Internet DRAFT - draft-ietf-babel-yang-model

draft-ietf-babel-yang-model







Babel Working Group                                      M. Jethanandani
Internet-Draft                                                    VMware
Intended status: Standards Track                                B. Stark
Expires: February 23, 2020                                          AT&T
                                                         August 22, 2019


                       YANG Data Model for Babel
                     draft-ietf-babel-yang-model-03

Abstract

   This document defines a data model for the Babel routing protocol.
   The data model is defined using the YANG data modeling language.

Requirements Language

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

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 February 23, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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



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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Note to RFC Editor  . . . . . . . . . . . . . . . . . . .   2
     1.2.  Tree Diagram Annotations  . . . . . . . . . . . . . . . .   3
   2.  Babel Module  . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Information Model . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   3
     2.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  28
     3.1.  URI Registrations . . . . . . . . . . . . . . . . . . . .  28
     3.2.  YANG Module Name Registration . . . . . . . . . . . . . .  28
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  28
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  30
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  30
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  30
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  31
   Appendix A.  An Appendix  . . . . . . . . . . . . . . . . . . . .  32
     A.1.  Statistics Gathering Enabled  . . . . . . . . . . . . . .  32
     A.2.  Automatic Detection of Properties . . . . . . . . . . . .  33
     A.3.  Override Default Properties . . . . . . . . . . . . . . .  34
     A.4.  Configuring other Properties  . . . . . . . . . . . . . .  36
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  37

1.  Introduction

   This document defines a data model for the Babel routing protocol
   [I-D.ietf-babel-rfc6126bis].  The data model is defined using YANG
   1.1 [RFC7950] data modeling language and is Network Management
   Datastore Architecture (NDMA) [RFC8342] compatible.  It is based on
   the Babel Information Model [I-D.ietf-babel-information-model].

1.1.  Note to RFC Editor

   Artwork in this document contains shorthand references to drafts in
   progress.  Please apply the following replacements and remove this
   note before publication.

   o  "XXXX" --> the assigned RFC value for this draft both in this
      draft and in the YANG models under the revision statement.




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   o  "ZZZZ" --> the assigned RFC value for Babel Information Model
      [I-D.ietf-babel-information-model]

   o  Revision date in model, in the format 2019-08-22 needs to get
      updated with the date the draft gets approved.  The date also
      needs to get reflected on the line with <CODE BEGINS>.

1.2.  Tree Diagram Annotations

   For a reference to the annotations used in tree diagrams included in
   this draft, please see YANG Tree Diagrams [RFC8340].

2.  Babel Module

   This document defines a YANG 1.1 [RFC7950] data model for the
   configuration and management of Babel.  The YANG module is based on
   the Babel Information Model [I-D.ietf-babel-information-model].

2.1.  Information Model

   There are a few things that should be noted between the Babel
   Information Model and this data module.  The information model
   mandates the definition of some of the attributes, e.g.  babel-
   implementation-version or the babel-self-router-id.  These attributes
   are marked a read-only objects in the information module as well as
   in this data module.  However, there is no way in the data module to
   mandate that a read-only attribute be present.  It is up to the
   implementation of this data module to make sure that the attributes
   that are marked read-only and are mandatory are indeed present.

2.2.  Tree Diagram

   The following diagram illustrates a top level hierarchy of the model.
   In addition to information like the version number implemented by
   this device, the model contains subtrees on constants, interfaces,
   routes and security.















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   module: ietf-babel
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol:
       +--rw babel!
          +--ro version?                  string
          +--rw enable                    boolean
          +--ro router-id?                binary
          +--ro seqno?                    uint16
          +--ro metric-comp-algorithms*   identityref
          +--ro security-supported*       identityref
          +--ro mac-algorithms*           identityref
          +--ro dtls-cert-types*          identityref
          +--rw stats-enable?             boolean
          +--rw constants
          |     ...
          +--rw interfaces* [reference]
          |     ...
          +--rw mac* [name]
          |     ...
          +--rw dtls* [name]
          |     ...
          +--ro routes* [prefix]
                ...

   The interfaces subtree describes attributes such as interface object
   that is being referenced, the type of link as enumerated by metric-
   algorithm and split-horizon and whether the interface is enabled or
   not.

   The constants subtree describes the UDP port used for sending and
   receiving Babel messages, and the multicast group used to send and
   receive announcements on IPv6.

   The routes subtree describes objects such as the prefix for which the
   route is advertised, a reference to the neighboring route, and next-
   hop address.

   Finally, for security two subtree are defined to contain MAC keys and
   DTLS certificates.  The mac-key-sets subtree contains keys used with
   the MAC security mechanism.  The boolean flag babel-mac-default-apply
   indicates whether the set of MAC keys is automatically applied to new
   interfaces.  The dtls subtree contains certificates used with DTLS
   security mechanism.  Similar to the MAC mechanism, the boolean flag
   babel-dtls-default-apply indicates whether the set of DTLS
   certificates is automatically applied to new interfaces.






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2.3.  YANG Module

   This module augments A YANG Data Model for Interface Management
   [RFC8343], YANG Routing Management [RFC8349], imports definitions
   from Common YANG Data Types [RFC6991], and references HMAC: Keyed-
   Hashing for Message Authentication [RFC2104], Using HMAC-SHA-256,
   HMAC-SHA-384, and HMAC-SHA-512 [RFC4868], Datagram Transport Layer
   Security Version 1.2 [RFC6347], The Blake2 Cryptographic Hash and
   Message Authentication Code (MAC) [RFC7693], Babel Information Model
   [I-D.ietf-babel-information-model], and The Babel Routing Protocol
   [I-D.ietf-babel-rfc6126bis].

 <CODE BEGINS> file "ietf-babel@2019-08-22.yang"

 module ietf-babel {
   yang-version 1.1;
   namespace "urn:ietf:params:xml:ns:yang:ietf-babel";
   prefix babel;

   import ietf-yang-types {
     prefix yt;
     reference
       "RFC 6991: Common YANG Data Types.";
   }
   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";
   }
   import ietf-routing {
     prefix "rt";
     reference
       "RFC 8349: YANG Routing Management";
   }

   organization
     "IETF Babel routing protocol Working Group";

   contact
     "WG Web: http://tools.ietf.org/wg/babel/
      WG List: babel@ietf.org

      Editor: Mahesh Jethanandani



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              mjethanandani@gmail.com
      Editor: Barbara Stark
              bs7652@att.com";

   description
     "This YANG module defines a model for the Babel routing
      protocol.

      Copyright (c) 2019 IETF Trust and the persons identified as
      the document authors.  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 2019-08-22 {
     description
       "Initial version.";
     reference
       "RFC XXXX: Babel YANG Data Model.";
   }

   /*
    * Identities
    */
   identity metric-comp-algorithms {
     description
       "Base identity from which all Babel metric comp algorithms
        are derived.";
   }
   identity two-out-of-three {
     base "metric-comp-algorithms";
     description
       "2-out-of-3 algorithm.";
   }
   identity etx {
     base "metric-comp-algorithms";
     description
       "Expected Transmission Count.";
   }

   /*
    * Babel security type identities



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    */
   identity security-supported {
     description
       "Base identity from which all Babel security types are
        derived.";
   }

   identity mac {
     base security-supported;
     description
       "Keyed MAC supported.";
   }

   identity dtls {
     base security-supported;
     description
       "Datagram Transport Layer Security (DTLS) supported.";
     reference
       "RFC 6347, Datagram Transport Layer Security Version 1.2.";
   }

   /*
    * Babel MAC algorithms identities.
    */
   identity mac-algorithms {
     description
       "Base identity for all Babel MAC algorithms.";
   }

   identity hmac-sha256 {
     base mac-algorithms;
     description
       "HMAC-SHA256 algorithm supported.";
     reference
       "RFC 4868: Using HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512
        with IPsec.";
   }

   identity blake2s {
     base mac-algorithms;
     description
       "BLAKE2s algorithm supported.";
     reference
       "RFC 7693: The BLAKE2 Cryptographic Hash and Message
        Authentication Code (MAC).";
   }

   /*



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    * Babel Cert Types
    */
   identity dtls-cert-types {
     description
       "Base identity for Babel DTLS certificate types.";
   }

   identity x-509 {
     base dtls-cert-types;
     description
       "X.509 certificate type.";
   }

   identity raw-public-key {
     base dtls-cert-types;
     description
       "Raw Public Key type.";
   }

   /*
    * Babel routing protocol identity.
    */
   identity babel {
     base "rt:routing-protocol";
     description
       "Babel routing protocol";
   }

   /*
    * Groupings
    */
   grouping routes {
     list routes {
       key "prefix";
       config false;

       leaf prefix {
         type inet:ip-prefix;
         description
           "Prefix (expressed in ip-address/prefix-length format) for
            which this route is advertised.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6.";
       }

       leaf router-id {
         type binary;
         description



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           "router-id of the source router for which this route is
            advertised.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6.";
       }

       leaf neighbor {
         type leafref {
           path "/rt:routing/rt:control-plane-protocols/" +
                "rt:control-plane-protocol/babel/interfaces/" +
                "neighbor-objects/neighbor-address";
         }
         description
           "Reference to the babel-neighbors entry for the neighbor
            that advertised this route.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6.";
       }

       leaf received-metric {
         type uint16;
         description
           "The metric with which this route was advertised by the
            neighbor, or maximum value (infinity) to indicate a the
            route was recently retracted and is temporarily
            unreachable. This metric will be 0 (zero) if the route
            was not received from a neighbor but was generated
            through other means. At least one of
            babel-route-calculated-metric or
            babel-route-received-metric MUST be non-NULL.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6,
            draft-ietf-babel-rfc6126bis: The Babel Routing Protocol,
                                         Section 3.5.5.";
       }

       leaf calculated-metric {
         type uint16;
         description
           "A calculated metric for this route. How the metric is
            calculated is implementation-specific. Maximum value
            (infinity) indicates the route was recently retracted
            and is temporarily unreachable. At least one of
            babel-route-calculated-metric or
            babel-route-received-metric MUST be non-NULL.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6,
            draft-ietf-babel-rfc6126bis: The Babel Routing Protocol,



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                                         Section 3.5.5.";
       }

       leaf seqno {
         type uint16;
         description
           "The sequence number with which this route was advertised.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6.";
       }

       leaf next-hop {
         type inet:ip-address;
         description
           "The next-hop address of this route. This will be empty if
            this route has no next-hop address.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6.";
       }

       leaf feasible {
         type boolean;
         description
           "A boolean flag indicating whether this route is feasible.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6,
            draft-ietf-babel-rfc6126bis, The Babel Routing Protocol,
            Section 3.5.1.";
       }

       leaf selected {
         type boolean;
         description
           "A boolean flag indicating whether this route is selected,
            i.e., whether it is currently being used for forwarding and
            is being advertised.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.6.";
       }
       description
         "A set of babel-route-obj objects. Includes received and
          routes routes.";
       reference
         "RFC ZZZZ: Babel Information Model, Section 3.1.";
     }
     description
       "Common grouping for routing used in RIB.";
   }



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   /*
    * Data model
    */

   augment "/rt:routing/rt:control-plane-protocols/" +
     "rt:control-plane-protocol" {
     when "derived-from-or-self(rt:type, 'babel')" {
       description
         "Augmentation is valid only when the instance of routing type
          is of type 'babel'.";
     }
     description
       "Augment the routing module to support a common structure
        between routing protocols.";
     reference
       "YANG Routing Management, RFC 8349, Lhotka & Lindem, March
        2018.";

     container babel {
       presence "A Babel container.";

       leaf version {
         type string;
         config false;
         description
           "The name and version of this implementation of the Babel
            protocol.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1.";
       }

       leaf enable {
         type boolean;
         mandatory true;
         description
           "When written, it configures whether the protocol should be
            enabled. A read from the <running> or <intended> datastore
            therefore indicates the configured administrative value of
            whether the protocol is enabled or not.

            A read from the <operational> datastore indicates whether
            the protocol is actually running or not, i.e. it indicates
            the operational state of the protocol.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1.";
       }

       leaf router-id {



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         type binary;
         config false;
         description
           "Every Babel speaker is assigned a router-id, which is an
            arbitrary string of 8 octets that is assumed to be unique
            across the routing domain";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1,
            draft-ietf-babel-rfc6126bis: The Babel Routing Protocol,
                                         Section 3.";
       }

       leaf seqno {
         type uint16;
         config false;
         description
           "Sequence number included in route updates for routes
          originated by this node.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1.";
       }

       leaf-list metric-comp-algorithms {
         type identityref {
           base "metric-comp-algorithms";
         }
         config false;
         min-elements 1;
         description
           "List of cost compute algorithms supported by this
            implementation of Babel.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1.";
       }

       leaf-list security-supported {
         type identityref {
           base "security-supported";
         }
         config false;
         min-elements 1;
         description
           "List of supported security mechanisms.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1.";
       }

       leaf-list mac-algorithms {



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         type identityref {
           base mac-algorithms;
         }
         config false;
         description
           "List of supported MAC computation algorithms. Possible
            values include 'HMAC-SHA256', 'BLAKE2s'.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1.";
       }

       leaf-list dtls-cert-types {
         type identityref {
           base dtls-cert-types;
         }
         config false;
         description
           "List of supported DTLS certificate types. Possible values
            include 'X.509' and 'RawPublicKey'.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1.";
       }

       leaf stats-enable {
         type boolean;
         description
           "Indicates whether statistics collection is enabled (true)
            or disabled (false) on all interfaces.";
       }

       container constants {
         leaf udp-port {
           type inet:port-number;
           default "6696";
           description
             "UDP port for sending and receiving Babel messages. The
              default port is 6696.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.2.";
         }

         leaf mcast-group {
           type inet:ip-address;
           default "ff02::1:6";
           description
             "Multicast group for sending and receiving multicast
              announcements on IPv6.";
           reference



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             "RFC ZZZZ: Babel Information Model, Section 3.2.";
         }
         description
           "Babel Constants object.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.1.";
       }

       list interfaces {
         key "reference";

         leaf reference {
           type if:interface-ref;
           description
             "References the name of the interface over which Babel
              packets are sent and received.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf enable {
           type boolean;
           default "true";
           description
             "If true, babel sends and receives messages on this
              interface. If false, babel messages received on this
              interface are ignored and none are sent.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf metric-algorithm {
           type identityref {
             base metric-comp-algorithms;
           }
           mandatory true;
           description
             "Indicates the metric computation algorithm used on this
              interface. The value MUST be one of those listed in
              'metric-comp-algorithms'.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.X.";
         }

         leaf split-horizon {
           type boolean;
           description
             "Indicates whether or not the split horizon optimization



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              is used when calculating metrics on this interface.
              A value of true indicates split horizon optimization
              is used.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.X.";
         }

         leaf mcast-hello-seqno {
           type uint16;
           config false;
           description
             "The current sequence number in use for multicast hellos
              sent on this interface.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf mcast-hello-interval {
           type uint16;
           units centiseconds;
           description
             "The current multicast hello interval in use for hellos
              sent on this interface.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf update-interval {
           type uint16;
           units centiseconds;
           description
             "The current update interval in use for this interface.
              Units are centiseconds.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf mac-enable {
           type boolean;
           description
             "Indicates whether the MAC security mechanism is enabled
              (true) or disabled (false).";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf-list mac-key-sets {
           type leafref {



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             path "../../mac/name";
           }
           description
             "List of references to the babel-mac entries that apply
              to this interface. When an interface instance is created,
              all babel-mac-key-sets instances with
              babel-mac-default-apply 'true' will be included in this
              list.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf mac-verify {
           type boolean;
           description
             "A Boolean flag indicating whether MAC hashes in
              incoming Babel packets are required to be present and
              are verified.  If this parameter is 'true', incoming
              packets are required to have a valid MAC hash.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf dtls-enable {
           type boolean;
           description
             "Indicates whether the DTLS security mechanism is enabled
              (true) or disabled (false).";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf-list dtls-certs {
           type leafref {
             path "../../dtls/name";
           }
           description
             "List of references to the babel-dtls-cert-sets entries
              that apply to this interface.  When an interface instance
              is created, all babel-dtls instances with
              babel-dtls-default-apply 'true' will be included in
              this list.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf dtls-cached-info {
           type boolean;



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           description
             "Indicates whether the cached_info extension is included
              in ClientHello and ServerHello packets. The extension
              is included if the value is 'true'.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf-list dtls-cert-prefer {
           type leafref {
             path "../../dtls/certs/type";
           }
           ordered-by user;
           description
             "List of supported certificate types, in order of
              preference. The values MUST be among those listed in the
              babel-dtls-cert-types parameter. This list is used to
              populate the server_certificate_type extension in a
              Client Hello.  Values that are present in at least one
              instance in the babel-dtls-certs object of a referenced
              babel-dtls instance and that have a non-empty
              babel-cert-private-key will be used to populate the
              client_certificate_type extension in a Client Hello.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf packet-log-enable {
           type boolean;
           description
             "If true, logging of babel packets received on this
              interface is enabled; if false, babel packets are not
              logged.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         leaf packet-log {
           type inet:uri;
           config false;
           description
             "A reference or url link to a file that contains a
              timestamped log of packets received and sent on
              babel-udp-port on this interface. The [libpcap] file
              format with .pcap file extension SHOULD be supported for
              packet log files. Logging is enabled / disabled by
              packet-log-enable.";
           reference



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             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         container stats {
           config false;
           leaf sent-mcast-hello {
             type yt:counter32;
             description
               "A count of the number of multicast Hello packets sent
                on this interface.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.4.";
           }

           leaf sent-mcast-update {
             type yt:counter32;
             description
               "A count of the number of multicast update packets sent
                on this interface.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.4.";
           }

           leaf sent-ucast-hello {
             type yt:counter32;
             description
               "A count of the number of unicast Hello packets sent
                to this neighbor.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.6.";
           }

           leaf sent-ucast-update {
             type yt:counter32;
             description
               "A count of the number of unicast update packets sent
                to this neighbor.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.6.";
           }

           leaf sent-ihu {
             type yt:counter32;
             description
               "A count of the number of IHU packets sent to this
                neighbor.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.6.";



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           }

           leaf received-packets {
             type yt:counter32;
             description
               "A count of the number of Babel packets received on
                this interface.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.4.";
           }
           action reset {
             description
               "The information model [RFC ZZZZ] defines this reset
                action as a system-wide reset of Babel statistics
                parameters, but in YANG the reset action has to be
                contained in the container where the action needs to
                be performed.";

             input {
               leaf reset-at {
                 type yt:date-and-time;
                 description
                   "The time when the reset was issued.";
               }
             }
             output {
               leaf reset-finished-at {
                 type yt:date-and-time;
                 description
                   "The time when the reset finished.";
               }
             }
           }
           description
             "Statistics collection object for this interface.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.3.";
         }

         list neighbor-objects {
           key "neighbor-address";
           config false;

           leaf neighbor-address {
             type inet:ip-address;
             description
               "IPv4 or v6 address the neighbor sends packets from.";
             reference



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               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf hello-mcast-history {
             type string;
             description
               "The multicast Hello history of whether or not the
                multicast Hello packets prior to babel-exp-mcast-
                hello-seqno were received, with a '1' for the most
                recent Hello placed in the most significant bit and
                prior Hellos shifted right (with '0' bits placed
                between prior Hellos and most recent Hello for any
                not-received Hellos); represented as a string using
                utf-8 encoded hex digits where a '1' bit = Hello
                received and a '0' bit = Hello not received.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf hello-ucast-history {
             type string;
             description
               "The unicast Hello history of whether or not the
                unicast Hello packets prior to babel-exp-ucast-
                hello-seqno were received, with a '1' for the most
                recent Hello placed in the most significant bit and
                prior Hellos shifted right (with '0' bits placed
                between prior Hellos and most recent Hello for any
                not-received Hellos); represented as a string using
                utf-8 encoded hex digits where a '1' bit = Hello
                received and a '0' bit = Hello not received.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf txcost {
             type int32;
             default "0";
             description
               "Transmission cost value from the last IHU packet
                received from this neighbor, or maximum value
                (infinity) to indicate the IHU hold timer for this
                neighbor has expired description.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf exp-mcast-hello-seqno {



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             type uint16;
             default "0";
             description
               "Expected multicast Hello sequence number of next Hello
                to be received from this neighbor; if multicast Hello
                packets are not expected, or processing of multicast
                packets is not enabled, this MUST be NULL.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf exp-ucast-hello-seqno {
             type uint16;
             default "0";
             description
               "Expected unicast Hello sequence number of next Hello to
                be received from this neighbor; if unicast Hello
                packets are not expected, or processing of unicast
                packets is not enabled, this MUST be NULL.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf ucast-hello-seqno {
             type uint16;
             description
               "Expected unicast Hello sequence number of next Hello
                to be received from this neighbor. If unicast Hello
                packets are not expected, or processing of unicast
                packets is not enabled, this MUST be 0.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf ucast-hello-interval {
             type uint16;
             units centiseconds;
             description
               "The current interval in use for unicast hellos sent to
                this neighbor. Units are centiseconds.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf rxcost {
             type int32;
             description
               "Reception cost calculated for this neighbor. This value



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                is usually derived from the Hello history, which may be
                combined with other data, such as statistics maintained
                by the link layer. The rxcost is sent to a neighbor in
                each IHU.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }

           leaf cost {
             type int32;
             description
               "Link cost is computed from the values maintained in
                the neighbor table. The statistics kept in the neighbor
                table about the reception of Hellos, and the txcost
                computed from received IHU packets.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.5.";
           }
           description
             "A set of Babel Neighbor Object.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.5.";
         }
         description
           "A set of Babel Interface objects.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.3.";
       }

       list mac {
         key "name";

         leaf name {
           type string;
           description
             "A string that uniquely identifies the mac object.";
         }

         leaf default-apply {
           type boolean;
           description
             "A Boolean flag indicating whether this babel-mac
              instance is applied to all new interfaces, by default. If
              'true', this instance is applied to new
              babel-interfaces instances at the time they are created,
              by including it in the babel-interface-mac-keys list.
              If 'false', this instance is not applied to new
              babel-interfaces instances when they are created.";



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           reference
             "RFC ZZZZ: Babel Information Model, Section 3.7.";
         }

         list keys {
           key "name";
           min-elements "1";

           leaf name {
             type string;
             mandatory true;
             description
               "A unique name for this MAC key that can be used to
                identify the key in this object instance, since the key
                value is not allowed to be read. This value can only be
                provided when this instance is created, and is not
                subsequently writable.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.8.";
           }

           leaf use-sign {
             type boolean;
             mandatory true;
             description
               "Indicates whether this key value is used to sign sent
                Babel packets. Sent packets are signed using this key
                if the value is 'true'. If the value is 'false', this
                key is not used to sign sent Babel packets.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.8.";
           }

           leaf use-verify {
             type boolean;
             mandatory true;
             description
               "Indicates whether this key value is used to verify
                incoming Babel packets. This key is used to verify
                incoming packets if the value is 'true'. If the value
                is 'false', no MAC is computed from this key for
                comparing an incoming packet.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.8.";
           }

           leaf value {
             type binary;



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             mandatory true;
             description
               "The value of the MAC key. An implementation MUST NOT
                allow this parameter to be read. This can be done by
                always providing an empty string, or through
                permissions, or other means. This value MUST be
                provided when this instance is created, and is not
                subsequently writable.

                This value is of a length suitable for the associated
                babel-mac-key-algorithm. If the algorithm is based on
                the HMAC construction [RFC2104], the length MUST be
                between 0 and the block size of the underlying hash
                inclusive (where 'HMAC-SHA256' block size is 64
                bytes as described in [RFC4868]). If the algorithm
                is 'BLAKE2s', the length MUST be between 0 and 32
                bytes inclusive, as described in [RFC7693].";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.8,
                RFC 2104: HMAC: Keyed-Hashing for Message
                          Authentication
                RFC 4868: Using HMAC-SHA-256, HMAC-SHA-384, and
                          HMAC-SHA-512 with IPsec,
                RFC 7693: The BLAKE2 Cryptographic Hash and Message
                          Authentication Code (MAC).";
           }

           leaf algorithm {
             type identityref {
               base mac-algorithms;
             }
             description
               "The name of the MAC algorithm used with this key. The
                value MUST be the same as one of the enumerations
                listed in the babel-mac-algorithms parameter.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.8.";
           }

           action test {
             input {
               leaf test-string {
                 type binary;
                 mandatory true;
                 description
                   "The test string on which this test has to be
                    performed.";
               }



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             }
             output {
               leaf resulting-hash {
                 type binary;
                 mandatory true;
                 description
                   "An operation that allows the MAC key and hash
                    algorithm to be tested to see if they produce an
                    expected outcome. Input to this operation is a
                    binary string. The implementation is expected to
                    create a hash of this string using the
                    babel-mac-key-value and the babel-mac-algorithm.
                    The output of this operation is the resulting hash,
                    as a binary string.";
                 reference
                   "RFC ZZZZ: Babel Information Model, Section 3.8.";
               }
             }
           }
           description
             "A set of babel-mac-keys-obj objects.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.8.";
         }
         description
           "A babel-mac-obj object. If this object is implemented, it
            provides access to parameters related to the MAC security
            mechanism.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.7.";
       }

       list dtls {
         key "name";

         leaf name {
           type string;
           description
             "A string that uniquely identifies a dtls object.";
         }

         leaf default-apply {
           type boolean;
           mandatory true;
           description
             "A Boolean flag indicating whether this babel-dtls
              instance is applied to all new interfaces, by default. If
              'true', this instance is applied to new babel-interfaces



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              instances at the time they are created, by including it
              in the babel-interface-dtls-certs list. If 'false',
              this instance is not applied to new babel-interfaces
              instances when they are created.";
           reference
             "RFC ZZZZ: Babel Information Model, Section 3.9.";
         }

         list certs {
           key "name";
           min-elements "1";

           leaf name {
             type string;
             description
               "A unique name for this DTLS certificate that can be
                used to identify the certificate in this object
                instance, since the value is too long to be useful
                for identification. This value MUST NOT be empty
                and can only be provided when this instance is created
                (i.e., it is not subsequently writable).";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.10.";
           }

           leaf value {
             type string;
             mandatory true;
             description
               "The DTLS certificate in PEM format [RFC7468]. This
                value can only be provided when this instance is
                created, and is not subsequently writable.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.10.";
           }

           leaf type {
             type identityref {
               base dtls-cert-types;
             }
             mandatory true;
             description
               "The name of the certificate type of this object
                instance. The value MUST be the same as one of the
                enumerations listed in the babel-dtls-cert-types
                parameter. This value can only be provided when this
                instance is created, and is not subsequently writable.";
             reference



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               "RFC ZZZZ: Babel Information Model, Section 3.10.";
           }

           leaf private-key {
             type binary;
             mandatory true;
             description
               "The value of the private key. If this is non-empty,
                this certificate can be used by this implementation to
                provide a certificate during DTLS handshaking. An
                implementation MUST NOT allow this parameter to be
                read. This can be done by always providing an empty
                string, or through permissions, or other means. This
                value can only be provided when this instance is
                created, and is not subsequently writable.";
             reference
               "RFC ZZZZ: Babel Information Model, Section 3.10.";
           }

           action test {
             input {
               leaf test-string {
                 type binary;
                 mandatory true;
                 description
                   "The test string on which this test has to be
                    performed.";
               }
             }
             output {
               leaf resulting-hash {
                 type binary;
                 mandatory true;
                 description
                   "The output of this operation is a binary string,
                    and is the resulting hash computed using the
                    certificate public key, and the SHA-256
                    hash algorithm.";
               }
             }
           }
           description
             "A set of babel-dtls-keys-obj objects. This contains
              both certificates for this implementation to present
              for authentication, and to accept from others.
              Certificates with a non-empty babel-cert-private-key
              can be presented by this implementation for
              authentication.";



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           reference
             "RFC ZZZZ: Babel Information Model, Section 3.10.";
         }
         description
           "A babel-dtls-obj object. If this object is implemented,
            it provides access to parameters related to the DTLS
            security mechanism.";
         reference
           "RFC ZZZZ: Babel Information Model, Section 3.9";
       }
       description
         "Babel Information Objects.";
       reference
         "RFC ZZZZ: Babel Information Model, Section 3.";

       uses routes;
     }
   }
 }

 <CODE ENDS>

3.  IANA Considerations

   This document registers one URIs and one YANG module.

3.1.  URI Registrations

   URI: urn:ietf:params:xml:ns:yang:ietf-babel

3.2.  YANG Module Name Registration

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

   Name:ietf-babel
   Namespace: urn:ietf:params:xml:ns:yang:ietf-babel
   prefix: babel
   reference: RFC XXXX

4.  Security Considerations

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



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

   There are a number of data nodes defined in the YANG module which are
   writable/created/deleted (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 from a config true perspective:

   babel: This container includes an "enable" parameter that can be used
   to enable or disable use of Babel on a router

   babel/constants: This container includes configuration parameters
   that can prevent reachability if misconfigured.

   babel/interfaces: This leaf-list has configuration parameters that
   can enable/disable security mechanisms and change performance
   characteristics of the Babel protocol.

   babel/hmac and babel/dtls: These contain security credentials that
   influence whether packets are trusted.

   Some of the readable data or config false 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 from a
   config false perpective:

   babel: Access to the information in the various nodes can disclose
   the network topology.  Additionally, the routes used by a network
   device may be used to mount a subsequent attack on traffic traversing
   the network device.

   babel/hmac and babel/dtls: These contain security credentials,
   include private credentials of the router.

   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 from a RPC operation
   perspective:






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   babel/hmac/hmac/keys/test and babel/dtls/certs/test: These can be
   used in a brute force attack to identify the credentials being used
   to secure the Babel protocol.

5.  Acknowledgements

   Juliusz Chroboczek provided most of the example configurations for
   babel that are shown in the Appendix.

6.  References

6.1.  Normative References

   [I-D.ietf-babel-rfc6126bis]
              Chroboczek, J. and D. Schinazi, "The Babel Routing
              Protocol", draft-ietf-babel-rfc6126bis-14 (work in
              progress), August 2019.

   [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>.

   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
              384, and HMAC-SHA-512 with IPsec", RFC 4868,
              DOI 10.17487/RFC4868, May 2007,
              <https://www.rfc-editor.org/info/rfc4868>.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <https://www.rfc-editor.org/info/rfc6347>.

   [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>.

   [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>.

   [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>.




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   [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>.

6.2.  Informative References

   [I-D.ietf-babel-information-model]
              Stark, B. and M. Jethanandani, "Babel Information Model",
              draft-ietf-babel-information-model-08 (work in progress),
              August 2019.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              DOI 10.17487/RFC2104, February 1997,
              <https://www.rfc-editor.org/info/rfc2104>.

   [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>.

   [RFC7693]  Saarinen, M-J., Ed. and J-P. Aumasson, "The BLAKE2
              Cryptographic Hash and Message Authentication Code (MAC)",
              RFC 7693, DOI 10.17487/RFC7693, November 2015,
              <https://www.rfc-editor.org/info/rfc7693>.

   [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>.

   [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>.

   [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>.



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   [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>.

   [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>.

Appendix A.  An Appendix

   This section is devoted to examples that demonstrate how Babel can be
   configured.

A.1.  Statistics Gathering Enabled

   In this example, interface eth0 is being configured for routing
   protocol Babel, and statistics gathering is enabled.

































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<?xml version="1.0" encoding="UTF-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
              xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
    <interface>
      <name>eth0</name>
      <type>ianaift:ethernetCsmacd</type>
      <enabled>true</enabled>
    </interface>
  </interfaces>
  <routing
      xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
    <control-plane-protocols>
      <control-plane-protocol>
        <type
            xmlns:babel="urn:ietf:params:xml:ns:yang:ietf-babel">babel:babel
        </type>
        <name>name:babel</name>
        <babel
            xmlns="urn:ietf:params:xml:ns:yang:ietf-babel">
          <enable>true</enable>
          <interfaces>
            <reference>eth0</reference>
            <metric-algorithm>two-out-of-three</metric-algorithm>
            <split-horizon>true</split-horizon>
          </interfaces>
          <stats-enable>true</stats-enable>
        </babel>
      </control-plane-protocol>
    </control-plane-protocols>
  </routing>
</config>

A.2.  Automatic Detection of Properties

<!-- In this example, babeld is configured on two interfaces

   interface eth0
   interface wlan0

   This says to run Babel on interfaces eth0 and wlan0.  Babeld will
   automatically detect that eth0 is wired and wlan0 is wireless, and
   will configure the right parameters automatically.
-->

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"



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              xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
    <interface>
      <name>eth0</name>
      <type>ianaift:ethernetCsmacd</type>
      <enabled>true</enabled>
    </interface>
    <interface>
      <name>wlan0</name>
      <type>ianaift:ieee80211</type>
      <enabled>true</enabled>
    </interface>
  </interfaces>
  <routing
      xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
    <control-plane-protocols>
      <control-plane-protocol>
        <type
            xmlns:babel="urn:ietf:params:xml:ns:yang:ietf-babel">babel:babel
        </type>
        <name>name:babel</name>
        <babel
            xmlns="urn:ietf:params:xml:ns:yang:ietf-babel">
          <enable>true</enable>
          <interfaces>
            <reference>eth0</reference>
            <enable>true</enable>
            <metric-algorithm>two-out-of-three</metric-algorithm>
            <split-horizon>true</split-horizon>
          </interfaces>
          <interfaces>
            <reference>wlan0</reference>
            <enable>true</enable>
            <metric-algorithm>etx</metric-algorithm>
            <split-horizon>false</split-horizon>
          </interfaces>
        </babel>
      </control-plane-protocol>
    </control-plane-protocols>
  </routing>
</config>

A.3.  Override Default Properties

<!-- In this example, babeld is configured on three interfaces

 interface eth0
 interface eth1 type wireless
 interface tun0 type tunnel



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 Here, interface eth1 is an Ethernet bridged to a wireless radio, so
 babeld's autodetection fails, and the interface type needs to be
 configured manually.  Tunnels are not detected automatically, so this
 needs to be specified.

 This is equivalent to the following:

 interface eth0 metric-algorithm 2-out-of-3 split-horizon true
 interface eth1 metric-algorithm etx split-horizon false
 interface tun0 metric-algorithm 2-out-of-3 split-horizon true
-->

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
              xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
    <interface>
      <name>eth0</name>
      <type>ianaift:ethernetCsmacd</type>
      <enabled>true</enabled>
    </interface>
    <interface>
      <name>eth1</name>
      <type>ianaift:ethernetCsmacd</type>
      <enabled>true</enabled>
    </interface>
    <interface>
      <name>tun0</name>
      <type>ianaift:tunnel</type>
      <enabled>true</enabled>
    </interface>
  </interfaces>
  <routing
      xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">
    <control-plane-protocols>
      <control-plane-protocol>
        <type
            xmlns:babel="urn:ietf:params:xml:ns:yang:ietf-babel">babel:babel
        </type>
        <name>name:babel</name>
        <babel
            xmlns="urn:ietf:params:xml:ns:yang:ietf-babel">
          <enable>true</enable>
          <interfaces>
            <reference>eth0</reference>
            <enable>true</enable>
            <metric-algorithm>two-out-of-three</metric-algorithm>
            <split-horizon>true</split-horizon>



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          </interfaces>
          <interfaces>
            <reference>eth1</reference>
            <enable>true</enable>
            <metric-algorithm>etx</metric-algorithm>
            <split-horizon>false</split-horizon>
          </interfaces>
          <interfaces>
            <reference>tun0</reference>
            <enable>true</enable>
            <metric-algorithm>two-out-of-three</metric-algorithm>
            <split-horizon>true</split-horizon>
          </interfaces>
        </babel>
      </control-plane-protocol>
    </control-plane-protocols>
  </routing>
</config>

A.4.  Configuring other Properties

<!-- In this example, two interfaces are configured for babeld

 interface eth0
 interface ppp0 hello-interval 30 update-interval 120

 Here, ppp0 is a metered 3G link used for fallback connectivity. It runs
 with much higher than default time constants in order to avoid control
 traffic as much as possible.
-->

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
              xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
    <interface>
      <name>eth0</name>
      <type>ianaift:ethernetCsmacd</type>
      <enabled>true</enabled>
    </interface>
    <interface>
      <name>ppp0</name>
      <type>ianaift:ppp</type>
      <enabled>true</enabled>
    </interface>
  </interfaces>
  <routing
      xmlns="urn:ietf:params:xml:ns:yang:ietf-routing">



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    <control-plane-protocols>
      <control-plane-protocol>
        <type
            xmlns:babel="urn:ietf:params:xml:ns:yang:ietf-babel">babel:babel
        </type>
        <name>name:babel</name>
        <babel
            xmlns="urn:ietf:params:xml:ns:yang:ietf-babel">
          <enable>true</enable>
          <interfaces>
            <reference>eth0</reference>
            <enable>true</enable>
            <metric-algorithm>two-out-of-three</metric-algorithm>
            <split-horizon>true</split-horizon>
          </interfaces>
          <interfaces>
            <reference>ppp0</reference>
            <enable>true</enable>
            <mcast-hello-interval>30</mcast-hello-interval>
            <update-interval>120</update-interval>
            <metric-algorithm>two-out-of-three</metric-algorithm>
          </interfaces>
        </babel>
      </control-plane-protocol>
    </control-plane-protocols>
  </routing>
</config>

Authors' Addresses

   Mahesh Jethanandani
   VMware
   California
   USA

   Email: mjethanandani@gmail.com


   Barbara Stark
   AT&T
   Atlanta, GA
   USA

   Email: barbara.stark@att.com







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