Internet-Draft YANG-Push Notification Envelope January 2025
Huang Feng, et al. Expires 31 July 2025 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-netana-netconf-notif-envelope-02
Updates:
RFC7950 RFC7951 RFC9254 (if approved)
Published:
Intended Status:
Standards Track
Expires:
Authors:
A. Huang Feng
INSA-Lyon
P. Francois
INSA-Lyon
T. Graf
Swisscom
B. Claise
Huawei

Extensible YANG Model for YANG-Push Notifications

Abstract

This document defines a new extensible notification structure, defined in YANG, for use in YANG-Push Notification messages 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 caracterizing the moment when the changed 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 31 July 2025.

▲

Table of Contents

1. Introduction

YANG-Push [RFC8639] allows publishers to send notifications to a data collection. 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 container from YANG-Push 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 offer a way to extend this header with new notification metadata. Additionally, 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 consumer 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 in generated messages so that lost notification messages can be detected in unreliable transports. This additional notification metadata is also helpful to correlate the data with other sources of Network Telemetry [RFC9232] information.

For such reasons, this document proposes the following:

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 "subscriber", "publisher", and "receiver" are used as defined in [RFC8639].

The terms "client" 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 messsage 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 nodes to send notifications to a collector. These are the key relationships between the current document and [RFC5277]:

2.2. Relationship to RFC8639

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

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]:

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]:

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]:

3. Solution

Section 4.2.10 of [RFC7950] defines the encoding of YANG notifications. A notification is created by defining a 'notification' statement in the YANG module. When a NETCONF server sends this notification, it is composed of two parts: a header containing notification metadata which 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 defined in the following sections are to be used in YANG-Push [RFC8641] environments and can be implemented with NETCONF [RFC6241] and RESTCONF [RFC8040]. Thus, when enabled, this new header replaces the notifications defined in Subscribed Notifications [RFC8639] and YANG-Push [RFC8641] notifications globally for all the entire server.

Section 3.1 defines how a client enables the header defined in this document. Section 3.2 extends the model from [RFC9196] to enable clients to discover the capability of using the new notification header for both implementation-time information and runtime information. Lastly, Section 3.3.2 defines the new notification header and how it is encoded using XML, JSON and CBOR.

3.1. Enabling the Notification Envelope

The use of the notification envelope defined in this document can be enabled during the configuration of a YANG-Push subscription. This document augments the "ietf-subscribed-notification" model [RFC8639] to support the configuration of "notification-envelope". When enabled, all the notifications defined in Subscribed Notification [RFC8639] and YANG-Push [RFC8641] are encoded as defined in Section 3.3.

module: ietf-yp-notification

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

  rpcs:
    +---x enable-notif-envelope
       +---w input
          +---w enable-notification-envelope?   boolean
          +---w metadata

When the node 'enable-notification-envelope' is set to true, the notifications published by a YANG-Push publisher MUST use the header defined in Section 3.3.1. If any notification metadata is enabled during the configuration of the subscription, the notification metadata nodes MUST be present in the header. When this node is disabled, notifications are encoded following [RFC5277].

This node 'enable-notification-envelope' MUST be enabled and disabled via the RPC 'enable-notif-envelope' only. This node MUST be changed prior to the creation of any Dynamic Subscriptions. If any Dynamic Subscription is sending YANG-Push notifications at the time of modifying this node, the server MUST refuse the change and send an 'invalid-notification-envelope-config' error.

When a client changes this node 'enable-notification-envelope', any new Dynamic Subscriptions send YANG-Push notifications according to the new value of this node. In Configured Subscriptions, when the node 'enable-notification-envelope' changes, the YANG-Push subscription is restarted using the header defined by this node, i.e. encoded as Section 3.3.1 when enabled and using [RFC5277] if disabled.

3.2. Discovering the support of this model

A client can discover the support of 'notification-envelope' model through the capabilities model defined in [RFC9196]. This documents extends the 'ietf-notification-capabilities' model with:

  • A container containing a leaf 'notification-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 3.4.

The YANG models defined in Section 5 augments the 'ietf-notification-capabilities' model with the leaf and container listed above.

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

This model can be retrieved via a NETCONF <get> RPC.

3.3. Notification Envelope

This section defines how YANG notifications are structured when the notification envelope is enabled on YANG-Push subscriptions. The following sections define how this model is encoded in XML, JSON and CBOR.

3.3.1. 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 a child nodes of the root "notification-envelope" container.
  • The content of the notification defined by the 'notification' statement is encoded in the 'notification-contents' leaf.
  • The 'notification-contents' element SHOULD be located at the end of the notification envelop structure.

The following YANG tree [RFC8340] illustrates the notification envelope supporting only the mandatory metadata 'event-time'. See Section 3.4 for more extensions to this header.

  notifications:
    +---n envelope
       +--ro event-time                   yang:date-and-time
       +--ro notification-contents?       <anydata>

3.3.2. Encoding of the Notification model

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

3.3.2.1. 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. The "event-time" node is defined within the same XML namespace as the "envelope" container. The "event-time" node MUST be compliant with [RFC3339]. Other notification metadata defined within the YANG module defined in Section 5.1.2 MUST use the same XML namespace. See Section 3.4 for more details.

When other notification metadata is enabled through configuration, the supplementary nodes are encoded at the same level of the mandatory "event-time" node and use the XML namespace defined in the YANG module.

The content of the notification that is defined by the 'notification' statement is encoded in the "notification-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:

  <envelope xmlns="urn:ietf:params:xml:ns:yang:ietf-yp-notification">
    <event-time>2024-10-10T10:59:55.32Z</event-time>
    <notification-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>
              <oper-status>up</oper-status>
            </interface>
          </interfaces>
        </datastore-contents>
      </push-update>
    </notification-contents>
  </envelope>
Figure 1: XML-encoded notification
3.3.2.2. 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 5.1.2.

Two mandatory child nodes within the "ietf-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 and is compliant with [RFC3339]. Other metadata specified within the YANG module defined in Section 5.1.2 MUST use the same namespace "ietf-yp-notification".

When other notification metadata is enabled through configuration, the supplementary nodes are encoded at the same level of the mandatory 'event-time' node and use the YANG module name as its namespace. See Section 3.4 for more details.

The content of the notification that is defined by the 'notification' statement is encoded in the "notification-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",
            "notification-contents": {
              "ietf-yang-push:push-update": {
                  "id": 1011,
                  "datastore-contents": {
                      "ietf-interfaces:interfaces": [
                          {
                              "interface": {
                                  "name": "eth0",
                                  "oper-status": "up"
                              }
                          }
                      ]
                  }
              }
            }
        }
    }
Figure 2: JSON-encoded notification
3.3.2.3. 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 container uses the YANG module name "ietf-yp-notification" defined in Section 5.1.2.

Notification encoded using YANG-SIDs replaces the names of the keys of the CBOR encoded message for 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 following [I-D.ietf-core-sid].

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 and is compliant with [RFC3339].

When other notification metadata is enabled through configuration, the supplementary nodes are encoded at the same level of the mandatory "event-time" node and use the YANG module name as its namespace when they are encoded as names. When they are encoded using YANG SIDs, a SID value assigned to the metadata node is used. See Section 3.4 for more details.

The content of the notification that is defined by the 'notification' statement is encoded in the "notification-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 well allocated.

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]:

  {
      "ietf-yp-notification:envelope": {
          "event-time": "2024-10-10T08:00:11.22Z",
          "notification-contents": {
            "ietf-yang-push:push-update": {
                "id": 1011,
                "datastore-contents": {
                    "ietf-interfaces:interfaces": [
                        {
                            "interface": {
                                "name": "eth0",
                                "oper-status": "up"
                            }
                        }
                    ]
                }
            }
          }
      }
  }
Figure 3: CBOR-encoded notification using diagnostic notation

And Figure 4 shows the same notifcation encoded using SIDs:

  {
      2551: {
          1: "2024-10-10T08:00:11.22Z",
          4: {
            "ietf-yang-push:push-update": {
                "id": 1011,
                "datastore-contents": {
                    "ietf-interfaces:interfaces": [
                        {
                            "interface": {
                                "name": "eth0",
                                "oper-status": "up"
                            }
                        }
                    ]
                }
            }
          }
      }
  }
Figure 4: CBOR-encoded notification using YANG SIDs in CBOR diagnostic notation

3.4. Extensions for the Notification Envelope

This section described two YANG notification header extensions which are sent by default when the notification envelope is enabled. When the envelope is enabled using the "enable-notification-envelope" node, the publisher includes by default the "hostname" and "sequence-number" defined in the following sections. The client discovers the support of these two extension headers with the mechanism defined in Section 3.2. When the extensions defined in this document are supported by the server, the client discovers the presence of these new metadata with the following augmentations in the 'ietf-notification-capabilities':

module: ietf-yp-notification

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

module: ietf-yp-observation

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

This document defines the following notification metadata as shown in the following YANG tree [RFC8340]. It also defines an extension to the YANG-Push header. See the following sections for more details.

  notifications:
    +---n envelope
       +--ro event-time                   yang:date-and-time
       +--ro hostname?                    inet:host
       |       {notification-hostname-sequence-number}?
       +--ro sequence-number?             yang:counter32
       |       {notification-hostname-sequence-number}?
       +--ro notification-contents?       <anydata>

3.4.1. 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 container. Therefore, the downstream system is unable to associate the message to 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 impacts 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.

To overcome these issues, this document proposes a notification container extension with 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 node's hostname according to the 'sysName' object definition in [RFC1213] from where the message was published from. This value is usually configured on the node by the administrator to uniquely identify the node in the network.
sequence-number:
Generates a unique sequence number for each published message by the publisher process. The number counts up at every published notification message as described in [RFC9187].

Figure 5 provides an example of a JSON encoded, [RFC8259], "push-update" notification message with hostname and sequence-number as extension.

========== NOTE: '\' line wrapping per RFC 8792) ===========

{
    "ietf-yp-notification:envelope": {
    "event-time": "2023-03-25T08:30:11.22Z",
    "hostname": "example-router",
    "sequence-number": 1,
    "notification-contents": {
      "ietf-yang-push:push-update": {
        "id": 6666,
        "datastore-contents": {
          "ietf-interfaces:interfaces": [
            {
              "interface": {
                "name": "eth0",
                "type": "iana-if-type:ethernetCsmacd",
                "oper-status": "up",
                "mtu": 1500
              }
            }
          ]
        }
      }
    }
  }
}
Figure 5: JSON Example for a 'push-update' notification message

3.5. Extensions for the YANG-Push Envelope

This section described two optional YANG push-update and push-change-update notification header extensions which are enabled by default. The client discovers the support of these two extension headers with the mechanism defined in Section 3.2.

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

module: ietf-yang-push

  rpcs:
    +---x resync-subscription {on-change}?
       +---w input
          +---w id    sn:subscription-id

  notifications:
    +---n push-update
    |  +--ro id?                      sn:subscription-id
    |  +--ro datastore-contents?      <anydata>
    |  +--ro incomplete-update?       empty
    |  +--ro ypot:timestamp?          yang:date-and-time
    |  +--ro ypot:point-in-time?      enumeration
    +---n push-change-update {on-change}?
       +--ro id?                      sn:subscription-id
       +--ro datastore-changes
       +--ro incomplete-update?       empty
       +--ro ypot:timestamp?          yang:date-and-time
       +--ro ypot:point-in-time?      enumeration

3.5.1. 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 defined in Section 3.1 of [RFC8641], observation timestamp describes when the state change was observed or when the data was accounted. This is essential for understanding the timely relationship among these different planes and YANG push subscription types.

With Section 3.4 the delay between the YANG Notification export and the arrival at the downstream system storing the data can be measured. With observation timestamp described in this document, the delay between the time of the network observation and the data export of the YANG-Push publisher process can be measured as well, extending the delay measurement scope from the time the network observation and storing the data.

When the time bucket length in a time series database and the periodical YANG-Push subscription time is identical, the 'event-time' of the netconf notification message header is used for indexing, there is variable delay between the observation timestamp and the 'event-time', and the anchor-time as described in Section 4.2 of [RFC8641] is close to the time bucket boundaries, a time bucket is going to have periodically 0 or 2 measurements indexed instead of 1. Leading to inconsistent accounting errors in the time series database. This problem is resolved by using the observation timestamp instead of the 'event-time' for time series database indexing.

By extending YANG-Push Notifications with the observation timestamp YANG object and a point-in-time enumeration for streaming update YANG-Push notifications it is ensured that the observation timestamp is always present with the best available time, it can be therefore used unconditionally in the data processing chain and with the point-in-time enumeration there is semantic describing at which point in time the observation timestamp was observed.

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 a "periodical" and for the "push-change-update" notification in a "on-change" subscription.

By comparing the observation timestamp of two "push-update" notifications in a periodical 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 for "periodical" subscriptions, the point-in-time where the metrics are being polled and observed.

initial-state states for "on-change sync on start" subscriptions, the initial point in time when the subscription was established and the state was observed.

state-changed states for "on-change" and "on-change sync on start" subscriptions, the point in time when the state change was observed after the subscription was established.

Figure 6 provides an example timeline of events to describe observation timestamp and point-in-time for "on-change sync on start" subscriptions. At "T2" when the "on-change sync on start" subscription is established, the timestamp of "T2" is used in observation timestamp and "point-in-time" is set to "initial-state". At "T3" and "T4" the timestamp of "T3" respectively "T4" is used in observation timestamp and point-in-time is set to "state-changed".

Timeline
---------------------------------------------------------------------->
 | (T1) Interface | (T2) YANG-Push   | (T3) Interface | (T4) Interface
 | state changed  | "on-change sync  | state changed  | state changed
 | to "Up".       | on start"        | to "Down".     | to "Up".
 |                | subscription for |                |
 |                | interface state  |                |
 |                | is established.  |                |
 v                v                  v                v
Figure 6: Example timeline for On-Change Sync on Start Subscription

Figure 7 provides an example of a JSON encoded, [RFC8259], "push-change-update" notification message with Section 3.4 as extension.

========== NOTE: '\' line wrapping per RFC 8792) ===========

{
    "ietf-yp-notification:envelope": {
    "event-time": "2023-03-25T08:30:12.22Z",
    "hostname": "example-router",
    "sequence-number": 1,
    "notification-contents": {
      "ietf-yang-push:push-change-update": {
        "id": 2222,
        "ietf-yp-observation:timestamp": \
        "2023-03-25T08:30:11.22Z",
        "ietf-yp-observation:point-in-time": \
        "state-changed",
        "datastore-contents": {
          "yang-patch": {
            "patch-id": "patch_54",
            "comment": "Changing encoding to JSON and increasing \
            the period to 10 minutes",
            "edit": [
              {
                "edit-id": "id_change_1",
                "operation": "merge",
                "target": "/ietf-subscribed-notifications\:subs\
                criptions/subscription[id=2222]",
                "value": {
                  "ietf-subscribed-notifications:encoding": \
                  "ietf-subscribed-notifications:encode-json",
                  "ietf-yang-push:periodic": {
                    "period": 60000
                  }
                }
              }
            ]
          }
        }
      }
    }
  }
}
Figure 7: JSON Push Example for a push-change-update notification message

Figure 8 provides an example timeline of events to describe point-in-time for "periodical" subscriptions. The timestamp of observation timestamp in "T2" is set at the start of the polling of the YANG data store to "T2" and point-in-time is set "current-accounting". At "T3" the timestamp of observation timestamp of "T3" is used. At "T4" the timestamp of observation timestamp of "T4" is used.

Timeline
---------------------------------------------------------------------->
 | (T1) YANG-Push | (T2) YANG-Push | (T3) YANG-Push | (T4) YANG-Push
 | "periodical"   | "periodical"   | "periodical"   | "periodical"
 | subscription   | current        | current        | current
 | for interface  | accounting     | accounting.    | accounting.
 | counter is     |                |                |
 | established    |                |                |
 v                v                v                v
Figure 8: Example timeline for Periodical Subscription

Figure 9 provides an example of a JSON encoded, [RFC8259], "push-update" notification message with Section 3.4 as extension.

========== NOTE: '\' line wrapping per RFC 8792) ===========

{
    "ietf-yp-notification:envelope": {
    "event-time": "2023-03-25T08:30:11.22Z",
    "hostname": "example-router",
    "sequence-number": 1,
    "notification-contents": {
      "ietf-yang-push:push-update": {
        "id": 6666,
        "ietf-yp-observation:timestamp": \
        "2023-03-25T08:30:11.22Z",
        "ietf-yp-observation:point-in-time": \
        "current-accounting",
        "datastore-contents": {
          "ietf-interfaces:interfaces": [
            {
              "interface": {
                "name": "eth0",
                "type": "iana-if-type:ethernetCsmacd",
                "oper-status": "up",
                "mtu": 1500
              }
            }
          ]
        }
      }
    }
  }
}
Figure 9: JSON Push Example for a push-update notification message

4. Operational Considerations

TBD: explain co-existence with RFC5277

5. YANG Modules

5.1. The 'ietf-yp-notification' Module

The following sections shows the YANG tree and YANG module for the 'ietf-yp-notification' module.

5.1.1. 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:
    +--ro enable-notification-envelope?   boolean
    +--ro metadata
  augment /sysc:system-capabilities/notc:subscription-capabilities:
    +--ro notification-metadata
       +--ro notification-envelope?   boolean
       +--ro metadata
          +--ro hostname-sequence-number?   boolean

  rpcs:
    +---x enable-notif-envelope
       +---w input
          +---w enable-notification-envelope?   boolean
          +---w metadata

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

5.1.2. 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@2025-01-27.yang"

module ietf-yp-notification {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-yp-notification";
  prefix inotenv;
  import ietf-yang-types {
    prefix yang;
    reference
      "RFC 6991: Common YANG Data Types";
  }
  import ietf-inet-types {
    prefix inet;
    reference
      "RFC 6991: 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.claise@huawei.com>";

  description
    "Defines a notification header for Subscribed Notifications
    [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 Y of RFC XXXX for more
    details.

    Copyright (c) 2024 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).

    This version of this YANG module is part of RFC XXXX
    (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
    for full legal notices.";

  revision 2025-01-27 {
    description
      "First revision";
    reference
      "RFC XXXX: YANG-Push Notification Envelope";
  }

  identity notif-envelope-error {
    description
      "Base identify for errors found while attempting to
      change configuration values during the
      'enable-notif-envelope' RPC requests.";
  }

  identity invalid-notification-envelope-config {
    base notif-envelope-error;
    description
      "This error is triggered and sent in the response of
      the RPC 'enable-notif-envelope' when attempting to change
      the value of the 'enable-notification-envelope' node
      while any Dynamic Subscription is active. The node
      'enable-notification-envelope' can only be changed prior to
      the creation of the Dynamic Subscription.";
  }

  grouping notif-env-capabilities {
    description
      "This grouping defines the capabilities for
      the notification-envelope defined in RFC XXXX
      and the different supported metadata.";
    leaf notification-envelope {
      type boolean;
      default false;
      description
        "Supports YANG-Push to use the notification-envelope
        defined in RFC XXXX.";
    }
    container metadata {
      description
        "Container with the supported optional metadata by the
        YANG-Push publisher.";
      leaf 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.";
      }
    }
  }

  sx:structure envelope {
    leaf event-time {
      type yang:date-and-time;
      mandatory true;
      description
        "The date and time the event was generated by the event
        source. This parameter is of type dateTime and compliant
        to [RFC3339].";
    }
    leaf hostname {
      type inet:host;
      description
        "The hostname of the network node according to
        [RFC1213]. This value is usually configured on the node
        by the administrator to uniquely identify the node in
        the network.";
    }
    leaf sequence-number {
      type yang:counter32;
      description
        "Unique sequence number as described in [RFC9187] for each
        published message.";
    }
    anydata notification-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 metadatas.";
    leaf enable-notification-envelope {
      config false;
      type boolean;
      default false;
      description
        "Enables YANG-Push to use the notification-envelope
        defined in RFC XXXX.";
    }
    container metadata {
      config false;
      description
        "Container for configuring optional metadata.";
    }
  }

  // RPCs
  rpc enable-notif-envelope {
    description
      "This RPC allows a client to enable the notification envelope
      globally for the server. When this option is enabled, all the YANG-Push
      Notifications from all the subscriptions are encoded following
      this structure.";
    input {
      leaf enable-notification-envelope {
        type boolean;
        default false;
        description
          "Enables YANG-Push to use the notification-envelope
          defined in RFC XXXX.";
      }
      container metadata {
        description
          "Container for configuring optional metadata.";
      }
    }
  }

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

5.2. The 'ietf-yp-observation' Module

The following sections shows the YANG tree and YANG module for the 'ietf-yp-observation' module.

5.2.1. 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-supported?
            inotifseq:notification-support
            {yang-push-observation-timestamp}?

5.2.2. YANG ietf-yp-observation Module

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

<CODE BEGINS> file "ietf-yp-observation@2024-12-17.yang"

module ietf-yp-observation {
  yang-version 1.1;
  namespace
    "urn:ietf:params:xml:ns:yang:ietf-yp-observation";
  prefix ypot;
  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";
  }
  import ietf-notification-sequencing {
    prefix inotifseq;
    reference
      "draft-tgraf-netconf-notif-sequencing-05: YANG Notifications
      Sequencing";
  }
  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.claise@huawei.com>
               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) 2024 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).

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

  revision 2024-12-17 {
    description
      "First revision";
    reference
      "RFC XXXX: Support of YANG-Push Notifications Observation Time";
  }

  feature yang-push-observation-timestamp {
    description
      "This feature indicates the YANG-push Notifications support
      the observation timestamps in streaming update 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 metrics were observed.";
    }
    leaf point-in-time {
      type enumeration {
        enum current-accounting {
          description "For periodical 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.";
        }
      }
      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 ypot: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 ypot:yang-push-observation;
  }

  // Event capabilities
  augment "/sysc:system-capabilities/notc:subscription-capabilities" {
    description
      "Add system level capabilities";
    leaf yang-push-observation-supported {
      if-feature "yang-push-observation-timestamp";
      type boolean;
      description
        "Specifies whether the publisher supports exporting
        observation-timestamp and point-in-time in notifications.";
      reference
        "RFC XXXX: YANG Notifications Observation Time";
    }
  }
}

<CODE ENDS>

6. Implementation Status

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

6.1. Huawei VRP

Huawei implemented in push-update and push-change-update notifications the timestamp and point-in-time extension as described in Section 3.5 for a YANG-Push publisher on UDP-based Transport for Configured Subscriptions [I-D.ietf-netconf-udp-notif] in their VRP platform.

6.2. 6WIND VSR

6WIND implemented in push-update and push-change-update notifications the timestamp and point-in-time extension as described in Section 3.5 for a YANG-Push publisher on UDP-based Transport for Configured Subscriptions [I-D.ietf-netconf-udp-notif] in their VSR platform.

6.3. Cisco IOS XR

Cisco implemented in push-update and push-change-update notifications the timestamp and point-in-time extension as described in Section 3.5 for a YANG-Push publisher on UDP-based Transport for Configured Subscriptions [I-D.ietf-netconf-udp-notif] in their IOS XR platform.

7. Security Considerations

TBD

8. IANA Considerations

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

8.1. 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-to-be
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-to-be

8.2. YANG module name

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

name: ietf-yp-notification
namespace: urn:ietf:params:xml:ns:yang:ietf-yp-notification
prefix: inotenv
reference: RFC-to-be
name: ietf-yp-observation
namespace: urn:ietf:params:xml:ns:yang:ietf-yp-observation
prefix: ypot
reference: RFC-to-be

8.3. YANG SID-file

IANA is requested to register a new ".sid" file in the "IETF YANG SID Registry" [I-D.ietf-core-sid]:

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

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

9. Acknowledgements

The authors would like to thank Per Anderson, Andy Bierman, Carsten Bormann, Mohamed Boucadair, Tom Petch, Jason Sterne, Kent Watsen and Rob Wilton for their review and valuable comments.

10. References

10.1. Normative References

[I-D.ietf-core-sid]
Veillette, M., Pelov, A., Petrov, I., Bormann, C., and M. Richardson, "YANG Schema Item iDentifier (YANG SID)", Work in Progress, Internet-Draft, draft-ietf-core-sid-24, , <https://datatracker.ietf.org/doc/html/draft-ietf-core-sid-24>.
[RFC1213]
McCloghrie, K. and M. Rose, "Management Information Base for Network Management of TCP/IP-based internets: MIB-II", STD 17, RFC 1213, DOI 10.17487/RFC1213, , <https://www.rfc-editor.org/info/rfc1213>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://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, , <https://www.rfc-editor.org/info/rfc3339>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC5277]
Chisholm, S. and H. Trevino, "NETCONF Event Notifications", RFC 5277, DOI 10.17487/RFC5277, , <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, , <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, , <https://www.rfc-editor.org/info/rfc6241>.
[RFC6991]
Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/info/rfc6991>.
[RFC7950]
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, , <https://www.rfc-editor.org/info/rfc7950>.
[RFC7951]
Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, , <https://www.rfc-editor.org/info/rfc7951>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <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, , <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, , <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, , <https://www.rfc-editor.org/info/rfc8641>.
[RFC8791]
Bierman, A., Björklund, M., and K. Watsen, "YANG Data Structure Extensions", RFC 8791, DOI 10.17487/RFC8791, , <https://www.rfc-editor.org/info/rfc8791>.
[RFC9187]
Touch, J., "Sequence Number Extension for Windowed Protocols", RFC 9187, DOI 10.17487/RFC9187, , <https://www.rfc-editor.org/info/rfc9187>.
[RFC9196]
Lengyel, B., Clemm, A., and B. Claise, "YANG Modules Describing Capabilities for Systems and Datastore Update Notifications", RFC 9196, DOI 10.17487/RFC9196, , <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, , <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, , <https://www.w3.org/TR/2000/REC-xml-20001006>.

10.2. Informative References

[I-D.ietf-netconf-udp-notif]
Zheng, G., Zhou, T., Graf, T., Francois, P., Feng, A. H., and P. Lucente, "UDP-based Transport for Configured Subscriptions", Work in Progress, Internet-Draft, draft-ietf-netconf-udp-notif-18, , <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-udp-notif-18>.
[RFC6470]
Bierman, A., "Network Configuration Protocol (NETCONF) Base Notifications", RFC 6470, DOI 10.17487/RFC6470, , <https://www.rfc-editor.org/info/rfc6470>.
[RFC8259]
Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, , <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, , <https://www.rfc-editor.org/info/rfc8340>.
[RFC9232]
Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and A. Wang, "Network Telemetry Framework", RFC 9232, DOI 10.17487/RFC9232, , <https://www.rfc-editor.org/info/rfc9232>.

Appendix A. .sid file

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

For CBOR encoding using YANG-SIDs identifiers, a ".sid" file is requested to IANA in Section 8.3.

<CODE BEGINS> file "ietf-yp-notification@2024-10-18.sid"

{
  "ietf-sid-file:sid-file": {
    "module-name": "ietf-yp-notification",
    "module-revision": "2024-10-10",
    "description": "YANG-Push Notification Envelope",
    "dependency-revision": [
      {
        "module-name": "ietf-yang-types",
        "module-revision": "2013-07-15"
      },
      {
        "module-name": "ietf-subscribed-notifications",
        "module-revision": "2019-09-09"
      }
    ],
    "assignment-range": [
      {
        "entry-point": "2550",
        "size": "50"
      }
    ],
    "item": [
      {
        "namespace": "module",
        "identifier": "ietf-yp-notification",
        "sid": "2550"
      },
      {
        "namespace": "data",
        "identifier": "/ietf-yp-notification:envelope",
        "sid": "2551"
      },
      {
        "namespace": "data",
        "identifier": "/ietf-yp-notification:envelope/event-time",
        "sid": "2552"
      },
      {
        "namespace": "data",
        "identifier": "/ietf-yp-notification:envelope/hostname",
        "sid": "2553"
      },
      {
        "namespace": "data",
        "identifier": "/ietf-yp-notification:envelope/sequence-number",
        "sid": "2554"
      },
      {
        "namespace": "data",
        "identifier": "/ietf-yp-notification:envelope/notification-contents",
        "sid": "2555"
      }
    ]
  }
}

<CODE ENDS>
Figure 10: .sid file for "ietf-yp-notification" module

Authors' Addresses

Alex Huang Feng
INSA-Lyon
Lyon
France
Pierre Francois
INSA-Lyon
Lyon
France
Thomas Graf
Swisscom
Binzring 17
CH-8045 Zurich
Switzerland
Benoit Claise
Huawei