Network Working Group M. Bjorklund
Internet-Draft Tail-f Systems
Obsoletes: rfc7223 (if approved) December 17, 2017
Intended status: Standards Track
Expires: June 20, 2018

A YANG Data Model for Interface Management
draft-ietf-netmod-rfc7223bis-01

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. The data model includes definitions for configuration and system state (status information and counters for the collection of statistics). This document obsoletes RFC 7223.

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 June 20, 2018.

Copyright Notice

Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.


Table of Contents

1. Introduction

This document defines a YANG [RFC7950] 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, configured, and monitored.

The data model includes configuration data and state data (status information and counters for the collection of statistics).

This version of the interfaces data model supports the Network Management Datastore Architecture (NMDA) [I-D.ietf-netmod-revised-datastores].

1.1. Summary of Changes from RFC 7223

The "/interfaces‑state" subtree with "config false" data nodes is deprecated. All "config false" data nodes are now present in the "/interfaces" subtree.

Servers that do not implement NMDA, or that wish to support clients that do not implement NMDA, MAY implement the deprecated "/interfaces‑state" tree.

1.2. 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] [RFC8174] when, and only when, they appear in all capitals, as shown here.

The following terms are used within this document:

The following terms are defined in [I-D.ietf-netmod-revised-datastores] and are not redefined here:

The following terms are defined in [RFC7950] and are not redefined here:

1.3. Tree Diagrams

Tree diagrams used in this document follow the notation defined in [I-D.ietf-netmod-yang-tree-diagrams].

2. Objectives

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

3. Interfaces Data Model

This document defines the YANG module "ietf‑interfaces", which has the following structure, excluding the deprecated "/interfaces‑state" subtree:

module: ietf-interfaces
    +--rw interfaces
       +--rw interface* [name]
          +--rw name                        string
          +--rw description?                string
          +--rw type                        identityref
          +--rw enabled?                    boolean
          +--rw link-up-down-trap-enable?   enumeration {if-mib}?
          +--ro admin-status                enumeration {if-mib}?
          +--ro oper-status                 enumeration
          +--ro last-change?                yang:date-and-time
          +--ro if-index                    int32 {if-mib}?
          +--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 ("/interfaces/interface"). Each interface in the list is identified by its name. Furthermore, each interface has a mandatory "type" leaf.

The "iana‑if‑type" module [RFC7224] defines YANG identities for the interface types in the IANA-maintained "ifType definitions" registry.

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

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";
  }
  import iana-if-type {
    prefix ianaift;
  }

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

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

For system-controlled interfaces, the "name" is the device-specific name of the interface.

If the device supports arbitrarily named user-controlled interfaces, then the server will advertise the "arbitrary‑names" feature. If the server does not advertise this feature, the names of user-controlled interfaces MUST match the device's naming scheme. How a client can learn the naming scheme of such devices is outside the scope of this document. See Appendix F.1 and Appendix F.2 for examples.

When a system-controlled interface is created in the operational state by the system, the system tries to apply the interface configuration in the intended configuration with the same name as the new interface. If no such interface configuration is found, or if the configured type does not match the real interface type, the system creates the interface without applying explicit configuration.

When a user-controlled interface is created, the configuration determines the name of the interface.

Depending on the operating system and the physical attachment point to which a network interface may be attached or removed, it may be impossible for an implementation to provide predictable and consistent names for system-controlled interfaces across insertion/removal cycles as well as in anticipation of initial insertion. The ability to provide configurations for such interfaces is therefore dependent on the implementation and cannot be assumed in all cases.

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" and typedef, which other YANG modules SHOULD use when they need to reference an 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.

  import interfaces {
      prefix "if";
  }
  import iana-if-type {
    prefix ianaift;
  }

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

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

While the interface layering is configured in interface-type-specific models, two generic state data leaf-lists, "higher‑layer‑if" and "lower‑layer‑if", represent a read-only view of the interface layering hierarchy.

4. Relationship to the IF-MIB

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

In most cases, the "name" of an "/interfaces/interface" entry is mapped to ifName. The IF-MIB allows two different ifEntries to have the same ifName. Devices that support this feature and also support the data model defined in this document cannot have a 1-1 mapping between the "name" leaf and ifName.

The configured "description" of an "interface" has traditionally been mapped to ifAlias in some implementations. This document allows this mapping, but implementers should be aware of the differences in the value space and persistence for these objects. See the YANG module definition of the leaf "description" in Section 5 for details.

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

The ifMtu object from the IF-MIB is not mapped to the "ietf‑interfaces" module. It is expected that interface-type-specific YANG modules provide interface-type-specific MTU leafs by augmenting the "ietf‑interfaces" model.

There are a number of counters in the IF-MIB that exist in two versions: one with 32 bits and one with 64 bits. The 64-bit versions were added to support high-speed interfaces with a data rate greater than 20,000,000 bits/second. Today's implementations generally support such high-speed interfaces, and hence only 64-bit counters are provided in this data model. Note that NETCONF and SNMP may differ in the time granularity in which they provide access to the counters. For example, it is common that SNMP implementations cache counter values for some time.

The objects ifDescr and ifConnectorPresent from the IF-MIB are not mapped to the "ietf‑interfaces" module.

The following tables list the YANG data nodes with corresponding objects in the IF-MIB.

YANG Data Nodes and Related IF-MIB Objects
YANG data node in /interfaces/interface IF-MIB object
name ifName
type ifType
description ifAlias
admin-status ifAdminStatus
oper-status ifOperStatus
last-change ifLastChange
if-index ifIndex
link-up-down-trap-enable ifLinkUpDownTrapEnable
phys-address ifPhysAddress
higher-layer-if and lower-layer-if ifStackTable
speed ifSpeed and ifHighSpeed
discontinuity-time ifCounterDiscontinuityTime
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

5. Interfaces YANG Module

This YANG module imports typedefs from [RFC6991].

<CODE BEGINS> file "ietf-interfaces@2017-12-16.yang"

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

  import ietf-yang-types {
    prefix yang;
  }

  organization
    "IETF NETMOD (Network Modeling) Working Group";

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

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

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

     Copyright (c) 2017 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

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

  revision 2017-12-16 {
    description
      "Updated to support NMDA.";
    reference
      "RFC XXXX: A YANG Data Model for Interface Management";
  }

  revision 2014-05-08 {
    description
      "Initial revision.";
    reference
      "RFC 7223: 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.";
  }

  /*
   * Identities
   */

  identity interface-type {
    description
      "Base identity from which specific interface types are
       derived.";
  }

  /*
   * Features
   */

  feature arbitrary-names {
    description
      "This feature indicates that the device allows user-controlled
       interfaces to be named arbitrarily.";
  }
  feature pre-provisioning {
    description
      "This feature indicates that the device supports
       pre-provisioning of interface configuration, i.e., it is
       possible to configure an interface whose physical interface
       hardware is not present on the device.";
  }
  feature if-mib {
    description
      "This feature indicates that the device implements
       the IF-MIB.";
    reference
      "RFC 2863: The Interfaces Group MIB";
  }

  /*
   * Data nodes
   */

  container interfaces {
    description
      "Interface parameters.";

    list interface {
      key "name";

      description
        "The list of interfaces on the device.

         The status of an interface is available in this list in the
         operational state.  If the configuration of a
         system-controlled interface cannot be used by the system
         (e.g., the interface hardware present does not match the
         interface type), then the configuration is not applied to
         the system-controlled interface shown in the operational
         state.  If the configuration of a user-controlled interface
         cannot be used by the system, the configured interface is
         not instantiated in the operational state.

         System-controlled interfaces created by the system are
         always present in this list in the operational state,
         whether they are configured or not.";

     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 of the interface.
           For system-controlled interfaces, this leaf is the
           device-specific name of the interface.

           If a client tries to create configuration for a
           system-controlled interface that is not present in the
           operational state, the server MAY reject the request if
           the implementation does not support pre-provisioning of
           interfaces or if the name refers to an interface that can
           never exist in the system.  A NETCONF server MUST reply
           with an rpc-error with the error-tag 'invalid-value' in
           this case.

           If the device supports pre-provisioning of interface
           configuration, the 'pre-provisioning' feature is
           advertised.

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

           When a configured user-controlled interface is created by
           the system, it is instantiated with the same name in the
           operational state.

           A server implementation MAY map this leaf to the ifName
           MIB object.  Such an implementation needs to use some
           mechanism to handle the differences in size and characters
           allowed between this leaf and ifName.  The definition of
           such a mechanism is outside the scope of this document.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifName";
      }

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

           A server implementation MAY map this leaf to the ifAlias
           MIB object.  Such an implementation needs to use some
           mechanism to handle the differences in size and characters
           allowed between this leaf and ifAlias.  The definition of
           such a mechanism is outside the scope of this document.

           Since ifAlias is defined to be stored in non-volatile
           storage, the MIB implementation MUST map ifAlias to the
           value of 'description' in the persistently stored
           configuration.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifAlias";
      }

      leaf type {
        type identityref {
          base interface-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.

           If a client tries to set the type of an interface to a
           value that can never be used by the system, e.g., if the
           type is not supported or if the type does not match the
           name of the interface, the server MUST reject the request.
           A NETCONF server MUST reply with an rpc-error with the
           error-tag 'invalid-value' in this case.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifType";
      }

      leaf enabled {
        type boolean;
        default "true";
        description
          "This leaf contains the configured, desired state of the
           interface.

           Systems that implement the IF-MIB use the value of this
           leaf in the intended configuration to set
           IF-MIB.ifAdminStatus to 'up' or 'down' after an ifEntry
           has been initialized, as described in RFC 2863.

           Changes in this leaf in the intended configuration are
           reflected in ifAdminStatus.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifAdminStatus";
      }

      leaf link-up-down-trap-enable {
        if-feature if-mib;
        type enumeration {
          enum enabled {
            value 1;
            description
              "The device will generate linkUp/linkDown SNMP
               notifications for this interface.";
          }
          enum disabled {
            value 2;
            description
              "The device will not generate linkUp/linkDown SNMP
               notifications for this interface.";
          }
        }
        description
          "Controls whether linkUp/linkDown SNMP notifications
           should be generated for this interface.

           If this node is not configured, the value 'enabled' is
           operationally used by the server for interfaces that 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 admin-status {
        if-feature if-mib;
        type enumeration {
          enum up {
            value 1;
            description
              "Ready to pass packets.";
          }
          enum down {
            value 2;
            description
              "Not ready to pass packets and not in some test mode.";
          }
          enum testing {
            value 3;
            description
              "In some test mode.";
          }
        }
        config false;
        mandatory true;
        description
          "The desired state of the interface.

           This leaf has the same read semantics as ifAdminStatus.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifAdminStatus";
      }

      leaf oper-status {
        type enumeration {
          enum up {
            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 (typically hardware) is missing.";
          }
          enum lower-layer-down {
            value 7;
            description
              "Down due to state of lower-layer interface(s).";
          }
        }
        config false;
        mandatory true;
        description
          "The current operational state of the interface.

           This leaf has the same semantics as ifOperStatus.";
        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;
        mandatory true;
        description
          "The ifIndex value for the ifEntry represented by this
           interface.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifIndex";
      }

      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 Media Access Control (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;
        description
            "An estimate of the interface's current bandwidth in bits
             per second.  For interfaces that 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 have 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;
          mandatory true;
          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, that were not addressed to a
             multicast or 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 - ifHCInUcastPkts";
        }

        leaf in-broadcast-pkts {
          type yang:counter64;
          description
            "The number of packets, delivered by this sub-layer to a
             higher (sub-)layer, that 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, that 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 that 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
             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 that 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 that 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
            "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 that 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 that 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 that were addressed to a
             multicast address at this sub-layer, including those
             that were discarded or not sent.  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 -
                       ifHCOutMulticastPkts";
        }

        leaf out-discards {
          type yang:counter32;
          description
            "The number of outbound packets that 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";
        }
      }

    }
  }

  /*
   * Legacy typedefs
   */

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

  /*
   * Legacy operational state data nodes
   */

  container interfaces-state {
    config false;
    status deprecated;
    description
      "Data nodes for the operational state of interfaces.";

    list interface {
      key "name";
      status deprecated;

      description
        "The list of interfaces on the device.

         System-controlled interfaces created by the system are
         always present in this list, whether they are configured or
         not.";

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

           A server implementation MAY map this leaf to the ifName
           MIB object.  Such an implementation needs to use some
           mechanism to handle the differences in size and characters
           allowed between this leaf and ifName.  The definition of
           such a mechanism is outside the scope of this document.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifName";
      }

      leaf type {
        type identityref {
          base interface-type;
        }
        mandatory true;
        status deprecated;
        description
          "The type of the interface.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifType";
      }

      leaf admin-status {
        if-feature if-mib;
        type enumeration {
          enum up {
            value 1;
            description
              "Ready to pass packets.";
          }
          enum down {
            value 2;
            description
              "Not ready to pass packets and not in some test mode.";
          }
          enum testing {
            value 3;
            description
              "In some test mode.";
          }
        }
        mandatory true;
        status deprecated;
        description
          "The desired state of the interface.

           This leaf has the same read semantics as ifAdminStatus.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifAdminStatus";
      }

      leaf oper-status {
        type enumeration {
          enum up {
            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 (typically hardware) is missing.";
          }
          enum lower-layer-down {
            value 7;
            description
              "Down due to state of lower-layer interface(s).";
          }
        }
        mandatory true;
        status deprecated;
        description
          "The current operational state of the interface.

           This leaf has the same semantics as ifOperStatus.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifOperStatus";
      }

      leaf last-change {
        type yang:date-and-time;
        status deprecated;
        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";
        }
        mandatory true;
        status deprecated;
        description
          "The ifIndex value for the ifEntry represented by this
           interface.";
        reference
          "RFC 2863: The Interfaces Group MIB - ifIndex";
      }

      leaf phys-address {
        type yang:phys-address;
        status deprecated;
        description
          "The interface's address at its protocol sub-layer.  For
           example, for an 802.x interface, this object normally
           contains a Media Access Control (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-state-ref;
        status deprecated;
        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-state-ref;
        status deprecated;
        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";
        status deprecated;
        description
            "An estimate of the interface's current bandwidth in bits
             per second.  For interfaces that 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 have no concept of bandwidth, this
             node is not present.";
        reference
          "RFC 2863: The Interfaces Group MIB -
                     ifSpeed, ifHighSpeed";
      }

      container statistics {
        status deprecated;
        description
          "A collection of interface-related statistics objects.";

        leaf discontinuity-time {
          type yang:date-and-time;
          mandatory true;
          status deprecated;
          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;
          status deprecated;
          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;
          status deprecated;
          description
            "The number of packets, delivered by this sub-layer to a
             higher (sub-)layer, that were not addressed to a
             multicast or 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 - ifHCInUcastPkts";
        }

        leaf in-broadcast-pkts {
          type yang:counter64;
          status deprecated;
          description
            "The number of packets, delivered by this sub-layer to a
             higher (sub-)layer, that 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;
          status deprecated;
          description
            "The number of packets, delivered by this sub-layer to a
             higher (sub-)layer, that 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;
          status deprecated;
          description
            "The number of inbound packets that 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
             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;
          status deprecated;
          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;
          status deprecated;
          description
            "For packet-oriented interfaces, the number of packets
             received via the interface that 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 that 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;
          status deprecated;
          description
            "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;
          status deprecated;
          description
            "The total number of packets that higher-level protocols
             requested be transmitted, and that 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;
          status deprecated;
          description
            "The total number of packets that higher-level protocols
             requested be transmitted, and that 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;
          status deprecated;
          description
            "The total number of packets that higher-level protocols
             requested be transmitted, and that were addressed to a
             multicast address at this sub-layer, including those
             that were discarded or not sent.  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 -
                       ifHCOutMulticastPkts";
        }

        leaf out-discards {
          type yang:counter32;
          status deprecated;
          description
            "The number of outbound packets that 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;
          status deprecated;
          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";
        }
      }
    }
  }
}
	    

<CODE ENDS>

6. IANA Considerations

This document registers a URI in the "IETF XML Registry" [RFC3688]. Following the format in RFC 3688, the following registration has been 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
	    

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]. The NETCONF access control model [RFC6536] provides the means to restrict access for particular NETCONF users to a pre-configured subset of all available NETCONF protocol operations and content.

There are a number of data nodes defined in the YANG module which are writable/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 whether an interface is enabled or not. Unauthorized access to this leaf could cause the device to ignore packets it should receive and process.

8. Acknowledgments

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

9. References

9.1. Normative References

[I-D.ietf-netmod-revised-datastores] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K. and R. Wilton, "Network Management Datastore Architecture", Internet-Draft draft-ietf-netmod-revised-datastores-07, November 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013.
[RFC7950] Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.

9.2. Informative References

[I-D.ietf-netmod-yang-tree-diagrams] Bjorklund, M. and L. Berger, "YANG Tree Diagrams", Internet-Draft draft-ietf-netmod-yang-tree-diagrams-02, October 2017.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, DOI 10.17487/RFC6536, March 2012.
[RFC7224] Bjorklund, M., "IANA Interface Type YANG Module", RFC 7224, DOI 10.17487/RFC7224, May 2014.

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 also shows how operational state parameters can be conditionally augmented to the operational interface list. The example is not intended as a complete module for Ethernet configuration.

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

  import ietf-interfaces {
    prefix if;
  }
  import iana-if-type {
    prefix ianaift;
  }

  // configuration and state parameters for Ethernet interfaces
  augment "/if:interfaces/if:interface" {
    when "if:type = 'ianaift:ethernetCsmacd'";

    container ethernet {
      container transmission {
        choice transmission-params {
          case auto {
            leaf auto-negotiate {
              type empty;
            }
          }
          case manual {
            container manual {
              leaf duplex {
                type enumeration {
                  enum "half";
                  enum "full";
                }
              }
              leaf speed {
                type enumeration {
                  enum "10Mb";
                  enum "100Mb";
                  enum "1Gb";
                  enum "10Gb";
                }
              }
            }
          }
        }
        leaf duplex {
          type enumeration {
            enum "half";
            enum "full";
          }
          config false;
        }
      }
      // other Ethernet-specific params...
    }
  }
}
	    

Appendix B. Example: Ethernet Bonding Interface Module

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

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

  import ietf-interfaces {
    prefix if;
  }
  import iana-if-type {
    prefix ianaift;
  }



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

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

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;
  }
  import iana-if-type {
    prefix ianaift;
  }

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

  augment "/if:interfaces/if:interface" {
    when "if:type = 'ianaift: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.";
      }
    }
  }
}
	    

Appendix D. Example: NETCONF <get‑config> Reply

This section gives an example of a reply to the NETCONF <get‑config> request for <running> 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"
        xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type"
        xmlns:vlan="http://example.com/vlan">

      <interface>
        <name>eth0</name>
        <type>ianaift:ethernetCsmacd</type>
        <enabled>false</enabled>
      </interface>

      <interface>
        <name>eth1</name>
        <type>ianaift:ethernetCsmacd</type>
        <enabled>true</enabled>
        <vlan:vlan-tagging>true</vlan:vlan-tagging>
      </interface>

      <interface>
        <name>eth1.10</name>
        <type>ianaift:l2vlan</type>
        <enabled>true</enabled>
        <vlan:base-interface>eth1</vlan:base-interface>
        <vlan:vlan-id>10</vlan:vlan-id>
      </interface>

      <interface>
        <name>lo1</name>
        <type>ianaift:softwareLoopback</type>
        <enabled>true</enabled>
      </interface>

    </interfaces>
  </data>
</rpc-reply>
	    

Appendix E. Example: NETCONF <get‑data> Reply

This section gives an example of a reply to the NETCONF <get‑data> request for <operational> 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"
        xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type"
        xmlns:vlan="http://example.com/vlan"
        xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin">

      <interface or:origin="or:intended">
        <name>eth0</name>
        <type>ianaift:ethernetCsmacd</type>
        <enabled>false</enabled>
        <admin-status>down</admin-status>
        <oper-status>down</oper-status>
        <if-index>2</if-index>
        <phys-address>00:01:02:03:04:05</phys-address>
        <statistics>
          <discontinuity-time>
            2013-04-01T03:00:00+00:00
          </discontinuity-time>
          <!-- counters now shown here -->
        </statistics>
      </interface>

      <interface or:origin="or:intended">
        <name>eth1</name>
        <type>ianaift:ethernetCsmacd</type>
        <enabled>true</enabled>
        <admin-status>up</admin-status>
        <oper-status>up</oper-status>
        <if-index>7</if-index>
        <phys-address>00:01:02:03:04:06</phys-address>
        <higher-layer-if>eth1.10</higher-layer-if>
        <statistics>
          <discontinuity-time>
            2013-04-01T03:00:00+00:00
          </discontinuity-time>
          <!-- counters now shown here -->
        </statistics>
        <vlan:vlan-tagging>true</vlan:vlan-tagging>
      </interface>

      <interface or:origin="or:intended">
        <name>eth1.10</name>
        <type>ianaift:l2vlan</type>
        <enabled>true</enabled>
        <admin-status>up</admin-status>
        <oper-status>up</oper-status>
        <if-index>9</if-index>
        <lower-layer-if>eth1</lower-layer-if>
        <statistics>
          <discontinuity-time>
            2013-04-01T03:00:00+00:00
          </discontinuity-time>
          <!-- counters now shown here -->
        </statistics>
        <vlan:base-interface>eth1</vlan:base-interface>
        <vlan:vlan-id>10</vlan:vlan-id>
      </interface>

      <!-- This interface is not configured -->
      <interface or:origin="or:system">
        <name>eth2</name>
        <type>ianaift:ethernetCsmacd</type>
        <admin-status>down</admin-status>
        <oper-status>down</oper-status>
        <if-index>8</if-index>
        <phys-address>00:01:02:03:04:07</phys-address>
        <statistics>
          <discontinuity-time>
            2013-04-01T03:00:00+00:00
          </discontinuity-time>
          <!-- counters now shown here -->
        </statistics>
      </interface>

      <interface or:origin="or:intended">
        <name>lo1</name>
        <type>ianaift:softwareLoopback</type>
        <enabled>true</enabled>
        <admin-status>up</admin-status>
        <oper-status>up</oper-status>
        <if-index>1</if-index>
        <statistics>
          <discontinuity-time>
            2013-04-01T03:00:00+00:00
          </discontinuity-time>
          <!-- counters now shown here -->
        </statistics>
      </interface>

    </interfaces>
  </data>
</rpc-reply>
	    

Appendix F. Examples: Interface Naming Schemes

This section gives examples of some implementation strategies.

The examples make use of the example data model "ex‑vlan" (see Appendix C) to show how user-controlled interfaces can be configured.

F.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 Ethernet or Gigabit Ethernet ports.

The device-specific names for these physical interfaces are "fastethernet‑N/M" or "gigabitethernet‑N/M".

The name of a VLAN interface is restricted to the form "<physical‑interface‑name>.<subinterface‑number>".

It is assumed that the operator is aware of this naming scheme. The implementation auto-initializes the value for "type" based on the interface name.

The NETCONF server does not advertise the "arbitrary‑names" feature in the <hello> message.

An operator can configure a physical 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 "ianaift:ethernetCsmacd". Thus, if the client performs a <get‑config> right after the <edit‑config> above, it will get:

  <interface>
    <name>fastethernet-1/0</name>
    <type>ianaift:ethernetCsmacd</type>
  </interface>
	    

The client can configure a VLAN interface by sending an <edit‑config> containing:

  <interface nc:operation="create">
    <name>fastethernet-1/0.10005</name>
    <type>ianaift:l2vlan</type>
    <vlan:base-interface>fastethernet-1/0</vlan:base-interface>
    <vlan:vlan-id>5</vlan:vlan-id>
  </interface>
	    

If the client tries to change the type of the physical interface with an <edit‑config> containing:

  <interface nc:operation="merge">
    <name>fastethernet-1/0</name>
    <type>ianaift:tunnel</type>
  </interface>
	    

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

F.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 Ethernet or Gigabit Ethernet ports.

The device-specific names for these physical interfaces are "fastethernet‑N/M" or "gigabitethernet‑N/M".

The implementation does not restrict the user-controlled interface names. This allows an operator to more easily apply the interface configuration to a different 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 NETCONF server advertises the "arbitrary‑names" feature in the <hello> message.

Physical interfaces are configured as in Appendix F.1.

An operator can configure a VLAN interface by sending an <edit‑config> containing:

  <interface nc:operation="create">
    <name>acme-interface</name>
    <type>ianaift:l2vlan</type>
    <vlan:base-interface>fastethernet-1/0</vlan:base-interface>
    <vlan:vlan-id>5</vlan:vlan-id>
  </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>
    <vlan:base-interface>fastethernet-1/1</vlan:base-interface>
  </interface>
	    

F.3. Ethernet Switch with Restricted Interface Names

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

The device-specific names for the physical interfaces are numbers that match the physical port number.

An operator can configure a physical 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" to "ianaift:ethernetCsmacd". Thus, if the client performs a <get‑config> right after the <edit‑config> above, it will get:

  <interface>
    <name>6</name>
    <type>ianaift:ethernetCsmacd</type>
  </interface>
	    

F.4. Generic Host with Restricted Interface Names

In this example, a generic host has interfaces named by the kernel. The system identifies the physical interface by the name assigned by the operating system to the interface.

The name of a VLAN interface is restricted to the form "<physical‑interface‑name>:<vlan‑number>".

The NETCONF server does not advertise the "arbitrary‑names" feature in the <hello> message.

An operator can configure an 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 "ianaift:ethernetCsmacd". Thus, if the client performs a <get‑config> right after the <edit‑config> above, it will get:

  <interface>
    <name>eth8</name>
    <type>ianaift:ethernetCsmacd</type>
  </interface>
	    

The client can configure a VLAN interface by sending an <edit‑config> containing:

  <interface nc:operation="create">
    <name>eth8:5</name>
    <type>ianaift:l2vlan</type>
    <vlan:base-interface>eth8</vlan:base-interface>
    <vlan:vlan-id>5</vlan:vlan-id>
  </interface>
	    

F.5. Generic Host with Arbitrary Interface Names

In this example, a generic host has interfaces named by the kernel. The system identifies the physical interface by the name assigned by the operating system to the interface.

The implementation does not restrict the user-controlled interface names. This allows an operator to more easily apply the interface configuration to a different 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 NETCONF server advertises the "arbitrary‑names" feature in the <hello> message.

Physical interfaces are configured as in Appendix F.4.

An operator can configure a VLAN interface by sending an <edit‑config> containing:

  <interface nc:operation="create">
    <name>acme-interface</name>
    <type>ianaift:l2vlan</type>
    <vlan:base-interface>eth8</vlan:base-interface>
    <vlan:vlan-id>5</vlan:vlan-id>
  </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>
    <vlan:base-interface>eth3</vlan:base-interface>
  </interface>
	    

Author's Address

Martin Bjorklund Tail-f Systems EMail: mbj@tail-f.com