Network Working Group                                          A. Lindem
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                                   Y. Qu
Expires: April 20, 2022                                        Futurewei
                                                        October 17, 2021


                     RIB Extension YANG Data Model
                  draft-ietf-rtgwg-yang-rib-extend-09

Abstract

   A Routing Information Base (RIB) is a list of routes and their
   corresponding administrative data and operational state.

   RFC 8349 defines the basic building blocks for RIB, and this model
   augments it to support multiple next-hops (aka, paths) for each route
   as well as additional attributes.

Status of This Memo

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

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

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

   This Internet-Draft will expire on April 20, 2022.

Copyright Notice

   Copyright (c) 2021 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



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology and Notation  . . . . . . . . . . . . . . . . . .   3
     2.1.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Prefixes in Data Node Names . . . . . . . . . . . . . . .   4
   3.  Design of the Model . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Tags and Preference . . . . . . . . . . . . . . . . . . .   4
     3.2.  Repair Path . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  RIB Model Tree  . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  RIB Extension YANG Model  . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Appendix A.  Combined Tree Diagram  . . . . . . . . . . . . . . .  17
   Appendix B.  ietf-rib-extension.yang example  . . . . . . . . . .  20
   Appendix C.  Acknowledgments  . . . . . . . . . . . . . . . . . .  25
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  25

1.  Introduction

   This document defines a YANG [RFC7950] data model which extends the
   RIBs defined in ietf-routing YANG module [RFC8349] with more route
   attributes.

   A RIB is a collection of routes with attributes controlled and
   manipulated by control-plane protocols.  Within a protocol, routes
   are selected based on the metrics in use by that protocol, and the
   protocol installs the routes to RIB.  RIB selects the preferred
   routes by comparing the route-preference (aka, administrative
   distance) of the associated protocol.

   The module defined in this document extends the RIBs to support more
   route attributes, such as multiple next-hops, route metrics, and
   administrative tags.

   The YANG modules in this document conform to the Network Management
   Datastore Architecture (NMDA) [RFC8342].








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2.  Terminology and Notation

   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 [RFC8342]:

   o  configuration

   o  system state

   o  operational state

   The following terms are defined in [RFC7950]:

   o  action

   o  augment

   o  container

   o  container with presence

   o  data model

   o  data node

   o  leaf

   o  list

   o  mandatory node

   o  module

   o  schema tree

   o  RPC (Remote Procedure Call) operation

   The following terms are defined in [RFC8349] Section 5.2:

   o  RIB






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2.1.  Tree Diagrams

   Tree diagrams used in this document follow the notation defined in
   [RFC8340].

2.2.  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 |
            +--------+---------------------------+-----------+
            | if     | ietf-interfaces           | [RFC8343] |
            |        |                           |           |
            | rt     | ietf-routing              | [RFC8349] |
            |        |                           |           |
            | v4ur   | ietf-ipv4-unicast-routing | [RFC8349] |
            |        |                           |           |
            | v6ur   | ietf-ipv6-unicast-routing | [RFC8349] |
            |        |                           |           |
            | inet   | ietf-inet-types           | [RFC6991] |
            +--------+---------------------------+-----------+

             Table 1: Prefixes and Corresponding YANG Modules

3.  Design of the Model

   The YANG module defined in this document augments the ietf-routing
   YANG model defined in [RFC8349], which provides a basis for routing
   system data model development.  Together with YANG modules defined in
   [RFC8349], a generic RIB YANG model is defined to implement and
   monitor a RIB.

   The models in [RFC8349] also define the basic configuration and
   operational state for both IPv4 and IPv6 static routes.  This
   document provides augmentations for static routes to support multiple
   next-hops and more next-hop attributes.

3.1.  Tags and Preference

   Individual route tags are supported at both the route and next-hop
   level.  A preference per next-hop is also supported for selection of
   the most preferred reachable static route.




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   The following tree snapshot shows tag and preference which augment
   static IPv4 unicast routes and IPv6 unicast routes next-hop.

     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/rt:static-routes/v4ur:ipv4
             /v4ur:route/v4ur:next-hop/v4ur:next-hop-options
             /v4ur:simple-next-hop:
       +--rw preference?   uint32
       +--rw tag?          uint32
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/rt:static-routes/v4ur:ipv4
             /v4ur:route/v4ur:next-hop/v4ur:next-hop-options
             /v4ur:next-hop-list/v4ur:next-hop-list/v4ur:next-hop:
       +--rw preference?   uint32
       +--rw tag?          uint32
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/rt:static-routes/v6ur:ipv6
             /v6ur:route/v6ur:next-hop/v6ur:next-hop-options
             /v6ur:simple-next-hop:
       +--rw preference?   uint32
       +--rw tag?          uint32
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/rt:static-routes/v6ur:ipv6
             /v6ur:route/v6ur:next-hop/v6ur:next-hop-options
             /v6ur:next-hop-list/v6ur:next-hop-list/v6ur:next-hop:
       +--rw preference?   uint32
       +--rw tag?          uint32

3.2.  Repair Path

   The IP Fast Reroute (IPFRR) pre-computes repair paths by routing
   protocols [RFC5714], and the repair paths are installed in the RIB.

   Each route in the RIB is augmented with repair paths if available,
   and is shown in the following tree snapshot.
















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     augment /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route
             /rt:next-hop/rt:next-hop-options/rt:simple-next-hop:
       +--ro repair-path
          +--ro outgoing-interface?   if:interface-state-ref
          +--ro next-hop-address?     inet:ip-address
          +--ro metric?               uint32
     augment /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route
             /rt:next-hop/rt:next-hop-options/rt:next-hop-list
             /rt:next-hop-list/rt:next-hop:
       +--ro repair-path
          +--ro outgoing-interface?   if:interface-state-ref
          +--ro next-hop-address?     inet:ip-address
          +--ro metric?               uint32

4.  RIB Model Tree

   The ietf-routing.yang tree with the augmentations herein is included
   in Appendix A.  The meaning of the symbols can be found in [RFC8340].

5.  RIB Extension YANG Model

   <CODE BEGINS> file "ietf-rib-extension@2021-10-17.yang"
   module ietf-rib-extension {
     yang-version "1.1";
     namespace "urn:ietf:params:xml:ns:yang:ietf-rib-extension";

     prefix rib-ext;

     import ietf-inet-types {
       prefix "inet";
       reference "RFC 6991: Common YANG Data Types";
     }

     import ietf-interfaces {
       prefix "if";
       reference "RFC 8343: A YANG Data Model for Interface
                            Management (NMDA Version)";
     }

     import ietf-routing {
       prefix "rt";
       reference "RFC 8349: A YANG Data Model for Routing
                            Management (NMDA Version)";
     }

     import ietf-ipv4-unicast-routing {
       prefix "v4ur";
       reference "RFC 8349: A YANG Data Model for Routing



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                            Management (NMDA Version)";
     }

     import ietf-ipv6-unicast-routing {
       prefix "v6ur";
       reference "RFC 8349: A YANG Data Model for Routing
                            Management (NMDA Version)";
     }

     organization
       "IETF RTGWG - Routing Working Group";

     contact
       "WG Web:   <http://datatracker.ietf.org/group/rtgwg/>
        WG List:  <mailto:rtgwg@ietf.org>

        Author:   Acee Lindem
                  <mailto:acee@cisco.com>
        Author:   Yingzhen Qu
                  <mailto:yingzhen.qu@futurewei.com>";

     description
       "This document defines a YANG data model which extends
        the RIBs defined in ietf-routing YANG module with more
        route attributes.

        This YANG model conforms to the Network Management
        Datastore Architecture (NDMA) as described in RFC 8342.

        Copyright (c) 2021 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.";

     revision 2021-10-17 {
       description
         "Initial Version";
       reference
         "RFC XXXX: A YANG Data Model for RIB Extensions.";
     }



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     /* Groupings */
     grouping rib-statistics {
       description
         "Statistics grouping used for RIB augmentation.";
       container statistics {
         config false;
         description
           "Container for RIB statistics.";
         leaf total-routes {
           type uint32;
           description
             "Total routes in the RIB";
         }
         leaf total-active-routes {
           type uint32;
           description
             "Total active routes in the RIB. An active route is
              preferred over other routes to the same destination
              prefix.";
         }
         leaf total-route-memory {
           type uint64;
           units "bytes";
           description
             "Total memory for all routes in the RIB.";
         }
         list protocol-statistics {
           description "RIB statistics per protocol.";
           leaf protocol {
             type identityref {
               base rt:routing-protocol;
             }
             description "Routing protocol.";
           }
           leaf routes {
             type uint32;
             description
               "Total routes for protocol in the RIB.";
           }
           leaf active-routes {
             type uint32;
             description
               "Total active routes for protocol in the RIB. An active
                route is preferred over other routes to the same
                destination prefix.";
           }
           leaf route-memory {
             type uint64;



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             units "bytes";
             description
               "Total memory for all routes for protocol in the RIB.";
           }
         }
       }
     }

     grouping next-hop {
       description
         "Next-hop grouping";
       leaf interface {
         type if:interface-ref;
         description
           "Outgoing interface";
       }
       leaf address {
         type inet:ip-address;
         description
           "IPv4 or IPv6 Address of the next-hop.";
       }
     }

     grouping attributes {
       description
         "Common attributes applicable to all routes.";
       leaf metric {
         type uint32;
         description
           "The metric is a numeric value indicating the cost
            of the route from the perspective of the routing
            protocol installing the route. In general, routes with
            a lower metric installed by the same routing protocol
            are lower cost to reach and are preferable to routes
            with a higher metric. However, metrics from different
            routing protocols are not directly comparable.";
       }
       leaf-list tag {
         type uint32;
         description
           "A tag is a 32-bit opaque value associated with the
            route that can be used for policy decisions such as
            advertisement and filtering of the route.";
       }
       leaf application-tag {
         type uint32;
         description
           "The application-specific tag is an additional tag that



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            can be used by applications that require semantics and/or
            policy different from that of the tag. For example,
            the tag is usually automatically advertised in OSPF
            AS-External Link State Advertisements (LSAs) while this
            application-specific tag is not advertised implicitly.";
       }
     }
     grouping repair-path {
       description
         "Grouping for IP Fast Reroute repair path.";
       container repair-path {
         description
           "IP Fast Reroute next-hop repair path.";
         leaf outgoing-interface {
           type if:interface-state-ref;
           description
             "Name of the outgoing interface.";
         }
         leaf next-hop-address {
           type inet:ip-address;
           description
             "IP address of the next hop.";
         }
         leaf metric {
           type uint32;
           description
             "The metric for the repair path. While the IP Fast
              Reroute re-route repair is local and the metric is
              not advertised externally, the metric for repair path
              is useful for troubleshooting purposes.";
         }
         reference
           "RFC 5714: IP Fast Reroute Framework.";
       }
     }

     augment "/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:static-routes/v4ur:ipv4/"
       + "v4ur:route/v4ur:next-hop/v4ur:next-hop-options/"
       + "v4ur:simple-next-hop"
     {
       description
         "Augment 'simple-next-hop' case in IPv4 unicast route.";
       leaf preference {
         type uint32;
         default "1";
         description
           "The preference is used to select among multiple static



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            routes. Routes with a lower preference next-hop are
            preferred and equal preference routes result in
            Equal-Cost-Multi-Path (ECMP) static routes.";
       }
       leaf tag {
         type uint32;
         default "0";
         description
           "The tag is a 32-bit opaque value associated with the
            route that can be used for policy decisions such as
            advertisement and filtering of the route.";
       }
     }

     augment "/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:static-routes/v4ur:ipv4/"
       + "v4ur:route/v4ur:next-hop/v4ur:next-hop-options/"
       + "v4ur:next-hop-list/v4ur:next-hop-list/v4ur:next-hop"
     {
       description
         "Augment static route configuration 'next-hop-list'.";

       leaf preference {
         type uint32;
         default "1";
         description
           "The preference is used to select among multiple static
            routes. Routes with a lower preference next-hop are
            preferred and equal preference routes result in
            Equal-Cost-Multi-Path (ECMP) static routes.";
       }
       leaf tag {
         type uint32;
         default "0";
         description
           "The tag is a 32-bit opaque value associated with the
            route that can be used for policy decisions such as
            advertisement and filtering of the route.";
       }
     }

     augment "/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:static-routes/v6ur:ipv6/"
       + "v6ur:route/v6ur:next-hop/v6ur:next-hop-options/"
       + "v6ur:simple-next-hop"
     {
       description
         "Augment 'simple-next-hop' case in IPv6 unicast route.";



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       leaf preference {
         type uint32;
         default "1";
         description
           "The preference is used to select among multiple static
            routes. Routes with a lower preference next-hop are
            preferred and equal preference routes result in
            Equal-Cost-Multi-Path (ECMP) static routes.";
       }
       leaf tag {
         type uint32;
         default "0";
         description
           "The tag is a 32-bit opaque value associated with the
            route that can be used for policy decisions such as
            advertisement and filtering of the route.";
       }
     }

     augment "/rt:routing/rt:control-plane-protocols/"
       + "rt:control-plane-protocol/rt:static-routes/v6ur:ipv6/"
       + "v6ur:route/v6ur:next-hop/v6ur:next-hop-options/"
       + "v6ur:next-hop-list/v6ur:next-hop-list/v6ur:next-hop"
     {
       description
         "Augment static route configuration 'next-hop-list'.";

       leaf preference {
         type uint32;
         default "1";
         description
           "The preference is used to select among multiple static
            routes. Routes with a lower preference next-hop are
            preferred and equal preference routes result in
            Equal-Cost-Multi-Path (ECMP) static routes.";
       }
       leaf tag {
         type uint32;
         default "0";
         description
           "The tag is a 32-bit opaque value associated with the
            route that can be used for policy decisions such as
            advertisement and filtering of the route.";
       }
     }

     augment "/rt:routing/rt:ribs/rt:rib"
     {



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       description
         "Augment a RIB with statistics.";
       uses rib-statistics;
     }

     augment "/rt:routing/rt:ribs/rt:rib/"
       + "rt:routes/rt:route"
     {
       description
         "Augment a route in RIB with attributes.";
       uses attributes;
     }

     augment "/rt:routing/rt:ribs/rt:rib/"
       + "rt:routes/rt:route/rt:next-hop/rt:next-hop-options/"
       + "rt:simple-next-hop"
     {
       description
         "Augment simple-next-hop with repair-path.";
       uses repair-path;
     }

     augment "/rt:routing/rt:ribs/rt:rib/"
       + "rt:routes/rt:route/rt:next-hop/rt:next-hop-options/"
       + "rt:next-hop-list/rt:next-hop-list/rt:next-hop"
     {
       description
         "Augment the multiple next hops with repair path.";
       uses repair-path;
     }
   }
   <CODE ENDS>

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 [RFC8341] provides the means to
   restrict access for particular NETCONF or RESTCONF users to a pre-
   configured subset of all available NETCONF or RESTCONF protocol
   operations and content.




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   There are a number of data nodes defined in ietf-rib-extensions.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:

      /v4ur:next-hop-options/v4ur:simple-next-hop/rib-ext:preference

      /v4ur:next-hop-options/v4ur:simple-next-hop/rib-ext:tag

      /v4ur:next-hop-options/v4ur:next-hop-list/v4ur:next-hop-list
      /v4ur:next-hop/rib-ext:preference

      /v4ur:next-hop-options/v4ur:next-hop-list/v4ur:next-hop-list
      /v4ur:next-hop/rib-ext:tag

      /v6ur:next-hop-options/v6ur:simple-next-hop/rib-ext:preference

      /v6ur:next-hop-options/v6ur:simple-next-hop/rib-ext:tag

      /v6ur:next-hop-options/v6ur:next-hop-list/v6ur:next-hop-list
      /v6ur:next-hop/rib-ext:preference

      /v6ur:next-hop-options/v6ur:next-hop-list/v6ur:next-hop-list
      /v6ur:next-hop/rib-ext:tag

      For these augmentations to ietf-routing.yang, the ability to
      delete, add, and modify IPv4 and IPv6 static route preference and
      tag would allow traffic to be misrouted.

   Some of the readable data nodes in the ietf-rib-extensions.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:ribs/rt:rib/rib-ext:statistics

      /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/rib-ext:metric

      /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/rib-ext:tag

      /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route /rib-
      ext:application-tag





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      /rt:route/rt:next-hop/rt:next-hop-options/rt:simple-next-hop /rib-
      ext:repair-path

      /rt:routes/rt:route/rt:next-hop/rt:next-hop-options /rt:next-hop-
      list/rt:next-hop-list/rt:next-hop/rib-ext:repair-path

      The exposure of the Routing Information Base (RIB) will expose the
      routing topology of the network.  This may be undesirable since
      both due to the fact that exposure may facilitate other attacks.
      Additionally, network operators may consider their topologies to
      be sensitive confidential data.

   All the security considerations for [RFC8349] writable and readable
   data nodes apply to the augmentations described herein.

7.  IANA Considerations

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

      URI: urn:ietf:params:xml:ns:yang:ietf-rib-extension
      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-rib-extension
      namespace: urn:ietf:params:xml:ns:yang:ietf-rib-extension
      prefix: rib-ext
      reference: RFC XXXX

8.  References

8.1.  Normative References

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

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






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   [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>.

   [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>.

   [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>.



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   [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>.

8.2.  Informative References

   [RFC5714]  Shand, M. and S. Bryant, "IP Fast Reroute Framework",
              RFC 5714, DOI 10.17487/RFC5714, January 2010,
              <https://www.rfc-editor.org/info/rfc5714>.

   [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>.

Appendix A.  Combined Tree Diagram

   This appendix includes the combined ietf-routing.yang, ietf-ipv4-
   unicast-routing.yang, ietf-ipv6-unicast-routing.yang and ietf-rib-
   extensions.yang tree diagram.

module: ietf-routing
+--rw routing
  +--rw router-id?                 yang:dotted-quad {router-id}?
  +--ro interfaces
  |  +--ro interface*   if:interface-ref
  +--rw control-plane-protocols
  |  +--rw control-plane-protocol* [type name]
  |     +--rw type             identityref
  |     +--rw name             string
  |     +--rw description?     string
  |     +--rw static-routes
  |        +--rw v4ur:ipv4
  |        |  +--rw v4ur:route* [destination-prefix]
  |        |     +--rw v4ur:destination-prefix    inet:ipv4-prefix
  |        |     +--rw v4ur:description?          string
  |        |     +--rw v4ur:next-hop
  |        |        +--rw (v4ur:next-hop-options)
  |        |           +--:(v4ur:simple-next-hop)
  |        |           |  +--rw v4ur:outgoing-interface?
  |        |           |  |   if:interface-ref
  |        |           |  +--rw v4ur:next-hop-address?
  |        |           |  |   inet:ipv4-address
  |        |           |  +--rw rib-ext:preference?        uint32
  |        |           |  +--rw rib-ext:tag?               uint32
  |        |           +--:(v4ur:special-next-hop)
  |        |           |  +--rw v4ur:special-next-hop?     enumeration
  |        |           +--:(v4ur:next-hop-list)
  |        |              +--rw v4ur:next-hop-list



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  |        |                 +--rw v4ur:next-hop* [index]
  |        |                    +--rw v4ur:index                 string
  |        |                    +--rw v4ur:outgoing-interface?
  |        |                    |   if:interface-ref
  |        |                    +--rw v4ur:next-hop-address?
  |        |                    |   inet:ipv4-address
  |        |                    +--rw rib-ext:preference?        uint32
  |        |                    +--rw rib-ext:tag?               uint32
  |        +--rw v6ur:ipv6
  |           +--rw v6ur:route* [destination-prefix]
  |              +--rw v6ur:destination-prefix    inet:ipv6-prefix
  |              +--rw v6ur:description?          string
  |              +--rw v6ur:next-hop
  |                 +--rw (v6ur:next-hop-options)
  |                    +--:(v6ur:simple-next-hop)
  |                    |  +--rw v6ur:outgoing-interface?
  |                    |  |   if:interface-ref
  |                    |  +--rw v6ur:next-hop-address?
  |                    |  |   inet:ipv6-address
  |                    |  +--rw rib-ext:preference?        uint32
  |                    |  +--rw rib-ext:tag?               uint32
  |                    +--:(v6ur:special-next-hop)
  |                    |  +--rw v6ur:special-next-hop?     enumeration
  |                    +--:(v6ur:next-hop-list)
  |                       +--rw v6ur:next-hop-list
  |                          +--rw v6ur:next-hop* [index]
  |                             +--rw v6ur:index                 string
  |                             +--rw v6ur:outgoing-interface?
  |                             |   if:interface-ref
  |                             +--rw v6ur:next-hop-address?
  |                             |   inet:ipv6-address
  |                             +--rw rib-ext:preference?        uint32
  |                             +--rw rib-ext:tag?               uint32
  +--rw ribs
     +--rw rib* [name]
        +--rw name                            string
        +--rw address-family                  identityref
        +--ro default-rib?                    boolean {multiple-ribs}?
        +--ro routes
        |  +--ro route* []
        |     +--ro route-preference?          route-preference
        |     +--ro next-hop
        |     |  +--ro (next-hop-options)
        |     |     +--:(simple-next-hop)
        |     |     |  +--ro outgoing-interface?      if:interface-ref
        |     |     |  +--ro v4ur:next-hop-address?   inet:ipv4-address
        |     |     |  +--ro v6ur:next-hop-address?   inet:ipv6-address
        |     |     |  +--ro rib-ext:repair-path



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        |     |     |     +--ro rib-ext:outgoing-interface?
        |     |     |     |   if:interface-state-ref
        |     |     |     +--ro rib-ext:next-hop-address?
        |     |     |     |   inet:ip-address
        |     |     |     +--ro rib-ext:metric?               uint32
        |     |     +--:(special-next-hop)
        |     |     |  +--ro special-next-hop?        enumeration
        |     |     +--:(next-hop-list)
        |     |        +--ro next-hop-list
        |     |           +--ro next-hop* []
        |     |              +--ro outgoing-interface?
        |     |              |   if:interface-ref
        |     |              +--ro v4ur:address?
        |     |              |   inet:ipv4-address
        |     |              +--ro v6ur:address?
        |     |              |   inet:ipv6-address
        |     |              +--ro rib-ext:repair-path
        |     |                 +--ro rib-ext:outgoing-interface?
        |     |                 |   if:interface-state-ref
        |     |                 +--ro rib-ext:next-hop-address?
        |     |                 |   inet:ip-address
        |     |                 +--ro rib-ext:metric?            uint32
        |     +--ro source-protocol            identityref
        |     +--ro active?                    empty
        |     +--ro last-updated?              yang:date-and-time
        |     +--ro v4ur:destination-prefix?   inet:ipv4-prefix
        |     +--ro v6ur:destination-prefix?   inet:ipv6-prefix
        |     +--ro rib-ext:metric?            uint32
        |     +--ro rib-ext:tag*               uint32
        |     +--ro rib-ext:application-tag?   uint32
        +---x active-route
        |  +---w input
        |  |  +---w v4ur:destination-address?   inet:ipv4-address
        |  |  +---w v6ur:destination-address?   inet:ipv6-address
        |  +--ro output
        |     +--ro route
        |        +--ro next-hop
        |        |  +--ro (next-hop-options)
        |        |     +--:(simple-next-hop)
        |        |     |  +--ro outgoing-interface?    if:interface-ref
        |        |     |  +--ro v4ur:next-hop-address? inet:ipv4-address
        |        |     |  +--ro v6ur:next-hop-address? inet:ipv6-address
        |        |     +--:(special-next-hop)
        |        |     |  +--ro special-next-hop?        enumeration
        |        |     +--:(next-hop-list)
        |        |        +--ro next-hop-list
        |        |           +--ro next-hop* []
        |        |              +--ro outgoing-interface?



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        |        |              |   if:interface-ref
        |        |              +--ro v4ur:next-hop-address?
        |        |              |   inet:ipv4-address
        |        |              +--ro v6ur:next-hop-address?
        |        |              |   inet:ipv6-address
        |        +--ro source-protocol            identityref
        |        +--ro active?                    empty
        |        +--ro last-updated?              yang:date-and-time
        |        +--ro v4ur:destination-prefix?   inet:ipv4-prefix
        |        +--ro v6ur:destination-prefix?   inet:ipv6-prefix
        +--rw description?                      string
        +--ro rib-ext:statistics
           +--ro rib-ext:total-routes?              uint32
           +--ro rib-ext:total-active-routes?       uint32
           +--ro rib-ext:total-route-memory?        uint64
           +--ro rib-ext:protocol-statistics* []
              +--ro rib-ext:protocol?             identityref
              +--ro rib-ext:routes?    uint32
              +--ro rib-ext:active-routes?   uint32
              +--ro rib-ext:route-memory?    uint64


Appendix B.  ietf-rib-extension.yang example

   The following is an XML example using the RIB extension module and
   RFC 8349.

  <routing xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
    <control-plane-protocols>
      <control-plane-protocol>
        <type>static</type>
        <name>static-routing-protocol</name>
        <static-routes>
          <ipv4 xmlns="urn:ietf:params:xml:ns:yang:\
            ietf-ipv4-unicast-routing">
            <route>
              <destination-prefix>0.0.0.0/0</destination-prefix>
              <next-hop>
                <next-hop-address>192.0.2.2</next-hop-address>
                <preference xmlns="urn:ietf:params:xml:ns:yang:\
                  ietf-rib-extension">30</preference>
                <tag xmlns="urn:ietf:params:xml:ns:yang:\
                  ietf-rib-extension">99</tag>
              </next-hop>
            </route>
          </ipv4>
          <ipv6 xmlns="urn:ietf:params:xml:ns:yang:\
            ietf-ipv6-unicast-routing">



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            <route>
              <destination-prefix>0::/0</destination-prefix>
              <next-hop>
                <next-hop-address>2001:db8:aaaa::1111</next-hop-address>
                <preference xmlns="urn:ietf:params:xml:ns:yang:\
                  ietf-rib-extension">30</preference>
                <tag xmlns="urn:ietf:params:xml:ns:yang:\
                  ietf-rib-extension">66</tag>
              </next-hop>
            </route>
          </ipv6>
        </static-routes>
      </control-plane-protocol>
    </control-plane-protocols>
    <ribs>
      <rib>
        <name>ipv4-master</name>
        <address-family xmlns:v4ur="urn:ietf:params:xml:ns:yang:\
          ietf-ipv4-unicast-routing">v4ur:ipv4-unicast</address-family>
        <default-rib>true</default-rib>
        <routes>
          <route>
            <destination-prefix xmlns="urn:ietf:params:xml:ns:yang:\
              ietf-ipv4-unicast-routing">0.0.0.0/0</destination-prefix>
            <next-hop>
              <next-hop-address xmlns="urn:ietf:params:xml:ns:yang:\
                ietf-ipv4-unicast-routing">192.0.2.2</next-hop-address>
            </next-hop>
            <route-preference>5</route-preference>
            <source-protocol>static</source-protocol>
            <last-updated>2015-10-24T18:02:45+02:00</last-updated>
          </route>
          <route>
            <destination-prefix xmlns="urn:ietf:params:xml:ns:yang:\
              ietf-ipv4-unicast-routing">198.51.100.0/24\
            </destination-prefix>
            <next-hop>
              <next-hop-address xmlns="urn:ietf:params:xml:ns:yang:\
                ietf-ipv4-unicast-routing">192.0.2.2</next-hop-address>
              <repair-path xmlns="urn:ietf:params:xml:ns:yang:\
                ietf-rib-extension">
                <next-hop-address>203.0.113.1</next-hop-address>
                <metric>200</metric>
              </repair-path>
            </next-hop>
            <route-preference>110</route-preference>
            <source-protocol xmlns:ospf="urn:ietf:params:xml:ns:yang:\
              ietf-ospf">ospf:ospf</source-protocol>



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            <last-updated>2015-10-24T18:02:45+02:00</last-updated>
          </route>
        </routes>
      </rib>
      <rib>
        <name>ipv6-master</name>
        <address-family xmlns:v6ur="urn:ietf:params:xml:ns:yang:\
          ietf-ipv6-unicast-routing">v6ur:ipv6-unicast</address-family>
        <default-rib>true</default-rib>
        <routes>
          <route>
            <destination-prefix xmlns="urn:ietf:params:xml:ns:yang:\
              ietf-ipv6-unicast-routing">0::/0</destination-prefix>
            <next-hop>
              <next-hop-address xmlns="urn:ietf:params:xml:ns:yang:\
                ietf-ipv6-unicast-routing">2001:db8:aaaa::1111\
              </next-hop-address>
            </next-hop>
            <route-preference>5</route-preference>
            <source-protocol>static</source-protocol>
            <last-updated>2015-10-24T18:02:45+02:00</last-updated>
          </route>
          <route>
            <destination-prefix xmlns="urn:ietf:params:xml:ns:yang:\
              ietf-ipv6-unicast-routing">2001:db8:bbbb::/64\
            </destination-prefix>
            <next-hop>
              <next-hop-address xmlns="urn:ietf:params:xml:ns:yang:\
                ietf-ipv6-unicast-routing">2001:db8:aaaa::1111\
              </next-hop-address>
              <repair-path xmlns="urn:ietf:params:xml:ns:yang:\
                ietf-rib-extension">
                <next-hop-address>2001:db8:cccc::2222</next-hop-address>
                <metric>200</metric>
              </repair-path>
            </next-hop>
            <route-preference>110</route-preference>
            <source-protocol xmlns:ospf="urn:ietf:params:xml:ns:yang:\
              ietf-ospf">ospf:ospf</source-protocol>
            <last-updated>2015-10-24T18:02:45+02:00</last-updated>
          </route>
        </routes>
      </rib>
    </ribs>
  </routing>


   The following is the same example using JSON format.



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  {
    "ietf-routing:routing": {
      "control-plane-protocols": {
        "control-plane-protocol": [
          {
            "type": "static",
            "name": "static-routing-protocol",
            "static-routes": {
              "ietf-ipv4-unicast-routing:ipv4": {
                "route": [
                  {
                    "destination-prefix": "0.0.0.0/0",
                    "next-hop": {
                      "next-hop-address": "192.0.2.2",
                      "ietf-rib-extension:preference": 30,
                      "ietf-rib-extension:tag": 99
                    }
                  }
                ]
              },
              "ietf-ipv6-unicast-routing:ipv6": {
                "route": [
                  {
                    "destination-prefix": "::/0",
                    "next-hop": {
                      "next-hop-address": "2001:db8:aaaa::1111",
                      "ietf-rib-extension:preference": 30,
                      "ietf-rib-extension:tag": 66
                    }
                  }
                ]
              }
            }
          }
        ]
      },
      "ribs": {
        "rib": [
          {
            "name": "ipv4-master",
            "address-family": "ietf-ipv4-unicast-routing:ipv4-unicast",
            "default-rib": true,
            "routes": {
              "route": [
                {
                  "next-hop": {
                    "ietf-ipv4-unicast-routing:next-hop-address": \
                    "192.0.2.2"



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                  },
                  "route-preference": 5,
                  "source-protocol": "static",
                  "last-updated": "2015-10-24T18:02:45+02:00",
                  "ietf-ipv4-unicast-routing:destination-prefix": \
                  "0.0.0.0/0"
                },
                {
                  "next-hop": {
                    "ietf-rib-extension:repair-path": {
                      "next-hop-address": "203.0.113.1",
                      "metric": 200
                    },
                    "ietf-ipv4-unicast-routing:next-hop-address": \
                    "192.0.2.2"
                  },
                  "route-preference": 110,
                  "source-protocol": "ietf-ospf:ospf",
                  "last-updated": "2015-10-24T18:02:45+02:00",
                  "ietf-ipv4-unicast-routing:destination-prefix": \
                  "198.51.100.0/24"
                }
              ]
            }
          },
          {
            "name": "ipv6-master",
            "address-family": "ietf-ipv6-unicast-routing:ipv6-unicast",
            "default-rib": true,
            "routes": {
              "route": [
                {
                  "next-hop": {
                    "ietf-ipv6-unicast-routing:next-hop-address": \
                    "2001:db8:aaaa::1111"
                  },
                  "route-preference": 5,
                  "source-protocol": "static",
                  "last-updated": "2015-10-24T18:02:45+02:00",
                  "ietf-ipv6-unicast-routing:destination-prefix": "::/0"
                },
                {
                  "next-hop": {
                    "ietf-rib-extension:repair-path": {
                      "next-hop-address": "2001:db8:cccc::2222",
                      "metric": 200
                    },
                    "ietf-ipv6-unicast-routing:next-hop-address": \



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                    "2001:db8:aaaa::1111"
                  },
                  "route-preference": 110,
                  "source-protocol": "ietf-ospf:ospf",
                  "last-updated": "2015-10-24T18:02:45+02:00",
                  "ietf-ipv6-unicast-routing:destination-prefix": \
                  "2001:db8:bbbb::/64"
                }
              ]
            }
          }
        ]
      }
    }
  }


Appendix C.  Acknowledgments

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

   The authors wish to thank Les Ginsberg, Krishna Deevi, and Suyoung
   Yoon for their helpful comments and suggestions.

   The authors wish to thank Tom Petch, Rob Wilton and Chris Hopps for
   their reviews and comments.

Authors' Addresses

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

   EMail: acee@cisco.com


   Yingzhen Qu
   Futurewei
   2330 Central Expressway
   Santa Clara, CA  95050
   USA

   EMail: yingzhen.qu@futurewei.com






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