RFC6022

Internet Engineering Task Force (IETF) M. Scott Request for Comments: 6022 Ericsson Category: Standards Track M. Bjorklund ISSN: 2070-1721 Tail-f Systems

                                                        October 2010

               YANG Module for NETCONF Monitoring

Abstract

This document defines a Network Configuration Protocol (NETCONF) data model to be used to monitor the NETCONF protocol. The monitoring data model includes information about NETCONF datastores, sessions, locks, and statistics. This data facilitates the management of a NETCONF server. This document also defines methods for NETCONF clients to discover data models supported by a NETCONF server and defines a new NETCONF <get-schema> operation to retrieve them.

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/rfc6022.

Copyright Notice

Copyright (c) 2010 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.

This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.

Introduction

This document defines a YANG RFC6020 model to be used to monitor the NETCONF protocol. It provides information about NETCONF sessions and supported schema as defined in RFC4741.

Considerations such as different schema formats, feature optionality, and access controls can all impact the applicability and level of detail the NETCONF server sends to a client during session setup. The methods defined in this document address the need for further means to query and retrieve schema and NETCONF state information from a NETCONF server. These are provided to complement existing base NETCONF capabilities and operations and in no way affect existing behaviour.

A new <get-schema> operation is also defined to support explicit schema retrieval via NETCONF.

Definition of Terms

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.

Data Model to Monitor NETCONF

The NETCONF monitoring data model defined in this document provides operational information on the NETCONF server. This includes details specific to the NETCONF protocol (e.g., protocol-specific counters such as 'in-sessions') as well as data related to schema retrieval (e.g., schema list).

A server that implements the data model defined in this document ("urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring") MUST advertise the capability URI as described in RFC6020.

This section presents an overview of the monitoring data model. For detailed descriptions, refer to the normative YANG module provided in this document (see Section 5).

The /netconf-state Subtree

The netconf-state container is the root of the monitoring data model.

netconf-state

   /capabilities
   /datastores
   /schemas
   /sessions
   /statistics

capabilities

  List of NETCONF capabilities supported by the server.

datastores

  List of NETCONF configuration datastores (e.g., running, startup,
  candidate) supported on this device and related information.

schemas

  List of schemas supported on the server.  Includes all the
  information required to identify the schemas and to support their
  retrieval.

sessions

  List of all active NETCONF sessions on the device.  Includes per-
  session counters for all NETCONF sessions.

statistics

  Includes global counters for the NETCONF server.

The /netconf-state/capabilities Subtree

The /netconf-state/capabilities subtree contains the capabilities supported by the NETCONF server. The list MUST include all capabilities exchanged during session setup still applicable at the time of the request.

The /netconf-state/datastores Subtree

The /netconf-state/datastores subtree contains the list of available datastores for the NETCONF server and includes information on their lock state.

datastore

   /name
   /locks

name (leaf, netconf-datastore-type)

  Enumeration of supported datastores; candidate, running, startup.

locks (grouping, lock-info)

  List of locks for the datastore.  Information is provided for both
  global and partial locks RFC5717.  For partial locks, the list
  of locked nodes and the select expressions originally used to
  request the lock are returned.

The /netconf-state/schemas Subtree

The list of supported schema for the NETCONF server.

schema

   /identifier   (key)
   /version      (key)
   /format       (key)
   /namespace
   /location

The elements identifier, version, and format are used as a key in the schema list. These are used in the <get-schema> operation.

identifier (string)

  Identifier for the schema list entry.  The identifier is used in
  the <get-schema> operation and may be used for other means such as
  file retrieval.

version (string)

  Version of the schema supported.  Multiple versions MAY be
  supported simultaneously by a NETCONF server.  Each version MUST
  be reported individually in the schema list, i.e., with same
  identifier, possibly different location, but different version.

  For YANG data models, version is the value of the most recent YANG
  'revision' statement in the module or submodule, or the empty
  string if no 'revision' statement is present.

format (identifyref, schema-format)

  The data modeling language the schema is written in.  The data
  modeling language is represented as a YANG identity.  This
  document defines the identities "xsd", "yang", "yin", "rng", and
  "rnc" (see Section 5).

namespace (inet:uri)

  The Extensible Markup Language (XML) namespace [XML-NAMES] defined
  by the schema.

location (union: enum, inet:uri)

  One or more locations from which this specific schema can be
  retrieved.  The list SHOULD contain at least one entry per schema.

The /netconf-state/sessions Subtree

Includes session-specific data for NETCONF management sessions. The session list MUST include all currently active NETCONF sessions.

session

   /session-id (key)
   /transport
   /username
   /source-host
   /login-time
   /in-rpcs
   /in-bad-rpcs
   /out-rpc-errors
   /out-notifications

session-id (uint32, 1..max)

  Unique identifier for the session.  This value is the NETCONF
  session identifier, as defined in RFC4741.

transport (identityref, transport)

  Identifies the transport for each session.  The transport is
  represented as a YANG identity.  This document defines the
  identities "netconf-ssh", "netconf-soap-over-beep", "netconf-soap-
  over-https", "netconf-beep", and "netconf-tls" (see Section 5).

username (string)

  The username is the client identity that was authenticated by the
  NETCONF transport protocol.  The algorithm used to derive the
  username is NETCONF transport protocol specific and in addition
  specific to the authentication mechanism used by the NETCONF
  transport protocol.

source-host (inet:host)

  Host identifier (IP address or name) of the NETCONF client.

login-time (yang:date-and-time)

  Time at the server at which the session was established.

in-rpcs (yang:zero-based-counter32)

  Number of correct <rpc> messages received.

in-bad-rpcs (yang:zero-based-counter32)

  Number of messages received when an <rpc> message was expected,
  that were not correct <rpc> messages.  This includes XML parse
  errors and errors on the rpc layer.

out-rpc-errors (yang:zero-based-counter32)

  Number of <rpc-reply> messages sent that contained an <rpc-error>
  element.

out-notifications (yang:zero-based-counter32)

  Number of <notification> messages sent.

The /netconf-state/statistics Subtree

Statistical data pertaining to the NETCONF server.

statistics

   /netconf-start-time
   /in-bad-hellos
   /in-sessions
   /dropped-sessions
   /in-rpcs
   /in-bad-rpcs
   /out-rpc-errors
   /out-notifications

statistics:

  Contains management-session-related performance data for the
  NETCONF server.

netconf-start-time (yang:date-and-time)

  Date and time at which the management subsystem was started.

in-bad-hellos (yang:zero-based-counter32)

  Number of sessions silently dropped because an invalid <hello>
  message was received.

in-sessions (yang:zero-based-counter32)

  Number of sessions started.

dropped-sessions (yang:zero-based-counter32)

  Number of sessions that were abnormally terminated, e.g., due to
  idle timeout or transport close.

in-rpcs (yang:zero-based-counter32)

  Number of correct <rpc> messages received.

in-bad-rpcs (yang:zero-based-counter32)

  Number of messages received when an <rpc> message was expected,
  which were not correct <rpc> messages.

out-rpc-errors (yang:zero-based-counter32)

  Number of <rpc-reply> messages sent that contained an <rpc-error>
  element.

out-notifications (yang:zero-based-counter32)

  Number of <notification> messages sent.

Schema Specific Operations

The <get-schema> Operation

Description:

  This operation is used to retrieve a schema from the NETCONF
  server.

Parameters:

  identifier (string):
     Identifier for the schema list entry.
     Mandatory parameter.

  version (string):
     Version of the schema requested.
     Optional parameter.

  format (identityref, schema-format):
     The data modeling language of the schema.
     Default value is 'yang' when not specified.
     Optional parameter.

Positive Response:

  The NETCONF server returns the requested schema.

Negative Response:

  If the requested schema does not exist, the <error-tag> is
  'invalid-value'.

  If more than one schema matches the requested parameters, the
  <error-tag> is 'operation-failed', and <error-app-tag> is
  'data-not-unique'.

Examples

Retrieving Schema List via <get> Operation

A NETCONF client retrieves the list of supported schema from a NETCONF server by retrieving the /netconf-state/schemas subtree via a <get> operation.

Available schema for the requesting session are returned in the reply containing the <identifier>, <version>, <format>, and <location> elements.

The response data can be used to determine the available schema and their versions. The schema itself (i.e., schema content) is not returned in the response. The optional <location> element contains a URI, which can be used to retrieve the schema by another protocol such as ftp RFC0959 or http(s) RFC2616 RFC2818, or the special value 'NETCONF', which means that the schema can be retrieved from the device via the <get-schema> operation.

Example:

<rpc message-id="101"

 xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
 <get>
<filter type="subtree">
  <netconf-state xmlns=
  "urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring">
    <schemas/>
  </netconf-state>
</filter>
 </get>

</rpc>

The NETCONF server returns a list of schema available for retrieval.

<rpc-reply message-id="101"

       xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
 
<netconf-state
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring">
  <schemas>
    <schema>
      <identifier>foo</identifier>
      <version>1.0</version>
      <format>xsd</format>
      <namespace>http://example.com/foo</namespace>
      <location>ftp://ftp.example.com/schemas/foo_1.0.xsd</location>
      <location>http://www.example.com/schema/foo_1.0.xsd</location>
      <location>NETCONF</location>
    </schema>
    <schema>
      <identifier>foo</identifier>
      <version>1.1</version>
      <format>xsd</format>
      <namespace>http://example.com/foo</namespace>
      <location>ftp://ftp.example.com/schemas/foo_1.1.xsd</location>
      <location>http://www.example.com/schema/foo_1.1.xsd</location>
      <location>NETCONF</location>
    </schema>
    <schema>
      <identifier>bar</identifier>
      <version>2008-06-01</version>
      <format>yang</format>
      <namespace>http://example.com/bar</namespace>
      <location>
        http://example.com/schema/[email protected]
      </location>
      <location>NETCONF</location>
    </schema>
    <schema>
      <identifier>bar-types</identifier>
      <version>2008-06-01</version>
      <format>yang</format>
      <namespace>http://example.com/bar</namespace>
      <location>
        http://example.com/schema/[email protected]
      </location>
      <location>NETCONF</location>
    </schema>
  </schemas>
</netconf-state>
 

</rpc-reply>

Retrieving Schema Instances

Given the reply in the previous section, the following examples illustrate the retrieval of 'foo', 'bar', and 'bar-types' schema at multiple locations, with multiple formats, and in multiple locations.

 1.  foo,  version 1.0 in xsd format:

   a.  Via FTP using location
       ftp://ftp.example.com/schemas/foo_1.0.xsd

   b.  Via HTTP using location
       http://www.example.com/schema/foo_1.0.xsd

   c.  Via <get-schema> using identifier, version, and
       format parameters.

   <rpc message-id="101"
     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <get-schema
     xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring">
       <identifier>foo</identifier>
       <version>1.0</version>
       <format>xsd</format>
     </get-schema>
   </rpc>

   <rpc-reply message-id="101"
     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     
       <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
       </xs:schema>
     
   </rpc-reply>

 2. bar, version 2008-06-01 in YANG format:

   a.  Via HTTP using location
       http://example.com/schema/[email protected]

   b.  Via <get-schema> using identifier and version
       parameters:

     <rpc message-id="102"
       xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <get-schema
       xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring">
         <identifer>bar</identifer>
         <version>2008-06-01</version>
       </get-schema>
     </rpc>

     <rpc-reply message-id="102"
       xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       
         module bar {
           //default format (yang) returned
           //bar version 2008-06-01 yang module
           //contents here ...
         }
       
     </rpc-reply>

 3. bar-types, version 2008-06-01 in default YANG format:

   a. Via <get-schema> using identifer parameter:

   <rpc message-id="103"
     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <get-schema
     xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring">
       <identifer>bar-types</identifer>
     </get-schema>
   </rpc>

   <rpc-reply message-id="103"
     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     
       module bar-types {
         //default format (yang) returned
         //latest revision returned
         //is version 2008-06-01 yang module
         //contents here ...
       }
     
   </rpc-reply>

NETCONF Monitoring Data Model

The data model described in this memo is defined in the following YANG module.

This YANG module imports typedefs from RFC6021 and references RFC4741, RFC4742, RFC4743, RFC4744, RFC5539, [xmlschema-1], RFC6020, [ISO/IEC19757-2:2008], and RFC5717.

file "[email protected]"

module ietf-netconf-monitoring {

 namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring";
 prefix "ncm";

 import ietf-yang-types { prefix yang; }
 import ietf-inet-types { prefix inet; }

 organization
"IETF NETCONF (Network Configuration) Working Group";

 contact
"WG Web:   <http://tools.ietf.org/wg/netconf/>
 WG List:  <mailto:[email protected]>

 WG Chair: Mehmet Ersue
           <mailto:[email protected]>

 WG Chair: Bert Wijnen
           <mailto:[email protected]>

 Editor:   Mark Scott
           <mailto:[email protected]>

 Editor:   Martin Bjorklund
           <mailto:[email protected]>";

 description
"NETCONF Monitoring Module.
 All elements in this module are read-only.

 Copyright (c) 2010 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 6022; see
 the RFC itself for full legal notices.";

 revision 2010-10-04 {
description
  "Initial revision.";
reference
  "RFC 6022: YANG Module for NETCONF Monitoring";
 }

 typedef netconf-datastore-type {
type enumeration {
  enum running;
  enum candidate;
  enum startup;
}
description
  "Enumeration of possible NETCONF datastore types.";
reference
  "RFC 4741: NETCONF Configuration Protocol";
 }

 identity transport {
description
  "Base identity for NETCONF transport types.";
 }

 identity netconf-ssh {
base transport;
description
  "NETCONF over Secure Shell (SSH).";
reference
  "RFC 4742: Using the NETCONF Configuration Protocol
             over Secure SHell (SSH)";
 }

 identity netconf-soap-over-beep {
base transport;
description
  "NETCONF over Simple Object Access Protocol (SOAP) over
   Blocks Extensible Exchange Protocol (BEEP).";

reference
  "RFC 4743: Using NETCONF over the Simple Object
             Access Protocol (SOAP)";
 }

 identity netconf-soap-over-https {
base transport;
description
  "NETCONF over Simple Object Access Protocol (SOAP)
  over Hypertext Transfer Protocol Secure (HTTPS).";
reference
  "RFC 4743: Using NETCONF over the Simple Object
             Access Protocol (SOAP)";
 }

 identity netconf-beep {
base transport;
description
  "NETCONF over Blocks Extensible Exchange Protocol (BEEP).";
reference
  "RFC 4744: Using the NETCONF Protocol over the
             Blocks Extensible Exchange Protocol (BEEP)";
 }

 identity netconf-tls {
base transport;
description
  "NETCONF over Transport Layer Security (TLS).";
reference
  "RFC 5539: NETCONF over Transport Layer Security (TLS)";
 }

 identity schema-format {
description
  "Base identity for data model schema languages.";
 }

 identity xsd {
base schema-format;
description
  "W3C XML Schema Definition.";
reference
  "W3C REC REC-xmlschema-1-20041028:
     XML Schema Part 1: Structures";
 }

 identity yang {
base schema-format;
description
  "The YANG data modeling language for NETCONF.";
reference
  "RFC 6020:  YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)";
 }

 identity yin {
base schema-format;
description
  "The YIN syntax for YANG.";
reference
  "RFC 6020:  YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)";
 }

 identity rng {
base schema-format;
description
  "Regular Language for XML Next Generation (RELAX NG).";
reference
  "ISO/IEC 19757-2:2008: RELAX NG";
 }

 identity rnc {
base schema-format;
description
  "Relax NG Compact Syntax";
reference
  "ISO/IEC 19757-2:2008: RELAX NG";
 }

 grouping common-counters {
description
  "Counters that exist both per session, and also globally,
   accumulated from all sessions.";

leaf in-rpcs {
  type yang:zero-based-counter32;
  description
    "Number of correct <rpc> messages received.";
}
leaf in-bad-rpcs {
  type yang:zero-based-counter32;

  description
    "Number of messages received when an <rpc> message was expected,
     that were not correct <rpc> messages.  This includes XML parse
     errors and errors on the rpc layer.";
}
leaf out-rpc-errors {
  type yang:zero-based-counter32;
  description
    "Number of <rpc-reply> messages sent that contained an
     <rpc-error> element.";
}
leaf out-notifications {
  type yang:zero-based-counter32;
  description
    "Number of <notification> messages sent.";
}
 }

 container netconf-state {
config false;
description
  "The netconf-state container is the root of the monitoring
   data model.";

container capabilities {
  description
    "Contains the list of NETCONF capabilities supported by the
     server.";

  leaf-list capability {
    type inet:uri;
    description
      "List of NETCONF capabilities supported by the server.";
  }
}

container datastores {
  description
    "Contains the list of NETCONF configuration datastores.";

  list datastore {
    key name;
    description
      "List of NETCONF configuration datastores supported by
       the NETCONF server and related information.";

    leaf name {
      type netconf-datastore-type;

      description
        "Name of the datastore associated with this list entry.";
    }
    container locks {
      presence
        "This container is present only if the datastore
         is locked.";
      description
        "The NETCONF <lock> and <partial-lock> operations allow
         a client to lock specific resources in a datastore.  The
         NETCONF server will prevent changes to the locked
         resources by all sessions except the one that acquired
         the lock(s).

         Monitoring information is provided for each datastore
         entry including details such as the session that acquired
         the lock, the type of lock (global or partial) and the
         list of locked resources.  Multiple locks per datastore
         are supported.";

      grouping lock-info {
        description
          "Lock related parameters, common to both global and
           partial locks.";

        leaf locked-by-session {
          type uint32;
          mandatory true;
          description
            "The session ID of the session that has locked
             this resource.  Both a global lock and a partial
             lock MUST contain the NETCONF session-id.

             If the lock is held by a session that is not managed
             by the NETCONF server (e.g., a CLI session), a session
             id of 0 (zero) is reported.";
          reference
            "RFC 4741: NETCONF Configuration Protocol";
        }
        leaf locked-time {
          type yang:date-and-time;
          mandatory true;
          description
            "The date and time of when the resource was
             locked.";
        }
      }

      choice lock-type {
        description
          "Indicates if a global lock or a set of partial locks
           are set.";

        container global-lock {
          description
            "Present if the global lock is set.";
          uses lock-info;
        }

        list partial-lock {
          key lock-id;
          description
            "List of partial locks.";
          reference
            "RFC 5717: Partial Lock Remote Procedure Call (RPC) for
                       NETCONF";

          leaf lock-id {
            type uint32;
            description
              "This is the lock id returned in the <partial-lock>
               response.";
          }
          uses lock-info;
          leaf-list select {
            type yang:xpath1.0;
            min-elements 1;
            description
              "The xpath expression that was used to request
               the lock.  The select expression indicates the
               original intended scope of the lock.";
          }
          leaf-list locked-node {
            type instance-identifier;
            description
              "The list of instance-identifiers (i.e., the
               locked nodes).

               The scope of the partial lock is defined by the list
               of locked nodes.";
          }
        }
      }
    }
  }
}

container schemas {
  description
    "Contains the list of data model schemas supported by the
     server.";

  list schema {
    key "identifier version format";

    description
      "List of data model schemas supported by the server.";

    leaf identifier {
      type string;
      description
        "Identifier to uniquely reference the schema.  The
         identifier is used in the <get-schema> operation and may
         be used for other purposes such as file retrieval.

         For modeling languages that support or require a data
         model name (e.g., YANG module name) the identifier MUST
         match that name.  For YANG data models, the identifier is
         the name of the module or submodule.  In other cases, an
         identifier such as a filename MAY be used instead.";
    }
    leaf version {
      type string;
      description
        "Version of the schema supported.  Multiple versions MAY be
         supported simultaneously by a NETCONF server.  Each
         version MUST be reported individually in the schema list,
         i.e., with same identifier, possibly different location,
         but different version.

         For YANG data models, version is the value of the most
         recent YANG 'revision' statement in the module or
         submodule, or the empty string if no 'revision' statement
         is present.";
    }
    leaf format {
      type identityref {
        base schema-format;
      }
      description
        "The data modeling language the schema is written
         in (currently xsd, yang, yin, rng, or rnc).

         For YANG data models, 'yang' format MUST be supported and
         'yin' format MAY also be provided.";
    }
    leaf namespace {
      type inet:uri;
      mandatory true;
      description
        "The XML namespace defined by the data model.

         For YANG data models, this is the module's namespace.
         If the list entry describes a submodule, this field
         contains the namespace of the module to which the
         submodule belongs.";
    }
    leaf-list location {
      type union {
        type enumeration {
          enum "NETCONF";
        }
        type inet:uri;
      }
      description
        "One or more locations from which the schema can be
         retrieved.  This list SHOULD contain at least one
         entry per schema.

         A schema entry may be located on a remote file system
         (e.g., reference to file system for ftp retrieval) or
         retrieved directly from a server supporting the
         <get-schema> operation (denoted by the value 'NETCONF').";
    }
  }
}

container sessions {
  description
    "The sessions container includes session-specific data for
     NETCONF management sessions.  The session list MUST include
     all currently active NETCONF sessions.";

  list session {
    key session-id;
    description
      "All NETCONF sessions managed by the NETCONF server
       MUST be reported in this list.";

    leaf session-id {
      type uint32 {
        range "1..max";
      }
      description
        "Unique identifier for the session.  This value is the
         NETCONF session identifier, as defined in RFC 4741.";
      reference
        "RFC 4741: NETCONF Configuration Protocol";
    }
    leaf transport {
      type identityref {
        base transport;
      }
      mandatory true;
      description
        "Identifies the transport for each session, e.g.,
        'netconf-ssh', 'netconf-soap', etc.";
    }
    leaf username  {
      type string;
      mandatory true;
      description
        "The username is the client identity that was authenticated
        by the NETCONF transport protocol.  The algorithm used to
        derive the username is NETCONF transport protocol specific
        and in addition specific to the authentication mechanism
        used by the NETCONF transport protocol.";
    }
    leaf source-host {
      type inet:host;
      description
        "Host identifier of the NETCONF client.  The value
         returned is implementation specific (e.g., hostname,
         IPv4 address, IPv6 address)";
    }

    leaf login-time {
      type yang:date-and-time;
      mandatory true;
      description
        "Time at the server at which the session was established.";
    }
    uses common-counters {
      description
        "Per-session counters.  Zero based with following reset
         behaviour:
           - at start of a session
           - when max value is reached";
    }
  }
}

container statistics {
  description
    "Statistical data pertaining to the NETCONF server.";

  leaf netconf-start-time {
    type yang:date-and-time;
    description
      "Date and time at which the management subsystem was
       started.";
  }
  leaf in-bad-hellos {
    type yang:zero-based-counter32;
    description
      "Number of sessions silently dropped because an
      invalid <hello> message was received.  This includes <hello>
      messages with a 'session-id' attribute, bad namespace, and
      bad capability declarations.";
  }
  leaf in-sessions {
    type yang:zero-based-counter32;
    description
      "Number of sessions started.  This counter is incremented
       when a <hello> message with a <session-id> is sent.

      'in-sessions' - 'in-bad-hellos' =
          'number of correctly started netconf sessions'";
  }
  leaf dropped-sessions {
    type yang:zero-based-counter32;

    description
      "Number of sessions that were abnormally terminated, e.g.,
       due to idle timeout or transport close.  This counter is not
       incremented when a session is properly closed by a
       <close-session> operation, or killed by a <kill-session>
       operation.";
  }
  uses common-counters {
    description
      "Global counters, accumulated from all sessions.
       Zero based with following reset behaviour:
         - re-initialization of NETCONF server
         - when max value is reached";
  }
}
 }

 rpc get-schema {
description
  "This operation is used to retrieve a schema from the
   NETCONF server.

   Positive Response:
     The NETCONF server returns the requested schema.

   Negative Response:
     If requested schema does not exist, the <error-tag> is
     'invalid-value'.

     If more than one schema matches the requested parameters, the
     <error-tag> is 'operation-failed', and <error-app-tag> is
     'data-not-unique'.";

input {
  leaf identifier {
    type string;
    mandatory true;
    description
      "Identifier for the schema list entry.";
  }
  leaf version {
    type string;
    description
      "Version of the schema requested.  If this parameter is not
       present, and more than one version of the schema exists on
       the server, a 'data-not-unique' error is returned, as
       described above.";
  }

  leaf format {
    type identityref {
      base schema-format;
    }
    description
       "The data modeling language of the schema.  If this
        parameter is not present, and more than one formats of
        the schema exists on the server, a 'data-not-unique' error
        is returned, as described above.";
  }
}
output {
    anyxml data {
      description
        "Contains the schema content.";
  }
}
 }

}

Security Considerations

The YANG module defined in this memo is designed to be accessed via the NETCONF protocol RFC4741. The lowest NETCONF layer is the secure transport layer and the mandatory to implement secure transport is SSH RFC4742.

Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes.

These are the containers, list nodes, and data nodes with their specific sensitivity/vulnerability:

/netconf-state/sessions/session/username: Contains identity

  information that could be used in an attempt to authenticate with
  the server.

  This username is only meant for monitoring, and SHOULD NOT be used
  for other purposes, such as access control, without a detailed
  discussion of the limitations of this reported username.  For
  example, it is possible that server A and server B might report
  the same username, but these might be for different persons.

Acknowledgements

The authors would like to thank Andy Bierman, Mehmet Ersue, Washam Fan, David Harrington, Balazs Lengyel, Hideki Okita, Juergen Schoenwaelder, Bert Wijnen, and many other members of the NETCONF WG for providing important input to this document. The authors would also like to specifically acknowledge Sharon Chisholm's work on "NETCONF Monitoring Schema" [NETCONF] and contribution to this document.

IANA Considerations

This document registers one URI in "The IETF XML Registry". Following the format in RFC3688, the following has been registered.

 URI: urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring
 Registrant Contact: The IESG.
 XML: N/A, the requested URI is an XML namespace.

This document registers one module in the "YANG Module Names" registry. Following the format in RFC6020, the following has been registered.

 name: ietf-netconf-monitoring
 namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring
 prefix: ncm
 reference: RFC 6022

References

Normative References

[ISO/IEC19757-2:2008]

          ISO/IEC, "Document Schema Definition Language (DSDL) --
          Part 2: Regular-grammar-based validation -- RELAX NG",
          December 2008, <http://www.iso.org/iso/
          catalogue_detail.htm?csnumber=37605>.

RFC2119 Bradner, S., "Key words for use in RFCs to Indicate

          Requirement Levels", BCP 14, RFC 2119, March 1997.

RFC4741 Enns, R., "NETCONF Configuration Protocol", RFC 4741,

          December 2006.

RFC4742 Wasserman, M. and T. Goddard, "Using the NETCONF

          Configuration Protocol over Secure SHell (SSH)", RFC 4742,
          December 2006.

RFC4743 Goddard, T., "Using NETCONF over the Simple Object Access

          Protocol (SOAP)", RFC 4743, December 2006.

RFC4744 Lear, E. and K. Crozier, "Using the NETCONF Protocol over

          the Blocks Extensible Exchange Protocol (BEEP)", RFC 4744,
          December 2006.

RFC5539 Badra, M., "NETCONF over Transport Layer Security (TLS)",

          RFC 5539, May 2009.

RFC5717 Lengyel, B. and M. Bjorklund, "Partial Lock Remote

          Procedure Call (RPC) for NETCONF", RFC 5717,
          December 2009.

RFC6020 Bjorklund, M., Ed., "YANG - A Data Modeling Language for

          the Network Configuration Protocol (NETCONF)",
          October 2010.

RFC6021 Schoenwaelder, J., Ed., "Common YANG Data Types",

          October 2010.

[XML-NAMES]

          Hollander, D., Tobin, R., Thompson, H., Bray, T., and A.
          Layman, "Namespaces in XML 1.0 (Third Edition)", World
          Wide Web Consortium Recommendation REC-xml-names-20091208,
          December 2009,
          <http://www.w3.org/TR/2009/REC-xml-names-20091208>.

[xmlschema-1]

          Biron, Paul V. and Ashok. Malhotra, "XML Schema Part 1:
          Structures Second Edition W3C Recommendation 28 October
          2004", October 2004, <http://www.w3.org/TR/xmlschema-1>.

Informative References

          [NETCONF]  Chisholm, S. and H. Trevino, "NETCONF
          Monitoring Schema", Work in Progress, February 2007.

RFC0959 Postel, J. and J. Reynolds, "File Transfer Protocol",

          STD 9, RFC 959, October 1985.

RFC2616 Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,

          Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
          Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

RFC2818 Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

RFC3688 Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,

          January 2004.

Authors' Addresses

Mark Scott Ericsson 3500 Carling Ave Nepean, Ontario K2H 8E9 Canada

EMail: [email protected]

Martin Bjorklund Tail-f Systems Klara Norra Kyrkogata 31 SE-111 22 Stockholm, Sweden

EMail: [email protected]