NETCONF                                               A. Gonzalez Prieto
Internet-Draft                                             Cisco Systems                                                    VMWare
Intended status: Standards Track                                A. Clemm
Expires: November 2, December 9, 2017                                         Huawei
                                                                 E. Voit
                                                       E. Nilsen-Nygaard
                                                             A. Tripathy
                                                           Cisco Systems
                                                             S. Chisholm
                                                                   Ciena
                                                              H. Trevino
                                                           Cisco Systems
                                                             May 1,
                                                            June 7, 2017

                NETCONF Support for Event Notifications
           draft-ietf-netconf-netconf-event-notifications-02
           draft-ietf-netconf-netconf-event-notifications-03

Abstract

   This document defines the support how to transport network subscriptions and
   event messages on top of [event-notifications] by the Network Configuration protocol
   (NETCONF). [event-notifications]
   describes capabilities  This includes the full set of RPCs, subscription state
   changes, and operations for providing asynchronous message notification payloads needing asynchronous delivery.  This document discusses how to
   provide them on top of NETCONF.  The
   capabilities and operations defined between in this document and [event-notifications] used in
   conjunction with [subscribe] are intended to obsolete RFC 5277. [RFC5277].  In
   addition, the capabilities within those two documents along with
   [yang-push] are intended to enable an extract of a YANG datastore on
   a remote device.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on November 2, December 9, 2017.

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

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Solution Overview . . . . . . . . . . . . . . . . . . . .   5
   2.   3
   3.  Solution  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Event Streams . . . . . . . . . . . . . . . . . . . . . .   6
     2.2.   3
     3.1.  Event Stream Discovery  . . . . . . . . . . . . . . . . .   6
     2.3.  Default Event Stream  . . . . . . . . . . . . . .   3
     3.2.  Mandatory NETCONF support for Streams and Datastores  . .   4
     3.3.  Dynamic Subscriptions . .   9
     2.4.  Creating a Subscription . . . . . . . . . . . . . . . .   4
     3.4.  Configured Subscriptions  .   9
     2.5.  Establishing a Subscription . . . . . . . . . . . . . . .  11
     2.6.  Modifying a Subscription  . . . . . . . . . . . . . . . .  16
     2.7.  Deleting a Subscription . . . . . . . . . . . . . .
   4.  Security Considerations . . .  21
     2.8.  Configured Subscriptions . . . . . . . . . . . . . . . .  24
     2.9.  Event (Data Plane) Notifications  . . . . . . . . .
   5.  Acknowledgments . . .  33
     2.10. Control Plane Notifications . . . . . . . . . . . . . . .  35
   3.  Backwards Compatibility . . . . .  25
   6.  References  . . . . . . . . . . . . . .  44
     3.1.  Capabilities . . . . . . . . . . .  25
     6.1.  Normative References  . . . . . . . . . . .  44
     3.2.  Stream Discovery . . . . . . .  25
     6.2.  Informative References  . . . . . . . . . . . . .  45
   4.  Security Considerations . . . .  26
   Appendix A.  Changes between revisions  . . . . . . . . . . . . .  26
     A.1.  v01 to v03  . .  45
   5.  Acknowledgments . . . . . . . . . . . . . . . . . . . . .  26
     A.2.  v00 to v01  . .  46
   6.  References . . . . . . . . . . . . . . . . . . . . .  26
   Authors' Addresses  . . . .  46
     6.1.  Normative References . . . . . . . . . . . . . . . . . .  46
     6.2.  Informative References . . . . . . . . . . . . . . . . .  47
   Appendix A.  Issues that are currently being worked . . . . . . .  47
   Appendix B.  Changes between revisions  . . . . . . . . . . . . .  47
     B.1.  v00 to v01  . . . . . . . . . . . . . . . . . . . . . . .  47
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  47  27

1.  Introduction

   [RFC6241] can be conceptually partitioned into four layers:

             Layer                 Example
        +-------------+      +-----------------+      +----------------+
    (4) |   Content   |      |  Configuration  |      |  Notification  |
        |             |      |      data       |      |      data      |
        +-------------+      +-----------------+      +----------------+
               |                       |                      |
        +-------------+      +-----------------+              |
    (3) | Operations  |      |  <edit-config>  |              |
        |             |      |                 |              |
        +-------------+      +-----------------+              |
               |                       |                      |
        +-------------+      +-----------------+      +----------------+
    (2) |  Messages   |      |     <rpc>,      |      | <notification> |
        |             |      |   <rpc-reply>   |      |                |
        +-------------+      +-----------------+      +----------------+
               |                       |                      |
        +-------------+      +-----------------------------------------+
    (1) |   Secure    |      |       SSH, TLS, SOAP/HTTP/TLS, ...      |
        |  Transport  |      |                                         |
        +-------------+      +-----------------------------------------+

                   Figure 1: NETCONF layer architecture

   This document defines mechanisms that provide an asynchronous message
   notification delivery service for the NETCONF protocol [RFC6241]
   based on [event-notifications]. [subscribe].  This is an optional capability built on top of
   the base NETCONF definition.

   [event-notifications] and

   [subscribe] plus this transport specification document enhance the capabilities of
   RFC 5277 while maintaining backwards capability with existing
   implementations.  It is intended that provides a final version
   superset of this
   document might obsolete the capabilities previously defined in [RFC5277].  The enhancements  Newly
   introduced capabilities include the ability to terminate subscriptions without terminating the client
   session, to modify existing subscriptions, and to have multiple
   subscriptions on a single NETCONF session.  [RFC5277] clients that do not
   require these enhancements are not affected by them.

   [event-notifications] covers session, the following functionality:

   o  Ability to subscribe ability to event notifications using two mechanisms:
      dynamic terminate
   subscriptions without terminating the client session, and configuration subscriptions.

   o  Ability to subscribe the ability
   to event notifications using two mechanisms:
      dynamic and configuration modify existing subscriptions.

   o  Ability to negotiate acceptable subscription parameters.

   o  Ability to filter

   In addition, [yang-push] plus the subset capabilities of notifications to be pushed with
      stream-specific semantics.

   o  Ability to support multiple encodings for the notification.

   o  Mechanism to communicate the notifications.

   o  Ability to replay locally logged notifications.

   To support this functionality, NETCONF agents must implement the
   operations, configuration and operational state defined in
   [event-notifications].  In addition, they need to:

   o  support multiple subscriptions over document
   provide a mechanism for a single NETCONF session.

   o  support client to maintain a revised definition subset/extract
   of the default NETCONF stream

   o  be backwards compatible with RFC 5277 implementations.

1.1. an actively changing YANG datastore.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

1.1.1.  NETCONF

   The following terms are defined in [RFC6241] :

   o  Client

   o  Server

   o  Operation

   o  RPC: remote procedure call

1.1.2.  Event Notifications [RFC6241]: client, server,
   operation, RPC.

   The following terms are defined in [event-notifications]:

   o  Event

   o  Event notification

   o  Stream (also referred to as "event stream")
   o  Subscriber

   o  Publisher

   o  Receiver

   o  Subscription

   o  Filter

   o  Dynamic subscription

   o  Configured subscription [subscribe]: event, event
   notification, stream, publisher, receiver, subscriber, subscription,
   configured subscription.

   Note that a publisher in [event-notifications] [subscribe] corresponds to a server in
   [RFC6241].  Similarly, a subscribers subscriber corresponds to a client.  A
   receiver is also a client.  In the remainder of this document, we
   will use the terminology in [RFC6241].

1.1.3.  NETCONF Access Control

   The following terms are defined in [RFC6536] :

   o  NACM: NETCONF Access Control Model

1.2.  Solution Overview

   [event-notifications] defines mechanisms that provide an asynchronous
   message notification delivery service.  This document discusses its
   realization on top of the NETCONF protocol [RFC6241].

   The functionality [RFC6241] to support is defined in [event-notifications].  It
   is formalized in a set of yang models.  The mapping of yang
   constructs into NETCONF is described in [RFC6020].

   Supporting [event-notifications] requires enhancements and
   modifications in NETCONF.  The key enhacement is suporting multiple
   subscriptions on a NETCONF session.  A key modification is the
   definition of the simplify [subscribe]'s
   mental mappings to embedded NETCONF stream.

   These enhancements do not affect [RFC5277] clients that do not
   support [event-notifications].

2. terminology.

3.  Solution

   In this section, we describe and exemplify how [event-notifications]
   must [subscribe] is to be
   supported over NETCONF.

2.1.

3.1.  Event Streams Stream Discovery

   In the context of NETCONF, [subscribe] an event stream is exposes a continuous
   set of events available for subscription subscription.  A NETCONF client can
   retrieve the list of available event streams from a NETCONF server
   using the "get" operation.  The reply contains the elements defined
   in the YANG model under the container "/streams", which includes the
   stream identities supported on the NETCONF server.  It is out

   The following example illustrates the retrieval of the
   scope list of this document to identify a) how streams are defined, b) how
   events are defined/generated, and c) how events are assigned to
   streams.

   The following is a high-level description of the flow of a
   notification.  Note that it does not mandate and/or preclude an
   implementation.  As events are raised, they are assigned to streams.
   An event may be assigned to multiple streams.  The event is
   distributed to subscribers and receivers based on the current
   subscriptions and access control.  Access control is needed because
   if any receiver of that subscription does not have permission to
   receive an event, then it never makes it into a notification, and
   processing of the event is completed for that subscription.

2.2.  Event Stream Discovery

   A NETCONF client can retrieve the list of available event streams
   from a NETCONF server using the <get> operation.  The reply contains
   the elements defined in the YANG model under the container
   "/streams", which includes the stream identifier.

   The following example ilustrates the retrieval of the list of
   available event
   available event streams using the <get> operation.

    <rpc message-id="101"
           xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
      <get>
        <filter type="subtree">
          <streams
          xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications"/>
          </filter>
      </get>
    </rpc>

                           Figure 2: 1: Get streams

   The NETCONF server returns a list of event streams available for
   subscription. available.  In
   this example, the list contains the NETCONF, SNMP, and syslog-critical SYSLOG
   streams.

    <rpc-reply message-id="101"
            xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
      <data>
        <streams
           xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications">
          <stream>NETCONF</stream>
          <stream>SNMP</stream>
         <stream>syslog-critical</stream>
         <stream>NETCONF</stream>
          <stream>SYSLOG</stream>
          </streams>
      </data>
    </rpc-reply>

                      Figure 3: 2: Get streams response

2.2.1.  Backwards Compatibility

   In order

   For [yang-push], a similar get is needed to maintain backwards compatibility, clients that only
   support [RFC5277] can retrieve the list of available event streams
   executing a <get> operation against the container "/netconf/streams".

   The following example ilustrates this mechanism.

   <rpc message-id="101"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <get>
       <filter type="subtree">
         <netconf
               xmlns="urn:ietf:params:xml:ns:netmod:notification">
           <streams/>
         </netconf>
       </filter>
     </get>
   </rpc>

              Figure 4: Get streams (backwards compatibility)

   The
   datastore names.

3.2.  Mandatory NETCONF server returns a list of event streams available support for
   subscription.  In this example, the list contains the NETCONF, SNMP, Streams and syslog-critical streams.

   <rpc-reply message-id="101"
           xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <data>
       <netconf
               xmlns="urn:ietf:params:xml:ns:netmod:notification">
         <streams>
           <stream>
             <name>
               NETCONF
             </name>
             <description>
               default NETCONF event stream
             </description>
             <replaySupport>
               true
             </replaySupport>
             <replayLogCreationTime>
               2016-02-05T00:00:00Z
             </replayLogCreationTime>
           </stream>
           <stream>
             <name>
               SNMP
             </name>
             <description>
               SNMP notifications
             </description>
             <replaySupport>
               false
             </replaySupport>
           </stream>
           <stream>
             <name>
               syslog-critical
             </name>
             <description>
               Critical and higher severity
             </description>
             <replaySupport>
               true
             </replaySupport>
             <replayLogCreationTime>
               2007-07-01T00:00:00Z
             </replayLogCreationTime>
           </stream>
         </streams>
       </netconf>
     </data>
   </rpc-reply>

         Figure 5: Get streams response (backwards compatibility)

2.3.  Default Event Stream Datastores

   A NETCONF server implementation supporting the notification
   capability MUST [subscribe] must support
   the "NETCONF" notification event stream.
   This stream contains all

   A NETCONF XML event notifications supported by server implementation supporting [yang-push] must support
   the NETCONF server, except for those belonging only to streams that
   explicitly indicate that they must be excluded from the NETCONF
   stream. "running" datastore.

3.3.  Dynamic Subscriptions

3.3.1.  Establishing Dynamic Subscriptions

   The exact string "NETCONF" is used during the advertisement
   of stream support during the <get> operation on <streams> and during
   the <create-subscription> dynamic subscription RFC and <establish-subscription> operations.

2.4.  Creating a Subscription

   This interactions operation was fully is defined in [RFC5277].

2.4.1.
   [subscribe].

3.3.1.1.  Usage Example

   The following demonstrates dynamically creating a subscription.

   An example of interactions over NETCONF transport for one sample
   subscription is below:

     <netconf:rpc message-id="101" netconf:message-id="102"
            xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <create-subscription
           xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
     </create-subscription>
       <establish-subscription
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
          <stream>NETCONF</stream>
          <filter-type>xpath</filter-type>
          <filter> xmlns:ex="http://example.com/event/1.0"
                  select="/ex:event[ex:eventClass='fault' and
                           (ex:severity='minor' or ex:severity='major'
                            or ex:severity='critical')]"
          </filter>
       </establish-subscription>
     </netconf:rpc>

               Figure 6: Create subscription

2.4.2. 3: establish-subscription over NETCONF

3.3.1.2.  Positive Response

   If the NETCONF server can satisfy the request, the server sends an
   <ok> element.

   <netconf:rpc netconf:message-id="102"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <create-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
       <filter netconf:type="xpath"
                   xmlns:ex="http://example.com/event/1.0"
                select="/ex:event[ex:eventClass='fault' a
   positive <subscription-result> element, and
                         (ex:severity='minor' or ex:severity='major'
                          or ex:severity='critical')]"/>
     </create-subscription>
   </netconf:rpc> the subscription-id of
   the accepted subscription.

      <rpc-reply message-id="102"
             xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <ok/>
        <subscription-result
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
          ok
        </subscription-result>
        <identifier
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
          52
        </identifier>
      </rpc-reply>

                Figure 7: 4: Successful create subscription

2.4.3. establish-subscription

3.3.1.3.  Negative Response

   If the request NETCONF server cannot be completed for any reason, an <rpc-error>
   element is included within satisfy the <rpc-reply>.  Subscription requests
   can fail for several reasons including if a filter with invalid
   syntax is provided request, or if client has no
   authorization to establish the name of a non-existent stream is
   provided.

   If a stopTime is specified in a request without having specified a
   startTime, subscription, the following error is returned:

   Tag: missing-element
   Error-type: protocol
   Severity: error
   Error-info: <bad-element>: startTime
   Description: An expected element is missing. server will send a
   negative <subscription-result> element.  For instance:

     <rpc-reply message-id="103"
            xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <subscription-result
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
         stream-unavailable
       </subscription-result>
     </rpc-reply>

               Figure 8: Create 5: Unsuccessful establish subscription missing an element

   If the optional replay feature is requested but client requests parameters the NETCONF server
   does not support it, cannot serve,
   the negative <subscription-result> may include additional
   information.  For instance, consider the following error is returned:

   Tag: operation-failed
   Error-type: protocol
   Severity: error
   Error-info: none
   Description: Request could not be completed because subscription from
   [yang-push], which augments the
                requested operation failed for establish-subscription with some reason
                not covered by any other error condition.

              Figure 9: Create subscription operation failed
   additional parameters, including "period".  If the client requests a stopTime is requested that is earlier than
   which period the specified
   startTime, NETCONF server cannot serve, the following error is returned:

   Tag: bad-element
   Error-type: protocol
   Severity: error
   Error-info: <bad-element>: stopTime
   Description: An element value is not correct;
                e.g., wrong type, out of range, pattern mismatch.

             Figure 10: Create subscription incorrect stopTime

   If a startTime is requested that is later than the current time, the
   following error is returned:

   Tag: bad-element
   Error-type: protocol
   Severity: error
   Error-info: <bad-element>: startTime
   Description: An element value is not correct;
                e.g., wrong type, out of range, pattern mismatch. back-and-forth
   exchange may be:

    <netconf:rpc message-id="101"
             xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
      <establish-subscription
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
        <stream>push-update</stream>
     <filter-type>subtree</filter-type>
            <filter>xmlns:ex="http://example.com/sample-data/1.0"
                        select="/ex:foo"</filter>
        <period xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
          500
        </period>
        <encoding>encode-xml</encoding>
      </establish-subscription>
    </netconf:rpc>

    <rpc-reply message-id="101"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
      <subscription-result
            xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
        error-insufficient-resources
      </subscription-result>
      <period
            xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
        2000
      </period>
    </rpc-reply>

             Figure 11: Create 6: Subscription establishment negotiation

3.3.1.4.  Message Flow Examples

   +------------+                 +-----------+
   |   Client   |                 |   Server  |
   +------------+                 +-----------+
         |                              |
         |    Capability Exchange       |
         |<---------------------------->|
         |                              |
         |                              |
         |    Establish Subscription    |
         |----------------------------->|
         | RPC Reply: OK, id = 22       |
         |<-----------------------------|
         |                              |
         |  Notification (id 22)        |
         |<-----------------------------|
         |                              |
         |                              |
         |    Establish Subscription    |
         |----------------------------->|
         | RPC Reply: OK, id = 23       |
         |<-----------------------------|
         |                              |
         |                              |
         |  Notification (id 22)        |
         |<-----------------------------|
         |  Notification (id 23)        |
         |<-----------------------------|
         |                              |
         |                              |

   Figure 7: Multiple subscription incorrect startTime

2.5.  Establishing establishments over a NETCONF session

3.3.2.  Modifying a Subscription

   This operation is defined in [event-notifications].

2.5.1. [subscribe] and enhanced in [yang-push].

3.3.2.1.  Usage Example

   The following illustrates the establishment of demonstrates modifying a simple subscription.  Consider a
   subscription from [yang-push], which augments the establish-
   subscription with some additional parameters, including "period".  A
   subscription may be established as follows.

    <netconf:rpc message-id="101"
           xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
      <establish-subscription
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
               xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
 /* Question, shouldn't this be yang-push 1.0 as that
 is where the referenced augmentations are? */
         <datastore>running</datastore>
         <filter-type>subtree</filter-type>
         <filter>xmlns:ex="http://example.com/sample-data/1.0"
                select="/ex:foo"</filter>
         <period xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
             1000
         </period>
      </establish-subscription>
    </netconf:rpc>

    <rpc-reply message-id="101"
           xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
      <subscription-result
               xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
        ok
      </subscription-result>
      <identifier
               xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
        1922
      </identifier>
    </rpc-reply>

              Figure 12: 8: Establish subscription

2.5.2. to be modified

   The subscription may be modified with and RPC request such as:

     <netconf:rpc message-id="102"
            xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
       <modify-subscription
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
         <identifier>1922</identifier>
         <period>100</period>
       </modify-subscription>
     </netconf:rpc>

                       Figure 9: Modify subscription

3.3.2.2.  Positive Response

   If the NETCONF server can satisfy the request, the server sends a
   positive <subscription-result> element, and the subscription-id of element.  This response is like that
   to an establish-subscription request, but without the accepted subscription.

   <netconf:rpc netconf:message-id="102"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <establish-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <filter netconf:type="xpath"
                   xmlns:ex="http://example.com/event/1.0"
                select="/ex:event[ex:eventClass='fault' and
                         (ex:severity='minor' or ex:severity='major'
                          or ex:severity='critical')]"/>
     </establish-subscription>
   </netconf:rpc> subscription
   identifier.

     <rpc-reply message-id="102"
            xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <subscription-result
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
         ok
       </subscription-result>
     <subscription-id
             xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       52
     </subscription-id>
     </rpc-reply>

                 Figure 13: 10: Successful establish-subscription

2.5.3. modify subscription

3.3.2.3.  Negative Response

   If the NETCONF server cannot satisfy the request, the server sends a
   negative <subscription-result> element.

   If the client has no authorization  Its contents and semantics
   are identical to establish the subscription, the
   <subscription-result> indicates those in an authorization error. establish-subscription request.  For
   instance:

   <netconf:rpc netconf:message-id="103"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <establish-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <stream>foo</stream>
     </establish-subscription>
   </netconf:rpc>

     <rpc-reply message-id="103" message-id="102"
            xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <subscription-result
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       error-data-not-authorized
     </subscription-result>
   </rpc-reply>

              Figure 14: Unsuccessful establish subscription

   If the request
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
  *** why is rejected because the server is namespace not able to serve
   it, the server SHOULD include in the returned error what subscription
   parameters would have been accepted for the request when it was
   processed.  However, they are no guarantee that subsequent requests
   with those parameters for this client or others will be accepted.
   For instance, consider a subscription from [yang-push], which
   augments the establish-subscription with some additional parameters,
   including "period".  If the client requests a period the NETCONF
   server cannot serve, the exchange may be:

   <netconf:rpc message-id="101"
            xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <establish-subscription
               xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <stream>push-update</stream>
       <filter netconf:type="xpath"
               xmlns:ex="http://example.com/sample-data/1.0"
               select="/ex:foo"/>
       <period xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
         500
       </period>
       <encoding>encode-xml</encoding>
     </establish-subscription>
   </netconf:rpc>

   <rpc-reply message-id="101"
         xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <subscription-result
           xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       error-insufficient-resources yang-push?
         period-unsupported
       </subscription-result>
     <period
           xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
       2000
     </period>
       <period-hint>500</period-hint>
     </rpc-reply>

                Figure 15: Subscription establishment negotiation

   Subscription requests will fail if a filter with invalid syntax is
   provided or if the name of a non-existent stream is provided.

2.5.4.  Multiple Subscriptions over a Single NETCONF Session

   Note that [event-notifications] requires supporting multiple
   subscription establishments over a single NETCONF session.  In
   contrast, [RFC5277] mandated servers to return an error when a
   create-subscription was sent while a 11: Unsuccessful modify subscription was active on that
   session.  Note that servers are not required to support multiple
   create-subscription over a single session, but they MUST support
   multiple establish-subscription over one session.

2.5.5.

3.3.2.4.  Message Flow Examples Example
   +------------+                 +-----------+
   |   Client   |                 |   Server  |
   +------------+                 +-----------+
         |                              |
         |    Capability Exchange       |
         |<---------------------------->|
         |                              |
         |                              |
         |    Establish Subscription    |
         |----------------------------->|
         | RPC Reply: OK, subs-id = 22  |
         |<-----------------------------|
         |<---------------------------->|
         |                              |
         |  Notification (subs-id (id 22)        |
         |<-----------------------------|
         |                              |
         |     Modify Subscription      |
         |----------------------------->|
         |  Notification (subs-id 22) RPC Reply: OK                |
         |<-----------------------------|
         |                              |
         |  Notification (subs-id (id 22)        |
         |<-----------------------------|
         |                              |
         |                              |

     Figure 16: 12: Message flow for successful subscription establishment

   +------------+                 +-----------+
   |   Client   |                 |   Server  |
   +------------+                 +-----------+
         |                              |
         |    Capability Exchange       |
         |<---------------------------->|
         |                              |
         |                              |
         |    Establish Subscription    |
         |----------------------------->|
         | RPC Reply: OK, subs-id = 22  |
         |<-----------------------------|
         |                              |
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |                              |
         |                              |
         |    Establish Subscription    |
         |----------------------------->|
         | RPC Reply: OK, subs-id = 23  |
         |<-----------------------------|
         |                              |
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |                              |
         |                              |
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |  Notification (subs-id 23)   |
         |<-----------------------------|
         |                              |
         |                              |

   Figure 17: Message Flow for multiple subscription establishments over
                             a single session

2.6.  Modifying a modification

3.3.3.  Deleting a Subscription

   This operation is defined in [event-notifications].

2.6.1. [subscribe] for events, and enhanced in
   [yang-push] for datastores.

3.3.3.1.  Usage Example

   The following demonstrates modifying deleting a subscription.  Consider a
   subscription from [yang-push], which augments the establish-
   subscription with some additional parameters, including "period".  A
   subscription may be established as follows.

     <netconf:rpc message-id="101"
            xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <establish-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <stream>push-update</stream>
       <filter netconf:type="xpath"
               xmlns:ex="http://example.com/sample-data/1.0"
               select="/ex:foo"/>
       <period xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
         500
       </period>
       <encoding>encode-xml</encoding>
     </establish-subscription>
   </netconf:rpc>

   <rpc-reply message-id="101"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <subscription-result
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       ok
     </subscription-result>
     <subscription-id
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       1922
     </subscription-id>
   </rpc-reply>

             Figure 18: Establish subscription to be modified

   The subscription may be modified with:

   <netconf:rpc message-id="102"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <modify-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <subscription-id>1922</subscription-id>
       <period>1000</period>
     </modify-subscription >
       <delete-subscription
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
         <identifier>1922</identifier>
       </delete-subscription>
     </netconf:rpc>

   <rpc-reply message-id="102"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <subscription-result
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       ok
     </subscription-result>
     <subscription-id
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       1922
     </subscription-id>
   </rpc-reply>

                      Figure 19: Modify 13: Delete subscription

2.6.2.

3.3.3.2.  Positive Response

   If the NETCONF server can satisfy the request, the server sends a
   positive <subscription-result> element.  This response is like that
   to an establish-subscription request, but without the subscription-id
   (which would be redundant).

   <netconf:rpc message-id="102"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <modify-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <subscription-id>1922</subscription-id>
       <period
                 xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
         1000
       </period>
     </modify-subscription >
   </netconf:rpc> OK
   element.  For example:

      <rpc-reply message-id="102" message-id="103"
             xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <subscription-result
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       ok
     </subscription-result>
        <ok/>
      </rpc-reply>

                 Figure 20: 14: Successful modify delete subscription

2.6.3.

3.3.3.3.  Negative Response

   If the NETCONF server cannot satisfy the request, the server sends a
   negative <subscription-result> element.  Its contents and semantics
   are identical to those in an establish-subscription request.
   error-rpc element indicating the modification didn't work.  For
   instance:

   <netconf:rpc message-id="102"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <modify-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <subscription-id>1922</subscription-id>
       <period xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push:1.0">
         100
       </period>
     </modify-subscription>
   </netconf:rpc>
   example:

   <rpc-reply message-id="102" message-id="101"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <subscription-result
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       error-insufficient-resources
     </subscription-result>
     <period>500</period>
     <rpc-error>
       <error-type>application</error-type>
       <error-tag>invalid-value</error-tag>
       <error-severity>error</error-severity>
       <error-path
              xmlns:t="urn:ietf:params:xml:ns:netconf:notification:2.0">
         /t:identifier
       </error-path>
       <error-message xml:lang="en">
         no-such-subscription
       </error-message>
     </rpc-error>
   </rpc-reply>

                Figure 21: 15: Unsuccessful modify delete subscription

2.6.4.  Message Flow Example
   +------------+                 +-----------+
   |   Client   |                 |   Server  |
   +------------+                 +-----------+
         |                              |
         |    Capability Exchange       |
         |<---------------------------->|
         |                              |
         |                              |
         |    Establish Subscription    |
         |----------------------------->|
         | RPC Reply: OK, subs-id = 22  |
         |<-----------------------------|
         |                              |
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |                              |
         |                              |
         |                              |
         |                              |
         |     Modify Subscription      |
         |----------------------------->|
         |                              |
         |                              |
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |                              |
         |                              |

           Figure 22: Message flow for

3.4.  Configured Subscriptions

   Configured subscriptions are established, modified, and deleted using
   configuration operations against the top-level subtree of [subscribe]
   or [yang-push] via normal NETCONF operations.  In this section, we
   present examples of how to manage the configuration subscriptions
   using a NETCONF client.  Key differences from dunamic subscriptions
   over NETCONF is that subscription modification

2.7.  Deleting lifetimes are decoupled from
   NETCONF sessions.

3.4.1.  Establishing a Configured Subscription

   This operation is defined in [event-notifications].

2.7.1.  Usage Example

   The following demonstrates deleting

   For subscription establishment, a subscription.

   <netconf:rpc NETCONF client may send:

    <rpc message-id="101"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <delete-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <subscription-id>1922</subscription-id>
     </delete-subscription>
   </netconf:rpc>
           xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
           xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
      <edit-config>
        <target>
          <running/>
        </target>
        <subscription-config
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
          <subscription>
            <identifier>
              1922
            </identifier>
            <stream>
              foo
            </stream>
            <receiver>
              <address>
                1.2.3.4
              </address>
              <port>
                1234
              </port>
            </receiver>
          </subscription>
        </subscription-config>
      </edit-config>
    </rpc>

                 Figure 23: Delete 16: Establish static subscription

2.7.2.  Positive Response

   If the NETCONF server can satisfy

   if the request, request is accepted, the server sends an OK
   element.  For example:

   <netconf:rpc message-id="103"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <delete-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <subscription-id>1922</subscription-id>
     </delete-subscription>
   </netconf:rpc> would reply:

      <rpc-reply message-id="103" message-id="101"
                xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
        <ok/>
      </rpc-reply>

   Figure 24: Successful delete subscription

2.7.3.  Negative 17: Response

   If to a successful static subscription establishment

   if the request is not accepted because the NETCONF server cannot satisfy the request, serve it, no
   configuration is changed.  Int this case the server sends an
   error-rpc element.  For example:

   <netconf:rpc message-id="103"
          xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
     <delete-subscription
              xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
       <subscription-id>2017</subscription-id>
     </delete-subscription>
   </netconf:rpc> may reply:

   <rpc-reply message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <rpc-error>
       <error-type>application</error-type>
       <error-tag>invalid-value</error-tag>
       <error-severity>error</error-severity>
       <error-path
              xmlns:t="urn:ietf:params:xml:ns:netconf:notification:1.1">
         /t:subscription-id
       </error-path>
         <error-tag>resource-denied</error-tag>
         <error-severity>error&lt;/error-severity>
         <error-message xml:lang="en">
         Subscription-id 2017 does not exist
       </error-message>
     </rpc-error>
   </rpc-reply>

                Figure 25: Unsuccessful delete subscription

2.7.4.  Message Flow Example
   +------------+                 +-----------+
   |   Client   |                 |   Server  |
   +------------+                 +-----------+
         |                              |
         |    Capability Exchange       |
         |<---------------------------->|
         |                              |
         |                              |
         |    Establish Subscription    |
         |----------------------------->|
         | RPC Reply: OK, subs-id = 22  |
         |<-----------------------------|
         |                              |
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |                              |
         |                              |
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |  Notification (subs-id 22)   |
         |<-----------------------------|
         |                              |
         |                              |
         |     Delete Subscription      |
         |----------------------------->|
         |                              |
         |                              |
         |                              |
         |                              |

             Figure 26: Message flow for subscription deletion

2.8.  Configured Subscriptions

   A configured subscription is a subscription installed via a
   configuration interface.  Configured subscriptions do not support
   negotiation.

   Supporting configured subscriptions is optional and advertised during
   the capabilities exchange using
           Temporarily the "configured-subscriptions"
   feature.

   Configured susbscriptions are supported by NETCONF servers using
   NETCONF Call Home [call-home]

   In server cannot serve this section, we present examples of how
           subscription due to manage configuration
   subscriptions using a NETCONF client.

2.8.1.  Call Home for Configured Subscriptions

   Configured subscriptions are established, modified, and deleted using
   configuration operations against the top-level subtree subscription-
   config.  Once the configuration is set, the server initiates a Call
   Home current workload.
       </error-message>
     </rpc-error>
   </rpc-reply>

     Figure 18: Response to each of the receivers in the a failed static subscription on the address and
   port specified.  Once the establishment

   For every configured receiver, once NETCONF transport session between
   the server and the receiver is established, recognized as active, the server will
   issue a "subscription-
   started" "subscription-started" notification.  After that, the server
   will send notifications to the receiver as per the subscription. subscription
   notification.

   Note that the server assumes the receiver is aware that calls on the
   configured port are intended only for pushing notifications.  It also
   assumes that the receiver is ready to accept
   notifications on the
   session created as part of the Call Home as soon as the NETCONF
   session is established. session.  This may require coordination
   between the client that configures the subscription and the clients
   for which the notifications are intended.  This coordination is out
   of the scope of this document.

2.8.2.  Establishing a

3.4.2.  Call Home for Configured Subscription Subscriptions are established using

   Once this configuration operations against
   the top-level subtree subscription-config.

   For example at subscription establishment, a is active, if NETCONF client may send:

   <rpc message-id="101"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
          xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
     <edit-config>
       <target>
         <running/>
       </target>
       <subscription-config
               xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
         <subscription>
           <subscription-id>
             1922
           </subscription-id>
           <stream>
             foo
           </stream>
           <receiver>
             <address>
               1.2.3.4
             </address>
             <port>
               1234
             </port>
           </receiver>
         </subscription>
       </subscription-config>
     </edit-config>
   </rpc>

                 Figure 27: Establish static subscription

   if the request is accepted, the server would reply:

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

   Figure 28: Response to a successful static subscription establishment

   if the request transport is needed but
   does not accepted because the server cannot serve it,
   the server may reply:

   <rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <rpc-error>
       <error-type>application</error-type>
         <error-tag>resource-denied</error-tag>
         <error-severity>error</error-severity>
         <error-message xml:lang="en">
           Temporarily exist to one or more target IP address plus port, the server cannot serve this
           subscription due
   initiates a transport session via [RFC8071] to those receiver(s) in
   the current workload.
       </error-message>
     </rpc-error>
   </rpc-reply>

     Figure 29: Response to a failed static subscription establishment

2.8.2.1. using the address and port specified.

3.4.3.  Full Establish Message Flow Example
 +----------+                 +-----------+     +---------+  +---------+
 |  Client  |                 |   Server  |     | Rcver A |  | Rcver B |
 +----------+                 +-----------+     +---------+  +---------+
       |                            |                |            |
       |    Capability Exchange     |                |            |
       |<-------------------------->|                |            |
       |                            |                |            |
       |                            |                |            |
       |        Edit-config         |                |            |
       |--------------------------->|                |            |
       |       RPC Reply: OK        |                |            |
       |<---------------------------|                |            |
       |                            |   Call Home    |            |
       |                            |<-------------->|            |
       |                            |<--------------------------->|
       |                            |                |            |
       |                            |  Subscription  |            |
       |                            |  Started       |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |  (subs-id  (id 22)       |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |  (subs-id  (id 22)       |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |

     Figure 30: 19: Message flow for configured subscription establishment (configured
                               subscription)

2.8.3.

3.4.4.  Modifying a Configured Subscription

   Configured subscriptions can be modified using configuration
   operations against the top-level subtree subscription-config.

   For example, the subscription established in the previous section
   could be modified as follows, choosing a different receiver:

    <rpc message-id="102"
           xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
           xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
      <edit-config>
        <target>
          <running/>
        </target>
        <subscription-config
               xmlns="urn:ietf:params:xml:ns:netconf:notification:1.1">
                xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
          <subscription>
           <subscription-id>
            <identifier>
              1922
           </subscription-id>
            </identifier>
            <stream>
              foo
            </stream>
            <receiver>
              <address>
                1.2.3.5
              </address>
              <port>
                1234
              </port>
            </receiver>
          </subscription>
        </subscription-config>
      </edit-config>
    </rpc>

                 Figure 31: 20: Modify configured subscription

   if the request is accepted, the server would reply:

      <rpc-reply message-id="102"
                xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
        <ok/>
      </rpc-reply>

       Figure 32: Response to a 21: A successful configured subscription modification

2.8.3.1.

3.4.4.1.  Message Flow Example
 +----------+                 +-----------+     +---------+  +---------+
 |  Client  |                 |   Server  |     | Rcver A |  | Rcver B |
 +----------+                 +-----------+     +---------+  +---------+
       |                            |                |            |
       |    Capability Exchange     |                |            |
       |<-------------------------->|                |            |
       |                            |                |            |
       |                            |                |            |
       |        Edit-config         |                |            |
       |--------------------------->|                |            |
       |       RPC Reply: OK        |                |            |
       |<---------------------------|                |            |
       |                            |   Call Home    |            |
       |                            |<-------------->|            |
       |                            |<--------------------------->|
       |                            |                |            |
       |                            |  Subscription  |            |
       |                            |  Started       |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |  (subs-id  (id 22)       |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |        Edit-config         |                |            |
       |--------------------------->|                |            |
       |       RPC Reply: OK        |                |            |
       |<---------------------------|                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |  Subscription  |            |
       |                            |  Modified      |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |

     Figure 33: Message flow for subscription modification (configured
                               subscription)

2.8.4.  Deleting a Configured Subscription

   Subscriptions can be deleted using configuration operations against
   the top-level subtree subscription-config.  For example:

   <rpc message-id="103"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <edit-config>
       <target>
         <running/>
       </target>
       <subscription-config
           xmlns:xc="urn:ietf:params:xml:ns:netconf:notification:1.1">
         <subscription xc:operation="delete">
           <subscription-id>
             1922
           </subscription-id>
         </subscription>
       </subscription-config>
     </edit-config>
   </rpc>

   <rpc-reply message-id="103"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <ok/>
   </rpc-reply>

               Figure 34: Deleting a configured subscription

2.8.4.1.  Message Flow Example

 +----------+                 +-----------+     +---------+  +---------+
 |  Client  |                 |   Server  |     | Rcver A |  | Rcver B |
 +----------+                 +-----------+     +---------+  +---------+
       |                            |                |            |
       |    Capability Exchange     |                |            |
       |<-------------------------->|                |            |
       |                            |                |            |
       |                            |                |            |
       |        Edit-config         |                |            |
       |--------------------------->|                |            |
       |       RPC Reply: OK        |                |            |
       |<---------------------------|                |            |
       |                            |   Call Home    |            |
       |                            |<-------------->|            |
       |                            |<--------------------------->|
       |                            |                |            |
       |                            |  Subscription  |            |
       |                            |  Started       |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |        Edit-config         |                |            |
       |--------------------------->|                |            |
       |       RPC Reply: OK        |                |            |
       |<---------------------------|                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |  Subscription  |            |
       |                            |  Terminated    |            |
       |                            |  (subs-id 22)  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |

       Figure 35: Message flow for subscription deletion (configured
                               subscription)

2.9.  Event (Data Plane) Notifications

   Once a subscription has been set up, the NETCONF server sends
   (asynchronously) the event notifications from the subscribed stream.
   We refer to these as data plane notifications.  For dynamic
   subscriptions set up via RPC operations, event notifications are sent
   over the NETCONF session used to create or establish the
   subscription.  For static subscriptions, event notifications are sent
   over the specified connections.

   An event notification is sent to the receiver(s) when an event of
   interest (i.e., meeting the specified filtering criteria) has
   occurred.  An event notification is a complete and well-formed XML
   document.  Note that <notification> is not a Remote Procedure Call
   (RPC) method but rather the top-level element identifying the one-way
   message as a notification.  Note that event notifications never
   trigger responses.

   The event notification always includes an <eventTime> element.  It is
   the time the event was generated by the event source.  This parameter
   is of type dateTime and compliant to [RFC3339].  Implementations must
   support time zones.

   The event notification also contains notification-specific tagged
   content, if any.  With the exception of <eventTime>, the content of
   the notification is beyond the scope of this document.

   For encodings other than XML, notifications include an additional XML
   element so that the notification is a well-formed XML.  The element
   is <notification-contents-{encoding}>, E.g., <notification-contents-
   json>.  That element contains the notification contents in the
   desired encoding

   The following is an example of an event notification from [RFC6020]:

   notification link-failure {
     description "A link failure has been detected";
       leaf if-name {
         type leafref {
           path "/interface/name";
         }
       }
       leaf if-admin-status {
         type admin-status;
       }
       leaf if-oper-status {
         type oper-status;
       }
   }

            Figure 36: Definition of a data plane notification

   <notification
          xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2007-09-01T10:00:00Z</eventTime>
     <link-failure xmlns="http://acme.example.com/system">
       <if-name>so-1/2/3.0</if-name>
       <if-admin-status>up</if-admin-status>
       <if-oper-status>down</if-oper-status>
     </link-failure>
   </notification>

                    Figure 37: Data plane notification

   The equivalent using JSON encoding would be

   <notification
          xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2007-09-01T10:00:00Z</eventTime>
     <notification-contents-json>
          {
             "acme-system:link-failure": {
               "if-name": "so-1/2/3.0",
               "if-admin-status": "up",
               "if-oper-status": "down"
             }
           }
     </notification-contents-json>
   </notification>                            |  Notification  |            |
       |                            |  (id 22)       |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |        Edit-config         |                |            |
       |--------------------------->|                |            |
       |       RPC Reply: OK        |                |            |
       |<---------------------------|                |            |
       |                            |  Subscription  |            |
       |                            |  Modified      |            |
       |                            |  (id 22)       |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |  (id 22)       |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |

     Figure 38: Data plane notification using JSON encoding

2.10.  Control Plane Notifications

   In addition to data plane notifications, a server may send control
   plane notifications (defined in [event-notifications]) to indicate to
   receivers that an event related to the 22: Message flow for subscription management has
   occurred.  Control plane notifications cannot modification (configured
                               subscription)

3.4.5.  Deleting a Configured Subscription

   Subscriptions can be filtered out.  Next
   we exemplify them deleted using both XML, and JSON encondings for configuration operations against
   the
   notification-specific content:

2.10.1.  replayComplete

  <notification
         xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0">
    <eventTime>2007-09-01T10:00:00Z</eventTime>
    <replayComplete xmlns="urn:ietf:params:xml:ns:netmod:notification"/>
  </notification>

           Figure 39: replayComplete control plane notification

   The equivalent using JSON encoding would be:

   <notification
          xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2007-09-01T10:00:00Z</eventTime>
     <notification-contents-json>
          {
             "netmod-notif:replayComplete": { }
           }
     </notification-contents-json>
   </notification> top-level subtree subscription-config.  For example:

     <rpc message-id="103"
            xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <edit-config>
         <target>
           <running/>
         </target>
         <subscription-config
             xmlns:xc="urn:ietf:params:xml:ns:netconf:notification:2.0">
           <subscription xc:operation="delete">
             <identifier>
               1922
             </identifier>
           </subscription>
         </subscription-config>
       </edit-config>
     </rpc>

     <rpc-reply message-id="103"
            xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <ok/>
     </rpc-reply>

               Figure 40: replayComplete control plane notification (JSON encoding)

2.10.1.1. 23: Deleting a configured subscription

3.4.5.1.  Message Flow Example
   +------------+
 +----------+                 +-----------+     +---------+  +---------+
 |  Client  |                 |   Server  |
   +------------+     | Rcver A |  | Rcver B |
 +----------+                 +-----------+     +---------+  +---------+
       |                            |                |            |
       |    Capability Exchange     |
         |<---------------------------->|                |            |
       |<-------------------------->|                |            |
       |    Establish Subscription                            |
         |----------------------------->|                | RPC Reply: OK, subs-id = 22            |
         |<-----------------------------|
       |                            |                |  Notification (subs-id 22)            |
         |<-----------------------------|
       |        Edit-config         |                |            |
       |--------------------------->|                |  Notification (subs-id 22)            |
         |<-----------------------------|
       | Replay Complete (subs-id 22)       RPC Reply: OK        |
         |<-----------------------------|                |            |
       |<---------------------------|                |            |
       |                            |   Call Home    |            |  Notification (subs-id 22)
       |
         |<-----------------------------|                            |<-------------->|            |
       |                            |<--------------------------->|
       |  Notification (subs-id 22)                            |
         |<-----------------------------|                |            |
       |                            |  Subscription  |            |

                  Figure 41: replayComplete notification

2.10.2.  notificationComplete

   <notification
       xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2007-09-01T10:00:00Z</eventTime>
     <notificationComplete
       xmlns="urn:ietf:params:xml:ns:netmod:notification"/>
   </notification>

        Figure 42: notificationComplete control plane notification

2.10.2.1.  Message Flow Example
   +------------+                 +-----------+
       |   Client                            |  Started       |   Server            |
   +------------+                 +-----------+
       |                            |  (id 22)       |    Capability Exchange            |
         |<---------------------------->|
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |    Establish Subscription                |
         |----------------------------->|            | RPC Reply: OK, subs-id = 22
       |
         |<-----------------------------|                            |                |            |  Notification (subs-id 22)
       |
         |<-----------------------------|                            |  Notification  |            |
       |                            |  Notification (subs-id  (id 22)       |
         |<-----------------------------|            | Replay Complete (subs-id 22)
       |
         |<-----------------------------|                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |  Notification (subs-id 22)        Edit-config         |
         |<-----------------------------|                |            |
       |--------------------------->|                |  Notification (subs-id 22)            |
         |<-----------------------------|
       |       RPC Reply: OK        |                |            |
       |<---------------------------|                |            |
       |                            |    Notification Complete  Subscription  |            |        (subs-id 22)
       |
         |<-----------------------------|                            |  Terminated    |            |
       |                            |  (id 22)       |            |            RPC
       |
         |----------------------------->|                            |--------------->|            |          RPC Reply
       |
         |<-----------------------------|                            |---------------------------->|
       |                            |                |            |

       Figure 43: notificationComplete 24: Message flow for subscription deletion (configured
                               subscription)

3.4.6.  Event (Data Plane) Notifications

   Once a dynamic or configured subscription has been created, the
   NETCONF server sends (asynchronously) event notifications from the
   subscribed stream to receiver(s) over NETCONF.  We refer to these as
   data plane notifications.

   The following is an example of an event notification from [RFC6020]:

      notification link-failure {
        description "A link failure has been detected";
          leaf if-name {
            type leafref {
              path "/interface/name";
            }
          }
          leaf if-admin-status {
            type admin-status;
          }
          leaf if-oper-status {
            type oper-status;
          }
      }

            Figure 25: Definition of a data plane notification

   This notification might result in the following, prior to it being
   placed into NETCONF.  Note that the mandatory eventTime and
   Subscription id have been added.

      <notification
             xmlns=" urn:ietf:params:xml:ns:netconf:notification:2.0">
        <eventTime>2007-09-01T10:00:00Z</eventTime>
        <subscription-id>39</subscription-id>
        <link-failure xmlns="http://acme.example.com/system">
          <if-name>so-1/2/3.0</if-name>
          <if-admin-status>up</if-admin-status>
          <if-oper-status>down</if-oper-status>
        </link-failure>
      </notification>

                    Figure 26: Data plane notification

   The equivalent using JSON encoding would be
      <notification
             xmlns="urn:ietf:params:xml:ns:netconf:notification:2.0">
        <eventTime>2007-09-01T10:00:00Z</eventTime>
        <subscription-id>39</subscription-id>
        <notification-contents-json>
             {
                "acme-system:link-failure": {
                  "if-name": "so-1/2/3.0",
                  "if-admin-status": "up",
                  "if-oper-status": "down"
                }
              }
        </notification-contents-json>
      </notification>

          Figure 27: Data plane notification

2.10.3. using JSON encoding

3.4.7.  Control Plane Notifications

   In addition to data plane notifications, a server may send control
   plane notifications (defined in [subscribe]) to indicate to receivers
   that an event related to the subscription management has occurred.
   Control plane notifications cannot be filtered out.  Next we
   exemplify them using both XML, and JSON encodings for the
   notification-specific content:

3.4.7.1.  subscription-started and subscription-modified

   A subscription-started would look like:

  <notification
      xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0"> urn:ietf:params:xml:ns:netconf:notification:2.0">
    <eventTime>2007-09-01T10:00:00Z</eventTime>
    <subscription-started
          xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications"/>
      <subscription-id>52</subscription-id>
      <identifier>39</identifier>
      <filter-type>xpath</filter-type>
      <filter netconf:type="xpath" xmlns:ex="http://example.com/event/1.0"
                 select="/ex:event[ex:eventClass='fault' and
                        (ex:severity='minor' or ex:severity='major'
                         or ex:severity='critical')]"/>
    </subscription-started/>
  </notification>

        Figure 44: 28: subscription-started control plane notification

   The equivalent using JSON encoding would be:

      <notification
             xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0"> urn:ietf:params:xml:ns:netconf:notification:2.0">
        <eventTime>2007-09-01T10:00:00Z</eventTime>
        <notification-contents-json>
             {
                "notif-bis:subscription-started": {
                 "subscription-id"
                    "identifier" : 52 39
          ((Open Item: express everything including the filter in json))
                }
              }
        </notification-contents-json>
      </notification>

     Figure 45: 29: subscription-started control plane notification (JSON
                                 encoding)

2.10.4. (JSON)

   The subscription-modified is identical, with just the word "started"
   being replaced by "modified".

3.4.7.2.  notification-complete, subscription-resumed, and replay-
          complete

   A notification-complete would look like:

   <notification
       xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0"> urn:ietf:params:xml:ns:netconf:notification:2.0">
     <eventTime>2007-09-01T10:00:00Z</eventTime>
    <subscription-modified
          xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications"/>
      <subscription-id>52</subscription-id>
      <filter netconf:type="xpath"
                 xmlns:ex="http://example.com/event/1.0"
                 select="/ex:event[ex:eventClass='fault']"/>
    </subscription-modified/>
     <notification-complete
           xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications">
       <identifier>39</identifier>
     </notification-complete>
   </notification>

          Figure 46: subscription-modified control plane 30: notification

2.10.5.  subscription-terminated

  <notification
      xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0">
    <eventTime>2007-09-01T10:00:00Z</eventTime>
    <subscription-terminated
          xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications"/>
      <subscription-id>52</subscription-id>
      <reason>subscription-deleted</reason>
    </subscription-terminated/>
  </notification>

       Figure 47: subscription-terminated control plane notification

2.10.6.  subscription-suspended XML

   The equivalent using JSON encoding would be:

      <notification
             xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0"> urn:ietf:params:xml:ns:netconf:notification:2.0">
        <eventTime>2007-09-01T10:00:00Z</eventTime>
    <subscription-suspended
          xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications"/>
      <subscription-id>52</subscription-id>
      <reason>internal-error</reason>
    </subscription-suspended/>
        <notification-contents-json>
             {
                "netmod-notif:notification-complete": {
                "identifier" : 39
              }
        </notification-contents-json>
      </notification>

          Figure 48: subscription-suspended 31: notification control plane notification

2.10.7. JSON

   The subscription-resumed and replay-complete are virutally identical,
   with "notification-complete" simply being replaced by "subscription-
   resumed" and "replay-complete" in both encodings.

3.4.7.3.  subscription-terminated and subscription-suspended

   A subscription-terminated would look like:

   <notification
       xmlns=" urn:ietf:params:xml:ns:netconf:notification:1.0"> urn:ietf:params:xml:ns:netconf:notification:2.0">
     <eventTime>2007-09-01T10:00:00Z</eventTime>
    <subscription-resumed
          xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications"/>
      <subscription-id>52</subscription-id>
      <reason>internal-error</reason>
    </subscription-resumed/>
     <subscription-terminated
           xmlns="urn:ietf:params:xml:ns:yang:ietf-event-notifications">
       <identifier>39</identifier>
       <error-id>no-such-subscription</error-id>
     </subscription-terminated>
   </notification>

        Figure 49: subscription-resumed 32: subscription-modified control plane notification

2.10.7.1.

   The above, and the subscription-suspended are virutally identical,
   with "subscription-terminated" simply being replaced by
   "subscription-suspended".

3.4.7.4.  Notification Message Flow Examples
   +------------+                 +-----------+
   |   Client   |                 |   Server  |
   +------------+                 +-----------+
         |                              |
         |    Capability Exchange       |
         |<---------------------------->|
         |                              |
         |                              |
         |    Establish Subscription    |
         |----------------------------->|
         | RPC Reply: OK, subs-id = 22  |
         |<-----------------------------|
         |                              |
         |        Notification          |
         |<-----------------------------|
         |                              |
         |                              |
         |<---------------------------->|
         |        Notification                              |
         |<-----------------------------|
         |        Notification          |
         |<-----------------------------|
         |                              |
         |                              |
         |   Subscription Suspended     |
         |<-----------------------------|
         |                              |
         |                              |
         |                              |
         |    Subscription Resumed      |
         |<-----------------------------|
         |                              |
         |                              |
         |                              |
         |                              |
         |        Notification          |
         |<-----------------------------|
         |                              |
         |                              |

        Figure 50: 33: subscription-suspended and Resumed Notifications

 +----------+                 +-----------+     +---------+  +---------+
 |  Client  |                 |   Server  |     | Rcver A |  | Rcver B |
 +----------+                 +-----------+     +---------+  +---------+
       |                            |                |            |
       |    Capability Exchange     |                |            |
       |<-------------------------->|                |            |
       |                            |                |            |
       |                            |                |            |
       |        Edit-config         |                |            |
       |--------------------------->|                |            |
       |       RPC Reply: OK        |                |            |
       |<---------------------------|                |            |
       |                            |  Subscription  |            |
       |                            |  Started       |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |  Subscription  |            |
       |                            |  Suspended     |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |                |            |                            |                |            |
       |                            |  Notification  |            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Subscription  |            |
       |                            |  Resumed       |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |  Notification  |            |
       |                            |--------------->|            |
       |                            |---------------------------->|
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
       |                            |                |            |
        Figure 51: subscription-suspended and subscription-resumed
                 notifications (configured subscriptions)

3.  Backwards Compatibility

3.1.  Capabilities

   Capabilities are advertised in messages sent by each peer during
   session establishment [RFC6241].  Servers supporting the features in
   this document must advertise both capabilities
   "urn:ietf:params:netconf:capability:notification:1.0" and
   "urn:ietf:params:netconf:capability:notification:1.1".

   An example of a hello message by a server during session
   establishment would be:

   <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:netconf:capability:startup:1.0
       </capability>
       <capability>
         urn:ietf:params:netconf:capability:notification:1.0
       </capability>
       <capability>
         urn:ietf:params:netconf:capability:notification:1.1
       </capability>
     </capabilities>
     <session-id>4</session-id>
   </hello>                |            |

     Figure 52: Hello message

   Clients that only support [RFC5277] recognize capability
   "urn:ietf:params:netconf:capability:notification:1.0" 34: Suspended and ignore
   capability "urn:ietf:params:netconf:capability:notification:1.1".
   This allows them interacting with the server as per [RFC5277].
   Clients that support the features in this document recognize both
   capabilities.  This allows them interacting with the server as per
   this document.

3.2.  Stream Discovery

   In order to maintain backwards compatibility, clients that only
   support [RFC5277] can retrieve the list of available event streams
   executing resumed for a <get> operation against the container "/netconf/streams". single configured receiver

4.  Security Considerations

   The security considerations from the base NETCONF document [RFC6241]
   also apply to the notification capability.

   The <notification> elements are never sent before the transport layer
   and the NETCONF layer, including capabilities exchange, have been
   established and the manager has been identified and authenticated.

   A secure transport must be used and the server must ensure that the
   user has sufficient authorization to perform the function they are
   requesting against the specific subset of NETCONF content involved.
   When a <get> is received that refers to the content defined in this
   memo, clients should only be able to view the content for which they
   have sufficient privileges.  <create-subscriptiont> and <establish-
   subscriptiont> operations can be considered like deferred <get>, and
   the content that different users can access may vary.  This different
   access is reflected in the <notificationt> that different users are
   able to subscribe to.

   The contents of notifications, as well as the names of event streams,
   may contain sensitive information and care should be taken to ensure
   that they are viewed only by authorized users.  The NETCONF server
   MUST NOT include any content in a notification that the user is not
   authorized to view.

   If a malicious or buggy NETCONF client sends a number of <create-
   subscription> requests, <establish-
   subscription>requests, then these subscriptions accumulate and may
   use up system resources.  In such a situation, subscriptions can MAY be
   terminated by terminating the suspect underlying NETCONF sessions
   using the <kill-session> operation.  If the client uses <establish-
   subscription>, the sessions.
   The server can MAY also suspend or terminate a subset of the active
   subscriptions
   with per-subscription granularity.

   A subscription could be configured on another receiver's behalf, with the goal of flooding that receiver with updates.  One NETCONF session .

   Configured subscriptions from one or more publishers could be used to
   overwhelm a receiver, which perhaps doesn't even support
   subscriptions.  Clients that do not want pushed data need only
   terminate or refuse any transport sessions from the publisher.
   In addition, the

   The NETCONF Authorization Control Model [RFC6536] SHOULD be used to
   control and restrict authorization of subscription configuration.
   This control models permits specifying per-user permissions to
   receive specific event notification types.  The permissions are
   specified as a set of access control rules.

   Note that streams can define additional authorization requirements.
   For instance, in [yang-push] each of the elements in its data plane
   notifications must also go through access control.

5.  Acknowledgments

   We wish to acknowledge the helpful contributions, comments, and
   suggestions that were received from: Andy Bierman, Yan Gang, Sharon
   Chisholm, Hector Trevino, Peipei Guo, Susan Hares, Tim Jenkins,
   Balazs Lengyel, Kent Watsen, and Guangying Zheng.

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <http://www.rfc-editor.org/info/rfc3339>.

   [RFC5277]  Chisholm, S. and H. Trevino, "NETCONF Event
              Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008,
              <http://www.rfc-editor.org/info/rfc5277>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <http://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <http://www.rfc-editor.org/info/rfc6241>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <http://www.rfc-editor.org/info/rfc6536>.

6.2.  Informative References

   [call-home]

   [RFC8071]  Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
              December 2015, <https://datatracker.ietf.org/doc/draft-
              ietf-netconf-call-home/>.

   [event-notifications]
              RFC 8071, DOI 10.17487/RFC8071, February 2017,
              <http://www.rfc-editor.org/info/rfc8071>.

6.2.  Informative References

   [subscribe]
              Voit, Eric., Clemm, A., Gonzalez Prieto, A., Voit, Eric., Nilsen-
              Nygaard, E., Tripathy, A., Chisholm, S., and H. Trevino, A. Tripathy, "Subscribing to Event
              Notifications", June April 2016,
              <https://datatracker.ietf.org/doc/draft-ietf-netconf-
              rfc5277bis/>.
              subscribed-notifications/>.

   [yang-push]
              Clemm, A., Gonzalez Prieto, A., Voit, Eric., Tripathy, A.,
              and E. Nilsen-Nygaard, "Subscribing to YANG datastore push
              updates", February 2016,
              <https://datatracker.ietf.org/doc/draft-ietf-netconf-yang-
              push/>. April 2017, <https://datatracker.ietf.org/doc/
              draft-ietf-netconf-yang-push/>.

Appendix A.  Issues that are currently being worked

   (To be removed by RFC editor prior to publication)

   o  NT1 - Express filter in JSON should be documented.

Appendix B.  Changes between revisions

   (To be removed by RFC editor prior to publication)

B.1.

A.1.  v01 to v03

   o  Text simplifications throughout

   o  v02 had no meaningful changes

A.2.  v00 to v01

   o  D1 -  Added Call Home in solution for configured subscriptions.

   o  D2 -  Clarified support for multiple subscription on a single session.
      No need to support multiple create-subscription.

   o  D3 -  Added mapping between terminology in [yang-push] and [RFC6241]
      (the one followed in this document).

   o  D4 -  Editorial improvements.

Authors' Addresses

   Alberto Gonzalez Prieto
   Cisco Systems
   VMWare

   Email: albertgo@cisco.com alberto.gonzalezprieto@yahoo.com

   Alexander Clemm
   Huawei

   Email: ludwig@clemm.org

   Eric Voit
   Cisco Systems

   Email: evoit@cisco.com

   Einar Nilsen-Nygaard
   Cisco Systems

   Email: einarnn@cisco.com

   Ambika Prasad Tripathy
   Cisco Systems

   Email: ambtripa@cisco.com

   Sharon Chisholm
   Ciena

   Email: schishol@ciena.com

   Hector Trevino
   Cisco Systems

   Email: htrevino@cisco.com