Network Working Group                                        S. Chisholm
Internet-Draft                                                    Nortel
Intended status: Standards Track                              H. Trevino
Expires: April 25, 2007                                            Cisco
                                                        October 22, 2006


                      NETCONF Event Notifications
                 draft-ietf-netconf-notification-04.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
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   This Internet-Draft will expire on April 25, 2007.

Copyright Notice

   Copyright (C) The Internet Society (2006).













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Abstract

   This document defines mechanisms which provide an asynchronous
   message notification delivery service for the NETCONF protocol.  This
   is an optional capability built on top of the base NETCONF
   definition.  This document defines the capabilities, operations,
   transport mappings, and data models necessary to support this
   service.


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
   2.  Notification-Related Operations  . . . . . . . . . . . . . . .  7
     2.1.  Subscribing to receive Event Notifications . . . . . . . .  7
       2.1.1.  <create-subscription>  . . . . . . . . . . . . . . . .  7
       2.1.2.  Filter Dependencies  . . . . . . . . . . . . . . . . .  8
     2.2.  Sending Event Notifications  . . . . . . . . . . . . . . .  8
       2.2.1.  <notification> . . . . . . . . . . . . . . . . . . . .  8
     2.3.  Terminating the Subscription . . . . . . . . . . . . . . .  9
   3.  Supporting Concepts  . . . . . . . . . . . . . . . . . . . . . 10
     3.1.  Capabilities Exchange  . . . . . . . . . . . . . . . . . . 10
     3.2.  Event Streams  . . . . . . . . . . . . . . . . . . . . . . 10
       3.2.1.  Event Stream Definition  . . . . . . . . . . . . . . . 11
       3.2.2.  Event Stream Content Format  . . . . . . . . . . . . . 11
       3.2.3.  Default Event Stream . . . . . . . . . . . . . . . . . 11
       3.2.4.  Event Stream Sources . . . . . . . . . . . . . . . . . 12
       3.2.5.  Event Stream Discovery . . . . . . . . . . . . . . . . 12
       3.2.6.  Event Stream Subscription  . . . . . . . . . . . . . . 15
     3.3.  Subscriptions not Configuration Data . . . . . . . . . . . 15
     3.4.  Querying Subscription Properties . . . . . . . . . . . . . 16
     3.5.  Filter Dependencies  . . . . . . . . . . . . . . . . . . . 20
       3.5.1.  Named Profiles . . . . . . . . . . . . . . . . . . . . 21
       3.5.2.  Filtering  . . . . . . . . . . . . . . . . . . . . . . 21
     3.6.  Message Flow . . . . . . . . . . . . . . . . . . . . . . . 21
   4.  XML Schema for Event Notifications . . . . . . . . . . . . . . 23
   5.  Mapping to Transport Protocols . . . . . . . . . . . . . . . . 25
     5.1.  SSH  . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
     5.2.  BEEP . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
       5.2.1.  One-way Notification Messages in Beep  . . . . . . . . 26
     5.3.  SOAP . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
       5.3.1.  A NETCONF over Soap over HTTP Example  . . . . . . . . 27
   6.  Filtering examples . . . . . . . . . . . . . . . . . . . . . . 30
     6.1.  Subtree Filtering  . . . . . . . . . . . . . . . . . . . . 30



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     6.2.  XPATH filters  . . . . . . . . . . . . . . . . . . . . . . 31
   7.  Notification Replay Capability . . . . . . . . . . . . . . . . 33
     7.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . 33
     7.2.  Dependencies . . . . . . . . . . . . . . . . . . . . . . . 33
     7.3.  Capability Identifier  . . . . . . . . . . . . . . . . . . 33
     7.4.  New Operations . . . . . . . . . . . . . . . . . . . . . . 34
     7.5.  Modifications to Existing Operations . . . . . . . . . . . 34
       7.5.1.  create-subscription  . . . . . . . . . . . . . . . . . 34
       7.5.2.  Interactions with Other Capabilities . . . . . . . . . 34
     7.6.  Replay Complete Notification . . . . . . . . . . . . . . . 34
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 36
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 37
   10. Normative References . . . . . . . . . . . . . . . . . . . . . 38
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39
   Intellectual Property and Copyright Statements . . . . . . . . . . 40




































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1.  Introduction

   [NETCONF] can be conceptually partitioned into four layers:

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


   This document defines mechanisms which provide an asynchronous
   message notification delivery service for the [NETCONF] protocol.
   This is an optional capability built on top of the base NETCONF
   definition.  This memo defines the capabilities, operations,
   transport mappings, and data models necessary to support this
   service.

                                 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 [RFC2119].

   Element:  An [XML] Element.

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

   Subscription:  A concept related to the delivery of notifications (if
      any to send) involving destination and selection of notifications.
      It is bound to the lifetime of a session.





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   Operation:  This term is used to refer to NETCONF protocol
      operations.  Specifically within this document, operation refers
      to NETCONF protocol operations defined in support of NETCONF
      notifications.

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 some event, outside the
   scope of this specification, causes the subscription to terminate.
   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.

   An NETCONF server is not required to process RPC requests on the
   session associated with the subscription until the notification
   stream is done.  A capability may be advertised to announce that a
   server is able to process RPCs while a notification stream is active
   on a session.

1.3.  Motivation

   The motivation for this work is to enable the sending of asynchronous
   messages that are consistent with the data model (content) and
   security model used within a Netconf implementation.

1.4.  Requirements

   The following requirements have been addressed by the solution:

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

   o  Data content must not preclude the use of the same data model as
      used in configuration



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   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 provide a subscription mechanism (A NETCONF server
      does not send notifications before asked to do so and the NETCONF
      client initiates the flow of notifications)

   o  solution should provide a filtering mechanism within the Netconf
      server

   o  solution should send sufficient information in a notification so
      that it can be analyzed independent of the transport mechanism
      (data content fully describes a notification; protocol information
      is not needed to understand a notification)

   o  solution should support replay of locally logged notifications

































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2.  Notification-Related Operations

2.1.  Subscribing to receive Event Notifications

   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.

   Content for an event notification subscription can be selected by
   applying user-specified filters.

2.1.1.  <create-subscription>

   Description:

      This operation initiates an event notification subscription which
      will send asynchronous event notifications to the initiator of the
      command until the NETCONF session terminates or some event,
      outside the scope of this specification, causes the subscription
      to terminate.

   Parameters:

      Streams:

         An optional parameter that indicates which stream(s) of events
         are of interest.  If not present, then events in the default
         NETCONF stream 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.

      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.  Note that changes to the profile
         after the subscription has been created will have no effect.






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      Start Time:

         A parameter used with the optional replay capability to signals
         that this is a replay subscription and that the replay should
         start at the time specified.  If start time is not present,
         this is not a replay subscription.  Stop time for replay is
         implicitly defined to be the time the create-subscription
         command was received by the Netconf server.

   Positive Response:

      If the NETCONF server can satisfy the request, the server sends 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 or stream is provided.

2.1.2.  Filter Dependencies

   When multiple filters are specified (in-line Filter, Named Profiles),
   they are applied collectively (i.e. logical AND operation).  That is,
   event notifications must pass all specified filters in order to be
   sent to the subscriber.

2.2.  Sending Event Notifications

   Once the subscription has been set up, the NETCONF server sends the
   event notifications asynchronously along the connection.

2.2.1.  <notification>

   Description:

      An event notification is sent to the initiator of a <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.  Note
      that <notification> is not an RPC method but rather the top level
      element identifying the one way message as a notification.

   Parameters:






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      Data:

         Contains notification-specific tagged content.

   Response:

      No response.  Not applicable.

2.3.  Terminating the Subscription

   Closing of the event notification subscription is done by terminating
   the Netconf session ( <kill-session> )or via some action outside the
   scope of this specification.






































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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:capability: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:capability:notification:1.0
          </capability>
       </capabilities>
     <session-id>4</session-id>
   </hello>


3.2.  Event Streams

   An event stream is defined herein as a set of event notifications
   matching some forwarding criteria.

   System components generate event notifications which are passed to a
   central component for classification and distribution.  The central
   component inspects each event notification and matches the event
   notification against the set of stream definitions.  When a match
   occurs, the event notification is considered to be a member of that
   event stream.  An event notification may be part of multiple event
   streams.

   When a NETCONF client subscribes to a given event stream, user-
   defined filters, if applicable, are applied to the event stream and
   matching event notifications are forwarded to the NETCONF server for
   distribution to subscribed NETCONF clients.






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   +----+
   | c1 |---+             available streams
   +----+   |    +---------+
   +----+   |    |central  |-> stream 1
   | c2 |   +--->|event    |-> stream 2    filter +-------+
   +----+   |    |processor|-> netconf stream --->|netconf|
    ...     |    |         |-> stream n           |server | see
   System   |    +---------+                      +-------+ below
   Components|        |                  //
    ...     |        |                 //
   +----+   |        |       (------------)
   | cn |---+        |       (notification)
   +----+            +-----> (  logging   )
                             (  service   )
                             (------------)



                +-------+     +-------+
                |netconf|<--->|netconf|
             -> |server |     |client |
                +-------+     +-------+


3.2.1.  Event Stream Definition

   Event streams are predefined on the managed device.  The
   configuration of event streams is outside the scope of this document.
   However, it is envisioned that event streams are either pre-
   established by the vendor (pre-configured) or user configurable (e.g.
   part of the device's configuration) or both.  Device vendors may
   allow event stream configuration via NETCONF protocol (i.e. edit-
   config operation)

3.2.2.  Event Stream Content Format

   The contents of all event streams made available to a NETCONF client
   (i.e. the notification sent by the NETCONF server) must be encoded in
   XML.

3.2.3.  Default Event Stream

   A NETCONF server implementation supporting the notification
   capability must support the "NETCONF" notification event stream.
   This stream contains all NETCONF XML event notifications supported by
   the NETCONF server.  The definition of the event notification and
   their contents for this event stream is outside the scope of this
   document.



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3.2.4.  Event Stream Sources

   With the exception of the default event stream (NETCONF
   notifications) specification of additional event stream sources (e.g.
   SNMP, syslog, etc.) is outside the scope of this document.  NETCONF
   server implementations may leverage any desired event stream source
   in the creation of supported event streams.

3.2.5.  Event Stream Discovery

   A NETCONF client retrieves the list of supported event streams from a
   NETCONF server using the <get> RPC request.

3.2.5.1.  Name Retrieval using <get> operation

   The list of available event streams is retrieved by requesting the
   <eventStreams> subtree via a <get>operation.  Available event streams
   for the requesting session are returned in the reply containing
   <name> and <description> elements, where <name> element is mandatory
   and its value is unique [Editor's Note: should we then define it as a
   key?].  The returned list must only include the names of those event
   streams for which the NETCONF sessions has sufficient privileges.
   The NETCONF session privileges are determined via access control
   mechanisms which are beyond the scope of this document.  An empty
   reply is returned if there are no available event streams.


























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   Retrieving available event stream list using <get> operation:


   <rpc message-id="101"
      xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">

     <get>
      <filter type="subtree">
          <top xmlns="urn:ietf:params:xml:ns:netmod:base:1.0">
            <eventStreams/>
         </top>
       </filter>
     </get>
   </rpc>


   <rpc-reply message-id="101"
                    xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <data>
       <top ="urn:ietf:params:xml:ns:netmod:base:1.0">
           <eventStreams>
             <stream>
                <name>NETCONF</name>
                <description>Default netconf event stream
                </description>
             </stream>
             <stream>
               <name>snmp</name>
                 <description>SNMP notifications</description>
             </stream>
             <stream>
               <name>syslog-critical</name>
               <description>Critical and higher severity
               </description>
             </stream>
           </eventStreams>
       </top>
     </data>
   </rpc-reply>


3.2.5.2.  Device Supported Event Streams (System)

   The list of all event streams configured on a device may be retrieved
   over a NETCONF session with sufficient privileges (e.g.
   administrator).  The information is retrieved by requesting the
   <eventStreams> subtree via a <get> operation.




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3.2.5.3.  Stream Retrieval Schema


   <?xml version="1.0" encoding="UTF-8"?>
   <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"
          elementFormDefault="qualified"
                    attributeFormDefault="unqualified">
     <xs:annotation>
       <xs:documentation xml:lang="en">
                        Schema for event streams
            </xs:documentation>
       <xs:appinfo>
         <nm:identity
              xmlns:nm="urn:ietf:params:xml:ns:netmod:base:1.0">
           <nm:Name>
                    NetconfNotificationSchema
           </nm:Name>
           <nm:LastUpdated>
                    2006-09-06T09:30:47-05:00
           </nm:LastUpdated>
           <nm:Organization>IETF
           </nm:Organization>
           <nm:Description>
                     A schema that can be used to learn about current
                     event streams.
                  </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:base:1.0"
              schemaLocation="./draft-ietf-netconf-prot-12.xsd"/>


     <xs:element name="eventStreams">
       <xs:annotation>
         <xs:documentation>
              The list of event streams supported by the system.
              When a query is issued, the returned set of streams is
             determined based on user privileges
        </xs:documentation>
       </xs:annotation>
       <xs:complexType>
         <xs:sequence maxOccurs="unbounded">



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           <xs:element name="stream">
             <xs:annotation>
               <xs:documentation>
                Stream name and description
                </xs:documentation>
             </xs:annotation>
             <xs:complexType>
               <xs:sequence>
                 <xs:element name="name" type="xs:string"/>
                 <xs:element name="description" type="xs:string"/>
               </xs:sequence>
             </xs:complexType>
           </xs:element>
         </xs:sequence>
       </xs:complexType>
     </xs:element>
   </xs:schema>


3.2.6.  Event Stream Subscription

   A NETCONF client may request from the NETCONF server the list of
   available event streams to this session and then issue a <create-
   subscription> request with the desired event stream name.  Omitting
   the event stream name from the <create-subscription> request results
   in subscription to the default NETCONF event stream.

3.2.6.1.  Filtering Event Stream Contents

   The set of event notifications delivered in an event stream may be
   further refined by applying a user-specified filter at subscription
   creation time ( <create-subscription> ).  This is a transient filter
   associated with the event notification subscription and does not
   modify the event stream configuration.

3.2.6.2.  Subscription to Multiple Event Streams

   Multiple event streams may be configured on a device and a NETCONF
   client may subscribe to one or more of the available event streams.

3.3.  Subscriptions not Configuration Data

   While it is possible to retrieve information about subscriptions via
   a get operation, subscriptions are not stored configuration.  They
   are non-persistent state information.  In this respect, they are
   comparable to NETCONF sessions.

   Named profiles, if used, are considered configuration data.



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3.4.  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>NetconfNotificationSchema</nm:Name>
               <nm:LastUpdated>2006-09-13T09:30:47-05:00
               </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:notification:1.0"
           schemaLocation=
             "urn:ietf:params:xml:ns:netconf:notification:1.0"/>
        <xs:import namespace="urn:ietf:params:xml:ns:netconf:base:1.0"
           schemaLocation="urn:ietf:params:xml:ns:netconf:base:1.0"/>

        <!-- Associations -->

        <xs:element name="associatedNamedProfile" type="xs:string"/>




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        <xs:element name="relationships">
        <xs:keyref name="subscriptionToNamedProfile"
             refer="nsub:namedProfileKey">
            <xs:selector xpath=".//netconfSubscription"/>
            <xs:field xpath="nsub:associatedNamedProfile"/>
        </xs:keyref>

        <!-- Keys -->

        <xs:key name="namedProfileKey">
            <xs:selector xpath=".//namedProfile"/>
            <xs:field xpath="name"/>
        </xs:key>
        </xs:element>

        <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 >

                 <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="streams"
                      type="ncEvent:StreamsList"  minOccurs="0">
                   <xs:annotation>
                     <xs:documentation xml:lang="en">
                       A list of event streams associated with this
                       subscription.
                     </xs:documentation>
                   </xs:annotation>
                </xs:element>

                 <xs:element name="filter"
                      type="netconf:filterInlineType"  minOccurs="0">
                   <xs:annotation>



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                     <xs:documentation xml:lang="en">
                       The filters associated with this subscription.
                     </xs:documentation>
                   </xs:annotation>
                 </xs:element>



                 <xs:element ref="nsub:associatedNamedProfile"
                                                       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: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:unsignedInt" 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="key">
                     <xs:key name="uniqueSubscription">
                        <xs:selector xpath=".//subscription"/>
                        <xs:field xpath="session-id"/>
                     </xs:key>
                  </xs:element>



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              </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="streams"
                        type="ncEvent:streamsList"  minOccurs="0">
                      <xs:annotation>
                         <xs:documentation xml:lang="en">
                            The event streams associated with this named
                            profile.
                          </xs:documentation>
                       </xs:annotation>
                     </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">



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                      <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: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>


3.5.  Filter Dependencies

   Note that when multiple filters are specified (in-line Filter, Named
   Profiles), they are applied collectively, so event notifications need
   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



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   configuration event notification where this field was not supported,
   then the notification would be filtered out.

   Note that the order that filters are applied does not matter since
   the resulting set of notifications is the intersection of the set of
   notifications that pass each filtering criteria.

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 .  Note
   that changes to the profile after the subscription has been created
   will have no effect on the subscription.  Since named profiles exist
   outside of the subscription, they persist after the subscription has
   been torn down.

3.5.2.  Filtering

   Just-in-time filtering is explicitly stated when the event
   notification subscription is created.  This is specified via the
   Filter parameter.  Filters only exist as parameters to the
   subscription.

3.6.  Message Flow



























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   The following figure depicts message flow between a Netconf client
   (C) and Netconf server (S) in order create a subscription and begin
   the flow of notifications.


                             C                           S
                             |                           |
                             |  capability exchange      |
                             |-------------------------->|
                             |<------------------------->|
                             |                           |
                             |  <create-subscription>    |
                             |-------------------------->|
                             |<--------------------------|
                             |     <rpc-reply>           |
                             |                           |
                             |     <notification>        |
                             |<--------------------------|
                             |                           |
                             |     <notification>        |
                             |<--------------------------|
                             |                           |
                             |                           |
                             |                           |
                             |     <notification>        |
                             |<--------------------------|
                             |                           |
                             |                           |























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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:complexType name="StreamsList">
          <xs:annotation>
            <xs:documentation>
              A list of event streams.
            </xs:documentation>
          </xs:annotation>
          <xs:sequence>
             <xs:element name="stream" maxOccurs="unbounded"/>
          </xs:sequence>
         </xs:complexType>

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

        <!-- <create-subscription> operation -->

        <xs:complexType name="createSubscriptionType">



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          <xs:complexContent>
            <xs:extension base="netconf:rpcOperationType">
              <xs:sequence>
                 <xs:element name="streams"
                     type="StreamsList" minOccurs="0"/>
                <xs:element name="filter"
                     type="netconf:filterInlineType" minOccurs="0"/>
                <xs:element name="named-profile"
                            type="xs:string" minOccurs="0"/>
                <xs:element name="startTime" type="xs:dateTime"
                        minOccurs="0" />
              </xs:sequence>
            </xs:extension>
          </xs:complexContent>
        </xs:complexType>

        <xs:element name="create-subscription"
                    type="createSubscriptionType"
                    substitutionGroup="netconf:rpcOperation"/>


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

        <!-- <Event> operation -->
        <xs:complexType name="NotificationType">
           <xs:sequence>
             <xs:element name="data" type="netconf:dataInlineType" />
           </xs:sequence>
        </xs:complexType>

        <xs:element name="notification" type="NotificationType"/>

     </xs:schema>


















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5.  Mapping to Transport Protocols

   Currently, the NETCONF family of specification allows for running
   NETCONF over a number of 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 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.  In the example below the event notification
   contents (delimited by <data> </data> tags) are not defined in this
   document and are provided herein simply for illustration purposes.
   The sample notification shows a configuration change on the running
   configuration as a result of an <edit-config> operation.  It has one
   containment node ( <interfaces> ), with one element <interface> and
   two changed attributes (<name> and <mtu>) (Note that this does not
   refer to XML attributes).  The same example is used in the BEEP and
   SOAP transport mapping sections.















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







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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"

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' [RFC3080].

   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>



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   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:         </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:       <data>
   S:      <eventClasses><configuration/><audit/></eventClasses>
   S:      <sequenceNumber>2</sequenceNumber>
   S:           <dateAndTime>2000-01-12T12:13:14Z</dateAndTime>
   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:                   <interfaces>
                          <interface>
   S:                       <name>Ethernet0/0</name>



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   S:                       <mtu>1500</mtu>
                         </interface>
   S:                  </interfaces>
   S:               </top>
   S:            </config>
   S:           </edit-config>
   S:         </operation>
   S:       </data>
   S:    </notification>
   S:   </soapenv:Body>
   S: </soapenv:Envelope>








































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6.  Filtering examples

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

6.1.  Subtree Filtering

   XML subtree filtering is not well suited for creating elaborate
   filter definitions given that it only supports equality comparisons
   and logical OR operations (e.g. in an 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
   event notification forwarding filters as shown below.

   In order to illustrate the use of filter expressions it is necessary
   to assume some of the event notification content (only for example
   purposes).  The examples herein assume that the event notification
   schema definition has an <eventClasses> element identifying the event
   category (e.g. fault, state, config, etc.) and events have a
   <severity> element

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

   ((severity=critical) | (severity=major) | (severity=minor))


   <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      <create-subscription
               xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
        <filter type="subtree">
           <event xmlns="http://example.com/event/1.0">
              <severity>critical</severity>
           </event>
           <event xmlns="http://example.com/event/1.0">
              <severity>major</severity>
           </event>
           <event xmlns="http://example.com/event/1.0">
              <severity>minor</severity>
           </event>
       </netconf:filter>
     </create-subscription>
   </rpc>






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   The following example illustrates selecting fault, state, config
   EventClasses or events which are related to card Ethernet0.  The
   filtering criteria evaluation is as follows:

   (fault | state | config | card=Ethernet0)


   <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      <create-subscription>
         <netconf:filter type="subtree">
            <top
                xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
              <event>
                 <eventClasses>fault</eventClasses>
              </event>
              <event>
                 <eventClasses>state</eventClasses>
              </event>
              <event>
                 <eventClasses>config</eventClasses>
              </event>
              <event>
                 <card>Ethernet0</card>
              </event>
            </top>
         </netconf:filter>
      </create-subscription>
   </rpc>


6.2.  XPATH filters

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

   ((fault) & ((severity=critical) | (severity=major) | (severity =
   minor)))












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   <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
      <create-subscription>
         <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 and 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:notification:1.0">
      <create-subscription>
         <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>













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7.   Notification Replay Capability

7.1.  Overview

   Replay is the ability to create an event subscription that will
   resend recently sent notifications.  These notifications are sent the
   same way as normal notifications.

   A replay of notifications is specified by including an optional
   parameter to the subscription command that indicates the start time
   of the replay.  The end time of the replay is implicitly defined to
   be the time the replay request was initiated.

   An implementation that supports replay is not expected to have an
   unlimited supply of saved notifications available to accommodate any
   replay request.  If a client requests a replay of notifications that
   predate the oldest notification available, then the NETCONF server
   must return a warning message in the RPC reply and start replaying
   the notifications it does have available, within the other
   constraints, such as filtering, that the client has provided.  The
   warning message enables the NETCONF client to differentiate between
   the case that there were no notifications generated within a given
   time period from the case that no notifications are currently in the
   log from that period.

   The actual number of stored notifications available for retrieval at
   any given time is an NETCONF server implementation specific matter.
   Control parameters for this aspect of the feature are outside the
   scope of the current work.

   A given subscription is either a replay subscription or a normal
   subscription, which sends event notifications as they happen.  A
   replay subscription terminates once the it has completed replaying
   past events.

7.2.  Dependencies

   This capability is dependent on the notification capability being
   supported.  It also requires that the device supporting the Netconf
   server also support some form of notification logging, although it
   puts no restrictions on the size or form of the log, nor where it
   resides within the device.

7.3.  Capability Identifier

   The Event Notification Replay capability is identified by following
   capability string:




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   http://ietf.org/netconf/notificationReplay/1.0

7.4.  New Operations

   None

7.5.  Modifications to Existing Operations

7.5.1.  create-subscription

   This capability adds an optional parameter to the <create-
   subscription> command called 'startTime'.  This identifies the
   earliest date and time of interest for event notifications being
   replayed.  Events generated before this time are not matched.

   Note that while a notification has three potential times associated
   it - the time it was generated, the time it was logged and the time
   it was sent out by the NETCONF server - the startTime parameter is
   related to generation time.

   Negative Response:

      An <rpc-error> element is included in the <rpc-reply> if the
      startTime in replay request predates the oldest notification
      available to be replayed.

         Error-tag: start-time-value

         Error-type: protocol

         Error-severity: warning

         Error-info: none

         Error-message: Start time predates oldest available
         notification to be replayed

7.5.2.  Interactions with Other Capabilities

   [Edtitor's Note: If this capability does not interact with other
   capabilities, this section may be omitted.]

7.6.  Replay Complete Notification

   The following notification is the last notification sent over a
   replay subscription.  It indicates that replay is complete.





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 <?xml version="1.0" encoding="UTF-8"?>
 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
     xmlns="urn:ietf:params:xml:ns:netconf:replayNotification:1.0"
     targetNamespace=
             "urn:ietf:params:xml:ns:netconf:replayNotification:1.0">

     <xs:element name="replayCompleteNotification" >
         <xs:annotation>
           <xs:documentation>
             This notification is sent to signal the end of a replay
             subscription.
           </xs:documentation>
         </xs:annotation>
       <xs:complexType>
           <xs:sequence>
             <xs:element name="eventClass" default="informational">
                 <xs:annotation>
                    <xs:documentation>
                        The event classification of this notification.
                    </xs:documentation>
                 </xs:annotation>
             </xs:element>
             <xs:element name="timeGenerated" type="xs:dateTime"/>
             <xs:element name="numberEventsReplayed" type="xs:integer"/>
          </xs:sequence>
       </xs:complexType>
    </xs:element>
 </xs:schema>























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8.  Security Considerations

   The access control framework and the choice of transport will have a
   major impact on the security of the solution.

   Note that the <notification> elements are never sent before the
   transport layer and the netconf layer (capabilities exchange) have
   been established, and the manager has been identified and
   authenticated.

   It is recommended that care be taken to ensure the secure operation
   of the following commands:

   o  <create-subscription> invocation

   o  use of <kill-session>

   o  read-only data models

   o  read-write data models

   o  notification content

   One issue related to the notifications draft is the transport of data
   from non-netconf streams, such as syslog and SNMP.  Note that this
   data may be more vulnerable (or is not more vulnerable) when being
   transported over netconf than when being transported using the
   protocol normally used for transporting it, depending on the security
   credentials of the two subsystems.






















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9.  Acknowledgements

   Thanks to Gilbert Gagnon, Greg Wilbur and Kim Curran 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 Balestriere,
   Yoshifumi Atarashi, Glenn Waters, Alexander Clemm, Dave Harrington,
   Dave Partain, Ray Atarashi and Dave Perkins and the following
   additional people from the Montreal editing session: Balazs Lengyel,
   Phil Shafer, Rob Ennes, Andy Bierman, Dan Romascanu, Bert Wijnen,
   Simon Leinen, Juergen Schoenwaelder, Hideki Okita, Vincent Cridlig,
   Martin Bjorklund, Olivier Festor, Radu State, Brian Trammell, William
   Chow






































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10.  Normative 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.

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

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

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

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

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

   [XML Schema]
              Fallside, D. and P. Walmsley, "XML Schema Part 0: Primer
              Second Edition", W3C XML Schema, October 2004.







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Authors' Addresses

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

   Email: schishol@nortel.com


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

   Email: htrevino@cisco.com
































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Full Copyright Statement

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