



Network Working Group                                      A. Huang-Feng
Internet-Draft                                               P. Francois
Intended status: Standards Track                               INSA-Lyon
Expires: 10 August 2026                                          T. Graf
                                                                Swisscom
                                                               B. Claise
                                                          Everything OPS
                                                         6 February 2026


           Extensible YANG Model for YANG-Push Notifications
                  draft-ietf-netconf-notif-envelope-04

Abstract

   This document defines a new extensible Notification structure,
   defined in YANG, for use in YANG-Push Notification messages, both for
   NETCONF and RESTCONF, enabling any YANG-compatible encodings such as
   XML, JSON, or CBOR.  Additionally, it defines two essential
   extensions to this structure, the support of a hostname and a
   sequence number and the support of a timestamp characterizing the
   moment when the data was observed.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 10 August 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.



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   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Relationship to past documents  . . . . . . . . . . . . . . .   4
     2.1.  Relationship to RFC5277 . . . . . . . . . . . . . . . . .   4
     2.2.  Relationship to RFC8639 . . . . . . . . . . . . . . . . .   5
     2.3.  Relationship to RFC7950 . . . . . . . . . . . . . . . . .   5
     2.4.  Relationship to RFC7951 . . . . . . . . . . . . . . . . .   5
     2.5.  Relationship to RFC9254 . . . . . . . . . . . . . . . . .   6
   3.  Notification Envelope Model . . . . . . . . . . . . . . . . .   6
     3.1.  Notification Envelope Structure . . . . . . . . . . . . .   7
       3.1.1.  Base Notification Model . . . . . . . . . . . . . . .   7
       3.1.2.  Encodings of the Notification Envelope  . . . . . . .   7
     3.2.  Extensions for the Notification Envelope  . . . . . . . .  14
       3.2.1.  Support of Hostname and Sequencing  . . . . . . . . .  14
     3.3.  Extensions for the YANG-Push Header . . . . . . . . . . .  16
       3.3.1.  Support of Observation Timestamp  . . . . . . . . . .  16
   4.  Enabling the Notification Envelope  . . . . . . . . . . . . .  22
   5.  Discovering the Support of the Notification Envelope  . . . .  23
   6.  Operational Considerations  . . . . . . . . . . . . . . . . .  24
   7.  YANG Modules  . . . . . . . . . . . . . . . . . . . . . . . .  24
     7.1.  The 'ietf-yp-notification' Module . . . . . . . . . . . .  25
       7.1.1.  YANG 'ietf-yp-notification' Tree Diagram  . . . . . .  25
       7.1.2.  YANG 'ietf-yp-notification' Module  . . . . . . . . .  25
     7.2.  The 'ietf-yp-observation' Module  . . . . . . . . . . . .  30
       7.2.1.  YANG 'ietf-yp-observation' Tree Diagram . . . . . . .  30
       7.2.2.  YANG 'ietf-yp-observation' Module . . . . . . . . . .  30
   8.  Implementation Status . . . . . . . . . . . . . . . . . . . .  33
     8.1.  Huawei VRP  . . . . . . . . . . . . . . . . . . . . . . .  34
     8.2.  6WIND VSR . . . . . . . . . . . . . . . . . . . . . . . .  34
     8.3.  Cisco IOS XR  . . . . . . . . . . . . . . . . . . . . . .  34
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  34
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  35
     10.1.  URI  . . . . . . . . . . . . . . . . . . . . . . . . . .  35
     10.2.  YANG module name . . . . . . . . . . . . . . . . . . . .  35
     10.3.  YANG SID-file  . . . . . . . . . . . . . . . . . . . . .  36
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  36
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  36
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  36
     12.2.  Informative References . . . . . . . . . . . . . . . . .  38
   Appendix A.  .sid file  . . . . . . . . . . . . . . . . . . . . .  39



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   Appendix B.  Example extending the Notification Envelope  . . . .  43
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  45

1.  Introduction

   YANG-Push [RFC8639] allows Publishers to send Notifications to a data
   collection system.  The YANG-Push Receiver decodes the message and
   optionally validates the header and the content before forwarding to
   the next process in the data collection system.

   The Notification encoded message from YANG-Push, as defined in
   Section 2.6 of [RFC8639], is currently based on the XML model from
   NETCONF Event Notifications [RFC5277].  This model has the drawback
   that only a single mandatory 'eventTime' leaf is defined and does not
   offer a way to extend this header with new Notification metadata.
   Additionally, the 'eventTime' reports "The time the event was
   generated by the event source" and not the metric observation time;
   the data collection system might draw the wrong conclusion in case of
   a busy Publisher that delays the YANG-Push export or in case a YANG-
   Push Publisher re-exports the YANG-Push message.  Finally, this XML
   model is only valid for XML-based environments.  When messages are
   encoded in other YANG encodings, such as JSON [RFC7951] or CBOR
   [RFC9254], validators cannot use YANG to validate the message schema.

   YANG data consumers receiving Notifications require additional
   Notification metadata to understand the full context of the received
   message.  For example, in addition to the timestamp of when the event
   was encoded, it is also important to know the timestamp when the
   metrics were observed, the hostname that sourced the message, and
   have sequence numbers.  The hostname is required because transport-
   level source information is not preserved once Notifications are
   forwarded to downstream systems, and having sequence numbers at the
   notification level enable operators to detect lost notifications
   throughout the data processing chain.  This additional Notification
   metadata is also helpful in correlating the data with other sources
   of Network Telemetry [RFC9232] information.

   For such reasons, this document proposes the following:

   *  First, it provides an extensible YANG Notification header allowing
      implementors and authors of Internet-Drafts to easily add new
      Notification metadata to the Notification message.

   *  Second, it provides the first crucial extensions enabling
      operators to identify which network node publishes which YANG-Push
      messages, when the events or metrics were observed on the network
      node, and in which order the messages were transmitted to the
      Receiver.



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   *  And finally, it provides a way to enable and disable these
      extensions globally at the Server, making the coexistence of
      different YANG-Push and NETCONF Event Notification [RFC5277]
      possible.

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   The terms "Subscription", "Dynamic Subscription", "Configured
   Subscription", "Publisher", "Receiver" and "Notification Message" are
   used as defined in [RFC8639].

   The term "Client" and "Server" is used as defined in [RFC6241] for
   NETCONF and [RFC8040] for RESTCONF.

   The terms "Implementation-time Information" and "Runtime Information"
   are used as defined in [RFC9196].

   In addition, this document defines the following terms:

   Notification Metadata: Additional data describing the context of a
   notification that is sent in each message, e.g. which node generated
   the message or at which time the notification was published.

   Notification Envelope: YANG structure encapsulating the payload of a
   notification, allowing the inclusion of metadata.

2.  Relationship to past documents

   This section shows the relationship to [RFC5277], [RFC8639],
   [RFC7951] and [RFC9254].

2.1.  Relationship to RFC5277

   [RFC5277] defines a mechanism for NETCONF Servers to send
   Notifications to collectors.  These are the key relationships between
   the current document and [RFC5277]:

   *  This document does not change the header defined by [RFC5277] nor
      update any behavior defined in [RFC5277].  Implementations of
      [RFC5277] use the header defined in Section 2.2.1 of [RFC5277].





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   *  The co-existence of the Notification model defined in [RFC5277]
      and the model defined in the current document is possible.  The
      co-existence is discussed in Section 6.

2.2.  Relationship to RFC8639

   Subscribed Notifications [RFC8639] defines a mechanism on top of
   [RFC5277] to stream Notifications from the Server.  These are the key
   relationships between the current document and [RFC8639]:

   *  Section 1.4 of [RFC8639] states that the solution uses the
      Notification header defined in [RFC5277].  This document proposes
      a new header, which Clients can enable to replace the header
      defined in [RFC5277] for YANG-defined event records.  When this
      new header is used, YANG-defined Notifications sent via Subscribed
      Notifications [RFC8639] are encoded as defined in Section 3.1.
      Servers MUST continue using the [RFC5277] header for NETCONF event
      streams.

   *  2.4 and 2.5 of [RFC8639] defines how a Dynamic Subscription and
      Configured Subscriptions are managed.  This document extends the
      Subscribed Notifications configuration [RFC8639] to support
      enabling the new header defined in this document.

2.3.  Relationship to RFC7950

   [RFC7950] defines how YANG data is encoded in XML.  These are the key
   relationship points between the current document and [RFC7950]:

   *  Section 7.16.2 of [RFC7950] defines the XML encoding of YANG
      Notification.  This document defines a new header for such
      Notifications.  When a YANG-Push Publisher implements the
      specifications in this document with the XML encoding, the
      Notifications are encoded according to Section 3.1.2.1.

2.4.  Relationship to RFC7951

   [RFC7951] defines how YANG data is encoded using JSON.  These are the
   key relationship points between the current document and [RFC7951]:

   *  [RFC7951] does not define explicitly how a YANG Notification
      should be encoded using JSON encoding.  This document specifies a
      new header for such Notifications.  When a YANG-Push Publisher
      implements the specifications in this document with JSON encoding,
      the Notifications are encoded according to Section 3.1.2.2.






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2.5.  Relationship to RFC9254

   [RFC9254] defines how YANG data is encoded using CBOR.  These are the
   key relationship points between the current document and [RFC9254]:

   *  [RFC9254] does not define explicitly how a YANG Notification
      should be encoded using CBOR encoding.  When a YANG-Push Publisher
      implements the specifications in this document in CBOR encoding,
      the Notifications are encoded according to Section 3.1.2.3 in this
      document.

3.  Notification Envelope Model

   Section 4.2.10 of [RFC7950] defines the encoding of YANG
   Notifications.  A Notification is defined by a 'notification'
   statement in the YANG module.  When a NETCONF Server sends a
   Notification, it comprises two parts: a header containing
   Notification metadata that encapsulates the content and the content
   defined by the 'notification' statement.

   In YANG 1.1 [RFC7950], the Notification header is based on the model
   defined in [RFC5277] which contains a single metadata 'eventTime'
   leaf.  An example extracted from [RFC7950] is shown in the following
   XML:

     <notification
         xmlns="urn:ietf:params:netconf:capability:notification:1.0">
       <eventTime>2007-09-01T10:00:00Z</eventTime>
       <link-failure xmlns="urn:example: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>

   This document defines a new Notification header and enables extending
   this header with new Notification metadata.  The Notification header
   and extensions in this document are to be used in YANG-Push [RFC8641]
   environments and can be implemented with NETCONF [RFC6241] and
   RESTCONF [RFC8040].  When enabled, this new header MUST replace all
   Notifications defined in both Subscribed Notifications [RFC8639] and
   YANG-Push [RFC8641] for the entire Server, for both Configured and
   Dynamic Subscriptions.








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   The remainder of this section is structured as follows.  Section 3.1
   defines the Notification Envelope and how this structure is encoded
   using XML, JSON, and CBOR.  Section 3.2 and Section 3.3 defines the
   first Notification extensions to both the Notification Envelope and
   the YANG-Push header.

   The Notification Envelope and extensions are enabled through the
   mechanism defined in Section 4.  Clients can discover the support of
   this header and extensions for both implementation-time and runtime
   through the discovery mechanism defined in Section 5.

3.1.  Notification Envelope Structure

   This section defines the structure of the Notification Envelope.  The
   following sections define how this structure is encoded in XML, JSON
   and CBOR.

3.1.1.  Base Notification Model

   When a YANG-Push Publisher uses the Notification model defined in
   this document, the Notification is structured as follows:

   *  The Notification is encapsulated in a root 'envelope' container.

   *  The header of the Notification contains the Notification metadata
      that is enabled during the configuration of the Subscription as
      child nodes of the root 'envelope' container.

   *  The content of the Notification defined by the 'notification'
      statement is encoded in the 'contents' leaf.

   The following YANG tree [RFC8340] illustrates the Notification
   Envelope supporting only the mandatory metadata 'event-time'.  Refer
   to Section 3.2 for more extensions to this header.

     structure envelope:
       +-- event-time         yang:date-and-time
       +-- contents?          <anydata>

3.1.2.  Encodings of the Notification Envelope

   The YANG Notification can be encoded using XML
   [W3C.REC-xml-20001006][RFC7951], JSON [RFC7951] and CBOR [RFC9254].








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3.1.2.1.  XML encoding

   A YANG Notification encoded in XML is structured as a root 'envelope'
   container.  The namespace of this container is the namespace defined
   in the YANG module 'ietf-yp-notification':

     urn:ietf:params:xml:ns:yang:ietf-yp-notification

   Two mandatory child nodes within the 'envelope' container are
   expected, representing the event time and the Notification payload.

   When other Notification metadata is enabled through configuration,
   the supplementary nodes are encoded at the same level as the
   mandatory 'event-time' node.  The YANG nodes in the Notification
   header use the XML namespace from the module that defines the nodes.
   This document defines two Notification metadata.  Refer to
   Section 3.2 for more details.

   The content of the Notification that is defined by the 'notification'
   statement is encoded in the 'contents' node.  The name and namespace
   of this payload element are determined by the YANG module containing
   the 'notification' statement representing the Notification message.

   The following example shows a 'push-update' Notification defined in
   the YANG module of YANG-Push [RFC8641] encoded in XML:


























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   <envelope xmlns="urn:ietf:params:xml:ns:yang:ietf-yp-notification">
     <event-time>2024-10-10T10:59:55.32Z</event-time>
     <contents>
       <push-update xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push">
         <id>1011</id>
         <datastore-contents>
           <interfaces
             xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces">
             <interface>
               <name>eth0</name>
               <type>iana-if-type:ethernetCsmacd</type>
               <if-index>1</if-index>
               <admin-status>down</admin-status>
               <oper-status>down</oper-status>
               <statistics>
                 <discontinuity-time>
                   2013-04-01T03:00:00+00:00
                 </discontinuity-time>
               </statistics>
            </interface>
           </interfaces>
         </datastore-contents>
       </push-update>
     </contents>
   </envelope>

                     Figure 1: XML-encoded notification

3.1.2.2.  JSON Encoding

   A YANG Notification encoded in JSON is structured as a root
   'envelope' container.  The namespace of this container is the name of
   the YANG module 'ietf-yp-notification' defined in Section 7.1.2.

   Two mandatory child nodes within the 'ietf-yp-notification:envelope'
   container are expected, representing the event time and the
   Notification payload.  The 'event-time' node is defined within the
   same namespace as the 'ietf-yp-notification:envelope' container.

   When other Notification metadata is enabled through configuration,
   the supplementary nodes are encoded at the same level as the
   mandatory 'event-time' node.  The YANG nodes in the Notification
   header use the YANG module name from the module that defines the
   nodes as its namespace.  Two additional metadata are described in
   this document.  Refer to Section 3.2 for more details.






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   The content of the Notification that is defined by the 'notification'
   statement is encoded in the 'contents' node.  The name and namespace
   of this payload element are determined by the YANG module containing
   the 'notification' statement representing the Notification message.

   The following example shows a "push-update" Notification defined in
   the YANG module of YANG-Push [RFC8641] encoded in JSON:

     {
       "ietf-yp-notification:envelope": {
         "event-time": "2024-10-10T08:00:11.22Z",
         "contents": {
           "ietf-yang-push:push-update": {
             "id": 1011,
             "datastore-contents": {
               "ietf-interfaces:interfaces": {
                 "interface": [
                   {
                     "name": "eth0",
                     "type": "iana-if-type:ethernetCsmacd",
                     "if-index": 1,
                     "admin-status": "up",
                     "oper-status": "up",
                     "statistics": {
                       "discontinuity-time": "2024-10-10T07:50:00Z"
                     }
                   }
                 ]
               }
             }
           }
         }
       }
     }

                    Figure 2: JSON-encoded Notification

3.1.2.3.  CBOR Encoding

   YANG Notifications can be encoded in CBOR using Names or SIDs in
   keys.

   Notifications encoded using names is similar to JSON encoding as
   defined in Section 3.3 of [RFC9254].  The key of the element can be
   the name of the element itself or be namespace-qualified.  In the
   latter case, the namespace of the Notification encoded message uses
   the YANG module name 'ietf-yp-notification', defined in
   Section 7.1.2.



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   Notification encoded using YANG-SIDs replaces the name of the keys of
   the CBOR encoded message with a 63-bit unsigned integer.  In this
   case, the keys of the encoded data use the SID value as defined in
   Section 3.2 of [RFC9254].  A SID allocation process is needed
   beforehand as defined in [RFC9595].

   In the Notification, two mandatory child nodes within the 'ietf-yp-
   notification:envelope' container are expected, representing the event
   time and the Notification payload.  The 'event-time' node is defined
   within the same namespace as the 'ietf-yp-notification:envelope'
   container.

   When other Notification metadata is enabled through configuration,
   the supplementary nodes are encoded at the same level as the
   mandatory 'event-time' node.  The YANG nodes in the Notification
   header use the YANG module name from the module that defines the
   nodes as its namespace when they are encoded as names.  When encoded
   using YANG SIDs, the SID value assigned to the metadata node is used.
   A .sid file requesting the SID values for the metadata defined in
   this document can be found in Appendix A.  The .sid file includes the
   metadata defined in Section 3.2.

   The content of the Notification that is defined by the 'notification'
   statement is encoded in the 'contents' node.  The name and namespace
   of this payload element are determined by the YANG module containing
   the 'notification' statement representing the Notification message.
   Similarly, SIDs can be used as keys if they are allocated following
   the process defined in [RFC9595].

   Figure 3 shows a 'push-update' Notification defined in the YANG
   module of YANG-Push [RFC8641] encoded in CBOR using names as keys.
   The example uses the CBOR diagnostic notation as defined in
   Section 3.1 of [RFC9254]:


















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     {
       "ietf-yp-notification:envelope": {
         "event-time": "2024-10-10T08:00:11.22Z",
         "contents": {
           "ietf-yang-push:push-update": {
             "id": 1011,
             "datastore-contents": {
               "ietf-interfaces:interfaces": {
                 "interface": [
                   {
                     "name": "eth0",
                     "type": "iana-if-type:ethernetCsmacd",
                     "if-index": 1,
                     "admin-status": "up",
                     "oper-status": "up",
                     "statistics": {
                       "discontinuity-time": "2024-10-10T07:50:00Z"
                     }
                   }
                 ]
               }
             }
           }
         }
       }
     }

       Figure 3: CBOR-encoded Notification using diagnostic notation

   Figure 4 shows the same Notification encoded using SIDs:





















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     {
       2957: {                                / ietf-yp-notification:envelope (SID 2957) /
         2: "2024-10-10T08:00:11.22Z",        / event-time (SID 2959) /
         1: {                                 / contents (SID 2958) /
           "ietf-yang-push:push-update": {
             "id": 1011,
             "datastore-contents": {
               "ietf-interfaces:interfaces": {
                 "interface": [
                   {
                     "name": "eth0",
                     "type": "iana-if-type:ethernetCsmacd",
                     "if-index": 1,
                     "admin-status": "up",
                     "oper-status": "up",
                     "statistics": {
                       "discontinuity-time": "2024-10-10T07:50:00.00Z"
                     }
                   }
                 ]
               }
             }
           }
         }
       }
     }

        Figure 4: CBOR-encoded Notification using YANG SIDs in CBOR
                            diagnostic notation

   Note to the RFC-Editor: Please change the SID values from the example
   Figure 4 with the ones allocated by IANA.

   Note that in the example shown in Figure 4, the Notification payload
   uses names as keys.  These keys can also be encoded as SIDs.  The
   corresponding SID values must be allocated in the IANA registry,
   following the procedures defined in [RFC9595].

   When SIDs are used throughout the Notification Envelope, they are
   encoded as deltas relative to the parent node by default.  The
   absolute SID can also be used using the tag 47.  Refer to [RFC9254]
   for more details.









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3.2.  Extensions for the Notification Envelope

   This section describes two optional YANG nodes for the Notification
   Envelope header: a 'hostname' and a 'sequence-number', which are
   enabled by default when using the Notification Envelope defined in
   this document.  The Client discovers the support of these two
   optional leafs with the mechanism defined in Section 5.

   The Notification Envelope, including the metadata, results in the
   following YANG tree [RFC8340].

     structure envelope:
       +-- event-time         yang:date-and-time
       +-- hostname?          inet:host-name {hostname-sequence-number}?
       +-- sequence-number?   yang:counter32 {hostname-sequence-number}?
       +-- contents?          <anydata>

3.2.1.  Support of Hostname and Sequencing

   When YANG-Push Notification messages are forwarded from a Receiver to
   another system, such as a message broker or a time series database,
   the transport context is lost since it is not part of the
   Notification metadata of the Notification encoded message.
   Therefore, the downstream system is unable to associate the message
   with the publishing process (the exporting network node), nor able to
   detect message loss or reordering.

   To correlate network data among different Network Telemetry planes as
   described in Section 3.1 of [RFC9232] or among different YANG-Push
   Subscription types as defined in Section 3.1 of [RFC8641], a
   reference to the node streaming the data is needed.  This is
   essential for understanding the timely relationship among these
   different planes and YANG-Push Subscription types.

   Today, network operators work around this impediment by preserving
   the transport source IP address and sequence numbers of the
   publishing process.  However, this implies encoding this information
   in the YANG-Push Notification messages which impact the semantic
   readability of the message in the downstream system.

   On top of that, the transport source IP address might not represent
   the management IP address by which the YANG-Push Publisher should be
   known.  In other terms, the 'source-host' [RFC6470], which is the
   "Address of the remote host for the session" might not be the
   management IP address.






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   To overcome these issues, this document defines an extension to the
   Notification Envelope to encode a hostname and a sequence number.
   This allows the downstream system to not only be able to identify
   from which network node, Subscription, and time the message was
   published but also, the order of the published messages.

   hostname:  Describes the hostname of the network node that published
      the message.  The hostname uniquely identifies the node within the
      network.

   sequence-number:  Generates a unique sequence number for each
      published message by the Publisher process.  The initial number is
      1 and counts up by 1 at every published Notification message until
      it reaches 4294967295.  Then, it wraps around and restarts at 0.
      The value 0 is used to detect wrap arounds.

   Figure 5 provides an example of a JSON encoded, [RFC8259], 'push-
   update' Notification message with 'hostname' and 'sequence-number'
   included.

   {
       "ietf-yp-notification:envelope": {
       "event-time": "2023-03-25T08:30:11.22Z",
       "hostname": "example-router.example.com",
       "sequence-number": 1,
       "contents": {
         "ietf-yang-push:push-update": {
           "id": 6666,
           "datastore-contents": {
             "ietf-interfaces:interfaces": {
               "interface": [
                 {
                   "name": "eth0",
                   "type": "iana-if-type:ethernetCsmacd",
                   "if-index": 1,
                   "admin-status": "up",
                   "oper-status": "up",
                   "statistics": {
                     "discontinuity-time": "2023-03-25T08:20:00.00Z"
                   }
                 }
               ]
             }
           }
         }
       }
     }
   }



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      Figure 5: JSON Example for a 'push-update' Notification message

3.3.  Extensions for the YANG-Push Header

   This section described two optional 'push-update' and 'push-change-
   update' Notification header extensions which are enabled by default
   when using the Notification Envelope defined in this document.  The
   Client discovers the support of these two leafs with the mechanism
   defined in Section 5.

   This document defines the following Notification metadata as shown in
   the following YANG tree [RFC8340].  See the following sections for
   more details.

   module: ietf-yp-observation

     augment /yp:push-update:
       +--ro timestamp?       yang:date-and-time
       +--ro point-in-time?   enumeration
     augment /yp:push-change-update:
       +--ro timestamp?       yang:date-and-time
       +--ro point-in-time?   enumeration

3.3.1.  Support of Observation Timestamp

   To correlate network data among different Network Telemetry planes,
   as described in Section 3.1 of [RFC9232], or among different YANG-
   Push Subscription types, as defined in Section 3.1 of [RFC8641], a
   Receiver needs a timestamp reference to align all the metrics and
   events.  The observation timestamp defined in this document
   characterizes the moment the state change was observed or the moment
   when the data was measured, so that a Receiver can correctly align
   the collected data.

   The delay between the YANG-Push export process and the reception of
   the message at the Receiver instance can be measured using the node
   'event-time' defined in Section 3.1.1.  However, as the 'event-time'
   node only establishes the moment when the YANG-Push message was
   crafted and sent, the moment when such metrics were collected or the
   state changes were observed cannot be measured using this timestamp.
   The observation timestamp defined in this section characterizes the
   moment when the metrics were observed, which enable aligning the
   received metrics to the actual moment they were measured.

   When the time bucket length in a time series database and the
   periodic YANG-Push Subscription time are configured with the same
   values, the 'event-time' of the NETCONF Notification message header
   can be used for indexing the data in the time series database.  There



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   is a variable delay between the observation timestamp, the 'event-
   time', and the 'anchor-time' as described in Section 4.2 of
   [RFC8641].  When these timestamps are close to the time bucket
   boundaries, a time bucket may experience data collection
   discrepancies, e.g. 0 measurements are aggregated into one time
   bucket while the next time bucket contains 2 measurements.  This
   leads to inconsistent accounting errors in the time series database.
   This problem is resolved using the observation timestamp instead of
   the 'event-time' for time series database indexation.

   By extending YANG-Push Notifications with the observation timestamp
   and a 'point-in-time' node, the data collection process can always
   ensure it has the best available time for indexing the data.  It can
   therefore use unconditionally the observation timestamp node in the
   data processing chain to correctly align the metrics and events.  At
   the same time, the 'point-in-time' node ensures that the semantics
   associated with the timestamp are not lost throughout the data
   processing chain.

   Besides the Subscription ID as described in Section 3.7 of [RFC8641],
   the following network observation time metadata objects are part of
   'push-update' and 'push-change-update' Notifications.

   timestamp:  States the measurement observation time for the 'push-
      update' Notification in 'periodic' Subscriptions and for the
      'push-change-update' Notification in 'on-change' Subscriptions.

      By comparing the observation timestamp of two 'push-update'
      Notifications in a periodic Subscription, the collector can deduce
      the actual cadence of the measurements, and compare it with the
      Subscription configuration.  In case of an 'on-change'
      Subscription it states the time when the network state change was
      observed.

   point-in-time:  The enumeration states at which point in time the
      value of the observation timestamp was observed.  Choices are:

      'current-accounting' states the point in time where the metrics
      are polled and observed in "periodic" Subscriptions.

      'initial-state' states the initial point in time when the
      Subscription was established and the state was observed for 'on-
      change sync on start' Subscriptions.

      'state-changed' states the point in time when the state change was
      observed after the Subscription was established for 'on-change'
      and 'on-change sync on start' Subscriptions.




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3.3.1.1.  Usage Example

   This section illustrates the usage of the 'point-in-time' node in two
   different Subscriptions.  Section 3.3.1.1.1 showcases a YANG-Push
   Subscription monitoring the state of an interface using an 'on-change
   sync on start' Subscription.  Section 3.3.1.1.2 illustrates the usage
   of the 'point-in-time' node within periodic Subscriptions.

3.3.1.1.1.  On-Change Subscriptions

   Figure 6 illustrates the set of events that lead to the generation of
   'on-change' YANG-Push Notifications.  This timeline depicts the
   following states and events:

   *  T1: At first, the operational state of the interface is "Up".  The
      Subscription is not configured yet at this stage and thus,
      Notifications are not triggered for this state change.

   *  T2: After configuring an 'on-change' Subscription supporting 'sync
      on start', the Publisher sends the initial state of the interface.
      The initial state is polled based on the event having happened at
      T1.

   *  T3: This is the moment the interface changes its operational
      status to "Down".

   *  T4: After the interface state changes at T3, the Publisher
      generates the 'on-change' Notification alerting the Receiver.

Timeline
---------------------------------------------------------------------->
 | (T1) Interface | (T2) YANG-Push   | (T3) Interface | (T4) YANG-Push
 | state changed  | "on-change sync  | state changed  | "on-change"
 | to "Up".       | on start"        | to "Down".     | Notification
 |                | Subscription for |                | with the new
 |                | interface state  |                | interface state.
 |                | is established.  |                |
 v                v                  v                v

 Figure 6: Example timeline for On-Change Sync on Start Subscription

   At T2, after configuring the Subscription, the Publisher triggers a
   'push-update' Notification as depicted in Figure 7.  The 'event-time'
   is the moment the YANG-Push process generates the Notification (T2).
   The 'ietf-yp-observation:timestamp' node characterizes the moment of
   the interface changed it status to "Up" (T1).  T1 is the latest
   moment this state was observed by the process.  In this case, the
   'point-in-time' node is set to 'initial-state'.



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   {
     "ietf-yp-notification:envelope": {
       "event-time": "2025-03-25T08:30:11.22Z",
       "hostname": "example-router.example.com",
       "sequence-number": 1,
       "contents": {
         "ietf-yang-push:push-update": {
           "id": 6666,
           "ietf-yp-observation:timestamp": "2025-03-25T08:29:30.22Z",
           "ietf-yp-observation:point-in-time": "initial-state",
           "datastore-contents": {
             "ietf-interfaces:interfaces": {
               "interface": [{
                 "name": "eth0",
                 "type": "iana-if-type:ethernetCsmacd",
                 "if-index": 1,
                 "admin-status": "up",
                 "oper-status": "up",
                 "statistics": {
                   "discontinuity-time": "2025-03-25T06:43:12Z"
                 }
               }]
             }
           }
         }
       }
     }
   }

       Figure 7: Example of 'push-update' Notification sent after the
                        Subscription is established.

   After T3, the Publisher triggers a 'push-change-update' Notification
   announcing an interface status change to the Receiver as depicted in
   Figure 8.  In this case, the 'ietf-yp-observation:timestamp' node
   characterizes the moment the interface changed its status at T3.  The
   value of the 'event-time' node characterizes the moment the YANG-Push
   process generated the Notification at T4.













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   {
     "ietf-yp-notification:envelope": {
       "event-time": "2025-03-25T08:35:12.22Z",
       "hostname": "example-router.example.com",
       "sequence-number": 1,
       "contents": {
         "ietf-yang-push:push-change-update": {
           "id": 2222,
           "ietf-yp-observation:timestamp": "2025-03-25T08:34:05.22Z",
           "ietf-yp-observation:point-in-time": "state-changed",
           "datastore-contents": {
             "yang-patch": {
               "patch-id": "52",
               "edit": {
                 "edit-id": "edit_example_1",
                 "operation": "replace",
                 "target": "/ietf-interfaces:interfaces",
                 "value": {
                   "ietf-interfaces:interfaces": {
                     "interface": [{
                       "name": "eth0",
                       "type": "iana-if-type:ethernetCsmacd",
                       "if-index": 1,
                       "admin-status": "up",
                       "oper-status": "down",
                       "statistics": {
                         "discontinuity-time": "2025-03-25T06:43:12Z"
                       }
                     }]
                   }
                 }
               }
             }
           }
         }
       }
     }
   }

     Figure 8: JSON Push Example for a push-change-update Notification
                                  message

3.3.1.1.2.  Periodic Subscriptions

   In periodic Subscription, the observation time characterizes the time
   when the metrics were polled from the datastore before it generates
   the actual YANG-Push message.




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   Figure 9 illustrates the delays associated with the generation of the
   YANG-Push message.  The timeline shows the following states:

   *  T1: This is the moment the periodic Subscription is configured to
      push the operational status of the interface every N interval.

   *  T2: This is the moment the YANG-Push process polls the state data
      and metrics from the datastore.  At this stage, the Notification
      is not built nor sent yet.

   *  T3: This is the moment the YANG-Push process generates the 'push-
      update' Notification and sends it to the Receiver.

   At every N interval, the process repeats the steps from T2 and T3,
   first polling the datastore to retrieve the data (T2) and then
   building and sending the Notification to the Receiver (T3).

       Timeline
       ------------------------------------------------------>
       | (T1) YANG-Push | (T2) YANG-Push | (T3) YANG-Push
       | "periodic"     | process polls  | "periodic"
       | Subscription   | the metrics    | current
       | for interface  | from the       | accounting.
       | counter is     | datastore.     |
       | established    |                |
       v                v                v

            Figure 9: Example timeline for Periodic Subscription

   An example of a 'push-update' Notification is illustrated in
   Figure 10.  This example represents a message sent at T3, after the
   process built the YANG-Push Notification.  The node 'event-time'
   characterizes the moment the YANG-Push process generated the message
   (T3).  The node 'ietf-yp-observation:timestamp' establishes the
   moment when the metrics were polled from the datastore (T2).  For
   these periodic Subscriptions, the 'point-in-time' node must be set to
   'current-accounting'.














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   {
     "ietf-yp-notification:envelope": {
       "event-time": "2023-03-25T08:30:12.25Z",
       "hostname": "example-router.example.com",
       "sequence-number": 1,
       "contents": {
         "ietf-yang-push:push-update": {
           "id": 6666,
           "ietf-yp-observation:timestamp": "2023-03-25T08:30:00.00Z",
           "ietf-yp-observation:point-in-time": "current-accounting",
           "datastore-contents": {
             "ietf-interfaces:interfaces": {
               "interface": [{
                 "name": "eth0",
                 "type": "iana-if-type:ethernetCsmacd",
                 "if-index": 1,
                 "admin-status": "up",
                 "oper-status": "up",
                 "statistics": {
                   "discontinuity-time": "2023-03-25T07:43:12Z",
                   "in-octets": 200,
                   "in-octets": 250
                 }
               }]
             }
           }
         }
       }
     }
   }

    Figure 10: JSON Push Example for a push-update Notification message

4.  Enabling the Notification Envelope

   The Notification Envelope defined in this document can be enabled
   either prior to or within the same NETCONF transaction that
   configures the YANG-Push Subscriptions.  This document augments the
   'ietf-subscribed-notification' model [RFC8639] to support the
   configuration of the Notification Envelope.

   When the node 'enable-notification-envelope' is enabled, all the
   Notifications defined in Subscribed Notification [RFC8639] and YANG-
   Push [RFC8641] are encoded as defined in Section 3.1.  If
   additionally, any Notification metadata is enabled, the Notification
   metadata nodes are present in the header.  When the node 'enable-
   notification-envelope' is disabled, Notifications are encoded as
   defined in NETCONF Event Notifications [RFC5277].  Both extensions



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   defined in Section 3.2 and Section 3.3 are sent by default when (1)
   they are supported and (2) the node 'enable-notification-envelope' is
   enabled.

   module: ietf-yp-notification

     augment /sn:subscriptions:
       +--rw enable-notification-envelope?   boolean
       +--rw metadata

   When there are existing Subscriptions and a Client changes the node
   'enable-notification-envelope', all existing Subscriptions MUST be
   terminated.  The Publisher MUST send a 'subscription-terminated'
   notification to all the existing Subscriptions using the header
   configured before the change.  Any new Subscription after the change
   uses the header defined by the node 'enable-notification-envelope',
   i.e. encoded as Section 3.1.1 when enabled and as defined in
   [RFC5277] if disabled.

   The container 'metadata' is intended to support optional extensions
   that may be enabled on a per-extension basis.  Defining explicit
   configuration knobs to enable or disable these extensions is optional
   and left to the extension designer.  Refer to Appendix B for an
   example.

   Per the YANG specifications (Section 7.17 of [RFC7950]), which does
   not allow making mandatory statements on augmentations, the 'enable-
   notification-envelope' YANG leaf must be made optional: the metadata
   fields MUST not be enabled when the Notification Envelope is not
   enabled.

   Per-subscription support for this header was considered during the
   definition of this specification, however, a network node-wide
   setting was chosen to simplify network operations.  In practice,
   operators use YANG-Push Subscriptions in large-scale deployments
   where numerous Subscriptions are created on each network node.  While
   per-subscription configuration provides more flexibility, maintaining
   the choice of header format for each Subscription adds significant
   operational complexity when troubleshooting or migrating to a new
   header format.  The desire for simplifying operations led to the
   definition of a global configuration knob for the Notification
   Envelope.

5.  Discovering the Support of the Notification Envelope

   A Client can discover the support of the Notification Envelope model
   through the capabilities model defined in [RFC9196].  This document
   extends the 'ietf-notification-capabilities' model with:



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   *  A container containing a leaf 'envelope', stating that the YANG
      Notification can be encoded following the Notification Envelope
      model.

   *  A container 'metadata' containing all the supported extensions to
      this header.  Extensions are defined in Section 3.2 and
      Section 3.3.

   When the leafs defined in this document are supported by the Server,
   the Client discovers the presence of new metadata with the following
   augmentations in the 'ietf-notification-capabilities' module:

   module: ietf-yp-notification

     augment /sysc:system-capabilities/notc:subscription-capabilities:
       +--ro notification-metadata
          +--ro envelope?   boolean
          +--ro metadata
             +--ro hostname-sequence-number?   boolean
                     {hostname-sequence-number}?

   module: ietf-yp-observation

     augment /sysc:system-capabilities/notc:subscription-capabilities:
       +--ro yang-push-observation-time-supported?   boolean

6.  Operational Considerations

   As stated in Section 4, the Notification Envelope defined in this
   document replaces the header defined by NETCONF Event Notifications
   [RFC5277] when enabled.  The NETCONF Event Notifications [RFC5277]
   header and the Notification Envelope defined in this document may
   coexist in the same network.  Since enabling or disabling the
   Notification Envelope is performed on a YANG-Push Publisher basis,
   Receivers must only receive Notifications in a format they support.
   Operators should ensure that Receivers support the corresponding
   format or that proper validation and filtering are implemented when
   both formats are present in the same network.

   In network devices where existing Subscriptions are active, enabling
   or disabling the Notification Envelope has operational impact.
   Operators should acknowledge that any existing Subscriptions will be
   terminated when enabling or disabling the Notification Envelope.
   Careful planning is therefore required to avoid unintended service
   disruption.

7.  YANG Modules




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7.1.  The 'ietf-yp-notification' Module

   The following sections show the YANG tree and YANG module for the
   'ietf-yp-notification' module.  This module defines the Notification
   Envelope structure, and extends the 'ietf-subscribed-notifications'
   and 'ietf-notification-capabilities' modules to enable both the
   configuration of the Notification Envelope and the discovery of
   supported extensions.  This module supports the 'hostname' and
   'sequence-number' as extensions to the Notification Envelope.

7.1.1.  YANG 'ietf-yp-notification' Tree Diagram

   This YANG module extends 'ietf-subscribed-notifications' [RFC8641]
   and 'ietf-notification-capabilities' [RFC9196] as shown in the
   following YANG tree [RFC8340]:

   module: ietf-yp-notification

     augment /sn:subscriptions:
       +--rw enable-notification-envelope?   boolean
       +--rw metadata
     augment /sysc:system-capabilities/notc:subscription-capabilities:
       +--ro notification-metadata
          +--ro envelope?   boolean
          +--ro metadata
             +--ro hostname-sequence-number?   boolean
                     {hostname-sequence-number}?

     structure envelope:
       +-- event-time         yang:date-and-time
       +-- hostname?          inet:host-name {hostname-sequence-number}?
       +-- sequence-number?   yang:counter32 {hostname-sequence-number}?
       +-- contents?          <anydata>

7.1.2.  YANG 'ietf-yp-notification' Module

   The YANG module augments the module 'ietf-subscribed-notifications'
   [RFC8641], augments the module "ietf-notification-capabilities"
   [RFC9196] and uses 'ietf-yang-types' module [RFC6991] and 'ietf-yang-
   structure-ext' module [RFC8791].

   <CODE BEGINS> file "ietf-yp-notification@2025-12-24.yang"
   module ietf-yp-notification {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-yp-notification";
     prefix iypn;

     import ietf-yang-types {



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       prefix yang;
       reference
         "draft-ietf-netmod-rfc6991-bis-18: Common YANG Data Types";
     }
     import ietf-inet-types {
       prefix inet;
       reference
         "draft-ietf-netmod-rfc6991-bis-18: Common YANG Data Types";
     }
     import ietf-subscribed-notifications {
       prefix sn;
       reference
         "RFC 8639: Subscription to YANG Notifications";
     }
     import ietf-system-capabilities {
       prefix sysc;
       reference
         "RFC 9196: YANG Modules Describing Capabilities for
          Systems and Datastore Update Notifications";
     }
     import ietf-notification-capabilities {
       prefix notc;
       reference
         "RFC 9196: YANG Modules Describing Capabilities for
          Systems and Datastore Update Notifications";
     }
     import ietf-yang-structure-ext {
       prefix sx;
       reference
         "RFC 8791: YANG Data Structure Extensions";
     }

     organization
       "IETF NETCONF (Network Configuration) Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/group/netconf/>
        WG List:  <mailto:netconf@ietf.org>

        Authors:  Alex Huang Feng
                  <mailto:alex.huang-feng@insa-lyon.fr>
                  Pierre Francois
                  <mailto:pierre.francois@insa-lyon.fr>
                  Thomas Graf
                  <mailto:thomas.graf@swisscom.com>
                  Benoit Claise
                  <mailto:benoit@everything-ops.net>";
     description
       "Defines a notification header for Subscribed Notifications



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       [RFC8639] and YANG-Push [RFC8641]. When this notification header
       is enabled through configuration, the root container of the
       notification is encoded as defined in RFCXXX.

       This module can be used to validate XML-encoded notifications
       [RFC7950], JSON-encoded messages [RFC7951], and CBOR-encoded
       messages [RFC9254]. Refer to Section 3.1.2 of RFC XXXX for more
       details.

       Copyright (c) 2025 IETF Trust and the persons identified as
       authors of the code.  All rights reserved.

       Redistribution and use in source and binary forms, with or without
       modification, is permitted pursuant to, and subject to the license
       terms contained in, the Revised BSD License set forth in Section
       4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
       (https://trustee.ietf.org/license-info).

       All revisions of IETF and IANA published modules can be found
       at the YANG Parameters registry group
       (https://www.iana.org/assignments/yang-parameters).

       This version of this YANG module is part of RFC XXXX; see
       the RFC itself for full legal notices.

       The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
       NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
       'MAY', and 'OPTIONAL' in this document are to be interpreted as
       described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
       they appear in all capitals, as shown here.";

     revision 2025-12-24 {
       description
         "Initial version.";
       reference
         "RFC XXXX: Extensible YANG Model for YANG-Push Notifications";
     }

     feature hostname-sequence-number {
       description
         "This feature indicates that hostname and sequence numbers are
         supported.";
     }

     grouping notif-env-capabilities {
       description
         "This grouping defines the capabilities for
          the notification-envelope defined in RFC XXXX



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          and the different supported metadata.";
       leaf envelope {
         type boolean;
         default "true";
         description
           "Supports YANG-Push to use the notification-envelope as
            defined in RFC XXXX. If set to true, the publisher supports
            the notification envelope. If set to false, the
            notification envelope is not supported by the publisher.";
       }
       container metadata {
         description
           "Container with the supported optional metadata by the
            YANG-Push publisher.";
         leaf hostname-sequence-number {
           if-feature "hostname-sequence-number";
           type boolean;
           default "false";
           description
             "Supports hostname and sequence-number
              in the YANG-Push notifications as defined in the
              YANG-Push notification-envelope in RFC XXXX.
              If set to true, the publisher supports
              sending the hostname and sequence numbers
              within the notification envelope. If set to false,
              the hostname and sequence numbers are not supported.";
         }
       }
     }

     sx:structure envelope {
       leaf event-time {
         type yang:date-and-time;
         mandatory true;
         description
           "The date and time the event was generated by the network
            node.";
       }
       leaf hostname {
         if-feature "hostname-sequence-number";
         type inet:host-name;
         description
           "The hostname of the network node. This value is usually
            configured on the node by the administrator to identify
            the node in the network uniquely.";
       }
       leaf sequence-number {
         if-feature "hostname-sequence-number";



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         type yang:counter32;
         description
           "Unique sequence number for each published message
            by the publisher process. The initial number is 1 and
            counts up by 1 at every published notification message
            until it reaches 4294967295. Then, it wraps around and
            restarts at 0. The value 0 is used to detect wrap
            arounds.";
       }
       anydata contents {
         description
           "This contains the values defined by the 'notification'
            statement unchanged.";
       }
     }

     // Subscription container
     augment "/sn:subscriptions" {
       description
         "This augmentation adds the configuration switches for
          enabling the notification envelope and metadata.";
       leaf enable-notification-envelope {
         type boolean;
         default "false";
         description
           "Enables YANG-Push to use the notification-envelope
           defined in RFC XXXX.

           Enabling or disabling this leaf terminates all
           existing active dynamic and configured YANG-Push
           subscriptions. The publisher MUST send a
           'subscription-terminated' notification to all the
           existing active subscriptions using
           the header configured before the change, then the
           subscription is terminated. Refer to
           Section 4 of RFC XXXX for more details.";
       }
       container metadata {
         description
           "Container for configuring optional metadata.
           Refer to Section 4 of RFC XXXX for more details.";
       }
     }

     // YANG-Push Capabilities extension
     augment "/sysc:system-capabilities"
           + "/notc:subscription-capabilities" {
       description



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         "Extension to the subscription-capabilities model to enable
          clients to learn whether the publisher supports the
          notification-envelope";
       container notification-metadata {
         description
           "Adds the notification metadata capabilities to subscription
            capabilities.";
         uses notif-env-capabilities;
       }
     }
   }
   <CODE ENDS>

7.2.  The 'ietf-yp-observation' Module

   The following sections show the YANG tree and YANG module for the
   'ietf-yp-observation' module.  This module extends the 'ietf-yang-
   push' module to support sending the observation timestamp in 'push-
   update' and 'push-change-update' Notifications.  Additionally, it
   augments the 'ietf-notification-capabilities' to enable Clients to
   discover the support of observation timestamps.

7.2.1.  YANG 'ietf-yp-observation' Tree Diagram

   This YANG module extends 'ietf-yang-push' [RFC8641] and 'ietf-
   notification-capabilities' [RFC9196] as shown in the following YANG
   tree [RFC8340]:

   module: ietf-yp-observation

     augment /yp:push-update:
       +--ro timestamp?       yang:date-and-time
       +--ro point-in-time?   enumeration
     augment /yp:push-change-update:
       +--ro timestamp?       yang:date-and-time
       +--ro point-in-time?   enumeration
     augment /sysc:system-capabilities/notc:subscription-capabilities:
       +--ro yang-push-observation-time-supported?   boolean

7.2.2.  YANG 'ietf-yp-observation' Module

   The YANG module augments the module 'ietf-yang-push' [RFC8641],
   augments the module 'ietf-system-capabilities' [RFC9196].








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   <CODE BEGINS> file "ietf-yp-observation@2025-12-24.yang"
   module ietf-yp-observation {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-yp-observation";
     prefix iypo;

     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 6991: Common YANG Data Types";
     }
     import ietf-yang-push {
       prefix yp;
       reference
         "RFC 8641: Subscription to YANG Notifications for Datastore
         Updates";
     }
     import ietf-system-capabilities {
       prefix sysc;
       reference
         "RFC 9196: YANG Modules Describing Capabilities for
          Systems and Datastore Update Notifications";
     }
     import ietf-notification-capabilities {
       prefix notc;
       reference
         "RFC 9196: YANG Modules Describing Capabilities for
          Systems and Datastore Update Notifications";
     }

     organization
       "IETF NETCONF (Network Configuration) Working Group";
     contact
       "WG Web:   <http:/tools.ietf.org/wg/netconf/>
        WG List:  <mailto:netconf@ietf.org>

        Authors:  Thomas Graf
                  <mailto:thomas.graf@swisscom.com>
                  Benoit Claise
                  <mailto:benoit@everything-ops.net>
                  Alex Huang Feng
                  <mailto:alex.huang-feng@insa-lyon.fr>";
     description
       "Defines YANG-Push event notification header with the observation
       time in streaming update notifications.

       Copyright (c) 2025 IETF Trust and the persons identified as
       authors of the code.  All rights reserved.



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       Redistribution and use in source and binary forms, with or without
       modification, is permitted pursuant to, and subject to the license
       terms contained in, the Revised BSD License set forth in Section
       4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
       (https://trustee.ietf.org/license-info).

       All revisions of IETF and IANA published modules can be found
       at the YANG Parameters registry group
       (https://www.iana.org/assignments/yang-parameters).

       This version of this YANG module is part of RFC XXXX; see
       the RFC itself for full legal notices.";

     revision 2025-12-24 {
       description
         "Initial version.";
       reference
         "RFC XXXX: Extensible YANG Model for YANG-Push Notifications";
     }

     grouping yang-push-observation {
       description
         "This grouping adds the observation timestamp for the
         observed metrics.";
       leaf timestamp {
         type yang:date-and-time;
         description
           "This is the time when the metrics were observed.";
       }
       leaf point-in-time {
         type enumeration {
           enum current-accounting {
             description
               "For periodic subscriptions, the point-in-time
                where the metrics are being polled and observed.";
           }
           enum initial-state {
             description
               "For 'on-change sync on start' subscriptions, the
                initial point in time when the subscription was
                established and the state was observed.";
           }
           enum state-changed {
             description
               "For 'on-change sync on start' subscriptions, the
                point in time when the state change was observed after
                the subscription was established.";
           }



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         }
         description
           "This describes at which point in time the metrics were
           observed.";
       }
     }

     // Event notifications
     augment "/yp:push-update" {
       description
         "This augmentation adds the observation timestamp of the
         accounted metrics in the push-update notification.";
       uses iypo:yang-push-observation;
     }

     augment "/yp:push-change-update" {
       description
         "This augmentation adds the observation timestamp of the
         event in the push-change-update notification.";
       uses iypo:yang-push-observation;
     }

     // Event capabilities
     augment "/sysc:system-capabilities"
           + "/notc:subscription-capabilities" {
       description
         "Add YANG-Push notification capabilities to system-level
         capability container.";
       leaf yang-push-observation-time-supported {
         type boolean;
         default "false";
         description
           "Specifies whether the publisher supports exporting
            observation-timestamp and point-in-time in notifications.
            If set to true, publisher supports. If set to false,
            the observation-timestamp is not supported.";
         reference
           "RFC XXXX: Extensible YANG Model for YANG-Push Notifications";
       }
     }
   }
   <CODE ENDS>

8.  Implementation Status

   Note to the RFC-Editor: Please remove this section before publishing.





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8.1.  Huawei VRP

   Huawei implemented in push-update and push-change-update
   Notifications the timestamp and point-in-time extension as described
   in Section 3.3 for a YANG-Push Publisher on UDP-based Transport for
   Configured Subscriptions [I-D.ietf-netconf-udp-notif] in their VRP
   platform.

8.2.  6WIND VSR

   6WIND implemented in push-update and push-change-update Notifications
   the timestamp and point-in-time extension as described in Section 3.3
   for a YANG-Push Publisher on UDP-based Transport for Configured
   Subscriptions [I-D.ietf-netconf-udp-notif] in their VSR platform.

8.3.  Cisco IOS XR

   Cisco implemented in push-update and push-change-update Notifications
   the timestamp and point-in-time extension as described in Section 3.3
   for a YANG-Push Publisher on UDP-based Transport for Configured
   Subscriptions [I-D.ietf-netconf-udp-notif] in their IOS XR platform.

9.  Security Considerations

   This section uses the template described in Section 3.7 of
   [I-D.ietf-netmod-rfc8407bis].

   The 'ietf-yp-notification' and 'ietf-yp-observation' YANG modules
   define data models that are designed to be accessed via YANG-based
   management protocols, such as NETCONF [RFC6241] and RESTCONF
   [RFC8040].  These YANG-based management protocols (1) have to use a
   secure transport layer (e.g., SSH [RFC6242], TLS [RFC8446], and QUIC
   [RFC9000]) and (2) have to use mutual authentication.

   The Network Configuration Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., "config true", which is the
   default).  All writable data nodes are likely to be reasonably
   sensitive or vulnerable in some network environments.  Write
   operations (e.g., edit-config) and delete operations to these data
   nodes without proper protection or authentication can have a negative
   effect on network operations.  The following subtrees and data nodes
   have particular sensitivities/vulnerabilities:




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   *  /sn:subscriptions/iypn:enable-notification-envelope

   The entries in the list above will show whether the mechanism defined
   in this document is enabled.  Access control MUST be set so that only
   someone with proper access permissions has the ability to access and
   modify this resource.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   Notification) to these data nodes.  Specifically, the following
   subtrees and data nodes have particular sensitivities/
   vulnerabilities:

   *  /iypn:envelope/hostname

   The entries in the list above will show the identity of the
   originating device.  Exposure of this information may assist an
   attacker in mapping the network or in injecting spoofed
   Notifications.  Implementations SHOULD ensure that access to this
   data is restricted and that Notifications are sent over secure and
   authenticated channels.

10.  IANA Considerations

   This document describes the URI used for the IETF XML Registry and
   registers a new YANG module name.

10.1.  URI

   IANA is requested to add this document as a reference in the
   following URI's in the IETF XML Registry [RFC3688].

   URI: urn:ietf:params:xml:ns:yang:ietf-yp-notification
   Registrant Contact: The IESG.
   XML: N/A; the requested URI is an XML namespace.
   Reference: RFC XXXX

   URI: urn:ietf:params:xml:ns:yang:ietf-yp-observation
   Registrant Contact: The IESG.
   XML: N/A; the requested URI is an XML namespace.
   Reference: RFC XXXX

10.2.  YANG module name

   This document registers the following YANG modules in the YANG Module
   Names Registry [RFC6020], within the "YANG Parameters" registry:




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   name: ietf-yp-notification
   namespace: urn:ietf:params:xml:ns:yang:ietf-yp-notification
   prefix: iypn
   reference: RFC XXXX

   name: ietf-yp-observation
   namespace: urn:ietf:params:xml:ns:yang:ietf-yp-observation
   prefix: iypo
   reference: RFC XXXX

10.3.  YANG SID-file

   IANA is requested to register a new ".sid" file in the "IETF YANG SID
   Registry" [RFC9595]:

   SID range entry point: TBD
   SID range size: 50
   YANG module name: ietf-yp-notification
   reference: RFC XXXX

   A ".sid" file is proposed in Appendix A.

   Note to the RFC-Editor:

   Please replace TBD with the value allocated by IANA.

11.  Acknowledgements

   The authors would like to thank Paul Aitken, Per Anderson, Andy
   Bierman, Carsten Bormann, Mohamed Boucadair, Tom Petch, Reshad
   Rahman, Jürgen Schönwälder, Jason Sterne, Kent Watsen, Rob Wilton and
   Qin Wu for their review and valuable comments.

12.  References

12.1.  Normative References

   [I-D.ietf-netmod-rfc6991-bis]
              Schönwälder, J., "Common YANG Data Types", Work in
              Progress, Internet-Draft, draft-ietf-netmod-rfc6991-bis-
              18, 23 June 2025, <https://datatracker.ietf.org/doc/html/
              draft-ietf-netmod-rfc6991-bis-18>.

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




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   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC5277]  Chisholm, S. and H. Trevino, "NETCONF Event
              Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008,
              <https://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,
              <https://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,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with YANG",
              RFC 7951, DOI 10.17487/RFC7951, August 2016,
              <https://www.rfc-editor.org/info/rfc7951>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8639]  Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard,
              E., and A. Tripathy, "Subscription to YANG Notifications",
              RFC 8639, DOI 10.17487/RFC8639, September 2019,
              <https://www.rfc-editor.org/info/rfc8639>.

   [RFC8641]  Clemm, A. and E. Voit, "Subscription to YANG Notifications
              for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
              September 2019, <https://www.rfc-editor.org/info/rfc8641>.





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   [RFC8791]  Bierman, A., Björklund, M., and K. Watsen, "YANG Data
              Structure Extensions", RFC 8791, DOI 10.17487/RFC8791,
              June 2020, <https://www.rfc-editor.org/info/rfc8791>.

   [RFC9196]  Lengyel, B., Clemm, A., and B. Claise, "YANG Modules
              Describing Capabilities for Systems and Datastore Update
              Notifications", RFC 9196, DOI 10.17487/RFC9196, February
              2022, <https://www.rfc-editor.org/info/rfc9196>.

   [RFC9254]  Veillette, M., Ed., Petrov, I., Ed., Pelov, A., Bormann,
              C., and M. Richardson, "Encoding of Data Modeled with YANG
              in the Concise Binary Object Representation (CBOR)",
              RFC 9254, DOI 10.17487/RFC9254, July 2022,
              <https://www.rfc-editor.org/info/rfc9254>.

   [W3C.REC-xml-20001006]
              Bray, T., Paoli, J., Sperberg-McQueen, M., and E. Maler,
              "Extensible Markup Language (XML) 1.0 (Second Edition)",
              W3C, October 2000,
              <https://www.w3.org/TR/2000/REC-xml-20001006>.

12.2.  Informative References

   [I-D.ietf-netconf-udp-notif]
              Feng, A. H., Francois, P., Zhou, T., Graf, T., and P.
              Lucente, "UDP-based Transport for Configured
              Subscriptions", Work in Progress, Internet-Draft, draft-
              ietf-netconf-udp-notif-25, 28 January 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
              udp-notif-25>.

   [I-D.ietf-netmod-rfc8407bis]
              Bierman, A., Boucadair, M., and Q. Wu, "Guidelines for
              Authors and Reviewers of Documents Containing YANG Data
              Models", Work in Progress, Internet-Draft, draft-ietf-
              netmod-rfc8407bis-28, 5 June 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netmod-
              rfc8407bis-28>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6470]  Bierman, A., "Network Configuration Protocol (NETCONF)
              Base Notifications", RFC 6470, DOI 10.17487/RFC6470,
              February 2012, <https://www.rfc-editor.org/info/rfc6470>.





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   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/info/rfc8259>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC9000]  Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
              Multiplexed and Secure Transport", RFC 9000,
              DOI 10.17487/RFC9000, May 2021,
              <https://www.rfc-editor.org/info/rfc9000>.

   [RFC9232]  Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and
              A. Wang, "Network Telemetry Framework", RFC 9232,
              DOI 10.17487/RFC9232, May 2022,
              <https://www.rfc-editor.org/info/rfc9232>.

   [RFC9595]  Veillette, M., Ed., Pelov, A., Ed., Petrov, I., Ed.,
              Bormann, C., and M. Richardson, "YANG Schema Item
              iDentifier (YANG SID)", RFC 9595, DOI 10.17487/RFC9595,
              July 2024, <https://www.rfc-editor.org/info/rfc9595>.

Appendix A.  .sid file

   This appendix is not normative.  For CBOR encoding using YANG-SIDs
   identifiers, a ".sid" file is requested to IANA in Section 10.3.

   The .sid file can be found in TBD2.

   Note to the RFC-Editor:

   1.  Please replace the entry-point and SID values with the ones
   allocated by IANA.

   2.  Please change the 'sid-file-status' to 'published' once the .sid
   file is published.




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   3.  Please remove the .sid file from the document and insert a link
   in TBD2 to the .sid file reference from IANA.


   <CODE BEGINS> file "ietf-yp-notification@2025-12-24.sid"
   {
     "ietf-sid-file:sid-file": {
       "module-name": "ietf-yp-notification",
       "module-revision": "2025-12-24",
       "sid-file-status":"unpublished",
       "description": "draft-ietf-netconf-notif-envelope-04: Extensible YANG Model for YANG-Push Notifications",
       "dependency-revision": [
         {
           "module-name":"ietf-datastores",
           "module-revision":"2018-02-14"
         },
         {
           "module-name":"ietf-interfaces",
           "module-revision":"2018-02-20"
         },
         {
           "module-name":"ietf-ip",
           "module-revision":"2018-02-22"
         },
         {
           "module-name":"ietf-netconf-acm",
           "module-revision":"2018-02-14"
         },
         {
           "module-name":"ietf-network-instance",
           "module-revision":"2019-01-21"
         },
         {
           "module-name":"ietf-restconf",
           "module-revision":"2017-01-26"
         },
         {
           "module-name":"ietf-yang-library",
           "module-revision":"2019-01-04"
         },
         {
           "module-name":"ietf-yang-patch",
           "module-revision":"2017-02-22"
         },
         {
           "module-name":"ietf-yang-schema-mount",
           "module-revision":"2019-01-14"
         },



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         {
           "module-name": "ietf-yang-types",
           "module-revision": "2025-06-23"
         },
         {
           "module-name": "ietf-inet-types",
           "module-revision": "2025-06-23"
         },
         {
           "module-name": "ietf-subscribed-notifications",
           "module-revision": "2019-09-09"
         },
         {
           "module-name": "ietf-system-capabilities",
           "module-revision": "2022-02-17"
         },
         {
           "module-name": "ietf-notification-capabilities",
           "module-revision": "2022-02-17"
         },
         {
           "module-name": "ietf-yang-structure-ext",
           "module-revision": "2020-06-17"
         }
       ],
       "assignment-range": [
         {
           "entry-point": "2950",
           "size": "50"
         }
       ],
       "item": [
         {
           "status":"unstable",
           "namespace":"module",
           "identifier":"ietf-yp-notification",
           "sid":"2950"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-subscribed-notifications:subscriptions/ietf-yp-notification:enable-notification-envelope",
           "sid":"2951"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-subscribed-notifications:subscriptions/ietf-yp-notification:metadata",



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           "sid":"2952"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-system-capabilities:system-capabilities/ietf-notification-capabilities:subscription-capabilities/ietf-yp-notification:notification-metadata",
           "sid":"2953"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-system-capabilities:system-capabilities/ietf-notification-capabilities:subscription-capabilities/ietf-yp-notification:notification-metadata/envelope",
           "sid":"2954"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-system-capabilities:system-capabilities/ietf-notification-capabilities:subscription-capabilities/ietf-yp-notification:notification-metadata/metadata",
           "sid":"2955"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-system-capabilities:system-capabilities/ietf-notification-capabilities:subscription-capabilities/ietf-yp-notification:notification-metadata/metadata/hostname-sequence-number",
           "sid":"2956"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-yp-notification:envelope",
           "sid":"2957"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-yp-notification:envelope/contents",
           "sid":"2958"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-yp-notification:envelope/event-time",
           "sid":"2959"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-yp-notification:envelope/hostname",



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           "sid":"2960"
         },
         {
           "status":"unstable",
           "namespace":"data",
           "identifier":"/ietf-yp-notification:envelope/sequence-number",
           "sid":"2961"
         }
       ]
     }
   }
   <CODE ENDS>

                 Figure 11: ietf-yp-notification .sid file

Appendix B.  Example extending the Notification Envelope

   This appendix provides a non-normative example illustrating how an
   extension to the Notification Envelope should be implemented.  The
   example does not define valid metadata, but serves to demonstrate how
   future extensions should be specified.

   Specifically, the example extends the Notification Envelope with a
   metadata field named "foo".  The YANG module illustrates the
   necessary augmentations to both the 'ietf-yp-notification' module and
   the 'ietf-notification-capabilities' module.

   <CODE BEGINS> file "example-foo-extension.yang"
   module example-foo-extension {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:example-foo-extension";
     prefix fooext;

     import ietf-subscribed-notifications {
       prefix sn;
     }
     import ietf-system-capabilities {
       prefix sysc;
     }
     import ietf-notification-capabilities {
       prefix notc;
     }
     import ietf-yang-structure-ext {
       prefix sx;
     }
     import ietf-yp-notification {
       prefix iypn;
     }



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     description
       "Defines a new 'foo' metadata for the notification envelope.";

     // Extending the notification envelope header with a new
     // 'foo' metadata
     sx:augment-structure "/iypn:envelope" {
       leaf foo {
         type string;
         description
           "Description of the 'foo' extension.";
       }
     }

     // Extending the notifications capabilities so that clients can
     // learn whether this new extension is supported or not
     augment "/sysc:system-capabilities"
           + "/notc:subscription-capabilities"
           + "/iypn:notification-metadata/iypn:metadata" {
       description
         "Extension to the subscription-capabilities model to enable
          clients to learn whether the publisher supports the new
          'foo' metadata.";
       leaf foo {
         type boolean;
         default "false";
         description
           "Adds the 'foo' capability.";
       }
     }

     // (Optional) A user can optionally add knobs for enabling and
     // disabling specific metadata.
     augment "/sn:subscriptions/iypn:metadata" {
       description
         "An user can optionally, support a configuration knob for enabling
          or disabling a metadata.";
       leaf foo {
         type boolean;
         default "false";
         description
           "Configuration knob for enabling and disabling the 'foo'
            metadata.";
       }
     }
   }
   <CODE ENDS>

   The extensions result in the following YANG tree:



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   module: example-foo-extension

     augment /sysc:system-capabilities/notc:subscription-capabilities
               /iypn:notification-metadata/iypn:metadata:
       +--ro foo?   boolean
     augment /sn:subscriptions/iypn:metadata:
       +--rw foo?   boolean

     augment-structure /iypn:envelope:
       +-- foo?   string

Authors' Addresses

   Alex Huang Feng
   INSA-Lyon
   Lyon
   France
   Email: alex.huang-feng@insa-lyon.fr


   Pierre Francois
   INSA-Lyon
   Lyon
   France
   Email: pierre.francois@insa-lyon.fr


   Thomas Graf
   Swisscom
   Binzring 17
   CH-8045 Zurich
   Switzerland
   Email: thomas.graf@swisscom.com


   Benoit Claise
   Everything OPS
   Email: benoit@everything-ops.net













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