Babel Information Model
RFC 9046

Document Type RFC - Informational (June 2021; No errata)
Authors Barbara Stark  , Mahesh Jethanandani 
Last updated 2021-06-30
Replaces draft-stark-babel-information-model
Stream Internet Engineering Task Force (IETF)
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Stream WG state Submitted to IESG for Publication
Document shepherd Donald Eastlake
Shepherd write-up Show (last changed 2019-10-13)
IESG IESG state RFC 9046 (Informational)
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(None)
Consensus Boilerplate Yes
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Responsible AD Martin Vigoureux
Send notices to Donald Eastlake <d3e3e3@gmail.com>
IANA IANA review state Version Changed - Review Needed
IANA action state No IANA Actions


Internet Engineering Task Force (IETF)                          B. Stark
Request for Comments: 9046                                          AT&T
Category: Informational                                  M. Jethanandani
ISSN: 2070-1721                                           Kloud Services
                                                               June 2021

                        Babel Information Model

Abstract

   The Babel information model provides structured data elements for a
   Babel implementation reporting its current state and may allow
   limited configuration of some such data elements.  This information
   model can be used as a basis for creating data models under various
   data modeling regimes.  This information model only includes
   parameters and parameter values useful for managing Babel over IPv6.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are candidates for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9046.

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

Table of Contents

   1.  Introduction
     1.1.  Requirements Language
     1.2.  Notation
   2.  Overview
   3.  The Information Model
     3.1.  Definition of babel-information-obj
     3.2.  Definition of babel-constants-obj
     3.3.  Definition of babel-interface-obj
     3.4.  Definition of babel-if-stats-obj
     3.5.  Definition of babel-neighbor-obj
     3.6.  Definition of babel-route-obj
     3.7.  Definition of babel-mac-key-set-obj
     3.8.  Definition of babel-mac-key-obj
     3.9.  Definition of babel-dtls-cert-set-obj
     3.10. Definition of babel-dtls-cert-obj
   4.  Extending the Information Model
   5.  Security Considerations
   6.  IANA Considerations
   7.  References
     7.1.  Normative References
     7.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   Babel is a loop-avoiding, distance-vector routing protocol defined in
   [RFC8966].  [RFC8967] defines a security mechanism that allows Babel
   packets to be cryptographically authenticated, and [RFC8968] defines
   a security mechanism that allows Babel packets to be both
   authenticated and encrypted.  This document describes an information
   model for Babel (including implementations using one or both of these
   security mechanisms) that can be used to create management protocol
   data models (such as a NETCONF [RFC6241] YANG [RFC7950] data model).

   Due to the simplicity of the Babel protocol, most of the information
   model is focused on reporting the Babel protocol operational state,
   and very little of that is considered mandatory to implement for an
   implementation claiming compliance with this information model.  Some
   parameters may be configurable.  However, it is up to the Babel
   implementation whether to allow any of these to be configured within
   its implementation.  Where the implementation does not allow
   configuration of these parameters, it MAY still choose to expose them
   as read-only.

   The information model is presented using a hierarchical structure.
   This does not preclude a data model based on this information model
   from using a referential or other structure.

   This information model only includes parameters and parameter values
   useful for managing Babel over IPv6.  This model has no parameters or
   values specific to operating Babel over IPv4, even though [RFC8966]
   does define a multicast group for sending and listening to multicast
   announcements on IPv4.  There is less likelihood of breakage due to
   inconsistent configuration and increased implementation simplicity if
   Babel is operated always and only over IPv6.  Running Babel over IPv6
   requires IPv6 at the link layer and does not need advertised
   prefixes, router advertisements, or DHCPv6 to be present in the
   network.  Link-local IPv6 is widely supported among devices where
   Babel is expected to be used.  Note that Babel over IPv6 can be used
   for configuration of both IPv4 and IPv6 routes.

1.1.  Requirements Language

   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.

1.2.  Notation

   This document uses a programming-language-like notation to define the
   properties of the objects of the information model.  An optional
   property is enclosed by square brackets, [ ], and a list property is
   indicated by two numbers in angle brackets, <m..n>, where m indicates
   the minimal number of list elements, and n indicates the maximum
   number of list elements.  The symbol "*" for n means there are no
   defined limits on the number of list elements.  Each parameter and
   object includes an indication of "ro" or "rw". "ro" means the
   parameter or object is read-only. "rw" means it is read-write.  For
   an object, read-write means instances of the object can be created or
   deleted.  If an implementation is allowed to choose to implement a
   "rw" parameter as read-only, this is noted in the parameter
   description.

   The object definitions use base types that are defined as follows:

   binary:       A binary string (sequence of octets).

   boolean:      A type representing a Boolean (true or false) value.

   datetime:     A type representing a date and time using the Gregorian
                 calendar.  The datetime format MUST conform to
                 [RFC3339], Section 5.6.

   ip-address:   A type representing an IP address.  This type supports
                 both IPv4 and IPv6 addresses.

   operation:    A type representing a remote procedure call or other
                 action that can be used to manipulate data elements or
                 system behaviors.

   reference:    A type representing a reference to another information
                 or data model element or to some other device resource.

   string:       A type representing a human-readable string consisting
                 of a (possibly restricted) subset of Unicode and ISO/
                 IEC 10646 [ISO.10646] characters.

   uint:         A type representing an unsigned integer number.  This
                 information model does not define a precision.

2.  Overview

   The information model is hierarchically structured as follows:

   +-- babel-information
      +-- babel-implementation-version
      +-- babel-enable
      +-- router-id
      +-- self-seqno
      +-- babel-metric-comp-algorithms
      +-- babel-security-supported
      +-- babel-mac-algorithms
      +-- babel-dtls-cert-types
      +-- babel-stats-enable
      +-- babel-stats-reset
      +-- babel-constants
      |  +-- babel-udp-port
      |  +-- babel-mcast-group
      +-- babel-interfaces
      |  +-- babel-interface-reference
      |  +-- babel-interface-enable
      |  +-- babel-interface-metric-algorithm
      |  +-- babel-interface-split-horizon
      |  +-- babel-mcast-hello-seqno
      |  +-- babel-mcast-hello-interval
      |  +-- babel-update-interval
      |  +-- babel-mac-enable
      |  +-- babel-if-mac-key-sets
      |  +-- babel-mac-verify
      |  +-- babel-dtls-enable
      |  +-- babel-if-dtls-cert-sets
      |  +-- babel-dtls-cached-info
      |  +-- babel-dtls-cert-prefer
      |  +-- babel-packet-log-enable
      |  +-- babel-packet-log
      |  +-- babel-if-stats
      |  |  +-- babel-sent-mcast-hello
      |  |  +-- babel-sent-mcast-update
      |  |  +-- babel-sent-ucast-hello
      |  |  +-- babel-sent-ucast-update
      |  |  +-- babel-sent-IHU
      |  |  +-- babel-received-packets
      |  +-- babel-neighbors
      |     +-- babel-neighbor-address
      |     +-- babel-hello-mcast-history
      |     +-- babel-hello-ucast-history
      |     +-- babel-txcost
      |     +-- babel-exp-mcast-hello-seqno
      |     +-- babel-exp-ucast-hello-seqno
      |     +-- babel-ucast-hello-seqno
      |     +-- babel-ucast-hello-interval
      |     +-- babel-rxcost
      |     +-- babel-cost
      +-- babel-routes
      |  +-- babel-route-prefix
      |  +-- babel-route-prefix-length
      |  +-- babel-route-router-id
      |  +-- babel-route-neighbor
      |  +-- babel-route-received-metric
      |  +-- babel-route-calculated-metric
      |  +-- babel-route-seqno
      |  +-- babel-route-next-hop
      |  +-- babel-route-feasible
      |  +-- babel-route-selected
      +-- babel-mac-key-sets
      |  +-- babel-mac-default-apply
      |  +-- babel-mac-keys
      |     +-- babel-mac-key-name
      |     +-- babel-mac-key-use-send
      |     +-- babel-mac-key-use-verify
      |     +-- babel-mac-key-value
      |     +-- babel-mac-key-algorithm
      |     +-- babel-mac-key-test
      +-- babel-dtls-cert-sets
         +-- babel-dtls-default-apply
         +-- babel-dtls-certs
            +-- babel-cert-name
            +-- babel-cert-value
            +-- babel-cert-type
            +-- babel-cert-private-key

   Most parameters are read-only.  The following is a descriptive list
   of the parameters that are not required to be read-only:

   *  enable/disable Babel

   *  create/delete Babel Message Authentication Code (MAC) Key sets

   *  create/delete Babel Certificate sets

   *  enable/disable statistics collection

   *  Constant: UDP port

   *  Constant: IPv6 multicast group

   *  Interface: enable/disable Babel on this interface

   *  Interface: metric algorithm

   *  Interface: split horizon

   *  Interface: sets of MAC keys

   *  Interface: verify received MAC packets

   *  Interface: set of certificates for use with DTLS

   *  Interface: use cached info extensions

   *  Interface: preferred order of certificate types

   *  Interface: enable/disable packet log

   *  MAC-keys: create/delete entries

   *  MAC-keys: key used for sent packets

   *  MAC-keys: key used to verify packets

   *  DTLS-certs: create/delete entries

   The following parameters are required to return no value when read:

   *  MAC key values

   *  DTLS private keys

   Note that this overview is intended simply to be informative and is
   not normative.  If there is any discrepancy between this overview and
   the detailed information model definitions in subsequent sections,
   the error is in this overview.

3.  The Information Model

3.1.  Definition of babel-information-obj

   object {
        string                    ro babel-implementation-version;
        boolean                   rw babel-enable;
        binary                    ro babel-self-router-id;
       [uint                      ro babel-self-seqno;]
        string                    ro babel-metric-comp-algorithms<1..*>;
        string                    ro babel-security-supported<0..*>;
       [string                    ro babel-mac-algorithms<1..*>;]
       [string                    ro babel-dtls-cert-types<1..*>;]
       [boolean                   rw babel-stats-enable;]
       [operation                    babel-stats-reset;]
        babel-constants-obj       ro babel-constants;
        babel-interface-obj       ro babel-interfaces<0..*>;
        babel-route-obj           ro babel-routes<0..*>;
       [babel-mac-key-set-obj     rw babel-mac-key-sets<0..*>;]
       [babel-dtls-cert-set-obj   rw babel-dtls-cert-sets<0..*>;]
   } babel-information-obj;

   babel-implementation-version:  The name and version of this
      implementation of the Babel protocol.

   babel-enable:  When written, it configures whether the protocol
      should be enabled (true) or disabled (false).  A read from the
      running or intended datastore indicates the configured
      administrative value of whether the protocol is enabled (true) or
      not (false).  A read from the operational datastore indicates
      whether the protocol is actually running (true) or not (i.e., it
      indicates the operational state of the protocol).  A data model
      that does not replicate parameters for running and operational
      datastores can implement this as two separate parameters.  An
      implementation MAY choose to expose this parameter as read-only
      ("ro").

   babel-self-router-id:  The router-id used by this instance of the
      Babel protocol to identify itself.  [RFC8966] describes this as an
      arbitrary string of 8 octets.

   babel-self-seqno:  The current sequence number included in route
      updates for routes originated by this node.  This is a 16-bit
      unsigned integer.

   babel-metric-comp-algorithms:  List of supported cost computation
      algorithms.  Possible values include "2-out-of-3", as described in
      [RFC8966], Appendix A.2.1, and "ETX", as described in [RFC8966],
      Appendix A.2.2.

   babel-security-supported:  List of supported security mechanisms.
      Possible values include "MAC" to indicate support of [RFC8967] and
      "DTLS" to indicate support of [RFC8968].

   babel-mac-algorithms:  List of supported MAC computation algorithms.
      Possible values include "HMAC-SHA256" and "BLAKE2s-128" to
      indicate support for algorithms indicated in [RFC8967].

   babel-dtls-cert-types:  List of supported certificate types.
      Possible values include "X.509" and "RawPublicKey" to indicate
      support for types indicated in [RFC8968].

   babel-stats-enable:  Indicates whether statistics collection is
      enabled (true) or disabled (false) on all interfaces.  When
      enabled, existing statistics values are not cleared and will be
      incremented as new packets are counted.

   babel-stats-reset:  An operation that resets all babel-if-stats
      parameters to zero.  This operation has no input or output
      parameters.

   babel-constants:  A babel-constants-obj object.

   babel-interfaces:  A set of babel-interface-obj objects.

   babel-routes:  A set of babel-route-obj objects.  Contains the routes
      known to this node.

   babel-mac-key-sets:  A set of babel-mac-key-set-obj objects.  If this
      object is implemented, it provides access to parameters related to
      the MAC security mechanism.  An implementation MAY choose to
      expose this object as read-only ("ro").

   babel-dtls-cert-sets:  A set of babel-dtls-cert-set-obj objects.  If
      this object is implemented, it provides access to parameters
      related to the DTLS security mechanism.  An implementation MAY
      choose to expose this object as read-only ("ro").

3.2.  Definition of babel-constants-obj

   object {
        uint         rw babel-udp-port;
       [ip-address   rw babel-mcast-group;]
   } babel-constants-obj;

   babel-udp-port:  UDP port for sending and listening for Babel
      packets.  Default is 6696.  An implementation MAY choose to expose
      this parameter as read-only ("ro").  This is a 16-bit unsigned
      integer.

   babel-mcast-group:  Multicast group for sending and listening to
      multicast announcements on IPv6.  Default is ff02::1:6.  An
      implementation MAY choose to expose this parameter as read-only
      ("ro").

3.3.  Definition of babel-interface-obj

   object {
        reference            ro babel-interface-reference;
       [boolean              rw babel-interface-enable;]
        string               rw babel-interface-metric-algorithm;
       [boolean              rw babel-interface-split-horizon;]
       [uint                 ro babel-mcast-hello-seqno;]
       [uint                 ro babel-mcast-hello-interval;]
       [uint                 ro babel-update-interval;]
       [boolean              rw babel-mac-enable;]
       [reference            rw babel-if-mac-key-sets<0..*>;]
       [boolean              rw babel-mac-verify;]
       [boolean              rw babel-dtls-enable;]
       [reference            rw babel-if-dtls-cert-sets<0..*>;]
       [boolean              rw babel-dtls-cached-info;]
       [string               rw babel-dtls-cert-prefer<0..*>;]
       [boolean              rw babel-packet-log-enable;]
       [reference            ro babel-packet-log;]
       [babel-if-stats-obj   ro babel-if-stats;]
        babel-neighbor-obj   ro babel-neighbors<0..*>;
   } babel-interface-obj;

   babel-interface-reference:  Reference to an interface object that can
      be used to send and receive IPv6 packets, as defined by the data
      model (e.g., YANG [RFC7950] and Broadband Forum (BBF) [TR-181]).
      Referencing syntax will be specific to the data model.  If there
      is no set of interface objects available, this should be a string
      that indicates the interface name used by the underlying operating
      system.

   babel-interface-enable:  When written, it configures whether the
      protocol should be enabled (true) or disabled (false) on this
      interface.  A read from the running or intended datastore
      indicates the configured administrative value of whether the
      protocol is enabled (true) or not (false).  A read from the
      operational datastore indicates whether the protocol is actually
      running (true) or not (i.e., it indicates the operational state of
      the protocol).  A data model that does not replicate parameters
      for running and operational datastores can implement this as two
      separate parameters.  An implementation MAY choose to expose this
      parameter as read-only ("ro").

   babel-interface-metric-algorithm:  Indicates the metric computation
      algorithm used on this interface.  The value MUST be one of those
      listed in the babel-metric-comp-algorithms parameter.  An
      implementation MAY choose to expose this parameter as read-only
      ("ro").

   babel-interface-split-horizon:  Indicates whether or not the split-
      horizon optimization is used when calculating metrics on this
      interface.  A value of "true" indicates split-horizon optimization
      is used.  Split-horizon optimization is described in [RFC8966],
      Section 3.7.4.  An implementation MAY choose to expose this
      parameter as read-only ("ro").

   babel-mcast-hello-seqno:  The current sequence number in use for
      multicast Hellos sent on this interface.  This is a 16-bit
      unsigned integer.

   babel-mcast-hello-interval:  The current interval in use for
      multicast Hellos sent on this interface.  Units are centiseconds.
      This is a 16-bit unsigned integer.

   babel-update-interval:  The current interval in use for all updates
      (multicast and unicast) sent on this interface.  Units are
      centiseconds.  This is a 16-bit unsigned integer.

   babel-mac-enable:  Indicates whether the MAC security mechanism is
      enabled (true) or disabled (false).  An implementation MAY choose
      to expose this parameter as read-only ("ro").

   babel-if-mac-key-sets:  List of references to the babel-mac-key-sets
      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.  An
      implementation MAY choose to expose this parameter as read-only
      ("ro").

   babel-mac-verify:  A Boolean flag indicating whether MACs 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.  An implementation MAY choose to expose this parameter
      as read-only ("ro").

   babel-dtls-enable:  Indicates whether the DTLS security mechanism is
      enabled (true) or disabled (false).  An implementation MAY choose
      to expose this parameter as read-only ("ro").

   babel-if-dtls-cert-sets:  List of references to the babel-dtls-cert-
      sets entries that apply to this interface.  When an interface
      instance is created, all babel-dtls-cert-sets instances with
      babel-dtls-default-apply "true" will be included in this list.  An
      implementation MAY choose to expose this parameter as read-only
      ("ro").

   babel-dtls-cached-info:  Indicates whether the cached_info extension
      (see [RFC8968], Appendix A) is included in ClientHello and
      ServerHello packets.  The extension is included if the value is
      "true".  An implementation MAY choose to expose this parameter as
      read-only ("ro").

   babel-dtls-cert-prefer:  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 (see [RFC8968], Appendix A)
      in a ClientHello.  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
      ClientHello.

   babel-packet-log-enable:  Indicates whether packet logging is enabled
      (true) or disabled (false) on this interface.

   babel-packet-log:  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 a .pcap file
      extension SHOULD be supported for packet log files.  Logging is
      enabled/disabled by babel-packet-log-enable.  Implementations will
      need to carefully manage and limit memory used by packet logs.

   babel-if-stats:  Statistics collection object for this interface.

   babel-neighbors:  A set of babel-neighbor-obj objects.

3.4.  Definition of babel-if-stats-obj

   object {
        uint   ro babel-sent-mcast-hello;
        uint   ro babel-sent-mcast-update;
        uint   ro babel-sent-ucast-hello;
        uint   ro babel-sent-ucast-update;
        uint   ro babel-sent-IHU;
        uint   ro babel-received-packets;
   } babel-if-stats-obj;

   babel-sent-mcast-hello:  A count of the number of multicast Hello
      packets sent on this interface.

   babel-sent-mcast-update:  A count of the number of multicast update
      packets sent on this interface.

   babel-sent-ucast-hello:  A count of the number of unicast Hello
      packets sent on this interface.

   babel-sent-ucast-update:  A count of the number of unicast update
      packets sent on this interface.

   babel-sent-IHU:  A count of the number of "I Heard You" (IHU) packets
      sent on this interface.

   babel-received-packets:  A count of the number of Babel packets
      received on this interface.

3.5.  Definition of babel-neighbor-obj

   object {
        ip-address   ro babel-neighbor-address;
       [binary       ro babel-hello-mcast-history;]
       [binary       ro babel-hello-ucast-history;]
        uint         ro babel-txcost;
        uint         ro babel-exp-mcast-hello-seqno;
        uint         ro babel-exp-ucast-hello-seqno;
       [uint         ro babel-ucast-hello-seqno;]
       [uint         ro babel-ucast-hello-interval;]
       [uint         ro babel-rxcost;]
       [uint         ro babel-cost;]
   } babel-neighbor-obj;

   babel-neighbor-address:  IPv4 or IPv6 address the neighbor sends
      packets from.

   babel-hello-mcast-history:  The multicast Hello history of whether or
      not the multicast Hello packets prior to babel-exp-mcast-hello-
      seqno were received.  A binary sequence where the most recently
      received Hello is expressed as a "1" placed in the leftmost bit,
      with prior bits shifted right (and "0" bits placed between prior
      Hello bits and most recent Hello for any not-received Hellos).
      This value should be displayed using hex digits ([0-9a-fA-F]).
      See [RFC8966], Appendix A.1.

   babel-hello-ucast-history:  The unicast Hello history of whether or
      not the unicast Hello packets prior to babel-exp-ucast-hello-seqno
      were received.  A binary sequence where the most recently received
      Hello is expressed as a "1" placed in the leftmost bit, with prior
      bits shifted right (and "0" bits placed between prior Hello bits
      and the most recent Hello for any not-received Hellos).  This
      value should be displayed using hex digits ([0-9a-fA-F]).  See
      [RFC8966], Appendix A.1.

   babel-txcost:  Transmission cost value from the last IHU packet
      received from this neighbor, or the maximum value to indicate the
      IHU hold timer for this neighbor has expired.  See [RFC8966],
      Section 3.4.2.  This is a 16-bit unsigned integer.

   babel-exp-mcast-hello-seqno:  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.  This is a
      16-bit unsigned integer; if the data model uses zero (0) to
      represent NULL values for unsigned integers, the data model MAY
      use a different data type that allows differentiation between zero
      (0) and NULL.

   babel-exp-ucast-hello-seqno:  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.  This is a 16-bit unsigned integer; if
      the data model uses zero (0) to represent NULL values for unsigned
      integers, the data model MAY use a different data type that allows
      differentiation between zero (0) and NULL.

   babel-ucast-hello-seqno:  The current sequence number in use for
      unicast Hellos sent to this neighbor.  If unicast Hellos are not
      being sent, this MUST be NULL.  This is a 16-bit unsigned integer;
      if the data model uses zero (0) to represent NULL values for
      unsigned integers, the data model MAY use a different data type
      that allows differentiation between zero (0) and NULL.

   babel-ucast-hello-interval:  The current interval in use for unicast
      Hellos sent to this neighbor.  Units are centiseconds.  This is a
      16-bit unsigned integer.

   babel-rxcost:  Reception cost calculated for this neighbor.  This
      value 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.  See
      [RFC8966], Section 3.4.3.  This is a 16-bit unsigned integer.

   babel-cost:  The link cost, as 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.  This is a 16-bit unsigned integer.

3.6.  Definition of babel-route-obj

   object {
        ip-address   ro babel-route-prefix;
        uint         ro babel-route-prefix-length;
        binary       ro babel-route-router-id;
        reference    ro babel-route-neighbor;
        uint         ro babel-route-received-metric;
        uint         ro babel-route-calculated-metric;
        uint         ro babel-route-seqno;
        ip-address   ro babel-route-next-hop;
        boolean      ro babel-route-feasible;
        boolean      ro babel-route-selected;
   } babel-route-obj;

   babel-route-prefix:  Prefix (expressed in IP address format) for
      which this route is advertised.

   babel-route-prefix-length:  Length of the prefix for which this route
      is advertised.

   babel-route-router-id:  The router-id of the router that originated
      this route.

   babel-route-neighbor:  Reference to the babel-neighbors entry for the
      neighbor that advertised this route.

   babel-route-received-metric:  The metric with which this route was
      advertised by the neighbor, or the maximum value to indicate the
      route was recently retracted and is temporarily unreachable (see
      Section 3.5.4 of [RFC8966]).  This metric will be NULL if the
      route was not received from a neighbor but was generated through
      other means.  At least one of the following MUST be non-NULL:
      babel-route-calculated-metric or babel-route-received-metric.
      Having both be non-NULL is expected for a route that is received
      and subsequently advertised.  This is a 16-bit unsigned integer;
      if the data model uses zero (0) to represent NULL values for
      unsigned integers, the data model MAY use a different data type
      that allows differentiation between zero (0) and NULL.

   babel-route-calculated-metric:  A calculated metric for this route.
      How the metric is calculated is implementation specific.  The
      maximum value indicates the route was recently retracted and is
      temporarily unreachable (see Section 3.5.4 of [RFC8966]).  At
      least one of the following MUST be non-NULL: babel-route-
      calculated-metric or babel-route-received-metric.  Having both be
      non-NULL is expected for a route that is received and subsequently
      advertised.  This is a 16-bit unsigned integer; if the data model
      uses zero (0) to represent NULL values for unsigned integers, the
      data model MAY use a different data type that allows
      differentiation between zero (0) and NULL.

   babel-route-seqno:  The sequence number with which this route was
      advertised.  This is a 16-bit unsigned integer.

   babel-route-next-hop:  The next-hop address of this route.  This will
      be empty if this route has no next-hop address.

   babel-route-feasible:  A Boolean flag indicating whether this route
      is feasible, as defined in Section 3.5.1 of [RFC8966]).

   babel-route-selected:  A Boolean flag indicating whether this route
      is selected (i.e., whether it is currently being used for
      forwarding and is being advertised).

3.7.  Definition of babel-mac-key-set-obj

   object {
        boolean             rw babel-mac-default-apply;
        babel-mac-key-obj   rw babel-mac-keys<0..*>;
   } babel-mac-key-set-obj;

   babel-mac-default-apply:  A Boolean flag indicating whether this
      object instance is applied to all new babel-interfaces instances
      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-if-mac-key-sets list.  If "false", this instance is
      not applied to new babel-interfaces instances when they are
      created.  An implementation MAY choose to expose this parameter as
      read-only ("ro").

   babel-mac-keys:  A set of babel-mac-key-obj objects.

3.8.  Definition of babel-mac-key-obj

   object {
        string      rw babel-mac-key-name;
        boolean     rw babel-mac-key-use-send;
        boolean     rw babel-mac-key-use-verify;
        binary      -- babel-mac-key-value;
        string      rw babel-mac-key-algorithm;
       [operation      babel-mac-key-test;]
   } babel-mac-key-obj;

   babel-mac-key-name:  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 MUST NOT be empty and can only
      be provided when this instance is created (i.e., it is not
      subsequently writable).  The value MAY be auto-generated if not
      explicitly supplied when the instance is created.

   babel-mac-key-use-send:  Indicates whether this key value is used to
      compute a MAC and include that MAC in the sent Babel packet.  A
      MAC for sent packets is computed using this key if the value is
      "true".  If the value is "false", this key is not used to compute
      a MAC to include in sent Babel packets.  An implementation MAY
      choose to expose this parameter as read-only ("ro").

   babel-mac-key-use-verify:  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 comparison with the MAC in an
      incoming packet.  An implementation MAY choose to expose this
      parameter as read-only ("ro").

   babel-mac-key-value:  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 when read, through permissions,
      or by 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 Hashed Message Authentication Code
      (HMAC) construction [RFC2104], the length MUST be between 0 and an
      upper limit that is at least the size of the output length (where
      the "HMAC-SHA256" output length is 32 octets as described in
      [RFC4868]).  Longer lengths MAY be supported but are not necessary
      if the management system has the ability to generate a suitably
      random value (e.g., by randomly generating a value or by using a
      key derivation technique as recommended in the security
      considerations in Section 7 of [RFC8967]).  If the algorithm is
      "BLAKE2s-128", the length MUST be between 0 and 32 bytes inclusive
      as specified by [RFC7693].

   babel-mac-key-algorithm  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.  An implementation MAY
      choose to expose this parameter as read-only ("ro").

   babel-mac-key-test:  An operation that allows the MAC key and MAC
      algorithm to be tested to see if they produce an expected outcome.
      Input to this operation is a binary string and a calculated MAC
      (also in the format of a binary string) for the binary string.
      The implementation is expected to create a MAC over the binary
      string using the babel-mac-key-value and the babel-mac-key-
      algorithm.  The output of this operation is a Boolean indication
      that the calculated MAC matched the input MAC (true) or the MACs
      did not match (false).

3.9.  Definition of babel-dtls-cert-set-obj

   object {
        boolean               rw babel-dtls-default-apply;
        babel-dtls-cert-obj   rw babel-dtls-certs<0..*>;
   } babel-dtls-cert-set-obj;

   babel-dtls-default-apply:  A Boolean flag indicating whether this
      object instance is applied to all new babel-interfaces instances
      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-dtls-certs list.  If "false", this instance
      is not applied to new babel-interfaces instances when they are
      created.  An implementation MAY choose to expose this parameter as
      read-only ("ro").

   babel-dtls-certs:  A set of babel-dtls-cert-obj objects.  This
      contains both certificates for this implementation to present for
      authentication and those to accept from others.  Certificates with
      a non-empty babel-cert-private-key can be presented by this
      implementation for authentication.

3.10.  Definition of babel-dtls-cert-obj

   object {
        string      rw babel-cert-name;
        string      rw babel-cert-value;
        string      rw babel-cert-type;
        binary      -- babel-cert-private-key;
   } babel-dtls-cert-obj;

   babel-cert-name:  A unique name for this 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).  The value MAY be
      auto-generated if not explicitly supplied when the instance is
      created.

   babel-cert-value:  The certificate in Privacy-Enhanced Mail (PEM)
      format [RFC7468].  This value MUST be provided when this instance
      is created and is not subsequently writable.

   babel-cert-type:  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.

   babel-cert-private-key:  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 when read, through permissions,
      or by other means.  This value can only be provided when this
      instance is created and is not subsequently writable.

4.  Extending the Information Model

   Implementations MAY extend this information model with other
   parameters or objects.  For example, an implementation MAY choose to
   expose Babel route filtering rules by adding a route filtering object
   with parameters appropriate to how route filtering is done in that
   implementation.  The precise means used to extend the information
   model would be specific to the data model the implementation uses to
   expose this information.

5.  Security Considerations

   This document defines a set of information model objects and
   parameters that may be exposed and visible from other devices.  Some
   of these information model objects and parameters may be configured.
   Securing access to and ensuring the integrity of this data is in
   scope of and the responsibility of any data model derived from this
   information model.  Specifically, any YANG [RFC7950] data model is
   expected to define security exposure of the various parameters, and a
   [TR-181] data model will be secured by the mechanisms defined for the
   management protocol used to transport it.

   Misconfiguration (whether unintentional or malicious) can prevent
   reachability or cause poor network performance (increased latency,
   jitter, etc.).  Misconfiguration of security credentials can cause a
   denial-of-service condition for the Babel routing protocol.  The
   information in this model discloses network topology, which can be
   used to mount subsequent attacks on traffic traversing the network.

   This information model defines objects that can allow credentials
   (for this device, for trusted devices, and for trusted certificate
   authorities) to be added and deleted.  Public keys may be exposed
   through this model.  This model requires that private keys and MAC
   keys never be exposed.  Certificates used by [RFC8968]
   implementations use separate parameters to model the public parts
   (including the public key) and the private key.

   MAC keys are allowed to be as short as zero length.  This is useful
   for testing.  It is RECOMMENDED that network operators follow current
   best practices for key length and generation of keys related to the
   MAC algorithm associated with the key.  Short (and zero-length) keys
   are highly susceptible to brute-force attacks and therefore SHOULD
   NOT be used.  See the security considerations as described in
   Section 7 of [RFC8967] for additional considerations related to MAC
   keys; note that there are some specific key value recommendations in
   the fifth paragraph.  It says that if it is necessary to derive keys
   from a human-readable passphrase, "only the derived keys should be
   communicated to the routers" and "the original passphrase itself
   should be kept on the host used to perform the key generation" (which
   would be the management system in the case of a remote management
   protocol).  It also recommends that keys "should have a length of 32
   octets (both for HMAC-SHA256 and BLAKE2s), and be chosen randomly".

   This information model uses key sets and certification sets to
   provide a means of grouping keys and certificates.  This makes it
   easy to use a different set per interface, use the same set for one
   or more interfaces, have a default set in case a new interface is
   instantiated, and change keys and certificates as needed.

6.  IANA Considerations

   This document has no IANA actions.

7.  References

7.1.  Normative References

   [ISO.10646]
              International Organization for Standardization,
              "Information technology - Universal Coded Character Set
              (UCS)", ISO Standard 10646:2014, 2014.

   [libpcap]  GitLab, "Libpcap File Format", Wireshark Foundation,
              November 2020, <https://gitlab.com/wireshark/wireshark/-
              /wikis/Development/LibpcapFileFormat>.

   [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>.

   [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>.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <https://www.rfc-editor.org/info/rfc3339>.

   [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>.

   [RFC7468]  Josefsson, S. and S. Leonard, "Textual Encodings of PKIX,
              PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468,
              April 2015, <https://www.rfc-editor.org/info/rfc7468>.

   [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>.

   [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>.

   [RFC8966]  Chroboczek, J. and D. Schinazi, "The Babel Routing
              Protocol", RFC 8966, DOI 10.17487/RFC8966, January 2021,
              <https://www.rfc-editor.org/info/rfc8966>.

   [RFC8967]  Dô, C., Kolodziejak, W., and J. Chroboczek, "MAC
              Authentication for the Babel Routing Protocol", RFC 8967,
              DOI 10.17487/RFC8967, January 2021,
              <https://www.rfc-editor.org/info/rfc8967>.

   [RFC8968]  Décimo, A., Schinazi, D., and J. Chroboczek, "Babel
              Routing Protocol over Datagram Transport Layer Security",
              RFC 8968, DOI 10.17487/RFC8968, January 2021,
              <https://www.rfc-editor.org/info/rfc8968>.

7.2.  Informative References

   [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>.

   [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>.

   [RFC8193]  Burbridge, T., Eardley, P., Bagnulo, M., and J.
              Schoenwaelder, "Information Model for Large-Scale
              Measurement Platforms (LMAPs)", RFC 8193,
              DOI 10.17487/RFC8193, August 2017,
              <https://www.rfc-editor.org/info/rfc8193>.

   [TR-181]   Broadband Forum, "Device Data Model", Issue: 2 Amendment
              14, November 2020,
              <http://cwmp-data-models.broadband-forum.org/>.

Acknowledgements

   Juliusz Chroboczek, Toke Høiland-Jørgensen, David Schinazi, Antonin
   Décimo, Roman Danyliw, Benjamin Kaduk, Valery Smyslov, Alvaro Retana,
   Donald Eastlake, Martin Vigoureux, Acee Lindem, and Carsten Bormann
   have been very helpful in refining this information model.

   The language in the "Notation" section was mostly taken from
   [RFC8193].

Authors' Addresses

   Barbara Stark
   AT&T
   TX
   United States of America

   Email: barbara.stark@att.com

   Mahesh Jethanandani
   Kloud Services
   CA
   United States of America

   Email: mjethanandani@gmail.com