontinuity-time?   yang:date-and-time
          |        +--ro bad-packets-rcvd?     yang:counter32
          |        +--ro bad-routes-rcvd?      yang:counter32
          |        +--ro updates-sent?         yang:counter32
          +--ro next-triggered-update?        uint32
          +--ro num-of-routes?                uint32
          +--ro ipv4
          |  +--ro neighbors
          |  |  +--ro neighbor* [ipv4-address]
          |  |     +--ro ipv4-address        inet:ipv4-address
          |  |     +--ro last-update?        yang:date-and-time
          |  |     +--ro bad-packets-rcvd?   yang:counter32
          |  |     +--ro bad-routes-rcvd?    yang:counter32
          |  +--ro routes
          |     +--ro route* [ipv4-prefix]
          |        +--ro ipv4-prefix
    inet:ipv4-prefix
          |        +--ro next-hop?
    inet:ipv4-address
          |        +--ro interface?
    if:interface-ref
          |        +--ro redistributed?                  boolean
          |        +--ro route-type?                     enumeration
          |        +--ro metric?                         uint8
          |        +--ro expire-time?                    uint16
          |        +--ro deleted?                        boolean
          |        +--ro holddown?                       boolean
          |        +--ro need-triggered-update?          boolean
          |        +--ro inactive?                       boolean
          |        +--ro flush-expire-before-holddown?   boolean
          +--ro ipv6
          |  +--ro neighbors
          |  |  +--ro neighbor* [ipv6-address]
          |  |     +--ro ipv6-address        inet:ipv6-address
          |  |     +--ro last-update?        yang:date-and-time
          |  |     +--ro bad-packets-rcvd?   yang:counter32
          |  |     +--ro bad-routes-rcvd?    yang:counter32
          |  +--ro routes
          |     +--ro route* [ipv6-prefix]
          |        +--ro ipv6-prefix
    inet:ipv6-prefix
          |        +--ro next-hop?
    inet:ipv6-address
          |        +--ro interface?
    if:interface-ref
          |        +--ro redistributed?                  boolean
          |        +--ro route-type?                     enumeration
          |        +--ro metric?                         uint8
          |        +--ro expire-time?                    uint16
          |        +--ro deleted?                        boolean
          |        +--ro holddown?                       boolean
          |        +--ro need-triggered-update?          boolean
          |        +--ro inactive?                       boolean
          |        +--ro flush-expire-before-holddown?   boolean
          +--ro statistics {global-statistics}?
             +--ro discontinuity-time?   yang:date-and-time
             +--ro requests-rcvd?        yang:counter32
             +--ro requests-sent?        yang:counter32
             +--ro responses-rcvd?       yang:counter32
             +--ro responses-sent?       yang:counter32

     rpcs:
       +---x clear-rip-route
          +---w input
             +---w rip-instance?   leafref

4.  YANG Module

   <CODE BEGINS> file "ietf-rip@2020-02-20.yang"
   module ietf-rip {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-rip";
     prefix rip;

     import ietf-inet-types {
       prefix inet;
     }
     import ietf-yang-types {
       prefix yang;
     }
     import ietf-interfaces {
       prefix if;
     }
     import ietf-ip {
       prefix ip;
     }
     import ietf-routing {
       prefix rt;
     }
     import ietf-key-chain {
       prefix key-chain;
     }
     import ietf-bfd-types {
       prefix bfd-types;
     }
     import ietf-ospf {
       prefix ospf;
     }
     import ietf-isis {
       prefix isis;
     }

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

        Editor:   Xufeng Liu
                  <mailto:xufeng.liu.ietf@gmail.com>

        Editor:   Prateek Sarda
                  <mailto:prateek.sarda@ericsson.com>

        Editor:   Vikram Choudhary
                  <mailto:vikschw@gmail.com>";
     description
       "This YANG module defines a model for managing Routing
        Information Protocol (RIP), including RIP version 2 and RIPng.

        Copyright (c) 2020 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 8695; see the
        RFC itself for full legal notices.";

     revision 2020-02-20 {
       description
         "Initial revision.";
       reference
         "RFC 8695: A YANG Data Model for Routing Information Protocol
          (RIP).
          RFC 2453: RIP Version 2.
          RFC 2080: RIPng for IPv6.
          RFC 1724: RIP Version 2 MIB Extension.";
     }

     /*
      * Features
      */

     feature bfd {
       description
         "This feature indicates that the RIP implementation on the
          system supports BFD (Bidirectional Forwarding Detection).";
     }

     feature explicit-neighbors {
       description
         "This feature indicates that the system supports explicit
          neighbor configuration on a RIP interface.";
     }

     feature global-statistics {
       description
         "This feature indicates that the system supports collecting
          global statistics data related to RIP.";
     }

     feature interface-statistics {
       description
         "This feature indicates that the system supports collecting
          per-interface statistics data related to RIP.";
     }

     /*
      * Typedefs
      */

     typedef prefix-set-ref {
       type string;
       description
         "A type for a reference to a prefix set.
          The string value is the name identifier for uniquely
          identifying the referenced prefix set, which contains a list
          of prefixes that a routing policy can applied.  The definition
          of such a prefix set is outside the scope of this document.";
     }

     typedef route-policy-ref {
       type string;
       description
         "A type for a reference to a route policy.
          The string value is the name identifier for uniquely
          identifying the referenced routing policy, which contains one
          or more policy rules that can be used for a routing decision.
          The definition of such a routing policy is outside the scope
          of this document.";
     }

     /*
      * Identities
      */

     identity rip {
       base rt:routing-protocol;
       description
         "Identity for the Routing Information Protocol.";
     }

     identity ripv2 {
       base rip:rip;
       description
         "Identity for RIPv2 (RIP version 2).";
     }

     identity ripng {
       base rip:rip;
       description
         "Identity for RIPng.";
     }

     /*
      * Groupings
      */

     grouping originate-default-route-container {
       description
         "Container for settings on whether to originate the default
          route in RIP routing instance.";
       container originate-default-route {
         description
           "Injects the default route into the RIP (RIPv2 or RIPng)
            routing instance.";
         leaf enabled {
           type boolean;
           default "false";
           description
             "'true' if originating default route is enabled.";
         }
         leaf route-policy {
           type route-policy-ref;
           description
             "The conditions of the route policy are applied to the
              default route.";
         }
       }
     }

     grouping redistribute-container {
       description
         "Container of redistribute attributes.";
       container redistribute {
         description
           "Redistributes routes learned from other routing protocols
            into the RIP routing instance.";
         list bgp {
           key "asn";
           description
             "Redistributes routes from the specified BGP (Border
              Gateway Protocol) autonomous system (AS) into the RIP
              routing instance.";
           leaf asn {
             type inet:as-number;
             description
               "BGP autonomous system (AS) number.";
           }
           uses redistribute-route-policy-attributes;
         }
         container cg-nat {
           presence "Present if Carrier-Grade Network Address
                     Translation (CGNAT) routes are redistributed.";
           description
             "Carrier-Grade Network Address Translation (CGNAT)
              routes.";
           uses redistribute-route-policy-attributes;
         }
         container connected {
           presence "Present if directly attached network routes are
                     redistributed.";
           description
             "Redistributes directly attached networks into the RIP
              routing instance.";
           uses redistribute-route-policy-attributes;
         }
         container ipsec {
           presence "Present if IP security routing instance routes
                     are redistributed.";
           description
             "Redistributes routes from the IP security routing
              instance into the RIP routing instance.";
           uses redistribute-route-policy-attributes;
         }
         list isis {
           key "instance";
           description
             "Redistributes IS-IS routes.";
           leaf instance {
             type leafref {
               path "../../../../../rt:control-plane-protocol/rt:name";
             }
             must "derived-from-or-self("
                + "../../../../../rt:control-plane-protocol"
                + "[rt:name = current()]/rt:type, 'isis:isis')" {
               description
                 "The type of the routing protocol must be 'isis'.";
             }
             description
               "Redistributes routes from the specified IS-IS routing
                instance into the RIP routing instance.";
           }
           leaf level {
             type enumeration {
               enum 1 {
                 description
                   "IS-IS level 1 routes.";
               }
               enum 2 {
                 description
                   "IS-IS level 2 routes.";
               }
               enum 1-2 {
                 description
                   "IS-IS level 1-2 routes.";
               }
             }
             description
               "IS-IS level.";
           }
           uses redistribute-route-policy-attributes;
         }
         container nat {
           presence "Present if Network Address Translation (NAT) routes
                     are redistributed.";
           description
             "Redistributes Network Address Translation (NAT)
              routes into the RIP routing instance.";
           uses redistribute-route-policy-attributes;
         }
         list ospfv2 {
           when "derived-from-or-self(../../../rt:type, 'rip:ripv2')" {
             description
               "Applicable to RIPv2.";
           }
           key "instance";
           description
             "Redistributes routes from the specified OSPFv2 routing
              instance into the RIPv2 routing instance.";
           leaf instance {
             type leafref {
               path "../../../../../rt:control-plane-protocol/rt:name";
             }
             must "derived-from-or-self("
                + "../../../../../rt:control-plane-protocol"
                + "[rt:name = current()]/rt:type, 'ospf:ospfv2')" {
               description
                 "The type of the routing protocol must be 'ospfv2'.";
             }
             description
               "OSPFv2 instance ID. Redistributes routes from the
                specified OSPFv2 routing instance into the RIPv2 routing
                instance.";
           }
           leaf route-type {
             type ospf:route-type;
             description
               "Redistributes only those OSPFv2 routes matching the
                specified route type into the RIPv2 routing instance.";
           }
           uses redistribute-route-policy-attributes;
         }
         list ospfv3 {
           when "derived-from-or-self(../../../rt:type, 'rip:ripng')" {
             description
               "Applicable to RIPng.";
           }
           key "instance";
           description
             "Redistributes routes from the specified OSPFv3 routing
              instance into the RIPng routing instance.";
           leaf instance {
             type leafref {
               path "../../../../../rt:control-plane-protocol/rt:name";
             }
             must "derived-from-or-self("
                + "../../../../../rt:control-plane-protocol"
                + "[rt:name = current()]/rt:type, 'ospf:ospfv3')" {
               description
                 "The type of the routing protocol must be 'ospfv3'.";
             }
             description
               "OSPFv3 instance ID. Redistributes routes from the
                specified OSPFv3 routing instance into the RIPng routing
                instance.";
           }
           leaf route-type {
             type ospf:route-type;
             description
               "Redistributes only those OSPFv3 routes matching the
                specified route type into the RIPng routing instance.";
           }
           uses redistribute-route-policy-attributes;
         }
         list ripv2 {
           when "derived-from-or-self(../../../rt:type, 'rip:ripv2')" {
             description
               "Applicable to RIPv2.";
           }
           key "instance";
           description
             "Redistributes routes from another RIPv2 routing instance
              into the current RIPv2 routing instance.";
           leaf instance {
             type leafref {
               path "../../../../../rt:control-plane-protocol/rt:name";
             }
             must "derived-from-or-self("
                + "../../../../../rt:control-plane-protocol"
                + "[rt:name = current()]/rt:type, 'rip:ripv2')" {
               description
                 "The type of the routing protocol must be 'ripv2'.";
             }
             description
               "Redistributes routes from the specified RIPv2 routing
                instance into the RIPv2 routing instance.";
           }
           uses redistribute-route-policy-attributes;
         }
         list ripng {
           when "derived-from-or-self(../../../rt:type, 'rip:ripng')" {
             description
               "Applicable to RIPng.";
           }
           key "instance";
           description
             "Redistributes routes from another RIPng routing instance
              into the current RIPng routing instance.";
           leaf instance {
             type leafref {
               path "../../../../../rt:control-plane-protocol/rt:name";
             }
             must "derived-from-or-self("
                + "../../../../../rt:control-plane-protocol"
                + "[rt:name = current()]/rt:type, 'rip:ripng')" {
               description
                 "The type of the routing protocol must be 'ripng'.";
             }
             description
               "Redistributes routes from the specified RIPng routing
                instance into the RIPng routing instance.";
           }
           uses redistribute-route-policy-attributes;
         }
         container static {
           presence "Present if redistributing static routes.";
           description
             "Redistributes static routes into the RIP routing
              instance.";
           uses redistribute-route-policy-attributes;
         }
       }
       // redistribute
     }
     // redistribute-container

     grouping redistribute-route-policy-attributes {
       description
         "Attributes for redistributing a route policy.";
       leaf metric {
         type uint8 {
           range "0..16";
         }
         description
           "Metric used for the redistributed route. If a metric is
            not specified, the metric configured with the
            default-metric attribute in RIP router configuration is
            used.  If the default-metric attribute has not been
            configured, the default metric for redistributed routes
            is 1.";
       }
       leaf route-policy {
         type route-policy-ref;
         description
           "Applies the conditions of the specified route policy to
            routes that are redistributed into the RIP routing
            instance.";
       }
     }
     // redistribute-route-policy-attributes

     grouping timers-container {
       description
         "Container for settings of basic timers";
       container timers {
         must 'invalid-interval >= (update-interval * 3)' {
           description
             "invalid-interval must be at least three times the value
              for the update-interval argument.";
         }
         must 'flush-interval > invalid-interval' {
           description
             "flush-interval must be larger than the value for the
              invalid-interval argument.";
         }
         description
           "Timers for the specified RIPv2 or RIPng instance or
            interface.";
         leaf update-interval {
           type uint16 {
             range "1..32767";
           }
           units "seconds";
           default "30";
           description
             "Interval at which RIPv2 or RIPng updates are sent.";
         }
         leaf invalid-interval {
           type uint16 {
             range "1..32767";
           }
           units "seconds";
           default "180";
           description
             "Interval before a route is declared invalid after no
              updates are received.  This value is at least three times
              the value for the update-interval argument.";
         }
         leaf holddown-interval {
           type uint16 {
             range "1..32767";
           }
           units "seconds";
           default "180";
           description
             "Interval before better routes are released.";
         }
         leaf flush-interval {
           type uint16 {
             range "1..32767";
           }
           units "seconds";
           default "240";
           description
             "Interval before a route is flushed from the routing
              table. This value must be larger than the value for the
              invalid-interval argument.";
         }
       }
       // timers
     }
     // timers-container

     grouping global-attributes {
       description
         "Global configuration and state attributes.";
       uses originate-default-route-container;
       leaf default-metric {
         type uint8 {
           range "0..16";
         }
         default "1";
         description
           "Set the default metric.";
       }
       leaf distance {
         type uint8 {
           range "1..255";
         }
         default "120";
         description
           "The administrative distance of the RIPv2 or RIPng for the
            current RIPv2 or RIPng instance.";
       }
       leaf triggered-update-threshold {
         type uint8 {
           range "1..30";
         }
         units "seconds";
         default "5";
         description
           "This attribute is used to suppress triggered updates.
            When the arrival of a regularly scheduled update matches the
            number of seconds or is less than the number seconds
            configured with this attribute, the triggered update is
            suppressed.";
       }
       leaf maximum-paths {
         type uint8 {
           range "1..16";
         }
         default "8";
         description
           "The number of multiple equal-cost RIPv2 or RIPng routes
            that can be used as the best paths for balancing the load
            of outgoing traffic packets.";
       }
       leaf output-delay {
         type uint8 {
           range "1..50";
         }
         units "milliseconds";
         description
           "A delay time between packets sent in multipacket
            RIPv2 or RIPng updates.";
       }
     }
     // global-attributes

     grouping distribute-lists {
       description
         "Grouping for distribute lists.";
       list distribute-list {
         key "prefix-set-name direction";
         description
           "List of distribute-lists, which are used to filter incoming
            or outgoing routing updates.";
         leaf prefix-set-name {
           type prefix-set-ref;
           description
             "Reference to a prefix list to be applied to RIPv2 or
              RIPng packets.";
         }
         leaf direction {
           type enumeration {
             enum in {
               description
                 "Apply the distribute-list to incoming routes.";
             }
             enum out {
               description
                 "Apply the distribute-list to outgoing routes.";
             }
           }
           description
             "Direction of the routing updates.";
         }
         leaf if-name {
           type if:interface-ref;
           description
             "Reference to an interface to which the prefix list is
              applied.";
         }
       }
       // distribute-list
     }
     // distribute-lists

     grouping route-attributes {
       description
         "Grouping for route attributes.";
       leaf redistributed {
         type boolean;
         description
           "Redistributed routes.";
       }
       leaf route-type {
         type enumeration {
           enum connected {
             description
               "Connected route.";
           }
           enum external {
             description
               "External route.";
           }
           enum external-backup {
             description
               "External backup route.";
           }
           enum rip {
             description
               "RIP route.";
           }
         }
         description
           "Route type.";
       }
       leaf metric {
         type uint8 {
           range "0..16";
         }
         description
           "Route metric.";
       }
       leaf expire-time {
         type uint16;
         description
           "Expiration time.";
       }
       leaf deleted {
         type boolean;
         description
           "Deleted route.";
       }
       leaf holddown {
         type boolean;
         description
           "Holddown route.";
       }
       leaf need-triggered-update {
         type boolean;
         description
           "The route needs triggered update.";
       }
       leaf inactive {
         type boolean;
         description
           "The route is inactive.";
       }
       leaf flush-expire-before-holddown {
         type boolean;
         description
           "The flush timer expired before holddown time.";
       }
     }
     // route-attributes

     /*
      * Configuration data and operational state data nodes
      */

     augment "/rt:routing/rt:control-plane-protocols/"
           + "rt:control-plane-protocol" {
       when "derived-from(rt:type, 'rip:rip')" {
         description
           "This augment is only valid for a routing protocol instance
            of RIP (type 'ripv2' or 'ripng').";
       }
       description
         "RIP augmentation.";
       container rip {
         description
           "RIP data.";
         uses global-attributes;
         uses distribute-lists;
         uses redistribute-container;
         uses timers-container;
         container interfaces {
           description
             "Containing a list of RIP interfaces.";
           list interface {
             key "interface";
             description
               "List of RIP interfaces.";
             leaf interface {
               type if:interface-ref;
               must "(derived-from-or-self("
                  + "../../../../rt:type, 'rip:ripv2') and "
                  + "/if:interfaces/if:interface[if:name=current()]/"
                  + "ip:ipv4) or "
                  + "(derived-from-or-self("
                  + "../../../../rt:type, 'rip:ripng') and "
                  + "/if:interfaces/if:interface[if:name=current()]/"
                  + "ip:ipv6)" {
                 error-message "Invalid interface type.";
                 description
                   "RIPv2 can be enabled on IPv4 interface, and
                    RIPng can be enabled on IPv6 interface.";
               }
               description
                 "Enable RIP on this interface.";
             }
             container authentication {
               when "derived-from-or-self("
                  + "../../../../rt:type, 'rip:ripv2')" {
                 description
                   "Only applicable to RIPv2.";
               }
               description
                 "Enables authentication and specifies the
                  authentication scheme for the RIP interface.";
               choice auth-type-selection {
                 description
                   "Specify the authentication scheme.";
                 reference
                   "RFC8177: YANG Data Model for Key Chains.";
                 case auth-key-chain {
                   leaf key-chain {
                     type key-chain:key-chain-ref;
                     description
                       "key-chain name.";
                   }
                 }
                 case auth-key {
                   leaf key {
                     type string;
                     description
                       "Key string in ASCII format.";
                   }
                   leaf crypto-algorithm {
                     type identityref {
                       base key-chain:crypto-algorithm;
                     }
                     description
                       "Cryptographic algorithm associated with the
                        key.";
                   }
                 }
               }
             }
             container bfd {
               if-feature "bfd";
               description
                 "BFD configuration.";
               uses bfd-types:client-cfg-parms;
             }
             leaf cost {
               type uint8 {
                 range "1..16";
               }
               default "1";
               description
                 "Interface cost.";
             }
             container neighbors {
               if-feature "explicit-neighbors";
               description
                 "Specifies the RIP neighbors.  Useful for a
                  non-broadcast multiple access (NBMA) network.";
               list neighbor {
                 key "address";
                 description
                   "Specify a RIP neighbor on a non-broadcast network.";
                 leaf address {
                   type inet:ip-address;
                   description
                     "Neighbor IP address.";
                 }
               }
             }
             leaf no-listen {
               type empty;
               description
                 "Disables listening to, and processing of, RIPv2 or
                  RIPng packets on the specified interface.";
             }
             uses originate-default-route-container;
             leaf passive {
               type empty;
               description
                 "Disables sending of RIPv2 or RIPng packets on the
                  specified interface.";
             }
             leaf split-horizon {
               type enumeration {
                 enum disabled {
                   description
                     "Disables split-horizon processing.";
                 }
                 enum simple {
                   description
                     "Enables simple split-horizon processing.";
                 }
                 enum poison-reverse {
                   description
                     "Enables split-horizon processing with poison
                      reverse.";
                 }
               }
               default "simple";
               description
                 "Controls RIPv2 or RIPng split-horizon processing on
                  the specified interface.";
             }
             container summary-address {
               description
                 "Summarizes information about RIPv2 or RIPng routes
                  sent over the specified interface in RIPv2 or RIPng
                  update packets.";
               leaf address {
                 type inet:ip-prefix;
                 description
                   "Specifies the IP address and the prefix length that
                    identify the routes to be summarized.  The IP
                    address can be specified in either IPv4 or IPv6
                    format, as specified in RFC6991.";
               }
               leaf metric {
                 type uint8 {
                   range "0..16";
                 }
                 description
                   "Metric used for the route.  If this attribute is not
                    used, the value set through the default-metric
                    attribute in RIPv2 or RIPng router configuration is
                    used for the route.";
               }
             }
             uses timers-container;

             /* Operational state */
             leaf oper-status {
               type enumeration {
                 enum up {
                   description
                     "RIPv2 or RIPng is operational on this interface.";
                 }
                 enum down {
                   description
                     "RIPv2 or RIPng is not operational on this
                      interface.";
                 }
               }
               config false;
               description
                 "Operational state.";
             }
             leaf next-full-update {
               type uint32;
               config false;
               description
                 "Next full update time.";
             }
             leaf valid-address {
               type boolean;
               config false;
               description
                 "The interface has a valid address.";
             }
             container statistics {
               if-feature "interface-statistics";
               config false;
               description
                 "Interface statistics counters.";
               leaf discontinuity-time {
                 type yang:date-and-time;
                 description
                   "The time on the most recent occasion at which any
                    one or more of the statistics counters suffered a
                    discontinuity.  If no such discontinuities have
                    occurred since the last re-initialization of the
                    local management subsystem, then this node contains
                    the time the local management subsystem
                    re-initialized itself.";
               }
               leaf bad-packets-rcvd {
                 type yang:counter32;
                 description
                   "The number of RIP invalid packets received by
                    the RIP process that were subsequently discarded
                    for any reason (e.g., a version 0 packet, or an
                    unknown command type).";
               }
               leaf bad-routes-rcvd {
                 type yang:counter32;
                 description
                   "The number of routes, in valid RIP packets,
                    which were ignored for any reason (e.g., unknown
                    address family, or invalid metric).";
               }
               leaf updates-sent {
                 type yang:counter32;
                 description
                   "The number of triggered RIP updates actually
                    sent on this interface.  This explicitly does
                    NOT include full updates sent containing new
                    information.";
               }
             }
           }
           // interface
         }
         // interfaces

         /* Operational state */
         leaf next-triggered-update {
           type uint32;
           config false;
           description
             "Next triggered update.";
         }
         leaf num-of-routes {
           type uint32;
           config false;
           description
             "The number of routes.";
         }
         container ipv4 {
           when "derived-from-or-self(../../rt:type, 'rip:ripv2')" {
             description
               "IPv4 address family is supported by RIPv2.";
           }
           config false;
           description
             "IPv4 address family information.";
           container neighbors {
             description
               "IPv4 neighbor information.";
             list neighbor {
               key "ipv4-address";
               description
                 "A RIPv2 neighbor.";
               leaf ipv4-address {
                 type inet:ipv4-address;
                 description
                   "IP address that a RIP neighbor is using as its
                    source address.";
               }
               leaf last-update {
                 type yang:date-and-time;
                 description
                   "The time when the most recent RIP update was
                    received from this neighbor.";
               }
               leaf bad-packets-rcvd {
                 type yang:counter32;
                 description
                   "The number of RIP invalid packets received from
                    this neighbor that were subsequently discarded
                    for any reason (e.g., a version 0 packet, or an
                    unknown command type).";
               }
               leaf bad-routes-rcvd {
                 type yang:counter32;
                 description
                   "The number of routes received from this neighbor,
                    in valid RIP packets that were ignored for any
                    reason (e.g., unknown address family, or invalid
                    metric).";
               }
             }
             // neighbor
           }
           // neighbors

           container routes {
             description
               "IPv4 route information.";
             list route {
               key "ipv4-prefix";
               description
                 "A RIPv2 IPv4 route.";
               leaf ipv4-prefix {
                 type inet:ipv4-prefix;
                 description
                   "IPv4 address and prefix length, in the format
                    specified in RFC6991.";
               }
               leaf next-hop {
                 type inet:ipv4-address;
                 description
                   "Next hop IPv4 address.";
               }
               leaf interface {
                 type if:interface-ref;
                 description
                   "The interface that the route uses.";
               }
               uses route-attributes;
             }
             // route
           }
           // routes
         }
         // ipv4

         container ipv6 {
           when "derived-from-or-self(../../rt:type, 'rip:ripng')" {
             description
               "IPv6 address family is supported by RIPng.";
           }
           config false;
           description
             "IPv6 address family information.";
           container neighbors {
             description
               "IPv6 neighbor information.";
             list neighbor {
               key "ipv6-address";
               description
                 "A RIPng neighbor.";
               leaf ipv6-address {
                 type inet:ipv6-address;
                 description
                   "IP address that a RIP neighbor is using as its
                    source address.";
               }
               leaf last-update {
                 type yang:date-and-time;
                 description
                   "The time when the most recent RIP update was
                    received from this neighbor.";
               }
               leaf bad-packets-rcvd {
                 type yang:counter32;
                 description
                   "The number of RIP invalid packets received from
                    this neighbor that were subsequently discarded
                    for any reason (e.g., a version 0 packet, or an
                    unknown command type).";
               }
               leaf bad-routes-rcvd {
                 type yang:counter32;
                 description
                   "The number of routes received from this neighbor,
                    in valid RIP packets that were ignored for any
                    reason (e.g., unknown address family, or invalid
                    metric).";
               }
             }
             // neighbor
           }
           // neighbors

           container routes {
             description
               "IPv6 route information.";
             list route {
               key "ipv6-prefix";
               description
                 "A RIPng IPv6 route.";
               leaf ipv6-prefix {
                 type inet:ipv6-prefix;
                 description
                   "IPv6 address and prefix length, in the format
                    specified in RFC6991.";
               }
               leaf next-hop {
                 type inet:ipv6-address;
                 description
                   "Next hop IPv6 address.";
               }
               leaf interface {
                 type if:interface-ref;
                 description
                   "The interface that the route uses.";
               }
               uses route-attributes;
             }
             // route
           }
           // routes
         }
         // ipv6

         container statistics {
           if-feature "global-statistics";
           config false;
           description
             "Global statistics counters.";
           leaf discontinuity-time {
             type yang:date-and-time;
             description
               "The time on the most recent occasion at which any one
                or more of the statistics counters suffered a
                discontinuity.  If no such discontinuities have occurred
                since the last re-initialization of the local
                management subsystem, then this node contains the time
                the local management subsystem re-initialized itself.";
           }
           leaf requests-rcvd {
             type yang:counter32;
             description
               "The number of requests received by RIP.";
           }
           leaf requests-sent {
             type yang:counter32;
             description
               "The number of requests sent by RIP.";
           }
           leaf responses-rcvd {
             type yang:counter32;
             description
               "The number of responses received by RIP.";
           }
           leaf responses-sent {
             type yang:counter32;
             description
               "The number of responses sent by RIP.";
           }
         }
         // statistics
       }
       // rip
     }

     /*
      * RPCs
      */

     rpc clear-rip-route {
       description
         "Clears RIP routes from the IP routing table and routes
          redistributed into RIP for the specified RIP instance
          or for all RIP instances in the current context.";
       input {
         leaf rip-instance {
           type leafref {
             path "/rt:routing/rt:control-plane-protocols/"
                + "rt:control-plane-protocol/rt:name";
           }
           description
             "Instance name identifying a specific RIP instance.
              This leaf is optional for the RPC.
              If it is specified, the RPC will clear all routes in the
              specified RIP instance;
              if it is not specified, the RPC will clear all routes in
              all RIP instances.";
         }
       }
     }
     // clear-rip-route

   }
   <CODE ENDS>

5.  IANA Considerations

   This document registers the following namespace URIs in the "IETF XML
   Registry" [RFC3688]:

   URI:  urn:ietf:params:xml:ns:yang:ietf-rip
   Registrant Contact:  The IESG.
   XML:  N/A; the requested URI is an XML namespace.

   This document registers the following YANG modules in the "YANG
   Module Names" registry [RFC6020]:

   Name:  ietf-rip
   Namespace:  urn:ietf:params:xml:ns:yang:ietf-rip
   Prefix:  rip
   Reference:  RFC 8695

6.  Security Considerations

   The YANG module specified in this document defines a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   The NETCONF Access Control Model (NACM) [RFC8341] provides the means
   to restrict access for particular NETCONF or RESTCONF users to a
   preconfigured subset of all available NETCONF or RESTCONF protocol
   operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

      /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/
      rip:rip

   Unauthorized access to any data node of these subtrees 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.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

      /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/
      rip:rip

   Unauthorized access to any data node of these subtrees can disclose
   the operational state information of RIP on this device.

   Some of the RPC operations in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control access to these operations.  These are the
   operations and their sensitivity/vulnerability:

   RPC clear-rip-route:

   Unauthorized access to the RPC above 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.

7.  References

7.1.  Normative References

   [RFC1724]  Malkin, G. and F. Baker, "RIP Version 2 MIB Extension",
              RFC 1724, DOI 10.17487/RFC1724, November 1994,
              <https://www.rfc-editor.org/info/rfc1724>.

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

   [RFC2453]  Malkin, G., "RIP Version 2", STD 56, RFC 2453,
              DOI 10.17487/RFC2453, November 1998,
              <https://www.rfc-editor.org/info/rfc2453>.

   [RFC2080]  Malkin, G. and R. Minnear, "RIPng for IPv6", RFC 2080,
              DOI 10.17487/RFC2080, January 1997,
              <https://www.rfc-editor.org/info/rfc2080>.

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

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

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

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

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8177]  Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
              Zhang, "YANG Data Model for Key Chains", RFC 8177,
              DOI 10.17487/RFC8177, June 2017,
              <https://www.rfc-editor.org/info/rfc8177>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

   [RFC8343]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
              <https://www.rfc-editor.org/info/rfc8343>.

   [RFC8344]  Bjorklund, M., "A YANG Data Model for IP Management",
              RFC 8344, DOI 10.17487/RFC8344, March 2018,
              <https://www.rfc-editor.org/info/rfc8344>.

   [RFC8349]  Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
              Routing Management (NMDA Version)", RFC 8349,
              DOI 10.17487/RFC8349, March 2018,
              <https://www.rfc-editor.org/info/rfc8349>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

7.2.  Informative References

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with YANG",
              RFC 7951, DOI 10.17487/RFC7951, August 2016,
              <https://www.rfc-editor.org/info/rfc7951>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8407]  Bierman, A., "Guidelines for Authors and Reviewers of
              Documents Containing YANG Data Models", BCP 216, RFC 8407,
              DOI 10.17487/RFC8407, October 2018,
              <https://www.rfc-editor.org/info/rfc8407>.

   [RFC8639]  Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard,
              E., and A. Tripathy, "Subscription to YANG Notifications",
              RFC 8639, DOI 10.17487/RFC8639, September 2019,
              <https://www.rfc-editor.org/info/rfc8639>.

   [RFC8641]  Clemm, A. and E. Voit, "Subscription to YANG Notifications
              for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
              September 2019, <https://www.rfc-editor.org/info/rfc8641>.

   [YANG-BFD] Rahman, R., Zheng, L., Jethanandani, M., Pallagatti, S.,
              and G. Mirsky, "YANG Data Model for Bidirectional
              Forwarding Detection (BFD)", Work in Progress, Internet-
              Draft, draft-ietf-bfd-yang-17, 2 August 2018,
              <https://tools.ietf.org/html/draft-ietf-bfd-yang-17>.

   [YANG-ISIS]
              Litkowski, S., Yeung, D., Lindem, A., Zhang, Z., and L.
              Lhotka, "YANG Data Model for IS-IS Protocol", Work in
              Progress, Internet-Draft, draft-ietf-isis-yang-isis-cfg-
              42, 15 October 2019, <https://tools.ietf.org/html/draft-
              ietf-isis-yang-isis-cfg-42>.

   [YANG-OSPF]
              Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem,
              "YANG Data Model for OSPF Protocol", Work in Progress,
              Internet-Draft, draft-ietf-ospf-yang-29, 17 October 2019,
              <https://tools.ietf.org/html/draft-ietf-ospf-yang-29>.

Appendix A.  Data Tree Example

   This section contains an example of an instance data tree in the JSON
   encoding [RFC7951], containing both configuration and state data.

                     +---------------------+
                     |                     |
                     | Router 203.0.113.1  |
                     |                     |
                     +----------+----------+
                                |eth1
                                |2001:db8:0:1::1/64
                                |
                                |
                                |2001:db8:0:1::2/64
                     +----------+----------+
                     |                     |         |
                     |   Another Router    +---------| 2001:db8:0:2::/64
                     |                     |         |
                     +---------------------+

                          Figure 1: RIPng Example

   The configuration instance data tree for Router 203.0.113.1 in
   Figure 1 could be as follows:

   {
     "ietf-interfaces:interfaces": {
       "interface": [
         {
           "name": "eth1",
           "description": "An interface with RIPng enabled.",
           "type": "iana-if-type:ethernetCsmacd",
           "ietf-ip:ipv6": {
             "address": [
               {
                 "ip": "2001:db8:0:1::1",
                 "prefix-length": 64
               }
             ],
             "forwarding": true
           }
         }
       ]
     },
     "ietf-routing:routing": {
       "router-id": "203.0.113.1",
       "control-plane-protocols": {
         "control-plane-protocol": [
           {
             "type": "ietf-rip:ripng",
             "name": "ripng-1",
             "description": "RIPng instance ripng-1.",
             "ietf-rip:rip": {
               "redistribute": {
                 "connected": {
                 }
               },
               "interfaces": {
                 "interface": [
                   {
                     "interface": "eth1",
                     "split-horizon": "poison-reverse"
                   }
                 ]
               }
             }
           }
         ]
       }
     }
   }

   The corresponding operational state data for Router 203.0.113.1 could
   be as follows:

   {
     "ietf-interfaces:interfaces": {
       "interface": [
         {
           "name": "eth1",
           "description": "An interface with RIPng enabled.",
           "type": "iana-if-type:ethernetCsmacd",
           "phys-address": "00:00:5e:00:53:01",
           "oper-status": "up",
           "statistics": {
             "discontinuity-time": "2016-10-24T17:11:27+02:00"
           },
           "ietf-ip:ipv6": {
             "forwarding": true,
             "mtu": 1500,
             "address": [
               {
                 "ip": "2001:db8:0:1::1",
                 "prefix-length": 64,
                 "origin": "static",
                 "status": "preferred"
               },
               {
                 "ip": "fe80::200:5eff:fe00:5301",
                 "prefix-length": 64,
                 "origin": "link-layer",
                 "status": "preferred"
               }
             ],
             "neighbor": [
               {
                 "ip": "2001:db8:0:1::2",
                 "link-layer-address": "00:00:5e:00:53:02",
                 "origin": "dynamic",
                 "is-router": [null],
                 "state": "reachable"
               },
               {
                 "ip": "fe80::200:5eff:fe00:5302",
                 "link-layer-address": "00:00:5e:00:53:02",
                 "origin": "dynamic",
                 "is-router": [null],
                 "state": "reachable"
               }
             ]
           }
         }
       ]
     },
     "ietf-routing:routing": {
       "router-id": "203.0.113.1",
       "interfaces": {
         "interface": [
           "eth1"
         ]
       },
       "control-plane-protocols": {
         "control-plane-protocol": [
           {
             "type": "ietf-rip:ripng",
             "name": "ripng-1",
             "description": "RIPng instance ripng-1.",
             "ietf-rip:rip": {
               "default-metric": 1,
               "next-triggered-update": 5,
               "interfaces": {
                 "interface": [
                   {
                     "interface": "eth1",
                     "oper-status": "up",
                     "cost": 1,
                     "split-horizon": "poison-reverse",
                     "valid-address": true
                   }
                 ]
               },
               "ipv6": {
                 "neighbors": {
                   "neighbor": [
                     {
                       "ipv6-address": "fe80::200:5eff:fe00:5302",
                       "last-update": "2017-01-02T10:34:55+02:00"
                     }
                   ]
                 },
                 "routes": {
                   "route": [
                     {
                       "ipv6-prefix": "2001:db8:0:1::/64",
                       "interface": "eth1",
                       "redistributed": true,
                       "route-type": "connected",
                       "metric": 1,
                       "expire-time": 22
                     },
                     {
                       "ipv6-prefix": "2001:db8:0:2::/64",
                       "next-hop": "fe80::200:5eff:fe00:5302",
                       "interface": "eth1",
                       "redistributed": false,
                       "route-type": "rip",
                       "metric": 2,
                       "expire-time": 82
                     }
                   ]
                 }
               },
               "statistics": {
                 "discontinuity-time": "2016-10-24T17:11:27+02:00",
                 "requests-rcvd": 523,
                 "requests-sent": 262,
                 "responses-rcvd": 261,
                 "responses-sent": 523
               }
             }
           }
         ]
       }
     }
   }

Authors' Addresses

   Xufeng Liu
   Volta Networks

   Email: xufeng.liu.ietf@gmail.com


   Prateek Sarda
   Ericsson
   Fern Icon, Survey No 28 and 36/5, Doddanakundi Village
   Bangalore 560037
   Karnataka
   India

   Email: prateek.sarda@ericsson.com


   Vikram Choudhary
   Individual
   Bangalore 560066
   India

   Email: vikschw@gmail.com