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Versions: (draft-bjorklund-netmod-interfaces-cfg) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 RFC 7223

Network Working Group                                       M. Bjorklund
Internet-Draft                                            Tail-f Systems
Intended status: Standards Track                       November 15, 2012
Expires: May 19, 2013


               A YANG Data Model for Interface Management
                  draft-ietf-netmod-interfaces-cfg-08

Abstract

   This document defines a YANG data model for the management of network
   interfaces.  It is expected that interface type specific data models
   augment the generic interfaces data model defined in this document.

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 http://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 May 19, 2013.

Copyright Notice

   Copyright (c) 2012 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
   (http://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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Objectives . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Interfaces Data Model  . . . . . . . . . . . . . . . . . . . .  5
     3.1.  The interface List . . . . . . . . . . . . . . . . . . . .  5
     3.2.  Interface References . . . . . . . . . . . . . . . . . . .  6
     3.3.  Interface Layering . . . . . . . . . . . . . . . . . . . .  6
   4.  Relationship to the IF-MIB . . . . . . . . . . . . . . . . . .  8
   5.  Interfaces YANG Module . . . . . . . . . . . . . . . . . . . . 10
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 23
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 24
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 25
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 26
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 26
   Appendix A.  Example: Ethernet Interface Module  . . . . . . . . . 27
   Appendix B.  Example: Ethernet Bonding Interface Module  . . . . . 29
   Appendix C.  Example: VLAN Interface Module  . . . . . . . . . . . 30
   Appendix D.  Example: NETCONF <get> reply  . . . . . . . . . . . . 31
   Appendix E.  Examples: Interface Naming Schemes  . . . . . . . . . 32
     E.1.  Router with Restricted Interface Names . . . . . . . . . . 32
     E.2.  Router with Arbitrary Interface Names  . . . . . . . . . . 33
     E.3.  Ethernet Switch with Restricted Interface Names  . . . . . 33
     E.4.  Generic Host with Restricted Interface Names . . . . . . . 34
     E.5.  Generic Host with Arbitrary Interface Names  . . . . . . . 35
   Appendix F.  ChangeLog . . . . . . . . . . . . . . . . . . . . . . 36
     F.1.  Version -08  . . . . . . . . . . . . . . . . . . . . . . . 36
     F.2.  Version -07  . . . . . . . . . . . . . . . . . . . . . . . 36
     F.3.  Version -06  . . . . . . . . . . . . . . . . . . . . . . . 36
     F.4.  Version -05  . . . . . . . . . . . . . . . . . . . . . . . 36
     F.5.  Version -04  . . . . . . . . . . . . . . . . . . . . . . . 36
     F.6.  Version -03  . . . . . . . . . . . . . . . . . . . . . . . 36
     F.7.  Version -02  . . . . . . . . . . . . . . . . . . . . . . . 37
     F.8.  Version -01  . . . . . . . . . . . . . . . . . . . . . . . 37
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 38














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1.  Introduction

   This document defines a YANG [RFC6020] data model for the management
   of network interfaces.  It is expected that interface type specific
   data models augment the generic interfaces data model defined in this
   document.

   Network interfaces are central to the management of many Internet
   protocols.  Thus, it is important to establish a common data model
   for how interfaces are identified and configured.

1.1.  Terminology

   The keywords "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].

   The following terms are defined in [RFC6241] and are not redefined
   here:

   o  client

   o  server

   The following terms are defined in [RFC6020] and are not redefined
   here:

   o  augment

   o  data model

   o  data node


















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2.  Objectives

   This section describes some of the design objectives for the model
   presented in Section 5.

   o  It is recognized that existing implementations will have to map
      the interface data model defined in this memo to their proprietary
      native data model.  The new data model should be simple to
      facilitate such mappings.

   o  The data model should be suitable for new implementations to use
      as-is, without requiring a mapping to a different native model.

   o  References to interfaces should be as simple as possible,
      preferably by using a single leafref.

   o  The mapping to ifIndex [RFC2863] used by SNMP to identify
      interfaces must be clear.

   o  The model must support interface layering, both simple layering
      where one interface is layered on top of exactly one other
      interface, and more complex scenarios where one interface is
      aggregated over N other interfaces, or when N interfaces are
      multiplexed over one other interface.

   o  The data model should support the pre-provisioning of interface
      configuration, i.e., it should be possible to configure an
      interface whose physical interface hardware is not present on the
      device.  It is recommended that devices that support dynamic
      addition and removal of physical interfaces also support pre-
      provisioning.




















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3.  Interfaces Data Model

   The data model in the module "ietf-interfaces" has the following
   structure, where square brackets are used to enclose a list's keys,
   "?" means that the leaf is optional, and "*" denotes a leaf-list:

      +--rw interfaces
         +--rw interface [name]
            +--rw name                        string
            +--rw description?                string
            +--rw type                        ianaift:iana-if-type
            +--rw location?                   string
            +--rw enabled?                    boolean
            +--ro oper-status?                enumeration
            +--ro last-change?                yang:date-and-time
            +--ro if-index?                   int32
            +--rw link-up-down-trap-enable?   enumeration
            +--ro phys-address?               yang:phys-address
            +--ro higher-layer-if*            interface-ref
            +--ro lower-layer-if*             interface-ref
            +--ro speed?                      yang:gauge64
            +--ro statistics
               +--ro discontinuity-time?   yang:date-and-time
               +--ro in-octets?            yang:counter64
               +--ro in-unicast-pkts?      yang:counter64
               +--ro in-broadcast-pkts?    yang:counter64
               +--ro in-multicast-pkts?    yang:counter64
               +--ro in-discards?          yang:counter32
               +--ro in-errors?            yang:counter32
               +--ro in-unknown-protos?    yang:counter32
               +--ro out-octets?           yang:counter64
               +--ro out-unicast-pkts?     yang:counter64
               +--ro out-broadcast-pkts?   yang:counter64
               +--ro out-multicast-pkts?   yang:counter64
               +--ro out-discards?         yang:counter32
               +--ro out-errors?           yang:counter32

3.1.  The interface List

   The data model for interfaces presented in this document uses a flat
   list of interfaces.  Each interface in the list is identified by its
   name.  Furthermore, each interface has a mandatory "type" leaf, and a
   "location" leaf.  The combination of "type" and "location" is unique
   within the interface list.

   It is expected that interface type specific data models augment the
   interface list, and use the "type" leaf to make the augmentation
   conditional.



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   As an example of such an interface type specific augmentation,
   consider this YANG snippet.  For a more complete example, see
   Appendix A.

     import interfaces {
         prefix "if";
     }

     augment "/if:interfaces/if:interface" {
         when "if:type = 'ethernetCsmacd'";

         container ethernet {
             leaf duplex {
                 ...
             }
         }
     }

   The "location" leaf is a string.  It is optional in the data model,
   but if the type represents a physical interface, it is mandatory.
   The format of this string is device- and type-dependent.  The device
   uses the location string to identify the physical or logical entity
   that the configuration applies to.  For example, if a device has a
   single array of 8 ethernet ports, the location can be one of the
   strings "1" to "8".  As another example, if a device has N cards of M
   ports, the location can be on the form "n/m", such as "1/0".

   How a client can learn which types and locations are present on a
   certain device is outside the scope of this document.

3.2.  Interface References

   An interface is identified by its name, which is unique within the
   server.  This property is captured in the "interface-ref" typedef,
   which other YANG modules SHOULD use when they need to reference an
   existing interface.

3.3.  Interface Layering

   There is no generic mechanism for how an interface is configured to
   be layered on top of some other interface.  It is expected that
   interface type specific models define their own data nodes for
   interface layering, by using "interface-ref" types to reference lower
   layers.

   Below is an example of a model with such nodes.  For a more complete
   example, see Appendix B.




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     import interfaces {
         prefix "if";
     }

     augment "/if:interfaces/if:interface" {
         when "if:type = 'ieee8023adLag'";

         leaf-list slave-if {
             type if:interface-ref;
             must "/if:interfaces/if:interface[if:name = current()]"
                + "/if:type = 'ethernetCsmacd'" {
                 description
                     "The type of a slave interface must be ethernet";
             }
         }
         // other bonding config params, failover times etc.
     }

   There are two state data leaf-list nodes "higher-layer-if" and
   "lower-layer-if" defined, that contains a read-only view of the
   interface layering hierarchy.






























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4.  Relationship to the IF-MIB

   If the device implements IF-MIB [RFC2863], each entry in the
   "interface" list is typically mapped to one ifEntry.  The "if-index"
   leaf contains the value of the corresponding ifEntry's ifIndex.

   In most cases, the "name" of an "interface" entry is mapped to
   ifName. ifName is defined as an DisplayString [RFC2579] which uses a
   7-bit ASCII character set.  An implementation MAY restrict the
   allowed values for "name" to match the restrictions of ifName.

   The IF-MIB allows two different ifEntries to have the same ifName.
   Devices that support this feature, and also support the configuration
   of these interfaces using the "interface" list, cannot have a 1-1
   mapping between the "name" leaf and ifName.

   The IF-MIB also defines the writable object ifPromiscuousMode.  Since
   this object typically is not a configuration object, it is not mapped
   to the "ietf-interfaces" module.

   The following table lists the YANG data nodes with corresponding
   objects in the IF-MIB.





























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       +----------------------------------+------------------------+
       | YANG data node                   | IF-MIB object          |
       +----------------------------------+------------------------+
       | interface                        | ifEntry                |
       | name                             | ifName                 |
       | description                      | ifAlias                |
       | type                             | ifType                 |
       | enabled                          | ifAdminStatus          |
       | oper-status                      | ifOperStatus           |
       | last-change                      | ifLastChange           |
       | if-index                         | ifIndex                |
       | link-up-down-trap-enable         | ifLinkUpDownTrapEnable |
       | phys-address                     | ifPhysAddress          |
       | higher-layer-if / lower-layer-if | ifStackTable           |
       | speed                            | ifSpeed                |
       | in-octets                        | ifHCInOctets           |
       | in-unicast-pkts                  | ifHCInUcastPkts        |
       | in-broadcast-pkts                | ifHCInBroadcastPkts    |
       | in-multicast-pkts                | ifHCInMulticastPkts    |
       | in-discards                      | ifInDiscards           |
       | in-errors                        | ifInErrors             |
       | in-unknown-protos                | ifInUnknownProtos      |
       | out-octets                       | ifHCOutOctets          |
       | out-unicast-pkts                 | ifHCOutUcastPkts       |
       | out-broadcast-pkts               | ifHCOutBroadcastPkts   |
       | out-multicast-pkts               | ifHCOutMulticastPkts   |
       | out-discards                     | ifOutDiscards          |
       | out-errors                       | ifOutErrors            |
       +----------------------------------+------------------------+

               Mapping of YANG data nodes to IF-MIB objects




















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5.  Interfaces YANG Module

   This YANG module imports a typedef from
   [I-D.ietf-netmod-iana-if-type].

   RFC Ed.: update the date below with the date of RFC publication and
   remove this note.

   <CODE BEGINS> file "ietf-interfaces@2012-11-15.yang"

   module ietf-interfaces {

     namespace "urn:ietf:params:xml:ns:yang:ietf-interfaces";
     prefix if;

     import ietf-yang-types {
       prefix yang;
     }
     import iana-if-type {
       prefix ianaift;
     }

     organization
       "IETF NETMOD (NETCONF Data Modeling Language) Working Group";

     contact
       "WG Web:   <http://tools.ietf.org/wg/netmod/>
        WG List:  <mailto:netmod@ietf.org>

        WG Chair: David Kessens
                  <mailto:david.kessens@nsn.com>

        WG Chair: Juergen Schoenwaelder
                  <mailto:j.schoenwaelder@jacobs-university.de>

        Editor:   Martin Bjorklund
                  <mailto:mbj@tail-f.com>";

     description
       "This module contains a collection of YANG definitions for
        managing network interfaces.

        Copyright (c) 2012 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Simplified BSD License



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        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX; see
        the RFC itself for full legal notices.";

     // RFC Ed.: replace XXXX with actual RFC number and remove this
     // note.

     // RFC Ed.: update the date below with the date of RFC publication
     // and remove this note.
     revision 2012-11-15 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for Interface Management";
     }

     /* Typedefs */

     typedef interface-ref {
       type leafref {
         path "/if:interfaces/if:interface/if:name";
       }
       description
         "This type is used by data models that need to reference
          interfaces.";
     }

     /* Features */

     feature arbitrary-names {
       description
         "This feature indicates that the server allows interfaces to
          be named arbitrarily.";
     }

     feature if-mib {
       description
         "This feature indicates that the server implements IF-MIB.";
       reference
         "RFC 2863: The Interfaces Group MIB";
     }

     /* Data nodes */

     container interfaces {



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       description
         "Interface parameters.";

       list interface {
         key "name";
         unique "type location";

         description
           "The list of interfaces on the device.";

         leaf name {
           type string;
           description
             "The name of the interface.

              A device MAY restrict the allowed values for this leaf,
              possibly depending on the type and location.

              If the device allows arbitrarily named interfaces, the
              feature 'arbitrary-names' is advertised.

              This leaf MAY be mapped to ifName by an implementation.
              Such an implementation MAY restrict the allowed values for
              this leaf so that it matches the restrictions of ifName.
              If a NETCONF server that implements this restriction is
              sent a value that doesn't match the restriction, it MUST
              reply with an rpc-error with the error-tag
              'invalid-value'.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifName";
         }

         leaf description {
           type string;
           description
             "A textual description of the interface.

              This leaf MAY be mapped to ifAlias by an implementation.
              Such an implementation MAY restrict the allowed values for
              this leaf so that it matches the restrictions of ifAlias.
              If a NETCONF server that implements this restriction is
              sent a value that doesn't match the restriction, it MUST
              reply with an rpc-error with the error-tag
              'invalid-value'.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifAlias";
         }




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         leaf type {
           type ianaift:iana-if-type;
           mandatory true;
           description
             "The type of the interface.

              When an interface entry is created, a server MAY
              initialize the type leaf with a valid value, e.g., if it
              is possible to derive the type from the name of the
              interface.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifType";
         }

         leaf location {
           type string;
           description
             "The device-specific location of the interface of a
              particular type.  The format of the location string
              depends on the interface type and the device.

              If the interface's type represents a physical interface,
              this leaf MUST be set.

              When an interface entry is created, a server MAY
              initialize the location leaf with a valid value, e.g., if
              it is possible to derive the location from the name of
              the interface.";
         }

         leaf enabled {
           type boolean;
           default "true";
           description
             "The desired state of the interface.

              This leaf contains the configured, desired state of the
              interface.  Systems that implement the IF-MIB use the
              value of this leaf to set IF-MIB.ifAdminStatus to 'up' or
              'down' after an ifEntry has been initialized, as described
              in RFC 2863.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifAdminStatus";
         }

         leaf oper-status {
           type enumeration {
             enum up {



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               value 1;
               description
                 "Ready to pass packets.";
             }
             enum down {
               value 2;
               description
                 "The interface does not pass any packets.";
             }
             enum testing {
               value 3;
               description
                 "In some test mode.  No operational packets can
                  be passed.";
             }
             enum unknown {
               value 4;
               description
                 "Status cannot be determined for some reason.";
             }
             enum dormant {
               value 5;
               description
                 "Waiting for some external event.";
             }
             enum not-present {
               value 6;
               description
                 "Some component is missing.";
             }
             enum lower-layer-down {
               value 7;
               description
                 "Down due to state of lower-layer interface(s).";
             }
           }
           config false;
           description
             "The current operational state of the interface.

              If 'enabled' is 'false' then 'oper-status'
              should be 'down'.  If 'enabled' is changed to 'true'
              then 'oper-status' should change to 'up' if the interface
              is ready to transmit and receive network traffic; it
              should change to 'dormant' if the interface is waiting for
              external actions (such as a serial line waiting for an
              incoming connection); it should remain in the 'down' state
              if and only if there is a fault that prevents it from



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              going to the 'up' state; it should remain in the
              'not-present' state if the interface has missing
              (typically, hardware) components.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifOperStatus";
         }

         leaf last-change {
           type yang:date-and-time;
           config false;
           description
             "The time the interface entered its current operational
              state.  If the current state was entered prior to the
              last re-initialization of the local network management
              subsystem, then this node is not present.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifLastChange";
         }

         leaf if-index {
           if-feature if-mib;
           type int32 {
             range "1..2147483647";
           }
           config false;
           description
             "The ifIndex value for the ifEntry represented by this
              interface.

              Media-specific modules must specify how the type is
              mapped to entries in the ifTable.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifIndex";
         }

         leaf link-up-down-trap-enable {
           if-feature if-mib;
           type enumeration {
             enum enabled {
               value 1;
             }
             enum disabled {
               value 2;
             }
           }
           description
             "Indicates whether linkUp/linkDown SNMP notifications
              should be generated for this interface.



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              If this node is not configured, the value 'enabled' is
              operationally used by the server for interfaces which do
              not operate on top of any other interface (i.e., there are
              no 'lower-layer-if' entries), and 'disabled' otherwise.";
           reference
             "RFC 2863: The Interfaces Group MIB -
                        ifLinkUpDownTrapEnable";
         }

         leaf phys-address {
           type yang:phys-address;
           config false;
           description
             "The interface's address at its protocol sub-layer.  For
             example, for an 802.x interface, this object normally
             contains a MAC address.  The interface's media-specific
             modules must define the bit and byte ordering and the
             format of the value of this object.  For interfaces that do
             not have such an address (e.g., a serial line), this node
             is not present.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifPhysAddress";
         }

         leaf-list higher-layer-if {
           type interface-ref;
           config false;
           description
             "A list of references to interfaces layered on top of this
              interface.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifStackTable";
         }

         leaf-list lower-layer-if {
           type interface-ref;
           config false;
           description
             "A list of references to interfaces layered underneath this
              interface.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifStackTable";
         }

         leaf speed {
           type yang:gauge64;
           units "bits / second";
           config false;



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           description
               "An estimate of the interface's current bandwidth in bits
                per second.  For interfaces which do not vary in
                bandwidth or for those where no accurate estimation can
                be made, this node should contain the nominal bandwidth.
                For interfaces that has no concept of bandwidth, this
                node is not present.";
           reference
             "RFC 2863: The Interfaces Group MIB -
                        ifSpeed, ifHighSpeed";
         }

         container statistics {
           config false;
           description
             "A collection of interface-related statistics objects.";

           leaf discontinuity-time {
             type yang:date-and-time;
             description
               "The time on the most recent occasion at which any one or
                more of this interface's counters suffered a
                discontinuity.  If no such discontinuities have occurred
                since the last re-initialization of the local management
                subsystem, then this node contains the time the local
                management subsystem re-initialized itself.";
           }

           leaf in-octets {
             type yang:counter64;
             description
               "The total number of octets received on the interface,
                including framing characters.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifHCInOctets";
           }
           leaf in-unicast-pkts {
             type yang:counter64;
             description
               "The number of packets, delivered by this sub-layer to a
                higher (sub-)layer, which were not addressed to a
                multicast or broadcast address at this sub-layer.




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                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifHCInUcastPkts";
           }
           leaf in-broadcast-pkts {
             type yang:counter64;
             description
               "The number of packets, delivered by this sub-layer to a
                higher (sub-)layer, which were addressed to a broadcast
                address at this sub-layer.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB -
                          ifHCInBroadcastPkts";
           }
           leaf in-multicast-pkts {
             type yang:counter64;
             description
               "The number of packets, delivered by this sub-layer to a
                higher (sub-)layer, which were addressed to a multicast
                address at this sub-layer.  For a MAC layer protocol,
                this includes both Group and Functional addresses.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB -
                          ifHCInMulticastPkts";
           }
           leaf in-discards {
             type yang:counter32;
             description
               "The number of inbound packets which were chosen to be
                discarded even though no errors had been detected to
                prevent their being deliverable to a higher-layer
                protocol.  One possible reason for discarding such a
                packet could be to free up buffer space.

                Discontinuities in the value of this counter can occur



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                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifInDiscards";
           }
           leaf in-errors {
             type yang:counter32;
             description
               "For packet-oriented interfaces, the number of inbound
                packets that contained errors preventing them from being
                deliverable to a higher-layer protocol.  For character-
                oriented or fixed-length interfaces, the number of
                inbound transmission units that contained errors
                preventing them from being deliverable to a higher-layer
                protocol.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifInErrors";
           }
           leaf in-unknown-protos {
             type yang:counter32;
             description
               "For packet-oriented interfaces, the number of packets
                received via the interface which were discarded because
                of an unknown or unsupported protocol.  For
                character-oriented or fixed-length interfaces that
                support protocol multiplexing the number of transmission
                units received via the interface which were discarded
                because of an unknown or unsupported protocol.  For any
                interface that does not support protocol multiplexing,
                this counter is not present.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifInUnknownProtos";
           }

           leaf out-octets {
             type yang:counter64;
             description



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               "The total number of octets transmitted out of the
                interface, including framing characters.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifHCOutOctets";
           }
           leaf out-unicast-pkts {
             type yang:counter64;
             description
               "The total number of packets that higher-level protocols
                requested be transmitted, and which were not addressed
                to a multicast or broadcast address at this sub-layer,
                including those that were discarded or not sent.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifHCOutUcastPkts";
           }
           leaf out-broadcast-pkts {
             type yang:counter64;
             description
               "The total number of packets that higher-level protocols
                requested be transmitted, and which were addressed to a
                broadcast address at this sub-layer, including those
                that were discarded or not sent.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB -
                          ifHCOutBroadcastPkts";
           }
           leaf out-multicast-pkts {
             type yang:counter64;
             description
               "The total number of packets that higher-level protocols
                requested be transmitted, and which were addressed to a
                multicast address at this sub-layer, including those
                that were discarded or not sent.  For a MAC layer



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                protocol, this includes both Group and Functional
                addresses.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB -
                          ifHCOutMulticastPkts";
           }
           leaf out-discards {
             type yang:counter32;
             description
               "The number of outbound packets which were chosen to be
                discarded even though no errors had been detected to
                prevent their being transmitted.  One possible reason
                for discarding such a packet could be to free up buffer
                space.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifOutDiscards";
           }
           leaf out-errors {
             type yang:counter32;
             description
               "For packet-oriented interfaces, the number of outbound
                packets that could not be transmitted because of errors.
                For character-oriented or fixed-length interfaces, the
                number of outbound transmission units that could not be
                transmitted because of errors.

                Discontinuities in the value of this counter can occur
                at re-initialization of the management system, and at
                other times as indicated by the value of
                'discontinuity-time'.";
             reference
               "RFC 2863: The Interfaces Group MIB - ifOutErrors";
           }
         }
       }
     }
   }




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   <CODE ENDS>


















































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6.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688].
   Following the format in RFC 3688, the following registration is
   requested to be made.

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

        Registrant Contact: The IESG.

        XML: N/A, the requested URI is an XML namespace.

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

     name:         ietf-interfaces
     namespace:    urn:ietf:params:xml:ns:yang:ietf-interfaces
     prefix:       if
     reference:    RFC XXXX
































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7.  Security Considerations

   The YANG module defined in this memo is designed to be accessed via
   the NETCONF protocol [RFC6241].  The lowest NETCONF layer is the
   secure transport layer and the mandatory-to-implement secure
   transport is SSH [RFC6242].

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

   /interfaces/interface:  This list specifies the configured interfaces
      on a device.  Unauthorized access to this list could cause the
      device to ignore packets it should receive and process.

   /interfaces/interface/enabled:  This leaf controls if an interface is
      enabled or not.  Unauthorized access to this leaf could cause the
      device to ignore packets it should receive and process.





























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8.  Acknowledgments

   The author wishes to thank Alexander Clemm, Per Hedeland, Ladislav
   Lhotka, and Juergen Schoenwaelder for their helpful comments.















































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9.  References

9.1.  Normative References

   [I-D.ietf-netmod-iana-if-type]
              Bjorklund, M., "IANA Interface Type and Address Family
              YANG Modules", draft-ietf-netmod-iana-if-type-02 (work in
              progress), April 2012.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2863]  McCloghrie, K. and F. Kastenholz, "The Interfaces Group
              MIB", RFC 2863, June 2000.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

9.2.  Informative References

   [RFC2579]  McCloghrie, K., Ed., Perkins, D., Ed., and J.
              Schoenwaelder, Ed., "Textual Conventions for SMIv2",
              STD 58, RFC 2579, April 1999.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)",
              RFC 6241, June 2011.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, June 2011.

















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Appendix A.  Example: Ethernet Interface Module

   This section gives a simple example of how an Ethernet interface
   module could be defined.  It demonstrates how media-specific
   configuration parameters can be conditionally augmented to the
   generic interface list.  It is not intended as a complete module for
   ethernet configuration.












































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   module ex-ethernet {
     namespace "http://example.com/ethernet";
     prefix "eth";

     import ietf-interfaces {
       prefix if;
     }

     augment "/if:interfaces/if:interface" {
       when "if:type = 'ethernetCsmacd'";

       container ethernet {
         must "../if:location" {
           description
             "An ethernet interface must specify the physical location
              of the ethernet hardware.";
         }
         choice transmission-params {
           case auto {
             leaf auto-negotiate {
               type empty;
             }
           }
           case manual {
             leaf duplex {
               type enumeration {
                 enum "half";
                 enum "full";
               }
             }
             leaf speed {
               type enumeration {
                 enum "10Mb";
                 enum "100Mb";
                 enum "1Gb";
                 enum "10Gb";
               }
             }
           }
         }
         // other ethernet specific params...
       }
     }
   }







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Appendix B.  Example: Ethernet Bonding Interface Module

   This section gives an example of how interface layering can be
   defined.  An ethernet bonding interface is defined, which bonds
   several ethernet interfaces into one logical interface.

   module ex-ethernet-bonding {
     namespace "http://example.com/ethernet-bonding";
     prefix "bond";

     import ietf-interfaces {
       prefix if;
     }

     augment "/if:interfaces/if:interface" {
       when "if:type = 'ieee8023adLag'";

       leaf-list slave-if {
         type if:interface-ref;
         must "/if:interfaces/if:interface[if:name = current()]"
            + "/if:type = 'ethernetCsmacd'" {
           description
             "The type of a slave interface must be ethernet.";
         }
       }
       leaf bonding-mode {
         type enumeration {
           enum round-robin;
           enum active-backup;
           enum broadcast;
         }
       }
       // other bonding config params, failover times etc.
     }
   }
















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Appendix C.  Example: VLAN Interface Module

   This section gives an example of how a vlan interface module can be
   defined.

   module ex-vlan {
     namespace "http://example.com/vlan";
     prefix "vlan";

     import ietf-interfaces {
       prefix if;
     }

     augment "/if:interfaces/if:interface" {
       when "if:type = 'ethernetCsmacd' or
             if:type = 'ieee8023adLag'";
       leaf vlan-tagging {
         type boolean;
         default false;
       }
     }

     augment "/if:interfaces/if:interface" {
       when "if:type = 'l2vlan'";

       leaf base-interface {
         type if:interface-ref;
         must "/if:interfaces/if:interface[if:name = current()]"
            + "/vlan:vlan-tagging = true" {
           description
             "The base interface must have vlan tagging enabled.";
         }
       }
       leaf vlan-id {
         type uint16 {
           range "1..4094";
         }
         must "../base-interface" {
           description
             "If a vlan-id is defined, a base-interface must
              be specified.";
         }
       }
     }
   }






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Appendix D.  Example: NETCONF <get> reply

   This section gives an example of a reply to the NETCONF <get> request
   for a device that implements the example data models above.

   <rpc-reply
       xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
       message-id="101">
     <data>
       <interfaces
           xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces">
         <interface>
           <name>eth0</name>
           <type>ethernetCsmacd</type>
           <location>0</location>
           <enabled>true</enabled>
           <if-index>2</if-index>
         </interface>
         <interface>
           <name>eth1</name>
           <type>ethernetCsmacd</type>
           <location>1</location>
           <enabled>true</enabled>
           <if-index>7</if-index>
           <vlan-tagging
               xmlns="http://example.com/vlan">true</vlan-tagging>
         </interface>
       </interfaces>
     </data>
   </rpc-reply>





















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Appendix E.  Examples: Interface Naming Schemes

   This section gives examples of some implementation strategies.

E.1.  Router with Restricted Interface Names

   In this example, a router has support for 4 line cards, each with 8
   ports.  The slots for the cards are physically numbered from 0 to 3,
   and the ports on each card from 0 to 7.  Each card has fast- or
   gigabit-ethernet ports.

   The implementation restricts the names of the interfaces to one of
   "fastethernet-N/M" or "gigabitethernet-N/M".  The "location" of an
   interface is a string on the form "N/M".  The implementation auto-
   initializes the values for "type" and "location" based on the
   interface name.

   An operator can configure a new interface by sending an <edit-config>
   containing:

     <interface nc:operation="create">
       <name>fastethernet-1/0</name>
     </interface>

   When the server processes this request, it will set the leaf "type"
   to "ethernetCsmacd" and "location" to "1/0".  Thus, if the client
   performs a <get-config> right after the <edit-config> above, it will
   get:

     <interface>
       <name>fastethernet-1/0</name>
       <type>ethernetCsmacd</type>
       <location>1/0</location>
     </interface>

   If the client tries to change the location of this interface with an
   <edit-config> containing:

     <interface nc:operation="merge">
       <name>fastethernet-1/0</name>
       <location>1/1</location>
     </interface>

   then the server will reply with an "invalid-value" error, since the
   new location does not match the name.






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E.2.  Router with Arbitrary Interface Names

   In this example, a router has support for 4 line cards, each with 8
   ports.  The slots for the cards are physically numbered from 0 to 3,
   and the ports on each card from 0 to 7.  Each card has fast- or
   gigabit-ethernet ports.

   The implementation does not restrict the interface names.  This
   allows to more easily apply the interface configuration to a
   different physical interface.  However, the additional level of
   indirection also makes it a bit more complex to map interface names
   found in other protocols to configuration entries.  The "location" of
   an interface is a string on the form "N/M".

   An operator can configure a new interface by sending an <edit-config>
   containing:

     <interface nc:operation="create">
       <name>acme-interface</name>
       <type>ethernetCsmacd</type>
       <location>1/0</location>
     </interface>

   If necessary, the operator can move the configuration named
   "acme-interface" over to a different physical interface with an
   <edit-config> containing:

     <interface nc:operation="merge">
       <name>acme-interface</name>
       <location>2/4</location>
     </interface>

E.3.  Ethernet Switch with Restricted Interface Names

   In this example, an ethernet switch has a number of ports, each port
   identified by a simple port number.

   The implementation restricts the interface names to numbers that
   match the physical port number.

   An operator can configure a new interface by sending an <edit-config>
   containing:

     <interface nc:operation="create">
       <name>6</name>
     </interface>

   When the server processes this request, it will set the leaf "type"



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   to "ethernetCsmacd" and "location" to "6".  Thus, if the client
   performs a <get-config> right after the <edit-config> above, it will
   get:

     <interface>
       <name>6</name>
       <type>ethernetCsmacd</type>
       <location>6</location>
     </interface>

   If the client tries to change the location of this interface with an
   <edit-config> containing:

     <interface nc:operation="merge">
       <name>6</name>
       <location>5</location>
     </interface>

   then the server will reply with an "invalid-value" error, since the
   new location does not match the name.

E.4.  Generic Host with Restricted Interface Names

   In this example, a generic host has interfaces named by the kernel
   and without easily usable location information.  The system
   identifies the physical interface by the name assigned by the
   operating system to the interface.

   The implementation restricts the interface name to the operating
   system level name of the physical interface.

   An operator can configure a new interface by sending an <edit-config>
   containing:

     <interface nc:operation="create">
       <name>eth8</name>
     </interface>

   When the server processes this request, it will set the leaf "type"
   to "ethernetCsmacd" and "location" to "eth8".  Thus, if the client
   performs a <get-config> right after the <edit-config> above, it will
   get:

     <interface>
       <name>eth8</name>
       <type>ethernetCsmacd</type>
       <location>eth8</location>
     </interface>



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   If the client tries to change the location of this interface with an
   <edit-config> containing:

     <interface nc:operation="merge">
       <name>eth8</name>
       <location>eth7</location>
     </interface>

   then the server will reply with an "invalid-value" error, since the
   new location does not match the name.

E.5.  Generic Host with Arbitrary Interface Names

   In this example, a generic host has interfaces named by the kernel
   and without easily usable location information.  The system
   identifies the physical interface by the name assigned by the
   operating system to the interface.

   The implementation does not restrict the interface name to the
   operating system level name of the physical interface.  This allows
   to more easily apply the interface configuration to a different
   physical interface.  However, the additional level of indirection
   also makes it a bit more complex to map interface names found in
   other protocols to configuration entries.

   An operator can configure a new interface by sending an <edit-config>
   containing:

     <interface nc:operation="create">
       <name>acme-interface</name>
       <type>ethernetCsmacd</type>
       <location>eth4</location>
     </interface>

   If necessary, the operator can move the configuration named
   "acme-interface" over to a different physical interface with an
   <edit-config> containing:

     <interface nc:operation="merge">
       <name>acme-interface</name>
       <location>eth3</location>
     </interface>









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Appendix F.  ChangeLog

   RFC Editor: remove this section upon publication as an RFC.

F.1.  Version -08

   o  Removed the mtu leaf.

   o  Added examples of different interface naming schemes.

F.2.  Version -07

   o  Made leaf speed config false.

F.3.  Version -06

   o  Added oper-status leaf.

   o  Added leaf-lists higher-layer-if and lower-layer-if, that show the
      interface layering.

   o  Added container statistics with counters.

F.4.  Version -05

   o  Added an Informative References section.

   o  Updated the Security Considerations section.

   o  Clarified the behavior of an NETCONF server when invalid values
      are received.

F.5.  Version -04

   o  Clarified why ifPromiscuousMode is not part of this data model.

   o  Added a table that shows the mapping between this YANG data model
      and IF-MIB.

F.6.  Version -03

   o  Added the section Relationship to the IF-MIB.

   o  Changed if-index to be a leaf instead of leaf-list.

   o  Explained the notation used in the data model tree picture.





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F.7.  Version -02

   o  Editorial fixes

F.8.  Version -01

   o  Changed leaf "if-admin-status" to leaf "enabled".

   o  Added Security Considerations










































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Author's Address

   Martin Bjorklund
   Tail-f Systems

   Email: mbj@tail-f.com













































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