Network Working Group                                        S. Chisholm
Internet-Draft                                                 K. Curran
Expires: October 30, December 23, 2006                                        Nortel
                                                              H. Trevino
                                                                   Cisco
                                                          April 28,
                                                           June 21, 2006

                      NETCONF Event Notifications
                 draft-ietf-netconf-notification-01.txt
                 draft-ietf-netconf-notification-02.txt

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Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This memo defines a framework for sending asynchronous messages, or
   event notifications in NETCONF.  It defines both the operations
   necessary to support this concept, and also discusses implications
   for the mapping to application transport protocols.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1   Definition of Terms  . . . . . . . . . . . . . . . . . . .  4
     1.2   Event Notifications in NETCONF . . . . . . . . . . . . . .  5
     1.3   Motivation . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.4   Requirements . . . . . . . . . . . . . . . . . . . . . . .  5
     1.5   Architecture . . . . . . . . . . . . . . . . . . . . . . .  7
   2.  Event-Related Operations . . . . . . . . . . . . . . . . . . .  6  8
     2.1   Subscribing to receive Events  . . . . . . . . . . . . . .  6  8
       2.1.1   create-subscription  . . . . . . . . . . . . . . . . .  6  8
     2.2   Sending Event Notifications  . . . . . . . . . . . . . . .  7  9
       2.2.1   Event Notification . . . . . . . . . . . . . . . . . .  7  9
     2.3   Changing the Subscription  . . . . . . . . . . . . . . . .  8 10
       2.3.1   modify-subscription  . . . . . . . . . . . . . . . . .  9 10
     2.4   Terminating the Subscription . . . . . . . . . . . . . . . 10 11
       2.4.1   cancel-subscription  . . . . . . . . . . . . . . . . . 10 12
   3.  Supporting Concepts  . . . . . . . . . . . . . . . . . . . . . 11 13
     3.1   Capabilities Exchange  . . . . . . . . . . . . . . . . . . 11 13
     3.2   Subscriptions and Datastores . . . . . . . . . . . . . . . 13
     3.3   Querying Subscription Properties . . . . . . . . . . . . . 11
     3.3 13
     3.4   One-way Notification Messages  . . . . . . . . . . . . . . 16
     3.4 18
     3.5   Filter Dependencies  . . . . . . . . . . . . . . . . . . . 16
       3.4.1 19
       3.5.1   Named Profiles . . . . . . . . . . . . . . . . . . . . 17
       3.4.2 19
       3.5.2   Filtering  . . . . . . . . . . . . . . . . . . . . . . 17
     3.5 19
     3.6   Event Classes  . . . . . . . . . . . . . . . . . . . . . . 17
     3.6 19
       3.6.1   Initial Set of Event Classes . . . . . . . . . . . . . 20
     3.7   Defining Event Notifications . . . . . . . . . . . . . . . 18
     3.7 21
     3.8   Interleaving Messages  . . . . . . . . . . . . . . . . . . 18 21
   4.  XML Schema for Event Notifications . . . . . . . . . . . . . . 20 23
   5.  Mapping to Application Transport Protocols . . . . . . . . . . . . . . . 24 . 27
     5.1   SSH  . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 27
     5.2   BEEP . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 28
       5.2.1   One-way Notification Messages in Beep  . . . . . . . . 25 28
     5.3   SOAP . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 29
       5.3.1   A NETCONF over Soap over HTTP Example  . . . . . . . . 26 29
   6.  Filtering examples . . . . . . . . . . . . . . . . . . . . . . 29 32
     6.1   Event Classes  . . . . . . . . . . . . . . . . . . . . . . 29 32
     6.2   Subtree Filtering  . . . . . . . . . . . . . . . . . . . . 29 32
     6.3   XPATH filters  . . . . . . . . . . . . . . . . . . . . . . 31 34
   7.  Additional Capabilities  . . . . . . . . . . . . . . . . . . . 33 36
     7.1   Call-Home Notifications  . . . . . . . . . . . . . . . . . 33 36
       7.1.1   Overview . . . . . . . . . . . . . . . . . . . . . . . 33 36
       7.1.2   Dependencies . . . . . . . . . . . . . . . . . . . . . 34 37
       7.1.3   Capability Identifier  . . . . . . . . . . . . . . . . 34 37
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 37 41
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 38 42
   10.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 39 43
   11.   References . . . . . . . . . . . . . . . . . . . . . . . . . 39 43
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 40 44
   A.  Design Alternatives  . . . . . . . . . . . . . . . . . . . . . 41 45
     A.1   Suspend And Resume . . . . . . . . . . . . . . . . . . . . 41 45
     A.2   Lifecycle  . . . . . . . . . . . . . . . . . . . . . . . . 41 45
   B.  Event Notifications and Syslog . . . . . . . . . . . . . . . . 42 46
     B.1   Leveraging Syslog Field Definitions  . . . . . . . . . . . 42 46
       B.1.1   Field Mapping  . . . . . . . . . . . . . . . . . . . . 43 47
       B.1.2   Severity Mapping . . . . . . . . . . . . . . . . . . . 44 48
     B.2   Syslog within NETCONF Events . . . . . . . . . . . . . . . 44 48
       B.2.1   Motivation . . . . . . . . . . . . . . . . . . . . . . 44 48
       B.2.2   Embedding syslog messages in a NETCONF Event . . . . . 44 48
       B.2.3   Supported Forwarding Options . . . . . . . . . . . . . 45 49
   C.  Example Configuration Notifications  . . . . . . . . . . . . . 47 51
     C.1   Types of Configuration Events  . . . . . . . . . . . . . . 47 51
     C.2   Config Event Notification Structure  . . . . . . . . . . . 48 52
     C.3   Configuration Event Content  . . . . . . . . . . . . . . . 50 54
       C.3.1   Target Datastore . . . . . . . . . . . . . . . . . . . 50 54
       C.3.2   User Info  . . . . . . . . . . . . . . . . . . . . . . 50 54
       C.3.3   Data Source  . . . . . . . . . . . . . . . . . . . . . 50 54
       C.3.4   Operation  . . . . . . . . . . . . . . . . . . . . . . 50 54
       C.3.5   Context  . . . . . . . . . . . . . . . . . . . . . . . 50 54
       C.3.6   Entered Command  . . . . . . . . . . . . . . . . . . . 51 55
       C.3.7   New Config . . . . . . . . . . . . . . . . . . . . . . 51 55
       C.3.8   Old Config . . . . . . . . . . . . . . . . . . . . . . 51 55
       C.3.9   Non-netconf commands in configuration notifications  . 51 55
   D.  IP Address Schema  . . . . . . . . . . . . . . . . . . . . . . 56
       Intellectual Property and Copyright Statements . . . . . . . . 52 58

1.  Introduction

   NETCONF [NETCONF-PROTO] can be conceptually partitioned into four
   layers:

   Layer                      Example
    +-------------+      +----------------------------------------+
    |   Content   |      |     Configuration data                 |
    +-------------+      +----------------------------------------+
              |                           |
    +-------------+      +-------------------------------------------+
    | Operations  |      | <get-config>, <edit-config> <notification>|
    +-------------+      +-------------------------------------------+
              |                           |                    |
    +-------------+      +-----------------------------+       |
    |     RPC     |      |    <rpc>, <rpc-reply>       |       |
    +-------------+      +-----------------------------+       |
             |                           |                     |
    +-------------+      +------------------------------------------+
    | Application |      |   BEEP, SSH, SSL, console                |
    |   Protocol  |      |                                          |
    +-------------+      +------------------------------------------+

   This document defines a framework for sending asynchronous messages,
   or event notifications in NETCONF.  It defines both the operations
   necessary to support this concept, and also discusses implications
   for the mapping to application transport protocols.

                                 Figure 1

1.1  Definition of Terms

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [3].

   Element: An XML Element[XML].

   Managed Entity: A node, which supports NETCONF[NETCONF] NETCONF[NETCONF-PROTO] and has
      access to management instrumentation.  This is also known as the
      NETCONF server.

   Managed Object: A collection of one of more Elements that define an
      abstract thing of interest.

1.2  Event Notifications in NETCONF

   An event is something that happens which may be of interest - a
   configuration change, a fault, a change in status, crossing a
   threshold, or an external input to the system, for example.  Often
   this results in an asynchronous message, sometimes referred to as a
   notification or event notification, being sent out to interested
   parties to notify them that this event has occurred.

   This memo defines a mechanism whereby the NETCONF client indicates
   interest in receiving event notifications from a NETCONF server by
   creating a subscription to receive event notifications.  The NETCONF
   server replies to indicate whether the subscription request was
   successful and, if it was successful, begins sending the event
   notifications to the NETCONF client as the events occur within the
   system.  These event notifications will continue to be sent until
   either the NETCONF session is terminated or an explicit command to
   cancel the subscription is sent.  The event notification subscription
   allows a number of options to enable the NETCONF client to specify
   which events are of interest.  These are specified when the
   subscription is created, but can be modified later using a modify
   subscription command.

2.  Event-Related Operations

2.1  Subscribing to receive Events

1.3  Motivation

   The event notification subscription motivation for this work is initiated by the NETCONF
   client and responded to by the NETCONF server.  When the event
   notification subscription is created, enable the events sending of interest asynchronous
   messages that are consistent with the data model (content) and
   security model used within a Netconf implementation.

1.4  Requirements

   The requirements for this solution are as follows:

   o  Initial release should ensure it supports notification in support
      of configuration operations

   o  Data content must be use the same data model as used in
      configuration

   o  solution should support structured hierarchical data

   o  solution should be able to carry configuration fragments

   o  solution should support a reasonable message size limit (syslog
      and SNMP are rather constrained in terms of message sizes)

   o  solution should provide reliable delivery of notifications
   o  solution should support preconfigured notification destinations

   o  solution should support agent initiated connections

   o  solution should provide a subscription mechanism

   o  solution should support multiple subscriptions

   o  solution should provide a filtering mechanism

   o  solution should support notification names

   o  solution should support notification timestamps

   o  solution should support notification classes

   o  solution should support notification info

   o  solution should provide the ability to specify the content of
      notifications to ensure predictability

   o  solution should send sufficient information in a notification so
      that it can be analyzed independent of the transport mechanism

   o  solution should allow notifications to refer to prior
      configuration change RPCs

   o  solution should not bind subscriptions to a connection

   o  channels for configuration change notifications should share fate
      with a session that includes a configuration channel

   o  solution should support replay of locally logged notifications

   o  solution should support message chunking capability in cases
      channels carry mixed RPCs

   o  solution should scale to 30.000-100.000 nodes which may emit
      notifications

   o  solution should scale to order 30.000-100.000 nodes to send
      notifications [BL]

   See also the external website tracking requirements at
   http://www.eecs.iu-bremen.de/wiki/index.php/Netconf_notifications

1.5  Architecture

   [Editor's Note: add pointers to the various architecture discussions
   in the document and identify what people view to be gaps in
   architecture discussion.  The following may not be what people were
   looking for in this section, but should at least give people
   something to discuss]

   The following figure illustrates that the netconf implementation
   leverages protocol-neutral event management software within the box
   rather then re-invent everything in Netconf specific methods.  The
   netconf client understands which notifications are of interest to it
   and creates a subscription that meets its requirements.  The network
   elements accepts the subscription requests and creates a temporary
   subscription to meet those needs.

   ----------------------------------------------
   | Network Element                            |
   |  ------------                              |
   | | Alarm      |                             |
   | | Management |          --------------     |        --------------
   |  ------------     |--->|Netconf Stack |<---------->| Netconf      |
   |       |           |    |              |    |       |              |
   |       |           |     --------------     |   --->|    Client    |
   |       V           |                        |   |    --------------
   |  ------------     |                        |   |
   | | Event      |--->|    ------------------  |   |
   | | Management |    |    |Other Protocols |  |   |
   |  ------------     |--->|                |  |   |
   |                        ------------------  |   |
   |---------------------------------------------   |
                                                    |
   ----------------------------------------------   |
   | Network Element                            |   |
   |  ------------                              |   |
   | | Alarm      |                             |   |
   | | Management |          --------------     |   |
   |  ------------     |--->|Netconf Stack |<-------|
   |       |           |    |              |    |
   |       |           |     --------------     |
   |       V           |                        |
   |  ------------     |                        |
   | | Event      |--->|    ------------------  |
   | | Management |    |    |Other Protocols |  |
   |  ------------     |--->|                |  |
   |                        ------------------  |
   |--------------------------------------------

2.  Event-Related Operations

2.1  Subscribing to receive Events

   The event notification subscription is initiated by the NETCONF
   client and responded to by the NETCONF server.  When the event
   notification subscription is created, the events of interest are
   specified.

   It is possible to create more than one event notification
   subscription on a single underlying connection.  Each event
   notification subscription therefore has its own unique identifier.

   Content for an event notification subscription can be selected by
   specifying which event classes are of interest and /or by applying
   user-specified filters.

2.1.1  create-subscription

   <create-subscription>

   Description:

      This command operation initiates an event notification subscription which
      will send asynchronous event notifications to the initiator of the
      command until the  <cancel-subscription >  command is sent.

   Parameters:

      Event Classes:

         An optional parameter that indicates which event classes are of
         interest.  If not present, events of all classes will be sent.

      Filter:

         An optional parameter that indicates which subset of all
         possible events are of interest.  The format of this parameter
         is the same as that of the filter parameter in the NETCONF
         protocol operations.  If not present, all events not precluded
         by other parameters will be sent.  These filter parameters can
         only be modified using the modify-subscription command.

      Named Profile
         An optional parameter that points to a separately defined
         filter profile.  The contents of the profile are specified in
         the provided XML Schema.  If not present, no additional
         filtering will be applied.  If the separate definition of these
         filters is updated, then these changes  If not present, no additional
         filtering will be reflected in applied.  Note that changes to the
         filtered events on this subscription. profile
         after the subscription has been created will have no effect
         unless a modify subscription command is issued.

   Positive Response:

      If the NETCONF server can satisfy the request, the server sends an
      <rpc-reply>  element containing a <data> element containing the
      subscription ID.

   Negative Response:

      An  <rpc-error> element is included within the <rpc-reply>  if the
      request cannot be completed for any reason.  Subscription requests
      will fail if a filter with invalid syntax is provided or if the
      name of a non-existent profile is provided.

2.2  Sending Event Notifications

   Once the subscription has been set up, the NETCONF server sends the
   event notifications asynchronously along the connection.
   Notifications are tagged with event classes, subscription ID,
   sequence number, and date and time.

2.2.1  Event Notification

   <notification>

   Description:

      An event notification is sent to the initiator of an <create-
      subscription>  command asynchronously when an event of interest
      (i.e. meeting the specified filtering criteria) to them has
      occurred.  An event notification is a complete XML document.

   Parameters:

      Event Classes:

         The event class or classes associated with this event
         notification
      Subscription Id:

         A unique identifier for this event subscription

      Sequence Number:

         A sequentially increasing number to uniquely identify event
         notifications for this subscription.  It starts at 0, always
         increases by just one and rolls back to 0 after its maximum
         value is reached.

      Date and Time:

         The date and time that the event notification was sent by the
         NETCONF server.

      Data:

         Contains event class and notification-specific tagged content.

   Positive Response:

      No response.

   Negative Response:

      No response.

2.2.1.1  Event Notification

   The NETCONF Event notification structure is shown in the following
   figure.

   ___________________________________________________________________
   || Notification Header                                      || Data |
   ||__________________________________________________________||______|
   || subscriptionId| eventClasses| sequenceNumber| dateAndTime||      |
   ||_______________|_____________|_______________|____________||______|

2.3  Changing the Subscription

   After an event notification subscription has been established, the
   NETCONF client can initiate a request to change properties of the
   event notification subscription.  This prevents loss of event
   notifications that might otherwise occur during a cancelling and
   recreation of the event notification subscription.  This command operation is
   responded to by the NETCONF server

2.3.1  modify-subscription

   <modify-subscription>

   Description:

      Change properties of the event notification subscription.

   Parameters:

      Subscription Id:

         A unique identifier for this event subscription.

      Event Classes:

         An optional parameter that indicates which Event Classes are of
         interest.  If not present, events of all classes will be sent.

      Filter:

         An optional parameter that indicates which subset of all
         possible events that are of interest.  The format is the same
         filter used for other NETCONF commands.  If not present,  all
         events not precluded by other parameters will be sent.  These
         filter parameters can only be modified using the modify-
         subscription command.

      Named Profile:

         An optional parameter that points to separately defined filter
         profile.  The contents of the profile are specified in provided
         XML Schema.  If not present, no additional filtering will be
         applied.  If the separate definition of these filters is
         updated, then these  Note that changes will be reflected in to the events
         seen on this subscription. profile after the
         subscription has been created will have no effect unless a
         modify subscription command is issued.

   Positive Response:

      If the NETCONF server was able to satisfy the request, an <rpc-
      reply> is sent that includes an  <ok>  element.

   Negative Response:

      An <rpc-error> element is included within the <rpc-reply> if the
      request cannot be completed for any reason.  Subscription requests
      will fail if a filter with invalid syntax is provided or if the
      name of a non-existent profile is provided.

2.4  Terminating the Subscription

   Closing of the event notification subscription is initiated by the
   NETCONF client.  The specific subscription to be closed is specified
   using a subscription ID.  The NETCONF server responds.  Note that the
   NETCONF session may also be torn down for other reasons and this will
   also result in the subscription being cancelled, but is not subjected
   to the behaviour of this command. operation.

2.4.1  cancel-subscription

   <cancel-subscription>

   Description:

      Stop and delete  the event notification subscription.

   Parameters:

      Subscription Id:

         A unique identifier for this event notification subscription.

   Positive Response:

      If the NETCONF server was able to satisfy the request, an <rpc-
      reply> is sent that includes an <ok> element.

   Negative Response:

      An <rpc-error> element is included within the <rpc-reply> if the
      request cannot be completed for any reason.

3.  Supporting Concepts

3.1  Capabilities Exchange

   The ability to process and send event notifications is advertised
   during the capability exchange between the NETCONF client and server.

   "urn:ietf:params:xml:ns:netconf:notification:1.0"

   For Example

      <hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
        <capabilities>
          <capability>
            urn:ietf:params:xml:ns:netconf:base:1.0
          </capability>
          <capability>
            urn:ietf:params:xml:ns:netconf:capability:startup:1.0
          </capability>
          <capability>
            urn:ietf:params:xml:ns:netconf:notification:1.0
          </capability>
        </capabilities>
        <session-id>4</session-id>
      </hello>

3.2  Subscriptions and Datastores

   Subscriptions are like Netconf sessions in that they don't exist
   Netconf datastores.  The two exceptions to this are named profiles
   and the optional call-home notification feature.

3.3  Querying Subscription Properties

   The following Schema can be used to retrieve information about active
   event notification subscriptions

    <xs:schema
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       xmlns:nsub="urn:ietf:params:xml:ns:netconf:subscription:1.0"
      targetNamespace= "urn:ietf:params:xml:ns:netconf:subscription:1.0"
      xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"
      xmlns:ncEvent= "urn:ietf:params:xml:ns:netconf:notification:1.0"
     xmlns:nm="urn:ietf:params:xml:ns:netconf:appInfo:1.0"
     elementFormDefault="qualified" attributeFormDefault="unqualified"
             xml:lang="en">
        <xs:annotation>
                       <xs:documentation xml:lang="en">
                     Schema for reporting on Event Subscriptions
         </xs:documentation>
         <xs:appinfo>
           <nm:identity
               xmlns:nm="urn:ietf:params:xml:ns:netmod:base:1.0">
               <nm:Name>NetConfStateSchema</nm:Name>
               <nm:Name>NetconfNotificationSchema</nm:Name>
               <nm:LastUpdated>2006-04-30T09:30:47-05:00
               </nm:LastUpdated>
               <nm:Organization>IETF</nm:Organization>
               <nm:Description>
                  A schema that can be used to learn about current
                  NetConf Event subscriptions and creating named
                  profiles
               </nm:Description>
             </nm:identity>
           </xs:appinfo>
              </xs:annotation>

       <xs:import namespace="http://www.w3.org/XML/1998/namespace"
                  schemaLocation="http://www.w3.org/2001/xml.xsd"/>
       <xs:import
            namespace="urn:ietf:params:xml:ns:netconf:notifications:1.0"
            schemaLocation="draft-ietf-netconf-notification-01.xsd"/>
       <xs:import namespace="urn:ietf:params:xml:ns:netconf:base:1.0"
                   schemaLocation="draft-ietf-netconf-prot-12.xsd"/>

      <xs:element name="netconfSubscription">
        <xs:annotation>
            <xs:appinfo>
              <nm:minAccess><read/></nm:minAccess>
              <nm:maxAccess><read/></nm:maxAccess>
            </xs:appinfo>
        </xs:annotation>
        <xs:complexType>
        <xs:sequence maxOccurs="unbounded">

          <xs:element name="session-id"
                            type="netconf:SessionId" >
            <xs:annotation>
              <xs:documentation xml:lang="en">
              The session id associated with this subscription.
              </xs:documentation>
           </xs:annotation>
          </xs:element>

                 <xs:element name="subscriptionID"
                            type="ncEvent:SubscriptionID" >
            <xs:annotation>
              <xs:documentation xml:lang="en">
              The subscription id associated with this subscription.
              </xs:documentation>
           </xs:annotation>
          </xs:element>

          <xs:element name="eventClasses">
            <xs:annotation>
              <xs:documentation xml:lang="en">
              The event classes associated with this subscription.
              </xs:documentation>
           </xs:annotation>
           <xs:complexType>
             <xs:sequence minOccurs="0" maxOccurs="unbounded">
               <xs:element ref="ncEvent:EventClass"/>
             </xs:sequence>
           </xs:complexType>
          </xs:element>

            <xs:element name="filter"
                       type="netconf:filterInlineType"  minOccurs="0">
            <xs:annotation>
              <xs:documentation xml:lang="en">
              The filters associated with this subscription.
              </xs:documentation>
           </xs:annotation>
          </xs:element>

          <xs:element name="namedProfile"
                type="xs:string" minOccurs="0">
                         <xs:annotation>
              <xs:documentation xml:lang="en">
              The named profile associated with this subscription. Note
               that the  contents of the named profile may have changed
             since it was last applied.
              </xs:documentation>
                         </xs:annotation>
              <xs:keyref name="namedProfileKeyRef"
                         refer="nsub:namedProfileKey">
                <xs:selector xpath=".//namedProfile"/>
                <xs:field xpath="namedProfile"/>
              </xs:keyref>
          </xs:element>
          <xs:element name="lastModified"
                type="xs:dateTime" >
                         <xs:annotation>
              <xs:documentation xml:lang="en">
              The last time this subscription was modified. If it has
              not been modified since creation, this is the time of
             subscription creation.
              </xs:documentation>
           </xs:annotation>
           </xs:element>

           <xs:element name="messagesSent"
                type="xs:integer" minOccurs="0">
                         <xs:annotation>
              <xs:documentation xml:lang="en">
              A count of event notifications sent along this connection
              since the subscription was created.
              </xs:documentation>
           </xs:annotation>
           </xs:element>

           <xs:element name="lastSequenceNumber"
                type="xs:integer" minOccurs="0">
                         <xs:annotation>
              <xs:documentation xml:lang="en">
              The sequence number of the last event notification sent to
               this subscription
              </xs:documentation>
           </xs:annotation>
           </xs:element>
          <xs:element name="key">
            <xs:key name="uniqueSubscription">
              <xs:selector xpath=".//subscription"/>
              <xs:field xpath="session-id"/>
              <xs:field xpath="subscriptionID"/>
            </xs:key>
          </xs:element>
         </xs:sequence>
         </xs:complexType>
         </xs:element>

     <xs:element name="netconfSubscriptions">
       <xs:complexType>
       <xs:sequence>
         <xs:element ref="nsub:netconfSubscription" minOccurs="0"
                                 maxOccurs="unbounded" />
         </xs:sequence>
       </xs:complexType>
     </xs:element>

      <xs:element name="namedProfile">
        <xs:annotation>
          <xs:appinfo>
            <nm:minAccess><read/></nm:minAccess>
            <nm:maxAccess><read/> <write/> <create/> <delete/>
             </nm:maxAccess>
          </xs:appinfo>
        </xs:annotation>
        <xs:complexType>
            <xs:sequence>
              <xs:element name="name"/>
              <xs:element name="eventClasses">
                <xs:annotation>
                  <xs:documentation xml:lang="en">
                    The event classes associated with this named
                     Profile.
                  </xs:documentation>
                </xs:annotation>
                <xs:complexType>
                  <xs:sequence minOccurs="0" maxOccurs="unbounded">
                    <xs:element ref="ncEvent:EventClass"/>
                  </xs:sequence>
                </xs:complexType>
              </xs:element>

              <xs:element name="filter"
                type="netconf:filterInlineType"  minOccurs="0">
                <xs:annotation>
                  <xs:documentation xml:lang="en">
                    The filters associated with this named Profile.
                  </xs:documentation>
                </xs:annotation>
              </xs:element>

              <xs:element name="lastModified" type="xs:dateTime">
                <xs:annotation>
                  <xs:documentation>
                    The timestamp of the last modification to this
                     named Profile. Note that modification of the
                     profile does not cause an immediate update
                     to all applicable subscription. Therefore, this
                     time should be compared with the last
                     modified time associated with the subscription.
                     If this time is earlier, then the subscription
                      is using the exact set of parameters associated
                      with this named profile.  If this time is
                     later, then the subscription is using an earlier
                     version of this named profile and the exact
                     parameters may not match.
                  </xs:documentation>
                  <xs:appinfo>
                    <nm:minAccess><read/></nm:minAccess>
                    <nm:maxAccess><read/> </nm:maxAccess>
                  </xs:appinfo>
                </xs:annotation>
              </xs:element>

              <xs:element name="key">
                  <xs:key name="namedProfileKey">
                    <xs:selector xpath="*/name" />
                    <xs:field xpath="name" />
                  </xs:key>
              </xs:element>
            </xs:sequence>
        </xs:complexType>
      </xs:element>

      <xs:element name="namedProfiles">
         <xs:complexType>
          <xs:sequence>
            <xs:element ref="nsub:namedProfile" minOccurs="0"
                                  maxOccurs="unbounded" />
          </xs:sequence>
           </xs:complexType>
       </xs:element>
       </xs:schema>

3.3

3.4  One-way Notification Messages

   In order to support the concept that each individual event
   notification is a well-defined XML-document that can be processed
   without waiting for all events to come in, it makes sense to define
   events, not as an endless reply to a subscription command, but as
   independent messages that originate from the NETCONF server.  In
   order to support this model, this memo introduces the concept of
   notifications, which are one-way  messages.

   A one-way  message is similar to the two-way RPC message, except that
   no response is expected to the command.  In the case of event
   notification, this message will originate from the NETCONF server,
   and not the NETCONF client.

3.4

3.5  Filter Dependencies

   Note that when multiple filters are specified (Event Class, in-line
   Filter, Named Profiles), they are applied collectively, so event
   notifications needs to pass all specified filters in order to be sent
   to the subscriber.  If a filter is specified to look for data of a
   particular value, and the data item is not present within a
   particular event  notification for its value to be checked against,
   it will be filtered out.  For example, if one were to check for
   'severity=critical' in a configuration event notification where this
   field was not supported, then the notification would be filtered out.

3.4.1

3.5.1  Named Profiles

   A named profile is a filter that is created ahead of time and applied
   at the time an event notification subscription is created or
   modified.  Note that changes to the profile after the subscription
   has been created will have no effect unless a modify subscription
   command is issued.  Since named profiles exist outside of the
   subscription, they persist after the subscription has been cancelled.

3.4.2

3.5.2  Filtering

   Just-in-time filtering is explicitly stated when the event
   notification subscription is created.  These filters can only be
   changed using the modify subscription command.  This is specified via
   the Filter parameter.  Filters only exist as parameters to the
   subscription.

3.5

3.6  Event Classes

   Events can be broadly classified into one more event classes.  Each event
   class identifies a set of event notifications which

      share
   important characteristics, such being similar content

      are generated from similar events

   The initial set of event classes is configuration, fault, state,
   audit, data, maintenance, metrics, security, information, heartbeat
   and syslogTunnel.  See the IANA Considerations section for
   information on defining new event classes.

   All events shall carry the following data: list of event class,
   timestamp and sequence number of the notification.  They may also
   carry additional data.

    ___________________________________________________________________
   || Notification Header                                      || Data |
   ||__________________________________________________________||______|
   || subscriptionId| eventClasses| sequenceNumber| dateAndTime||      |
   ||_______________|_____________|_______________|____________||______|

3.6.1  Initial Set of Event Classes

   A configuration event, alternatively known as an inventory event, is
   used to indicate that hardware, software, or a service has been
   added,  changed or removed.  In keeping aligned with NETCONF protocol
   operations,  configuration events may included copy configuration
   event, delete configuration event, or sharing much of the same content.

   The initial set of edit configuration event classes
   (create, delete, merge, replace).  As configuration notifications
   could potentially carry huge amounts of data in order to properly
   support functions such as security audit logs, so it is fault, configuration, state,
   audit, data, maintenance, metrics, security, information, heartbeat expected that
   netconf clients will engineer their subscriptions to meet their needs
   and syslog. to not overwhelm their capacity to process and store event
   notifications.  Examples include hardware board removed, software
   module loaded or DNS server reconfigured.  Changes are reported to
   all subscribed clients, not just to those clients whose actions
   triggered the changes.

   A fault event notification is generated when a fault condition (error
   or warning) occurs.  A fault event may result in an alarm.  Examples
   of fault events could be a communications alarm, environmental alarm,
   equipment alarm, processing error alarm, quality of service alarm, or
   a threshold crossing event.  See RFC3877 and RFC2819 for more
   information.

   A configuration event, alternatively known as an inventory event, is
   used to notify that hardware, software, or a service has been added/
   changed/removed.  In keeping aligned with NETCONF protocol
   operations,  configuration events may included copy configuration
   event, delete configuration event, or  The fault notification should carry the edit configuration following data:
   severity, event
   (create, delete, merge, replace). source, probable cause, specific problem, additional
   information.

   A state event indicates a change from one state to another, where a
   state is a condition or stage in the existence of a managed entity.
   State change events are seen in many specifications.  For Entity
   state changes, see [Entity-State-MIB] for more information.  The
   notification shall identify the object who's state changed and the
   new state.  Internal states of a node are important for supervision
   purposes and also effect how a node can be configured.

   Audit events provide event of very specific actions within a managed
   device.  In isolation an audit events provides very limited data.  A
   collection of audit information forms an audit trail.

   A data dump event is an asynchronous event containing information
   about a system, its configuration, state, etc.

   A maintenance event signals the beginning, process or end of an
   action either generated by a manual or automated maintenance action.
   If the maintenance event is a direct result of a configuration
   management operation on this Netconf session then an rpc-reply
   notification should be used.  This event class is intended instead
   for reporting on scheduled maintenance activities.  Expected data
   includes a description of the maintenance process, the stage the
   process has reached, the manual action, automatic process that
   triggered the notification.  Examples include automatic backup
   completed.

   A metrics event contains a metric or a collection of metrics.  This
   includes performance metrics.

   A heart beat event is sent periodically to enable testing that the
   communications channel is still functional.  It behaves much like the
   other event classes, with the exception that implementations may not
   want to include an event log, if supported.  Although widely used
   throughout the industry, no current corresponding work within the
   IETF.  However, other standards bodies such as the TeleManagement
   Forum have similar definitions.

   An Information event is something that happens of interest which is
   within the expected operational behaviour and not otherwise covered
   by another class.

   The syslog

   syslogTunnel event class is used to indicate tunneled when syslog content.
   The content and format of the message will be compliant to syslog
   standards.

3.6 is sent, unmodified, within
   a Netconf event Notification.  See appendix X.X for more
   information..

3.7  Defining Event Notifications

   Event Notifications are defined ahead of time by defining an XML
   element and assigning it to particular event classes.  This will be
   done using an "eventClasses" attribute.

3.7

3.8  Interleaving Messages

   While each NETCONF message must be a complete XML document, the
   design of the event system allows for the interleaving of complete
   asynchronous event notifications with complete synchronous messages.
   It is possible to still send command-response type messages such as
   <modify-subscription> while events are being generated.  The only
   restriction is that each message must be complete

   The following sequence diagram demonstrates an example NETCONF
   session where after basic session establishment and capability
   exchange, NETCONF client (C), subscribes to receive event
   notifications.  The NETCONF server (S), starts sending event
   notifications as events of interest happen within the system.  The
   NETCONF client decides to change the characteristics of their event
   subscription by sending a  <modify-subscription> command.  Before the
   NETCONF server, receives this command, another event is generated and
   the NETCONF server starts to send the event notification.  The
   NETCONF server finishes sending this event notification before
   processing the  <modify-subscription> command and sending the reply.

                             C                           S
                             |                           |
                             |  capability exchange      |
                             |-------------------------->|
                             |<------------------------->|
                             |                           |
                             |  <create-subscription>    |
                             |-------------------------->|
                             |<--------------------------|
                             |                           |
                             |     <notification>        |
                             |<--------------------------|
                             |                           |
                             |     <notification>        |
                             |<--------------------------|
                             |                           |
                             |  <modify-subscription>    |
                             |-------------------------->| (buffered)
                             |     <notification>        |
                             |<--------------------------|
                             |  <rpc-reply>              |
                             |<--------------------------|

4.  XML Schema for Event Notifications

   <?xml version="1.0" encoding="UTF-8"?>
      <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"
             xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"
       targetNamespace="urn:ietf:params:xml:ns:netconf:notification:1.0"
             elementFormDefault="qualified"
             attributeFormDefault="unqualified"
               xml:lang="en">
        <!--
          import standard XML definitions
          -->
        <xs:import namespace="http://www.w3.org/XML/1998/namespace"
                   schemaLocation="http://www.w3.org/2001/xml.xsd">
          <xs:annotation>
            <xs:documentation>
              This import accesses the xml: attribute groups for the
              xml:lang as declared on the error-message element.
            </xs:documentation>
          </xs:annotation>
        </xs:import>

        <!-- import base netconf definitions -->
    <xs:import namespace="urn:ietf:params:xml:ns:netconf:base:1.0"
          schemaLocation="urn:ietf:params:xml:ns:netconf:base:1.0" />

   <!-- ************** Type definitions ***********************-->

        <xs:simpleType name="SubscriptionID">
        <xs:annotation>
          <xs:documentation>
          The unique identifier for this particular subscription within
          the session.
          </xs:documentation>
          </xs:annotation>
           <xs:restriction base="xs:string"/>
           </xs:simpleType>

           <xs:simpleType name="SequenceNumber">
        <xs:annotation>
          <xs:documentation>
          A monotonically  increasing integer. Starts at 0.
          Always increases by just one. Roll back to 0 after maximum
          value is reached.
          </xs:documentation>
          </xs:annotation>
           <xs:restriction base="xs:integer"/>
           </xs:simpleType>

           <xs:complexType name="EventClassType"/>
           <xs:element name="EventClass"
                       type="EventClassType" abstract="true"/>
           <xs:element name="fault" type="EventClassType"
                       substitutionGroup="EventClass"/>
           <xs:element name="information" type="EventClassType"
                       substitutionGroup="EventClass"/>
           <xs:element name="state" type="EventClassType"
                       substitutionGroup="EventClass"/>
           <xs:element name="configuration" type="EventClassType"
                       substitutionGroup="EventClass"/>
           <xs:element name="data" type="EventClassType"
                       substitutionGroup="EventClass"/>
           <xs:element name="maintenance" type="EventClassType"
                       substitutionGroup="EventClass"/>
           <xs:element name="metrics" type="EventClassType"
                       substitutionGroup="EventClass"/>
           <xs:element name="security" type="EventClassType"
                       substitutionGroup="EventClass"/>
           <xs:element name="heartbeat" type="EventClassType"
                       substitutionGroup="EventClass"/>

         <xs:complexType name="EventClasses">
           <xs:sequence maxOccurs="unbounded">
             <xs:element ref="EventClasses" />
           </xs:sequence>
         </xs:complexType>

   <!-- ************** Symmetrical Operations  ********************-->

        <!--
          <create-subscription> operation
          -->
        <xs:complexType name="createSubscriptionType">
          <xs:complexContent>
            <xs:extension base="netconf:rpcOperationType">
              <xs:sequence>
                <xs:element name="event-classes"
                                     minOccurs="0">
                  <xs:complexType>
                     <xs:complexContent>
                       <xs:extension base="EventClasses"/>
                     </xs:complexContent>
                   </xs:complexType>
                 </xs:element>
                <xs:element name="filter"
                     type="netconf:filterInlineType" minOccurs="0"/>
                <xs:element name="named-profile"
                            type="xs:string" minOccurs="0"/>
              </xs:sequence>
            </xs:extension>
          </xs:complexContent>
        </xs:complexType>
        <xs:element name="create-subscription"
                    type="createSubscriptionType"
                    substitutionGroup="netconf:rpcOperation"/>

        <!--
          <modify-subscription> operation
          -->
        <xs:complexType name="modifySubscriptionType">
          <xs:complexContent>
            <xs:extension base="netconf:rpcOperationType">
              <xs:sequence>
                <xs:element name="subscription-id"
                                 type="SubscriptionID" />
                <xs:element name="event-classes"
                                      minOccurs="0">
                  <xs:complexType>
                     <xs:complexContent>
                       <xs:extension base="EventClasses"/>
                     </xs:complexContent>
                   </xs:complexType>
                 </xs:element>
                <xs:element name="filter"
                            type="netconf:filterInlineType"
                            minOccurs="0"/>
                <xs:element name="named-profile"
                            type="xs:string" minOccurs="0"/>
              </xs:sequence>
            </xs:extension>
          </xs:complexContent>
        </xs:complexType>
        <xs:element name="modify-subscription"
                    type="modifySubscriptionType"
                    substitutionGroup="netconf:rpcOperation"/>

        <!--
          <cancel-subscription> operation
          -->
        <xs:complexType name="cancelSubscriptionType">
          <xs:complexContent>
            <xs:extension base="netconf:rpcOperationType">
              <xs:sequence>
                <xs:element name="subscription-id"
                     type="SubscriptionID" />
              </xs:sequence>
            </xs:extension>
          </xs:complexContent>
        </xs:complexType>
        <xs:element name="cancel-subscription"
                    type="cancelSubscriptionType"
                    substitutionGroup="netconf:rpcOperation"/>

   <!-- ************** One-way Operations  ******************-->

          <!--
          <Event> operation
          -->
      <xs:complexType name="NotificationType">
          <xs:complexContent>
              <xs:sequence>
              <xs:element name="subscription-id"
                                     type="SubscriptionID"/> name="subscriptionId" type="SubscriptionID" />
              <xs:element name="event-classes" type="EventClasses"/> name="eventClasses" type="EventClasses" />
              <xs:element name="sequence-number"
                                  type="SequenceNumber"/> name="sequenceNumber" type="SequenceNumber" />
              <xs:element name="date-time" name="dateAndTime" type="xs:dateTime">
                   <xs:annotation>
                      <xs:documentation>
                      The date and time that the event notification was sent
                      by the netconf server.
                      </xs:documentation>
                   </xs:annotation>
                </xs:element>
              </xs:sequence>
            </xs:extension>
          </xs:complexContent>
        </xs:complexType>
        <xs:element name="notification" type="NotificationType"/>

      </xs:schema>

5.  Mapping to Application Transport Protocols

   Currently, the NETCONF family of specification allows for running
   NETCONF over a number of application transport protocols, some of which support
   multiple configurations.  Some of these options will be better suited
   for supporting event notifications then others.

5.1  SSH

   Session establishment and two-way messages are based on the NETCONF
   over SSH transport mapping [NETCONF-SSH]

   One-way  event messages are supported as follows: Once the session
   has been established and capabilities have been exchanged, the server
   may send complete XML documents to the NETCONF client containing
   notification elements.  No response is expected from the NETCONF
   client.

   As the other examples in [NETCONF-SSH] illustrate, a special
   character sequence, MUST be sent by both the client and the server
   after each XML document in the NETCONF exchange.  This character
   sequence cannot legally appear in an XML document, so it can be
   unambiguously used to identify the end of the current document in the
   event notification of an XML syntax or parsing error, allowing
   resynchronization of the NETCONF exchange.

   The NETCONF over SSH session to receive an event notification might
   look like the following.  Note the event notification contents
   (delimited by <data> </data> tags) are not defined in this document
   and are provided herein simply for illustration purposes:

       <?xml version="1.0" encoding="UTF-8"?>
          <notification
                xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
            <subscription-id>123456</subscription-id>
            <event-class><configuration/><audit/></event-classes>
            <sequence-number>2</sequence-number>
            <date-time>2000-01-12T12:13:14Z</date-time>
            <eventClasses><configuration/><audit/></eventClasses>
            <sequenceNumber>2</sequenceNumber>
            <dateAndTime>2000-01-12T12:13:14Z</dateAndTime>
              <data>
                 <user>Fred Flinstone</user>
                 <operation>
                  <edit-config>
                    <target>
                     <running/>
                    </target>
                    <config>
                      <top xmlns="http://example.com/schema/1.2/config">
                         <interface>
                           <name>Ethernet0/0</name>
                           <mtu>1500</mtu>
                        </interface>
                      </top>
                   </config>
                 </edit-config>
               </operation>
             </data>
          </notification>
        ]]>
    ]]>

5.2  BEEP

   Session establishment and two-way messages are based on the NETCONF
   over BEEP transport mapping NETCONF-BEEP

5.2.1  One-way Notification Messages in Beep

   One-way notification messages can be supported either by mapping to
   the existing one-to-many BEEP construct or by creating a new one-to-
   none construct.

   This area is for future study.

5.2.1.1  One-way messages via the One-to-many Construct

   Messages in one-to-many exchanges: "rpc", "notification", "rpc-reply"

   Messages in positive replies: "rpc-reply", "rpc-one-way"

5.2.1.2  One-way notification messages via the One-to-none Construct

   Note that this construct would need to be added to an extension or
   update to 'The Blocks Extensible Exchange Protocol Core' RFC 3080.

   MSG/NoANS: the client sends a "MSG" message, the server, sends no
   reply.

   In one-to-none exchanges, no reply to the "MSG" message is expected.

5.3  SOAP

   Session management and message exchange are based on the NETCONF over
   SOAP transport mapping NETCONF-SOAP

   Note that the use of "persistent connections" "chunked transfer-
   coding" when using HTTP becomes even more important in the supporting
   of event notifications

5.3.1  A NETCONF over Soap over HTTP Example

      C: POST /netconf HTTP/1.1
      C: Host: netconfdevice
      C: Content-Type: text/xml; charset=utf-8
      C: Accept: application/soap+xml, text/*
      C: Cache-Control: no-cache
      C: Pragma: no-cache
      C: Content-Length: 465
      C:
      C: <?xml version="1.0" encoding="UTF-8"?>
      C: <soapenv:Envelope
      C:   xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
      C:   <soapenv:Body>
      C:     <rpc message-id="101"
      C:        xmlns=
              "xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      C:       <create-subscription>
      C:       </create-subscription>
      C:     </rpc>
      C:   </soapenv:Body>
      C: </soapenv:Envelope>

      The response:

      S: HTTP/1.1 200 OK
      S: Content-Type: application/soap+xml; charset=utf-8
      S: Content-Length: 917
      S:

      S: <?xml version="1.0" encoding="UTF-8"?>
      S: <soapenv:Envelope
      S:   xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
      S:   <soapenv:Body>
      S:     <rpc-reply message-id="101"
      S:        xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      S:       <data>
      S:         <top xmlns=
                      "http://example.com/schema/1.2/notification">
      S:           <subscriptionId>123456</subscriptionId>
      S:         </top>
      S:       </data>
      S:     </rpc-reply>
      S:   </soapenv:Body>
      S: </soapenv:Envelope>

      And then some time later

      S: HTTP/1.1 200 OK
      S: Content-Type: application/soap+xml; charset=utf-8
      S: Content-Length: 917
      S:
      S: <?xml version="1.0" encoding="UTF-8"?>
      S: <soapenv:Envelope
      S:   xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
      S:   <soapenv:Body>
      S:     <notification
                xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      S:      <subscriptionID>123456</subscriptionID>
      S:      <eventClass><configuration/><audit/></eventClass>      <eventClasses><configuration/><audit/></eventClasses>
      S:      <sequenceNumber>2</sequenceNumber>
      S:           <dateAndTime>2000-01-12T12:13:14Z</dateAndTime>
      S:        <data>
      S:           <user>Fred Flinstone</user>
      S:              <operation>
      S:               <edit-config>
      S:              <target>
      S:               <running/>
      S:              </target>
      S:             <config>
      S:              <top xmlns="http://example.com/schema/1.2/config">
      S:                   <interface>
      S:                     <name>Ethernet0/0</name>
      S:                     <mtu>1500</mtu>
      S:                  </interface>
      S:               </top>
      S:            </config>
      S:           </edit-config>
      S:         </operation>
      S:       </data>
      S:    </notification>
      S:   </soapenv:Body>
      S: </soapenv:Envelope>

6.  Filtering examples

   The following section provides examples to illustrate the various
   methods of filtering content on an event notification subscription.

6.1  Event Classes

   The following example illustrates selecting all event notifications
   for EventClasses fault, state or config

        <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
          <create-subscription>
            <eventClasses>
               <fault/>
               <state/>
               <config/>
            </eventClasses>
          </create-subscription>
        </rpc>

6.2  Subtree Filtering

   XML subtree filtering is not well suited for creating elaborate
   filter definitions given that it only supports equality comparisons
   (e.g. in the event subtree give me all event notifications which have
   severity=critical or severity=major or severity=minor).
   Nevertheless, it may be used for defining simple notification
   forwarding filters as shown below.

   The following example illustrates selecting fault EventClass which
   have severities of critical, major, or minor.  The filtering criteria
   evaluation is as follows:

   ((fault) & ((severity=critical) | (severity=major) | (severity =
   minor)))
        <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
          <create-subscription>
            <eventClasses>
               <fault/>
            </eventClasses>
            <netconf:filter type="subtree">
              <neb xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
               xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
                <event>
                    <severity>critical</severity>
                </event>
                <event>
                    <severity>major</severity>
                </event>
                <event>
                    <severity>minor</severity>
                </event>
              </neb>
            </netconf:filter>
          </create-subscription>
        </rpc>

   The following example illustrates selecting fault, state, config
   EventClasses which have severities of critical, major, or minor and
   come from card Ethernet0.  The filtering criteria evaluation is as
   follows:

   ((fault | state | config) & ((fault & severity=critical) | (fault &
   severity=major) | (fault & severity = minor) | (card=Ethernet0)))
        <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
          <create-subscription>
            <eventClasses>
               <fault/>
               <state/>
               <config/>
            </eventClasses>
            <netconf:filter type="subtree">
              <neb xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
                xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
                <event>
                    <eventClasses>fault</eventClasses>
                    <severity>critical</severity>
                </event>
                <event>
                    <eventClasses>fault</eventClasses>
                    <severity>major</severity>
                </event>
                <event>
                    <eventClasses>fault</eventClasses>
                    <severity>minor</severity>
                </event>
                <event>
                    <card>Ethernet0</card>
                </event>
              </neb>
            </netconf:filter>
          </create-subscription>
        </rpc>

6.3  XPATH filters

   The following example illustrates selecting fault EventClass which
   have severities of critical, major, or minor.  The filtering criteria
   evaluation is as follows:

   ((fault) & ((severity=critical) | (severity=major) | (severity =
   minor)))
        <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
          <create-subscription>
            <eventClasses>
               <fault/>
            </eventClasses>
            <netconf:filter type="xpath">
              (/event[eventClasses/fault] and
              (/event[severity="critical"] or
               /event[severity="major"] or /event[severity="minor"]))
            </netconf:filter>
          </create-subscription>
        </rpc>

   The following example illustrates selecting fault, state, config
   EventClasses which have severities of critical, major, or minor and
   come from card Ethernet0.  The filtering criteria evaluation is as
   follows:

   ((fault | state | config) & ((fault & severity=critical) | (fault &
   severity=major) | (fault & severity = minor) | (card=Ethernet0)))

        <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:event:1.0">
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
          <create-subscription>
            <eventClasses>
               <fault/>
               <state/>
               <config/>
            </eventClasses>
            <netconf:filter type="xpath">
               ((/event[eventClasses/fault]  or
               /event[eventClasses/state]     or
                /event[eventClasses/config]) and
                ( (/event[eventClasses/fault] and
                /event[severity="critical"]) or
                (/event[eventClasses/fault]    and
                /event[severity="major"])    or
                (/event[eventClasses/fault]    and
                /event[severity="minor"])    or
                /event[card="Ethernet0"]))
            </netconf:filter>
          </create-subscription>
        </rpc>

7.  Additional Capabilities

7.1  Call-Home Notifications

7.1.1  Overview

   Call-Home Notifications are an alternative model for providing
   notifications that may be preferred for two particular use cases.
   The first use case is NAT traversal as in this model, the Netconf
   server initiates the Notification session.  The second use case is
   when a manager has a large number of low-priority devices that it
   only wants to deal with when there a known issue.  While this risks
   loss of information, for this particular use case, this is not
   considered an issue.  The Call-home-Notification feature supports the
   concept of a short-lived notification session that only exists when
   there is something to report.

   In this feature, a subscription consists of a named profile, and an
   association with a Netconf client.  Unlike normal subscriptions,
   which only exist when they are active, these subscriptions live while
   both dormant and active.  When an event of interest happens on the
   managed resource, the Netconf server checks the list of dormant
   subscriptions and if the filtering parameters in the subscription
   indicate interest in the Notification resulting from the event, then
   the Netconf server initiates the connection to the specific Netconf
   client and sends the Notification.  When the Notification has been
   sent, the connection is terminated.

   A subscription is active when it is currently session between the
   Netconf client and server related to this subscription on which
   Notifications can be sent.  A subscription is dormant when there is
   currently no session set up between the Netconf client and server
   related to this notification subscription.

7.1.1.1  Session Lifecycle

   In order to avoid situations in which a sessions is continuously
   setup and torn down, an inactivity timer is configured on the server.
   The timeout interval value is the same for all sessions (i.e. system
   wide) and each session has its own timer.  Upon expiration of the
   inactivity timer, the connection is terminated, otherwise if activity
   is detected, the timer is reset.

   [Editor's note: alternatives here were to either create and tear down
   the session for each notification received or to have the server
   somehow figure out that there are more notifications coming soon
   after it has sent a notification and therefore keeps the connection
   up.]
   The session establishment procedure is as follows:

   1) The NETCONF server checks to ensure there isn't already a suitable
   notification session open.

   2)	The NETCONF server initiates a session using a recognized
   application
   transport protocol (SSH, Beep, SOAP, etc).  In order to "activate"
   this reverse behaviour behavior a new SSH subsystem may need to be defined.
   This is for further study.  In addition, the NE hosting the NETCONF
   server must support both client and server modes in the case of SSH.

   2)

   3)	Client and server are authenticated according to the underlying
   application
   transport protocol (e.g.  SSH, BEEP)

   3)

   4)	If using BEEP, as described in [NETCONF-BEEP] either party may
   initiate the BEEP session.  Once this occurs, the assumption is that
   both parties know their roles.  At this point, the NETCONF client,
   initiates NETCONF session establishment whether running SSH or BEEP.

7.1.2  Dependencies

   This feature is dependant on the named profiles concept from the
   normal subscription method as well as the definition of
   <notification>.

   It also uses the same  <notification>

7.1.3  Capability Identifier

   urn:ietf:params:xml:ns:netconf:callHomeNotification:1.0

7.1.3.1  New Operations

7.1.3.1.1  New Data Model

   <xs:schema
      xmlns:xs="http://www.w3.org/2001/XMLSchema"
      xmlns:nsub="urn:ietf:params:xml:ns:netconf:subscription:1.0"
      targetNamespace=
              "urn:ietf:params:xml:ns:netconf:callHomeSubscription:1.0"
      xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"
      xmlns:ncEvent= "urn:ietf:params:xml:ns:netconf:event:1.0" "urn:ietf:params:xml:ns:netconf:notification:1.0"
      xmlns:nm="urn:ietf:params:xml:ns:netconf:appInfo:1.0"
      elementFormDefault="qualified"
                     attributeFormDefault="unqualified" xml:lang="en">
   <xs:annotation>
     <xs:documentation xml:lang="en">
          Schema for reporting on dormant Call-Home Notification
          Subscriptions
     </xs:documentation>
      <xs:appinfo>
          <nm:identity
                  xmlns:nm="urn:ietf:params:xml:ns:netmod:base:1.0">
                <nm:Name>NetConfCallHomeSchema</nm:Name>
                 <nm:LastUpdated>2006-04-30T09:30:47-05:00
                 </nm:LastUpdated>
                 <nm:Organization>IETF</nm:Organization>
                  <nm:Description>
                       A schema that can be used to learn about callHome
                       Notification subscriptions
                   </nm:Description>
            </nm:identity>
     </xs:appinfo>
    </xs:annotation>

   <xs:import
      namespace="urn:ietf:params:xml:ns:netconf:subscription:1.0"
      schemaLocation="urn:ietf:params:xml:ns:netconf:subscription:1.0"/>

    <xs:element name="callHomeSubscription">
        <xs:annotation>
               <xs:appinfo>
                    <nm:minAccess><read/></nm:minAccess>
                    <nm:maxAccess><read/></nm:maxAccess>
               </xs:appinfo>
       </xs:annotation>
       <xs:complexType>
             <xs:sequence>
                   <xs:element name="subscriber" type="xs:string"> >
                       <xs:annotation>
                           <xs:documentation>
                               This needs
                               The Netconf client that is subscribed to be replaced with a more
                               prescriptive data type
                               receive these notifications as part of
                               the call-home subscription.
                           </xs:documentation>
                       </xs:annotation>
                       <xs:complexType>
                       <xs:sequence>
                           <xs:element type="ip:IPAddressOrSysname"
                              name="iPAddressOrSysname"/>
                           <xs:element type="xs:integer" name="port"/>
                       </xs:sequence>
                       </xs:complexType>
                   </xs:element>
                   <xs:element name="namedProfile"
                           type="xs:string" minOccurs="0">
                         <xs:annotation>
                             <xs:documentation xml:lang="en">
                               The named profile associated with this
                               subscription. Note that the
                               contents of the named profile may have
                               changed since it was last applied
                             </xs:documentation>
                         </xs:annotation>
                         <xs:keyref refer="nsub:namedProfileKey"
                             name="namedProfileKeyRef">
                             <xs:selector xpath=".//namedProfile">
                              </xs:selector>
                             <xs:field xpath="namedProfile"></xs:field>
                         </xs:keyref>
                     </xs:element>

                     <xs:element name="status">
                           <xs:simpleType>
                             <xs:restriction base="xs:string">
                               <xs:enumeration value="Dormant"/>
                               <xs:enumeration value="Active"/>

                             </xs:restriction>
                           </xs:simpleType>

                         </xs:element>

                       </xs:sequence>
                     </xs:complexType>

                   </xs:element>

                 </xs:schema>

7.1.3.1.2  Modifications to Existing Operations

7.1.3.1.2.1   <create-subscription>

   This capability adds a new attribute to the <create-subscription>
   command.  This attribute is

   callHome:

   An optional parameter that, when present, indicates whether this will
   be a call-home Notification subscription.  If not present, this will
   be a normal subscription.

7.1.3.1.3  Interactions with Other Capabilities

   It is only when these subscriptions move from the dormant state to
   the active state that they have sessions associated with them.  It is
   only at this point that they show up in the active subscription list.

8.  Security Considerations

   To be determined once specific aspects of this solution are better
   understood.  In particular, the access control framework and the
   choice of transport will have a major impact on the security of the
   solution

9.  IANA Considerations

   Event Classes will likely be an IANA-managed resource.  The initial
   set of values is defined in this specification.

   In order for new event classes to be allocated, the following
   requirements must be met:

   o  There must be working group consensus to add the new class

   o  A detailed description of its purpose in the netconf protocol must
      be provided

   o  A detailed description of all manager and agent implementation
      requirements associated with the event class must be provided

   o  The description must make clear to developers how to determine
      when it is appropriate to choose this event classification for a
      new notification type

   list

10.  Acknowledgements

   Thanks to Gilbert Gagnon and Greg Wilbur for providing their input
   into the early work on this document.  In addition, the editors would
   like to acknowledge input at the Vancouver editing session from the
   following people: Orly Nicklass, James Bakstrieve, Yoshifumi
   Atarashi, Glenn Waters, Alexander Clemm, Dave Harrington, Dave
   Partain, Ray Atarashi and Dave Perkins.  In addition, they would like
   to thank Balazs Lengyel his contributions to the event class text.

11.  References

   [NETCONF]  Enns, R., "NETCONF Configuration Protocol",
              ID draft-ietf-netconf-prot-12, February 2006.

   [NETCONF BEEP]
              Lear, E. and K. Crozier, "Using the NETCONF Protocol over
              Blocks Extensible Exchange Protocol (BEEP)",
              ID draft-ietf-netconf-beep-10, March 2006.

   [NETCONF Datamodel]
              Chisholm, S. and S. Adwankar, "Framework for NETCONF
              Content", ID draft-chisholm-netconf-model-05.txt,
              April 2006.

   [NETCONF SOAP]
              Goddard, T., "Using the Network Configuration Protocol
              (NETCONF) Over the Simple Object Access Protocol (SOAP)",
              ID draft-ietf-netconf-soap-08, March 2006.

   [NETCONF SSH]
              Wasserman, M. and T. Goddard, "Using the NETCONF
              Configuration Protocol over Secure Shell (SSH)",
              ID draft-ietf-netconf-ssh-06.txt, March 2006.

   [URI]      Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifiers (URI): Generic Syntax", RFC 2396,
              August 1998.

   [XML]      World Wide Web Consortium, "Extensible Markup Language
              (XML) 1.0", W3C XML, February 1998,
              <http://www.w3.org/TR/1998/REC-xml-19980210>.

   [refs.RFC2026]
              Bradner, S., "The Internet Standards Process -- Revision
              3", RFC 2026, BCP 9, October 1996.

   [refs.RFC2119]
              Bradner, s., "Key words for RFCs to Indicate Requirements
              Levels", RFC 2119, March 1997.

   [refs.RFC2223]
              Postel, J. and J. Reynolds, "Instructions to RFC Authors",
              RFC 2223, October 1997.

   [refs.RFC3080]
              Rose, M., "The Blocks Extensible Exchange Protocol Core",
              RFC 3080, March 2001.

Authors' Addresses

   Sharon Chisholm
   Nortel
   3500 Carling Ave
   Nepean, Ontario  K2H 8E9
   Canada

   Email: schishol@nortel.com

   Kim Curran
   Nortel
   3500 Carling Ave
   Nepean, Ontario  K2H 8E9
   Canada

   Email: kicurran@nortel.com

   Hector Trevino
   Cisco
   Suite 400
   9155 E. Nichols Ave
   Englewood, CO  80112
   USA

   Email: htrevino@cisco.com

Appendix A.  Design Alternatives

A.1  Suspend And Resume

   The purpose of the <cancel-subscription> operation is to stop event
   notification forwarding and since the notification subscription is
   transient the operation naturally  removes all subscription
   configuration; For this reasons, a different mechanism might be
   needed for shutting down the notification session but preserving the
   subscription information thus allowing the NETCONF server to re-
   establish the parameters and reproduce the notification subscription.

   The suspend and resume commands would allows a NETCONF client to
   suspend event notification forwarding without removing the existing
   subscription information.  It could be used for both subscriptions
   based on persistent and non-persistent subscription information.
   Operations <suspend-subscription> and  ><resume-subscription> are
   proposed for this purpose.

   If event subscription information is now persistent, unsolicited
   session termination (i.e. other than <cancel-subscription))  is
   treated as if a  <suspend-subscription>  command was issued.  Event
   forwarding is resumed by sending a <resume-subscription> to the
   NETCONF server on a new connection.

A.2  Lifecycle

   Configuration information associated with the event subscription
   (event classes and  filters) could persist beyond the life of the
   event subscription session. (i.e. it is maintained by the network
   element as part of its configuration).  This configuration
   information is subject to the behaviour of the datastore it resides
   in and may or may not persist across re-boots (e.g. it could be part
   of the running configuration but not the startup configuration).

Appendix B.  Event Notifications and Syslog

   This appendix describes the mapping between syslog message fields and
   NETCONF event notification fields.  The purpose of this mapping is to
   provide an unambiguous mapping to enable consistent multi-protocol
   implementations as well as to enable future migration.

   The second part of the appendix describes an optional capability to
   embed an entire syslog message (hereafter referred to as syslog
   message(s) to avoid confusion with the message field in syslog)
   within a NETCONF event notification.

B.1  Leveraging Syslog Field Definitions

   This section provides a semantic mapping between NETCONF event fields
   and syslog message fields.

     -------------------------------------------------------------------
     |         PRI         |          HEADER         |    MESSAGE      |
     -------------------------------------------------------------------
     | FACILITY | SEVERITY |  TIMESTAMP  | HOSTNAME  |  TAG CONTENT    |
     -------------------------------------------------------------------
     Figure 2 - syslog message (RFC3164)

     -------------------------------------------------------------------
     |     HEADER         |    STRUCTURED DATA        |    MESSAGE     |
     -------------------------------------------------------------------
     Figure 3 - syslog message (draft-ietf-syslog-protocol-14.txt)

   HEADER (Version, Facility, Severity, Truncate, Flag, TimeStamp,
   HostName, AppName, ProcId, MsgId)

   STRUCTURED DATA (Zero or more Structured Data Elements - SDEs)

   MESSAGE ( Text message )

B.1.1  Field Mapping

     ------------------------------------------------------
     RFC3164      Syslog ID       NETCONF Event
     ------------------------------------------------------
     VERSION
     ------------------------------------------------------
     FACILITY      FACILITY
     ------------------------------------------------------
     SEVERITY      SEVERITY        PerceivedSeverity
     ------------------------------------------------------
     TRUNCATE FLAG
     ------------------------------------------------------
     TIMESTAMP     TIMESTAMP       EventTime
     ------------------------------------------------------
     HOSTNAME      HOSTNAME        EventOrigin
     ------------------------------------------------------
     TAG           APP-NAME        EventOrigin
     ------------------------------------------------------
     PROC-ID
     ------------------------------------------------------
     MSG-ID
     ------------------------------------------------------
     CONTENT       CONTENT         AdditionalText
     ------------------------------------------------------

     Figure 4 - syslog to NETCONF Event field mapping

   Notes:

   VERSION:  Schema version is found in XML Schema namespace.  However,
   no correspondence to syslog.

   FACILITY: No well defined semantics for this field.  Therefore not
   used at this time.

   TRUNCATE: Not applicable.  NETCONF events must be complete XML
   documents therefore cannot be truncated.

   TIME: TIMESTAMP in syslog ID is derived from RFC3339 but with
   additional restrictions

   PROC-ID: No equivalent field

   CONTENT: This is a free form text field with not defined semantics.
   The contents of this field may be included in the AdditionalText
   field.

B.1.2  Severity Mapping

   The severity value mappings stated in (draft-ietf-syslog-protocol-14)
   are used:

     ITU Perceived Severity      syslog SEVERITY
     Critical                    Alert
     Major                       Critical
     Minor                       Error
     Warning                     Warning
     Indeterminate               Notice
     Cleared                     Notice

   Figure 5.  ITU Perceived Severity to syslog SEVERITY mapping.

B.2  Syslog within NETCONF Events

B.2.1  Motivation

   The syslog protocol (RFC3164) is widely used by equipment vendors as
   a means to deliver event messages.  Due to the widespread use of
   syslog as well as a potential phased availability and coverage of
   NETCONF events by equipment vendors, it is envisioned that users will
   also follow a phased migration.  As a way to facilitate migration and
   at the same time allow equipment vendors to provide comprehensive
   event coverage over a NETCONF event subscription session, syslog
   messages could be embedded in their entirety within the body of a
   NETCONF event notification.

   The information provided in this appendix describes a mechanism to
   leverage syslog messages for the purpose of complementing the
   available NETCONF event notification set.  The intent is to promote
   the use of the NETCONF interface and not to simply provide a wrapper
   and additional delivery mechanism for syslog messages.  NETCONF
   events are intended to be well defined and structured, therefore
   providing an advantage over the unstructured and often times
   arbitrarily defined syslog messages (i.e. the message field).

   Covered herein is the syslog protocol as defined in RFC3164 and
   draft-ietf-syslog-protocol-14.txt.

B.2.2  Embedding syslog messages in a NETCONF Event

   When event notifications are supported, the default behaviour for a
   NETCONF server is to send NETCONF event notifications over an
   established event subscription.  As an option, the NETCONF server may
   embed a syslog message in its entirety (e.g.  RFC3164 - PRI, Header,
   and Message fields), placing it within the Event Info field
   (SyslogInfo sub-field) - see Figure 1.

     ______________________________________________________
    | NETCONF Event  Header   |            Data           |
    |________________________ |___________________________|
    |                         |        Event Info         |
    |_________________________|___________________________|
                                           |
                                           v
                       ____________________________
                      | Event Fields | SyslogInfo |
                      |___________________________|

           Figure 1 - Embedding syslog in a NETCONF Event Notifications

B.2.3  Supported Forwarding Options

   Three event forwarding options may be supported by the NETCONF
   server: a) XML only (mandatory if NETCONF events capability is
   supported) b) XML and syslog (Optional) c) syslog only (optional)

   Note to the reader: Option "a" above refers to event notification
   messages defined for use over the NETCONF protocol.  While their use
   is not necessarily limited to NETCONF protocol, they are referred to
   as "NETCONF XML-event" in the remainder of this section simply to
   avoid ambiguity.

B.2.3.1  XML and Syslog option - Forwarding Behaviour

   It is possible, due to coverage, for a given NETCONF implementation
   to not support a comprehensive set of NETCONF event notifications.
   Therefore, it is possible for a given event to trigger the generation
   of a syslog message without a NETCONF-aware counterpart.  In such
   situations, the NETCONF server could form a NETCONF event
   notification, embed the syslog message in the SyslogInfo field and
   forward the NETCONF event notifications to all subscribed
   destinations.  Otherwise, both NETCONF event and syslog messages must
   be included in the Event Info field.

B.2.3.2  Event Class Identification

   The event class field is found in the NETCONF event header
   information as described in the main body of this document.  It
   conveys information describing what type of event for which the event
   notification is generated and lets the consumer of the message know
   what sort of content to expect.  NETCONF event notifications which
   only contain a syslog message (Options c) must have the EventClass
   field set to "syslog".  The NETCONF client parses the message in the
   same manner as any other message, finds the normal fields (ie, XML-
   marked content) not present and either proceeds to parse the
   SyslogInfo field or hands the syslog message to the entity
   responsible for processing syslog messages.

B.2.3.3  Event Subscription Options

   A NETCONF client may request subscription to options b) XML and
   syslog or c) syslog only listed in "Supported Forwarding Options" at
   subscription time via the user-specified filter.  The FILTER or NAMED
   FILTER parameter in <create-subscription>.  As previously indicated,
   the default behaviour is to forward NETCONF XML only event
   notifications.  [Editor's Note: How is this done exactly?]

B.2.3.4  Supported Forwarding Option Discovery

   A potential means for a NETCONF server to convey its feature set
   support is via capabilities.  However, in this particular case, the
   event content is not a protocol feature therefore other means are
   needed.  A future version of this document will address this issue.

Appendix C.  Example Configuration Notifications

   This non-normative appendix provides a detailed description of a
   configuration change event notification definition in support of the
   configuration operations, particularly those defined by the NETCONF
   protocol.

C.1  Types of Configuration Events

   Configuration event notifications include:

   o  All-triggered Configuration Events

   o  NETCONF-triggered Configuration Events

   All-triggered Configuration events report on changes from the
   perspective of the managed resource, rather than the commands which
   created the configuration change.  They are reported regardless of
   what specific method was used to initiate the change.  They indicate
   that a change has occurred around hardware, software, services or
   other managed resources within a system.  Specific events includes

   o  Resource Added

   o  Resource Removed

   o  Resource Modified

   NETCONF-triggered events are those which correspond to the execution
   of explicit NETCONF operations.  These include:

   o  copy-config event

      *  This is a data store level event generated following the
         successful completion of a copy-config operation.  This
         represents the creation of a new configuration file or
         replacement of an existing one.

   o  delete-config event

      *  This is a data store level event generated following the
         successful completion of a delete-config operation.  This
         represents the deletion of a configuration file.

   o  edit-config event

      *  This is an event generated following a change in configuration
         due to an edit-config operation, e.g., due to the completion of
         an edit-config operation which successfully changed some part
         of the configuration.  See edit-config error-options (stop-on-
         error, ignore-error, rollback-on-error)  The contents of this
         event are dependent on the type of operation performed: edit-
         config (merge, replace, delete, create).  This event is not
         intended to report completely unsuccessful configuration
         operations.

   o  lock-config event

      *  This is a data store level event generated following the
         successful locking of a configuration data store.

   o  unlock-config event

      *  This is a data store level event generated following the
         successful release of a lock previously held on a configuration
         data store.

C.2  Config Event Notification Structure

   The table below lists the EventInfo parameters for a config event
   notification.

   Nomenclature:

   O - This is marked optional field because it is implementation/
   notification category dependent.  In some cases this may be user
   configurable.

   M - This is a mandatory field that must be included.  Dependency on
   event class may exist as noted below
    -----------------------------------------------------
              Parameter Name               Restrictions
    -----------------------------------------------------
               EventInfo
    -----------------------------------------------------
                EventID                          O
    -----------------------------------------------------
                ResourceInstance                 M
    -----------------------------------------------------
                ConfigChangeType                 M
    -----------------------------------------------------
                TargetDataStore                  M
    -----------------------------------------------------
                UserInfo                         O
    -----------------------------------------------------
                 UserName
    -----------------------------------------------------
                 SourceIndicator
    -----------------------------------------------------
                 TransactionId
    -----------------------------------------------------
                 CopyConfigInfo        -- copy-config only
    -----------------------------------------------------
                  DataSource                    M
    -----------------------------------------------------
                  EditConfigInfo        -- edit-config only
    -----------------------------------------------------
                  EventTime                     M
    -----------------------------------------------------
                  Context                       O
    -----------------------------------------------------
                  EnteredCommand                M
    -----------------------------------------------------
                  NewConfig                     M
    -----------------------------------------------------
                  MergeReplaceInfo
    -----------------------------------------------------
                  OldConfig                  O
    -----------------------------------------------------
                  EventTime                        M
    -----------------------------------------------------
                  EventGenerationTime
     -----------------------------------------------------
                  EventSysUpTime
    -----------------------------------------------------

C.3  Configuration Event Content

   The applicability of these fields to other event classes is for
   further study.

C.3.1  Target Datastore

   Target datastore refers to the data store (startup, candidate,
   running) which was modified by the management operation.

C.3.2  User Info

   This is used to convey information describing who originated the
   configuration event and the means for submitting the request.  The
   user info field contains the following information:

      user Name: User id which was authorized to execute the associated
      management operation causing the generation of this event.

      source Indicator: Indicates the method employed to initiate the
      management operation telnet, NETCONF, console, etc.

      transaction Id: If available, this field contains a unique
      identifier for the associated management operation.  This is
      implementation dependent and may require additional information to
      be communicated between server and client.  A possible option is
      to make use of the message-id in the NETCONF rpc header

C.3.3  Data Source

   The data source is used, for example, in the copy configuration
   command to indicated the source of information used in the copy
   operation

   Applicable Event Classes: configuration (useful for copy-config)

C.3.4  Operation

   Operation is used, for example, in the edit configuration command to
   indicated the specific operation that has taken place - create,
   delete, merge, replace.

   Applicable Event Classes: configuration (useful for edit-config)

C.3.5  Context

   The configuration sub-mode under which the command was executed.

   Applicable Event Classes: configuration

C.3.6  Entered Command

   The command entered and executed on the device.

C.3.7  New Config

   The device's configuration following the successful execution of the
   entered command.

   Applicable Event Classes: configuration

C.3.8  Old Config

   The configuration prior to the execution of the entered command.

   Applicable Event Classes: configuration

C.3.9  Non-netconf commands in configuration notifications

   To support legacy implementations and for better integration with
   other deployed solutions on the box, sending information via netconf
   about configuration changes that were originated via other solutions,
   such as command line interfaces is necessary.  In order to do this,
   the information in the message needs to be clearly tagged so that the
   consumer of the information knows what to expect.  In addition, the
   creation of the subscription needs allow for the client to indicate
   whether this non-XML formatted information is of interest

   The latter is done by identifying the XML namespace under which the
   data syntax/schema is defined.  A NETCONF client requests the format
   in which it wants the NETCONF server to issue the event notifications
   at subscription time by specifying the appropriate namespace under
   the Filter parameter in the  <create-subscription>  operation.  An
   example is provided below:

          <netconf:filter>
             <data-format:config-format-xml
                           xmlns="http://www.example.com/xmlnetevents"/>
          </netconf:filter>

Appendix D.  IP Address Schema

               <?xml version="1.0" encoding="UTF-8"?>
   <!--   IETF Netconf Working Group
       http://www.ietf.org/html.charters/netconf-charter.html
   -->
       <xs:schema elementFormDefault="qualified"
          attributeFormDefault="unqualified" version="0.2"
          xmlns:xs="http://www.w3.org/2001/XMLSchema"
          xmlns="urn:ietf:params:xml:ns:netmod:ipAddress:1.0"
          targetNamespace="urn:ietf:params:xml:ns:netmod:ipAddress:1.0">

           <xs:simpleType name = "ipV4Addr">
               <xs:annotation>
                   <xs:documentation>
                     An IP version 4 address in dotted notation decimal.
                     Example:  15.13.120.22
                   </xs:documentation>
               </xs:annotation>
               <xs:restriction base = "xs:string">
                   <xs:pattern value =
                      "[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"/>
               </xs:restriction>
           </xs:simpleType>

           <xs:simpleType name = "ipV6Addr">
               <xs:annotation>
                   <xs:documentation>
                       An IP version 6 address in colon separated 2 byte
                       block hexadecimal notation.
                       Example:  FEDC:AB19:12FE:0234:98EF:1178:8891:CAFF
                   </xs:documentation>
               </xs:annotation>
               <xs:restriction base = "xs:string">
                   <xs:pattern value =
                        "[0-9a-fA-F]{4}:[0-9a-fA-F]{4}:[0-9a-fA-F]{4}:
                         [0-9a-fA-F]{4}:[0-9a-fA-F]{4}:
                         [0-9a-fA-F]{4}:[0-9a-fA-F]{4}:[0-9a-fA-F]{4}"/>
               </xs:restriction>
           </xs:simpleType>

           <xs:complexType name="IPAddressOrSysname">
               <xs:choice>
                   <xs:element name="ipv4Address" type="ipV4Addr"/>
                   <xs:element name="ipv6Address" type="ipV6Addr"/>
                   <xs:element name="sysName" type="xs:string"/>
               </xs:choice>
           </xs:complexType>
       </xs:schema>

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