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Babel routing protocol                                          B. Stark
Internet-Draft                                                      AT&T
Intended status: Informational                          October 22, 2018
Expires: April 25, 2019


                        Babel Information Model
                 draft-ietf-babel-information-model-04

Abstract

   This Babel Information Model can be used to create data models under
   various data modeling regimes (e.g., YANG).  It allows a Babel
   implementation (via a management protocol such as NETCONF) to report
   on its current state and may allow some limited configuration of
   protocol constants.

Status of This Memo

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

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

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

   This Internet-Draft will expire on April 25, 2019.

Copyright Notice

   Copyright (c) 2018 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.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Notation  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  The Information Model . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Definition of babel-information-obj . . . . . . . . . . .   5
     3.2.  Definition of babel-constants-obj . . . . . . . . . . . .   6
     3.3.  Definition of babel-interfaces-obj  . . . . . . . . . . .   7
     3.4.  Definition of babel-neighbors-obj . . . . . . . . . . . .   8
     3.5.  Definition of babel-security-obj  . . . . . . . . . . . .  10
     3.6.  Definition of babel-routes-obj  . . . . . . . . . . . . .  11
   4.  Common Objects  . . . . . . . . . . . . . . . . . . . . . . .  12
     4.1.  Definition of babel-credential-obj  . . . . . . . . . . .  12
     4.2.  Definition of babel-log-obj . . . . . . . . . . . . . . .  13
   5.  Extending the Information Model . . . . . . . . . . . . . . .  13
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Appendix A.  Open Issues  . . . . . . . . . . . . . . . . . . . .  17
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  19
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   Babel is a loop-avoiding distance-vector routing protocol defined in
   [I-D.ietf-babel-rfc6126bis].  [I-D.ietf-babel-hmac] defines a
   security mechanism that allows Babel messages to be cryptographically
   authenticated, and [I-D.ietf-babel-dtls] defines a security mechanism
   that allows Babel messages to be encrypted.  This document describes
   an information model for Babel (including implementations using one
   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 Babel protocol operational state, and
   very little of that is considered mandatory to implement (contingent
   on a management protocol with Babel support being implemented).  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.



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   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.

1.1.  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 [RFC2119] and updated
   by [RFC8174].

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 value.

   counter     A non-negative integer that monotonically increases.
               Counters may have discontinuities and they are not
               expected to persist across restarts.

   credentials An opaque type representing credentials needed by a
               cryptographic mechanism to secure communication.  Data
               models must expand this opaque type as needed and
               required by the security protocols utilized.

   datetime    A type representing a date and time using the Gregorian
               calendar.  The datetime format MUST conform to RFC 3339
               [RFC3339].

   int         A type representing signed or unsigned integer numbers.
               This information model does not define a precision nor



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               does it make a distinction between signed and unsigned
               number ranges.

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

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

   uri         A type representing a Uniform Resource Identifier as
               defined in STD 66 [RFC3986].

2.  Overview

   The Information Model is hierarchically structured as follows:

   information object
      includes implementation version, router id, this node seqno,
        enable flag parameters, supported security mechanisms
      constants object (exactly one per information object)
         includes UDP port and optional multicast group
           parameters
      interfaces object
         includes interface reference, Hello seqno and intervals,
           update interval, link type, metric computation parameters
         neighbors object
            includes neighbor IP address, Hello history, cost
              parameters
         security object (per interface)
            includes enable flag, self credentials (credential
              object), trusted credentials (credential object)
      security object (common to all interfaces)
         includes enable flag, self credentials (credential
           object), trusted credentials (credential object)
      routes object
         includes route prefix, source router, reference to
           advertising neighbor, metric, sequence number, whether
           route is feasible, whether route is selected

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

   o  enable/disable Babel

   o  Constant: UDP port

   o  Constant: IPv6 multicast group



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   o  Interface: Link type

   o  Interface: External cost (must be configurable if implemented, but
      implementation is optional)

   o  Interface: enable/disable Babel on this interface

   o  Interface: enable/disable message log

   o  Security: enable/disable this security mechanism

   o  Security: self credentials

   o  Security: trusted credentials

   o  Security: enable/disable security log

   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;
          string               ro babel-supported-link-types<1..*>;
         [int                  ro babel-self-seqno;]
          string               ro babel-metric-comp-algorithms<1..*>;
          string               ro babel-security-supported<0..*>;
          babel-constants-obj  ro babel-constants;
          babel-interfaces-obj ro babel-interfaces<0..*>;
          babel-routes-obj     ro babel-routes<0..*>;
          babel-security-obj   ro babel-security<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 shoud
      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



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      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.  [I-D.ietf-babel-rfc6126bis]
      describes this as an arbitrary string of 8 octets.

   babel-supported-link-types:  Lists the set of link types supported by
      this instance of Babel.  Valid enumeration values are defined in
      the Babel Link Types registry (see Section 7).

   babel-self-seqno:  The current sequence number included in route
      updates for routes originated by this node.

   babel-metric-comp-algorithms:  List of supported cost computation
      algorithms.  Possible values include "k-out-of-j", and "ETX".

   babel-security-supported:  List of supported security mechanisms.  As
      Babel security mechanisms are defined, they will need to indicate
      what enumeration value is to be used to represent them in this
      parameter.

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

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

   babel-security:  A babel-security-obj object that applies to all
      interfaces.  If this object is implemented, it allows a security
      mechanism to be enabled or disabled in a manner that applies to
      all Babel messages on all interfaces.

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

3.2.  Definition of babel-constants-obj

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

   babel-udp-port:  UDP port for sending and listening for Babel
      messages.  Default is 6696.  An implementation MAY choose to
      expose this parameter as read-only ("ro").




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   babel-mcast-group:  Multicast group for sending and listening to
      multicast announcements on IPv6.  Default is ff02:0:0:0:0:0:1:6.
      An implementation MAY choose to expose this parameter as read-only
      ("ro").

3.3.  Definition of babel-interfaces-obj

     object {
          string               ro babel-interface-reference;
         [boolean              rw babel-interface-enable;]
          int                  rw babel-link-type;
          string               ro babel-interface-metric-algorithm;
         [int                  ro babel-mcast-hello-seqno;]
         [int                  ro babel-mcast-hello-interval;]
         [int                  ro babel-update-interval;]
         [boolean              rw babel-message-log-enable;]
         [babel-log-obj        ro babel-message-log<0..*>;]
          babel-neighbors-obj  ro babel-neighbors<0..*>;
         [babel-security-obj   ro babel-interface-security<0..*>;]
      } babel-interfaces-obj;

   babel-interface-reference:  Reference to an interface object as
      defined by the data model (e.g., YANG [RFC7950], BBF [TR-181]).
      Data model is assumed to allow for referencing of interface
      objects which may be at any layer (physical, Ethernet MAC, IP,
      tunneled IP, etc.).  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-link-type:  Indicates the type of link.  Valid enumeration
      values are identified in Babel Link Types registry.  An
      implementation MAY choose to expose this parameter as read-only
      ("ro").





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   babel-interface-metric-algorithm:  Indicates the metric computation
      algorithm used on this interface.  The value MUST be one of those
      listed in the babel-information-obj babel-metric-comp-algorithms
      parameter.

   babel-mcast-hello-seqno:  The current sequence number in use for
      multicast hellos sent on this interface.

   babel-mcast-hello-interval:  The current interval in use for
      multicast hellos sent on this interface.

   babel-update-interval:  The current interval in use for all updates
      (multicast and unicast) sent on this interface.

   babel-message-log-enable:  When written, it configures whether
      logging should be enabled (true) or disabled (false).  A read from
      the running or intended datastore indicates the configured
      administrative value of whether logging is enabled (true) or not
      (false).  A read from the operational datastore indicates whether
      logging is actually running (true) or not (i.e., it indicates the
      operational state).  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-message-log:  Log entries that have timestamp of a received
      Babel message and the entire received Babel message (including
      Ethernet frame and IP headers, if possible).  An implementation
      must restrict the size of this log, but how and what size is
      implementation-specific.  If this log is implemented, a mechanism
      to clear it SHOULD be provided.

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

   babel-interface-security:  A babel-security-obj object that applies
      to this interface.  If implemented, this allows security to be
      enabled only on specific interfaces or allows different security
      mechanisms to be enabled on different interfaces.

3.4.  Definition of babel-neighbors-obj











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

   babel-neighbor-address:  IPv4 or IPv6 address the neighbor sends
      messages from

   babel-hello-mcast-history:  The multicast Hello history of whether or
      not the multicast Hello messages 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 left-most 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 [I-D.ietf-babel-rfc6126bis], section A.1.

   babel-hello-ucast-history:  The unicast Hello history of whether or
      not the unicast Hello messages 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 left-most 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 [I-D.ietf-babel-rfc6126bis], section A.1.

   babel-txcost:  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.  See
      [I-D.ietf-babel-rfc6126bis], section 3.4.2.

   babel-exp-mcast-hello-seqno:  Expected multicast Hello sequence
      number of next Hello to be received from this neighbor.  If
      multicast Hello messages are not expected, or processing of
      multicast messages is not enabled, this MUST be 0.

   babel-exp-ucast-hello-seqno:  Expected unicast Hello sequence number
      of next Hello to be received from this neighbor.  If unicast Hello
      messages are not expected, or processing of unicast messages is
      not enabled, this MUST be 0.



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   babel-ucast-hello-seqno:  The current sequence number in use for
      unicast hellos sent to this neighbor.

   babel-ucast-hello-interval:  The current interval in use for unicast
      hellos sent to this neighbor.

   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
      [I-D.ietf-babel-rfc6126bis], section 3.4.3.

   babel-cost:  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.

3.5.  Definition of babel-security-obj

     object {
          string                ro babel-security-mechanism
          boolean               rw babel-security-enable;
          babel-credential-obj  ro babel-security-self-cred<0..*>;
          babel-credential-obj  ro babel-security-trust<0..*>;
         [boolean               rw babel-credvalid-log-enable;]
         [babel-log-obj         ro babel-credvalid-log<0..*>;]
      } babel-security-obj;

   babel-security-mechanism:  The name of the security mechanism this
      object instance is about.  The value MUST be the same as one of
      the enumerations listed in the babel-security-supported parameter.

   babel-security-enable:  When written, it configures whether this
      security mechanism should be enabled (true) or disabled (false).
      A read from the running or intended datastore indicates the
      configured administrative value of whether this security mechanism
      is enabled (true) or not (false).  A read from the operational
      datastore indicates whether this security mechanism is actually
      running (true) or not (i.e., it indicates the operational state).
      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-security-self-cred:  Credentials this router presents to
      participate in the enabled security mechanism.  Any private key
      component of a credential MUST NOT be readable.  Adding and
      deleting credentials MAY be allowed.



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   babel-security-trust:  A set of babel-credential-obj objects that
      identify the credentials of routers whose Babel messages may be
      trusted or of a certificate authority (CA) whose signing of a
      router's credentials implies the router credentials can be
      trusted, in the context of this security mechanism.  How a
      security mechanism interacts with this list is determined by the
      mechanism.  A security algorithm may do additional validation of
      credentials, such as checking validity dates or revocation lists,
      so presence in this list may not be sufficient to determine trust.
      Adding and deleting credentials MAY be allowed.

   babel-credvalid-log-enable:  When written, it configures whether
      logging should be enabled (true) or disabled (false).  A read from
      the running or intended datastore indicates the configured
      administrative value of whether logging is enabled (true) or not
      (false).  A read from the operational datastore indicates whether
      logging is actually running (true) or not (i.e., it indicates the
      operational state).  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-credvalid-log:  Log entries that have the timestamp a message
      containing credentials used for peer authentication (e.g., DTLS
      Server Hello) was received on a Babel port, and the entire
      received message (including Ethernet frame and IP headers, if
      possible).  An implementation must restrict the size of this log,
      but how and what size is implementation-specific.  If this log is
      implemented, a mechanism to clear it SHOULD be provided.

3.6.  Definition of babel-routes-obj

     object {
          ip-address           ro babel-route-prefix;
          int                  ro babel-route-prefix-length;
          binary               ro babel-route-router-id;
          string               ro babel-route-neighbor;
         [int                  ro babel-route-received-metric;]
         [int                  ro babel-route-calculated-metric;]
          int                  ro babel-route-seqno;
          ip-address           ro babel-route-next-hop;
          boolean              ro babel-route-feasible;
          boolean              ro babel-route-selected;
      } babel-routes-obj;

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




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

   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 maximum value (infinity) to
      indicate the route was recently retracted and is temporarily
      unreachable (see Section 3.5.5 of [I-D.ietf-babel-rfc6126bis]).
      This metric will be 0 (zero) if the route was not received from a
      neighbor but was generated through other means.  Either babel-
      route-calculated-metric or babel-route-received-metric MUST be
      provided.

   babel-route-calculated-metric:  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 (see Section 3.5.5 of
      [I-D.ietf-babel-rfc6126bis]).  Either babel-route-calculated-
      metric or babel-route-received-metric MUST be provided.

   babel-route-seqno:  The sequence number with which this route was
      advertised.

   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
      [I-D.ietf-babel-rfc6126bis]).

   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).

4.  Common Objects

4.1.  Definition of babel-credential-obj

        object {
             credentials          ro babel-cred;
       } babel-credential-obj;

   babel-cred:  A credential, such as an X.509 certificate, a public
      key, etc.  used for signing and/or encrypting Babel messages.




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4.2.  Definition of babel-log-obj

        object {
             datetime           ro babel-log-time;
             string             ro babel-log-entry;
       } babel-log-obj;

   babel-log-time:  The date and time (according to the device internal
      clock setting, which may be a time relative to boot time, acquired
      from NTP, configured by the user, etc.) when this log entry was
      created.

   babel-log-entry:  The logged message, as a string of utf-8 encoded
      hex characters.

5.  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.

6.  Security Considerations

   This document defines a set of information model objects and
   parameters that may be exposed to be visible from other devices, and
   some of which 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.

   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 and shared secrets
   may be exposed through this model.  This model requires that private
   keys never be exposed.  The Babel security mechanisms that make use
   of these credentials (e.g., [I-D.ietf-babel-dtls],
   [I-D.ietf-babel-hmac]) are expected to define what credentials can be
   used with those mechanisms.






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7.  IANA Considerations

   This document defines a Babel Link Type registry for the values of
   the babel-link-type and babel-supported-link-types parameters to be
   listed under the Babel Routing Protocol registry.

   Valid Babel Link Type names are normatively defined as

   o  MUST be at least 1 character and no more than 20 characters long

   o  MUST contain only US-ASCII [RFC0020] letters 'A' - 'Z' and 'a' -
      'z', digits '0' - '9', and hyphens ('-', ASCII 0x2D or decimal 45)

   o  MUST contain at least one letter ('A' - 'Z' or 'a' - 'z')

   o  MUST NOT begin or end with a hyphen

   o  hyphens MUST NOT be adjacent to other hyphens

   The rules for Link Type names, excepting the limit of 20 characters
   maximum, are also expressed below (as a non-normative convenience)
   using ABNF [RFC5234].

         SRVNAME = *(1*DIGIT [HYPHEN]) ALPHA *([HYPHEN] ALNUM)
         ALNUM   = ALPHA / DIGIT     ; A-Z, a-z, 0-9
         HYPHEN  = %x2D              ; "-"
         ALPHA   = %x41-5A / %x61-7A ; A-Z / a-z [RFC5234]
         DIGIT   = %x30-39           ; 0-9       [RFC5234]

   The allocation policy of this registry is Specification Required
   [RFC8126].

   The initial values in the "Babel Link Type" registry are:

   +----------+-------------------------------------------+------------+
   | Name     | Used for Links Defined By                 | Reference  |
   +----------+-------------------------------------------+------------+
   | ethernet | [IEEE-802.3-2018]                         | (this      |
   |          |                                           | document)  |
   | other    | to be used when no link type information  | (this      |
   |          | available                                 | document)  |
   | tunnel   | to be used for a tunneled interface over  | (this      |
   |          | unknown physical link                     | document)  |
   | wireless | [IEEE-802.11-2016]                        | (this      |
   |          |                                           | document)  |
   | exp-*    | Reserved for Experimental Use             | (this      |
   |          |                                           | document)  |
   +----------+-------------------------------------------+------------+



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8.  Acknowledgements

   Juliusz Chroboczek, Toke Hoeiland-Joergensen, David Schinazi, Mahesh
   Jethanandani, 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].

9.  References

9.1.  Normative References

   [I-D.ietf-babel-rfc6126bis]
              Chroboczek, J. and D. Schinazi, "The Babel Routing
              Protocol", draft-ietf-babel-rfc6126bis-05 (work in
              progress), May 2018.

   [RFC0020]  Cerf, V., "ASCII format for network interchange", STD 80,
              RFC 20, DOI 10.17487/RFC0020, October 1969,
              <https://www.rfc-editor.org/info/rfc20>.

   [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>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [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>.

9.2.  Informative References

   [I-D.ietf-babel-dtls]
              Decimo, A., Schinazi, D., and J. Chroboczek, "Babel
              Routing Protocol over Datagram Transport Layer Security",
              draft-ietf-babel-dtls-01 (work in progress), October 2018.

   [I-D.ietf-babel-hmac]
              Do, C., Kolodziejak, W., and J. Chroboczek, "Babel
              Cryptographic Authentification", draft-ietf-babel-hmac-00
              (work in progress), August 2018.





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   [IEEE-802.11-2016]
              "IEEE Standard 802.11-2016 - IEEE Standard for Information
              Technology - Telecommunications and information exchange
              between systems Local and metropolitan area networks -
              Specific requirements - Part 11: Wireless LAN Medium
              Access Control (MAC) and Physical Layer (PHY)
              Specifications.".

   [IEEE-802.3-2018]
              "IEEE Standard 802.3-2018 - IEEE Approved Draft Standard
              for Ethernet.".

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

   [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>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

   [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",
              <http://cwmp-data-models.broadband-forum.org/>.



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Appendix A.  Open Issues

   1.  I want to get rid of the security log, because all Babel messages
       (which should be defined as all messages to/from the udp-port)
       are be logged by message-log.  I don't like message log as it is.
       I think if logging is enabled it should just write to a text
       file.  This will mean there also needs to be a means of
       downloading/reading the log file.

   2.  Consider the following statistics: under interface object: sent
       multicast Hello, sent updates, received Babel messages; under
       neighbor object: sent unicast Hello, sent updates, sent IHU,
       received Hello, received updates, received IHUs.  Would also need
       to enable/disable stats and clear stats.

   3.  Security section needs furter review

   4.  Commands to add and delete credentials, and parameters that allow
       credential to be identified without allowing access to private
       credential info

   5.  Check description of enable parameters to make sure ok for YANG
       and TR-181.  Closed by updating description to be useful for YANG
       and TR-181, using language consistent with YANG descriptions.

   6.  Distinguish signed and unsigned integers?

   7.  Review new IANA Considerations section.  Should ABNF be
       normative?

   Closed Issues:

   1.   Datatype of the router-id: Closed by introducing binary datatype
        and using that for router-id

   2.   babel-neighbor-address as IPv6-only: Closed by leaving as is
        (IPv4 and IPv6)

   3.   babel-implementation-version includes the name of the
        implementation: Closed by adding "name" to description

   4.   Delete external-cost?: Closed by deleting.

   5.   Would it be useful to define some parameters for reporting
        statistics or logs? [2 logs are now included.  If others are
        needed they need to be proposed.  See Open Issues for additional
        thoughts on logs and statistics.]




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   6.   Closed by defining base64 type and using it for all router IDs:
        "babel-self-router-id: Should this be an opaque 64-bit value
        instead of int?"

   7.   Closed as "No": Do we need a registry for the supported security
        mechanisms?  [Given the current limited set, and unlikelihood of
        massive expansion, I don't think so.  But we can if someone
        wants it.]

   8.   This draft must be reviewed against draft-ietf-babel-rfc6126bis.
        [I feel like this has been adequately done, but I could be
        wrong.]

   9.   babel-interfaces-obj: Juliusz:"This needs further discussion, I
        fear some of these are implementation details."  [In the absence
        of discussion, the current model stands.  Note that all but
        link-type and the neighbors sub-object are optional.  If an
        implementation does not have any of the optional elements then
        it simply doesn't have them and that's fine.]

   10.  Would it be useful to define some parameters specifically for
        security anomalies?  [The 2 logs should be useful in identifying
        security anomalies.  If more is needed, someone needs to
        propose.]

   11.  I created a basic security model.  It's useful for single (or
        no) active security mechanism (e.g., just HMAC, just DTLS, or
        neither); but not multiple active (both HMAC and DTLS -- which
        is not the same as HMAC of DTLS and would just mean that HMAC
        would be used on all unencrypted messages -- but right now the
        model doesn't allow for configuring HMAC of unencrypted messages
        for routers without DTLS, while DTLS is used if possible).  OK?
        [No-one said otherwise.]

   12.  babel-external-cost may need more work. [if no comment, it will
        be left as is]

   13.  babel-hello-[mu]cast-history: the Hello history is formated as
        16 bits, per A.1 of 6126bis.  Is that a too implementation
        specific?  [We also now have an optional-to-implement log of
        received messages, and I made these optional.  So maybe this is
        ok?]

   14.  rxcost, txcost, cost: is it ok to model as integers, since
        6126bis 2.1 says costs and metrics need not be integers.  [I
        have them as integers unless someone insists on something else.]





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   15.  For the security log, should it also log whether the credentials
        were considered ok?  [Right now it doesn't and I think that's ok
        because if you log Hellos it was ok and if you don't it wasn't.]

   16.  Should Babel link types have an IANA registry?  [Agreed to do
        this at IETF 102.]

Appendix B.  Change Log

   Individual Drafts:

   v00 2016-07-07  EBD:  Initial individual draft version

   v01 2017-03-13:  Addressed comments received in 2016-07-15 email from
      J.  Chroboczek

   Working group drafts:

   v00 2017-07-03:  Addressed points noted with "oops" in
      https://www.ietf.org/proceedings/98/slides/slides-98-babel-babel-
      information-model-00.pdf

   v01 2018-01-02:  Removed item from issue list that was agreed (in
      Prague) not to be an issue.  Added description of data types under
      Notation section, and used these in all data types.  Added babel-
      security and babel-trust.

   v02 2018-04-05:

      *  changed babel-version description to babel-implementation-
         version

      *  replace optional babel-interface-seqno with optional babel-
         mcast-hello-seqno and babel-ucast-hello-seqno

      *  replace optional babel-interface-hello-interval with optional
         babel-mcast-hello-interval and babel-ucast-hello-interval

      *  remove babel-request-trigger-ack

      *  remove "babel-router-id: router-id of the neighbor"; note that
         parameter had previously been removed but description had
         accidentally not been removed

      *  added an optional "babel-cost" field to babel-neighbors object,
         since the spec does not define how exactly the cost is computed
         from rxcost/txcost




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      *  deleted babel-source-garbage-collection-time

      *  change babel-lossy-link to babel-link-type and make this an
         enumeration; added at top level babel-supported-link-types so
         which are supported by this implementation can be reported

      *  changes to babel-security-obj to allow self credentials to be
         one or more instances of a credential object.  Allowed trusted
         credentials to include CA credentials; made some parameter name
         changes

      *  updated references and Introduction

      *  added Overview section

      *  deleted babel-sources-obj

      *  added feasible Boolean to routes

      *  added section to briefly describe extending the information
         model.

      *  deleted babel-route-neighbor

      *  tried to make definition of babel-interface-reference clearer

      *  added security and message logs

   v03 2018-05-31:

      *  added reference to RFC 8174 (update to RFC 2119 on key words)

      *  applied edits to Introduction text per Juliusz email of
         2018-04-06

      *  Deleted sentence in definition of "int" data type that said it
         was also used for enumerations.  Changed all enumerations to
         strings.  The only enumerations were for link types, which are
         now "ethernet", "wireless", "tunnel", and "other".

      *  deleted [ip-address babel-mcast-group-ipv4;]

      *  babel-external-cost description changed

      *  babel-security-self-cred: Added "any private key component of a
         credential MUST NOT be readable;"





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      *  hello-history parameters put recent Hello in most significant
         bit and length of parameter is not constrained.

      *  babel-hello-seqno in neighbors-obj changed to babel-exp-mcast-
         hello-seqno and babel-exp-ucast-hello-seqno

      *  added babel-route-neighbor back again.  It was mistakenly
         deleted

      *  changed babel-route-metric and babel-route-announced-metric to
         babel-route-received-metric and babel-route-calculated-metric

      *  changed model of security object to put list of supported
         mechanisms at top level and separate security object per
         mechanism.  This caused some other changes to the security
         object

   v04 2018-10-15:

      *  changed babel-mcast-group-ipv6 to babel-mcast-group

      *  link type parameters changed to point to newly defined registry

      *  babel-ucast-hello-interval moved to neighbor object

      *  babel-ucast-hello-seqno moved to neighbor object

      *  babel-neighbor-ihu-interval deleted

      *  in log descriptions, included statement that there SHOULD be
         ability to clear logs

      *  added IANA registry for link types

      *  added "ro" and "rw" to tables for read-write and read-only

      *  added metric computation parameter to interface

Author's Address

   Barbara Stark
   AT&T
   Atlanta, GA
   US

   Email: barbara.stark@att.com





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