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RFC 7223

A YANG Data Model for Interface Management

Pages: 39
Obsoleted by:  8343

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Internet Engineering Task Force (IETF)                      M. Bjorklund
Request for Comments: 7223                                Tail-f Systems
Category: Standards Track                                       May 2014
ISSN: 2070-1721


               A YANG Data Model for Interface Management

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 configuration data and state data (status information and counters for the collection of statistics). Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7223. Copyright Notice Copyright (c) 2014 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 ....................................................2 1.1. Terminology ................................................3 1.2. Tree Diagrams ..............................................4 2. Objectives ......................................................4 3. Interfaces Data Model ...........................................5 3.1. The Interface Lists ........................................6 3.2. Interface References .......................................7 3.3. Interface Layering .........................................7 4. Relationship to the IF-MIB ......................................8 5. Interfaces YANG Module .........................................11 6. IANA Considerations ............................................26 7. Security Considerations ........................................26 8. Acknowledgments ................................................27 9. References .....................................................27 9.1. Normative References ......................................27 9.2. Informative References ....................................28 Appendix A. Example: Ethernet Interface Module ....................29 Appendix B. Example: Ethernet Bonding Interface Module ............30 Appendix C. Example: VLAN Interface Module ........................31 Appendix D. Example: NETCONF <get> Reply ..........................32 Appendix E. Examples: Interface Naming Schemes ....................35 E.1. Router with Restricted Interface Names .....................35 E.2. Router with Arbitrary Interface Names ......................36 E.3. Ethernet Switch with Restricted Interface Names ............37 E.4. Generic Host with Restricted Interface Names ...............38 E.5. Generic Host with Arbitrary Interface Names ................39

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, configured, and monitored. The data model includes configuration data and state data (status information and counters for the collection of statistics).
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1.1. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119]. The following terms are used within this document: o system-controlled interface: An interface is said to be system- controlled if the system creates and deletes the interface independently of what has been explicitly configured. Examples are interfaces representing physical hardware that appear and disappear when hardware (e.g., a line card or hot-pluggable wireless interface) is added or removed. System-controlled interfaces may also appear if a certain functionality is enabled (e.g., a loopback interface might appear if the IP protocol stack is enabled). o user-controlled interface: An interface is said to be user- controlled if the creation of the interface is controlled by adding explicit interface configuration to the running configuration datastore and the removal of the interface is controlled by removing explicit interface configuration from the running configuration datastore. Examples are VLAN interfaces configured on a system-controlled Ethernet interface. The following terms are defined in [RFC6241] and are not redefined here: o client o configuration data o server o state data The following terms are defined in [RFC6020] and are not redefined here: o augment o data model o data node o presence container
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1.2. Tree Diagrams

A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is as follows: o Brackets "[" and "]" enclose list keys. o Abbreviations before data node names: "rw" means configuration (read-write), and "ro" means state data (read-only). o Symbols after data node names: "?" means an optional node, "!" means a presence container, and "*" denotes a list and leaf-list. o Parentheses enclose choice and case nodes, and case nodes are also marked with a colon (":"). o Ellipsis ("...") stands for contents of subtrees that are not shown.

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. To facilitate such mappings, the data model should be simple. 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 the Simple Network Management Protocol (SNMP) to identify interfaces must be clear. o The model must support interface layering: both (1) simple layering, where one interface is layered on top of exactly one other interface, and (2) more complex scenarios, where one interface results from the aggregation of N other interfaces or when N interfaces are multiplexed over one other interface.
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   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.

   o  The data model should support physical interfaces as well as
      logical interfaces.

   o  The data model should include read-only counters in order to
      gather statistics for sent and received octets and packets,
      received packets with errors, and packets that could not be sent
      due to errors.

3. Interfaces Data Model

This document defines the YANG module "ietf-interfaces", which has the following structure: +--rw interfaces | +--rw interface* [name] | +--rw name string | +--rw description? string | +--rw type identityref | +--rw enabled? boolean | +--rw link-up-down-trap-enable? enumeration +--ro interfaces-state +--ro interface* [name] +--ro name string +--ro type identityref +--ro admin-status enumeration +--ro oper-status enumeration +--ro last-change? yang:date-and-time +--ro if-index int32 +--ro phys-address? yang:phys-address +--ro higher-layer-if* interface-state-ref +--ro lower-layer-if* interface-state-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
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               +--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 Lists

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. The "iana-if-type" module [RFC7224] defines YANG identities for the interface types in the IANA-maintained "ifType definitions" registry. There is one list of configured interfaces ("/interfaces/interface"), and a separate list for the operational state of all interfaces ("/interfaces-state/interface"). It is expected that interface-type-specific data models augment the interface lists 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 { ... } } }
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   For system-controlled interfaces, the "name" is the device-specific
   name of the interface.  The 'config false' list
   "/interfaces-state/interface" contains all existing interfaces on the
   device.

   If the device supports arbitrarily named user-controlled interfaces,
   the Network Configuration Protocol (NETCONF) server advertises the
   "arbitrary-names" feature.  If the device 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 Appendices
   E.1 and E.2 for examples.

   When a system-controlled interface is created by the system, the
   system tries to apply the interface configuration in "/interfaces/
   interface" 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 "interface-state-ref" typedefs, which other YANG modules SHOULD use when they need to reference a configured interface or operationally used interface, respectively.

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

   +--------------------------------------+----------------------------+
   | YANG data node in /interfaces-       | IF-MIB object              |
   | state/interface                      |                            |
   +--------------------------------------+----------------------------+
   | name                                 | ifName                     |
   | type                                 | ifType                     |
   | 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                |
   +--------------------------------------+----------------------------+

             YANG State Data Nodes and Related IF-MIB Objects

        +-----------------------------------------+---------------+
        | YANG data node in /interfaces/interface | IF-MIB object |
        +-----------------------------------------+---------------+
        | description                             | ifAlias       |
        +-----------------------------------------+---------------+

             YANG Config Data Nodes and Related IF-MIB Objects
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5. Interfaces YANG Module

This YANG module imports typedefs from [RFC6991]. <CODE BEGINS> file "ietf-interfaces@2014-05-08.yang" module ietf-interfaces { namespace "urn:ietf:params:xml:ns:yang:ietf-interfaces"; prefix if; import ietf-yang-types { prefix yang; } 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: Thomas Nadeau <mailto:tnadeau@lucidvision.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) 2014 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 7223; see the RFC itself for full legal notices.";
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     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
          configured interfaces.";
     }

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

     /*
      * Configuration data nodes
      */

     container interfaces {
       description
         "Interface configuration parameters.";

       list interface {
         key "name";

         description
           "The list of configured interfaces on the device.

            The operational state of an interface is available in the
            /interfaces-state/interface list.  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
            /interfaces-state/interface list.  If the configuration
            of a user-controlled interface cannot be used by the system,
            the configured interface is not instantiated in the
            /interfaces-state/interface list.";

        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.
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              For system-controlled interfaces, this leaf is the
              device-specific name of the interface.  The 'config false'
              list /interfaces-state/interface contains the currently
              existing interfaces on the device.

              If a client tries to create configuration for a
              system-controlled interface that is not present in the
              /interfaces-state/interface list, 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
              /interface-state/interface list.";
         }

         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
              datastore.

              Specifically, if the device supports ':startup', when
              ifAlias is read the device MUST return the value of
              'description' in the 'startup' datastore, and when it is
              written, it MUST be written to the 'running' and 'startup'
              datastores.  Note that it is up to the implementation to
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              decide whether to modify this single leaf in 'startup' or
              perform an implicit copy-config from 'running' to
              'startup'.

              If the device does not support ':startup', ifAlias MUST
              be mapped to the 'description' leaf in the 'running'
              datastore.";
           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 'running' datastore to set
              IF-MIB.ifAdminStatus to 'up' or 'down' after an ifEntry
              has been initialized, as described in RFC 2863.
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              Changes in this leaf in the 'running' datastore are
              reflected in ifAdminStatus, but if ifAdminStatus is
              changed over SNMP, this leaf is not affected.";
           reference
             "RFC 2863: The Interfaces Group MIB - ifAdminStatus";
         }

         leaf link-up-down-trap-enable {
           if-feature if-mib;
           type enumeration {
             enum enabled {
               value 1;
             }
             enum disabled {
               value 2;
             }
           }
           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";
         }
       }
     }

     /*
      * Operational state data nodes
      */

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

       list interface {
         key "name";
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         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;
           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;
           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.";
             }
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             enum testing {
               value 3;
               description
                 "In some test mode.";
             }
           }
           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.";
             }
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             enum lower-layer-down {
               value 7;
               description
                 "Down due to state of lower-layer interface(s).";
             }
           }
           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;
           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;
           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;
           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
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              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;
           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;
           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";
           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";
         }
ToP   noToC   RFC7223 - Page 21
         container statistics {
           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";
           }
ToP   noToC   RFC7223 - Page 22
           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'.";
ToP   noToC   RFC7223 - Page 23
             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";
           }
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           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";
           }
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           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.
ToP   noToC   RFC7223 - Page 26
                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 7223

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>)
ToP   noToC   RFC7223 - Page 27
   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

[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. [RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, July 2013.
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9.2. Informative References

[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. [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, March 2012. [RFC7224] Bjorklund, M., "IANA Interface Type YANG Module", RFC 7224, May 2014.
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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 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 parameters for Ethernet interfaces augment "/if:interfaces/if:interface" { when "if:type = 'ianaift:ethernetCsmacd'"; container ethernet { choice transmission-params { case auto { leaf auto-negotiate { type empty; } } case manual { leaf duplex { type enumeration { enum "half"; enum "full"; } }
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             leaf speed {
               type enumeration {
                 enum "10Mb";
                 enum "100Mb";
                 enum "1Gb";
                 enum "10Gb";
               }
             }
           }
         }
         // other Ethernet-specific params...
       }
     }

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

       container ethernet {
         leaf duplex {
           type enumeration {
             enum "half";
             enum "full";
           }
         }
         // 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; }
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     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; } }
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     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> 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" 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>
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         <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>

       <interfaces-state
           xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
           xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">

         <interface>
           <name>eth0</name>
           <type>ianaift:ethernetCsmacd</type>
           <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>
           <name>eth1</name>
           <type>ianaift:ethernetCsmacd</type>
           <admin-status>up</admin-status>
           <oper-status>up</oper-status>
           <if-index>7</if-index>
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           <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>
         </interface>

         <interface>
           <name>eth1.10</name>
           <type>ianaift:l2vlan</type>
           <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>
         </interface>

         <!-- This interface is not configured -->
         <interface>
           <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>
           <name>lo1</name>
           <type>ianaift:softwareLoopback</type>
           <admin-status>up</admin-status>
           <oper-status>up</oper-status>
           <if-index>1</if-index>
           <statistics>
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             <discontinuity-time>
               2013-04-01T03:00:00+00:00
             </discontinuity-time>
             <!-- counters now shown here -->
           </statistics>
         </interface>

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

Appendix E. 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.

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 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>
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   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.

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 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.
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   Physical interfaces are configured as in Appendix E.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>

E.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>
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E.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>
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E.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 E.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