NETCONF                                                          T. ZhouInternet-Draft                                                  G. ZhengIntended status: Standards Track                                  HuaweiExpires: 9 August 2026                                           E. Voit                                                           Cisco Systems                                                                 T. Graf                                                                Swisscom                                                             P. Francois                                                               INSA-Lyon                                                         5 February 2026      Subscription to Notifications in a Distributed Architecture                draft-ietf-netconf-distributed-notif-17Abstract   This document describes extensions to the YANG notifications   subscription to allow metrics being published directly from   processors on line cards to target receivers, while subscription is   still maintained at the route processor in a distributed forwarding   system of a network node.Requirements Language   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.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 9 August 2026.Zhou, et al.              Expires 9 August 2026                 [Page 1]Internet-Draft          Distributed Notifications          February 2026Copyright 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.   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  . . . . . . . . . . . . . . . . . . . . . . . .   2   2.  Terminologies . . . . . . . . . . . . . . . . . . . . . . . .   3   3.  Motivation and Solution Overview  . . . . . . . . . . . . . .   4   4.  Solution Detail . . . . . . . . . . . . . . . . . . . . . . .   5   5.  Subscription Decomposition  . . . . . . . . . . . . . . . . .   7   6.  Publication Composition . . . . . . . . . . . . . . . . . . .   7   7.  Subscription State Change Notifications . . . . . . . . . . .   8   8.  Publisher Configurations  . . . . . . . . . . . . . . . . . .   8   9.  YANG Tree . . . . . . . . . . . . . . . . . . . . . . . . . .   9   10. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .   9   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12   12. Implementation Status . . . . . . . . . . . . . . . . . . . .  12     12.1.  Huawei VRP . . . . . . . . . . . . . . . . . . . . . . .  13     12.2.  6WIND VSR  . . . . . . . . . . . . . . . . . . . . . . .  13   13. Security Considerations . . . . . . . . . . . . . . . . . . .  13   14. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  14   15. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14   16. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14     16.1.  Normative References . . . . . . . . . . . . . . . . . .  14     16.2.  Informative References . . . . . . . . . . . . . . . . .  15   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .  16     A.1.  Dynamic Subscription  . . . . . . . . . . . . . . . . . .  16     A.2.  Configured Subscription . . . . . . . . . . . . . . . . .  20   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  221.  Introduction   The mechanism to support a subscription of a continuous and   customized stream of updates from a YANG datastore [RFC8342] is   defined in [RFC8639] and [RFC8641].  Requirements for Subscription to   YANG Datastores are defined in [RFC7923].Zhou, et al.              Expires 9 August 2026                 [Page 2]Internet-Draft          Distributed Notifications          February 2026   By streaming YANG-Push notifications from publishers to receivers,   much better performance and fine-grained sampling can be achieved   than with a polling-based mechanism.  In a distributed forwarding   system on a network node, the packet forwarding is delegated to   multiple processors on line cards.  In order not to overwhelm the   route processor resources, it is not uncommon that data records are   published directly from processors on line cards to target receivers   to further increase efficiency on the routing system.   This document complements the general subscription requirements   defined in Section 4.2.1 of [RFC7923] by the paragraph: A   Subscription Service MAY support the ability to export from multiple   software processes on a single routing system and expose the   information which software process produced which message.2.  Terminologies   The following terms are defined in [RFC8639] and are not redefined   here:   Subscriber   Publisher   Receiver   Subscription   The following terms are defined in [RFC9196] and are not redefined   here:   Capability   In addition, this document defines the below terms.  Some of these   terms are distinguished between global versus component and parent   versus agent to distinguish their role within the distributed system.   Global and component is used to distinguish wherever the system   component is reachable outside the distributed system or not.  Parent   and agent is used to distinguish wherever it manages or is being   managed within the distributed system.   Global Subscription: The Subscription requested by the Subscriber as   described in Sections 2.4 and 2.5 of [RFC8639].  It may be decomposed   into multiple Component Subscriptions.   Component Subscription: The Subscription that defines a data source   which is managed and controlled by a single Publisher.Zhou, et al.              Expires 9 August 2026                 [Page 3]Internet-Draft          Distributed Notifications          February 2026   Global Capability: The overall subscription capability that the group   of Publishers can expose to the Subscriber as defined in [RFC9196]   for the distributed system.  This includes which YANG nodes can be   subscribed at which minimum-update-period for periodical   subscriptions respectively which minimum-dampening-period for on-   change subscriptions.   Component Capability: The subscription capability that each Publisher   exposes to the Publisher Parent.  This includes which YANG nodes with   which minimum-update-period for periodical subscriptions respectively   which minimum-dampening-period for on-change subscriptions can be   subscribed on which Component.   Publisher Parent: The component of a Publisher that interacts with   the Subscriber to deal with the Global Subscription.  It decomposes   the Global Subscription to multiple Component Subscriptions and   interacts with the Publisher Agents.   Publisher Agent: The component of a Publisher that interacts with the   Publisher Parent to deal with the Component Subscription and pushing   the data to the Receiver.   Network Node: Is the network node of a distributed system which   contains one or more Publishers that obtains the data from the YANG   datastore and pushes it to the Receiver.   Message Publisher: The Publisher that pushes the message to the   Receiver.   Message Publisher ID: A 32-bit identifier of the publishing process   that is locally unique to the Network Node.  With this identifier the   publishing process from where the message was published from can be   uniquely identified.  Receivers SHOULD use the transport session and   the Publisher ID field to separate different publisher streams   originating from the same network Node.3.  Motivation and Solution Overview   In distributed forwarding systems of Network Nodes much YANG data is   subscribed to processors on line cards but published from the route   processor instead.  This creates an unnecessary overhead at the route   processor and a potential bottleneck.  Instead, publishing the YANG   data directly from line cards avoids this inefficiency.Zhou, et al.              Expires 9 August 2026                 [Page 4]Internet-Draft          Distributed Notifications          February 2026   This document proposes that subscribed YANG data can be published   from processors on line cards.  The route processor is only involved   in maintaining and decomposing the Subscription, which includes   notifying the Receiver which Subscription is being published from   which line card processor with subscription state change   notifications.   To enable Receivers to map notification messages to a particular   Publisher, the Message Publisher ID in the transport message header   of the YANG notification message is introduced.  In case of UDP   transport, this is described in Section 3.2 of   [I-D.ietf-netconf-udp-notif].  With unique sequence-numbers per   publishing process described in Section 3.4.1 of   [I-D.ietf-netconf-notif-envelope], each message can uniquely be   identified, loss recognized and related to a transport session and   publishing process.4.  Solution Detail   Figure 1 below shows the distributed data export framework.   A collector usually includes two components,   *  the Subscriber generates the subscription instructions to express      what and how the Receiver wants to receive the data;   *  the Receiver is the target for the data publication.   For one subscription, there can be one or more Receivers.  And the   Subscriber does not necessarily share the same IP address as the   Receivers.   In this framework, the Publisher pushes messages to the Receiver   according to the subscription.  The Publisher is either in the Parent   or Agent role.  The Publisher Parent knows all the capabilities that   his Agents can provide and exposes the Global Capability to the   collector.  The Subscriber maintains the Global Subscription at the   Publisher Parent and disassembles the Global Subscription to multiple   Component Subscriptions, depending upon which source data is needed.   The Component Subscriptions are then distributed to the corresponding   Publisher Agents on route and processors on line cards.Zhou, et al.              Expires 9 August 2026                 [Page 5]Internet-Draft          Distributed Notifications          February 2026   Publisher Agents collects metrics according to the Component   Subscription, add its metadata, encapsulates, and pushes messages.   Messages may require segmentation depending on the amount of YANG   data subscribed and maximum transmission unit of the interface where   the message is published from.  The Receiver then decapsulates   packets and reassembles notifications accordingly.                +-----------------------------------------+                |        Collector        |-------------+ |                |                        +------------+ | |                |      +------------+    || Receiver  | | |                |      | Subscriber |    |--------------+ |                |      +-----^-+----+    +------^-----^   |                |            | |                |     |   |                +-----------------------------------------+                   Global    | | Global         |     |                   Capability| | Subscription   |     |                +-----------------------------------------+                |            | |                |     |   |                |            | |   Subscription |     |   |                |            | |  State Changes |     |   |                |            | |                |     |   |                |   +--------+-v-------------------+  |   |                |   |       Publisher(Parent)      |  |   |                |   +--------^-+-------------------+  |   |                |            | |                      |   |                |            | |                      |   |                |  Component | | Component       Push |   |                |  Capability| | Subscription         |   |                |   +--------+-v-------------------+  |   |                |   |       Publisher(Agent)       +--+   |                |   +------------------------------+      |                |                                         |                |            Network Node                 |                +-----------------------------------------+              Figure 1: The Distributed Data Export Framework   Publisher Parent and Publisher Agents interact with each other in   several ways:   *  Publisher Agents need to register with the Parent at the beginning      of their process life cycle.   *  Contracts are created and maintained throughout the subscription      lifecycle between the Publisher Parent and each Agent and on its      Component Capability, and the format for notification data      structure.Zhou, et al.              Expires 9 August 2026                 [Page 6]Internet-Draft          Distributed Notifications          February 2026   *  The Publisher Parent relays the component subscriptions to the      Publisher Agents.   *  The Publisher Agents announce the status of their Component      Subscriptions to the Publisher Parent.  The status of the overall      subscription is maintained by the Publisher Parent.  The Publisher      Parent is responsible for notifying the subscriber in case of      problems with the Component Subscriptions.   The technical mechanisms or protocols used for the coordination of   operational information between Publisher Parent and Agent is out of   scope of this document.5.  Subscription Decomposition   The Collector can send subscription requests only to the Parent.   This requires the Publisher Parent to:   1.  expose the Global Capability that can be served by multiple       Publisher Agents;   2.  disassemble the Global Subscription to multiple Component       Subscriptions, and distribute them to the Publisher Agents of the       corresponding metric sources from the YANG schema tree so that       they do not overlap; How the subscription is being distributed is       implementation specific and not part of this document.   3.  notify changes related to the existing subscriptions to the       different Publisher Agents.   And the Publisher Agent to:   *  Inherit the Global Subscription properties from Publisher Parent      for its Component Subscription;   *  share the same life-cycle as the Global Subscription;   *  share the same Subscription ID as the Global Subscription.6.  Publication Composition   The Publisher Agent collects data and encapsulates the packets per   Component Subscription.  The format and structure of the data records   are defined by the YANG schema, so that the decomposition at the   Receiver can benefit from the structured and hierarchical data   records.Zhou, et al.              Expires 9 August 2026                 [Page 7]Internet-Draft          Distributed Notifications          February 2026   The Receiver can associate the YANG data records with Subscription ID   [RFC8639] to the subscribed subscription.  Additionally, it can use   the Message Publisher ID to determine the corresponding publisher   process.   For the dynamic subscription, the output of the "establish-   subscription" RPC defined in [RFC8639] MUST include a list of Message   Publisher IDs to indicate how the Global Subscription is decomposed   into several Component Subscriptions.   The "subscription-started" and "subscription-modified" notification   defined in [RFC8639] and "push-update" and "push-change-update"   notification defined in [RFC8641] MUST also include a list of Message   Publisher IDs to notify the current Publishers for the corresponding   Global Subscription.7.  Subscription State Change Notifications   In addition to sending event records to Receivers, the Parent MUST   also send subscription state change notifications [RFC8639] when   events related to subscription management have occurred.  All the   subscription state change notifications MUST be delivered by the   Parent.   When the subscription decomposition result changes, the   "subscription-modified" notification MUST be sent to indicate the new   list of Publisher Agents.8.  Publisher Configurations   This document assumes that all Publisher Agents are preconfigured to   push data.  Publisher Agents that send data are selected based on the   subscription decomposition result.   From the Receivers perspective, all Publisher Agents share the same   source IP address for data export.  Depending on the distributed   system architecture this may be implemented by using network address   translation within the distributed system.  For connectionless data   transport such as UDP based transport [I-D.ietf-netconf-udp-notif]   the same Layer 4 source port for data export can be used.  For   connection based data transport such as HTTPS based transport   [I-D.ietf-netconf-https-notif], each Publisher Agent MUST be able to   acknowledge packet retrieval from Receivers, and therefore requires a   dedicated Layer 4 source port per software process.   The specific configuration on transports is described in the   respective documents.Zhou, et al.              Expires 9 August 2026                 [Page 8]Internet-Draft          Distributed Notifications          February 20269.  YANG Tree   module: ietf-distributed-notif     augment /sn:subscriptions/sn:subscription:       +--ro message-publisher-id*   uint32     augment /sn:subscription-started:       +--ro message-publisher-id*   uint32     augment /sn:subscription-modified:       +--ro message-publisher-id*   uint32     augment /sn:establish-subscription/sn:output:       +--ro message-publisher-id*   uint32     augment /yp:push-update:       +--ro message-publisher-id?   uint32     augment /yp:push-change-update:       +--ro message-publisher-id?   uint32      Figure 2: YANG tree diagram for 'ietf-distributed-notif' module.10.  YANG Module   This YANG module imports definitions from [RFC8639] and [RFC8641].   <CODE BEGINS> file "ietf-distributed-notif@2025-04-12.yang"   module ietf-distributed-notif {     yang-version 1.1;     namespace "urn:ietf:params:xml:ns:yang:ietf-distributed-notif";     prefix dn;     import ietf-subscribed-notifications {       prefix sn;       reference         "RFC 8639: Subscription to YANG Notifications";     }     import ietf-yang-push {       prefix yp;       reference         "RFC 8641: Subscription to YANG Notifications for Datastore         Updates";     }     organization       "IETF NETCONF (Network Configuration) Working Group";     contact       "WG Web:   <https://datatracker.ietf.org/wg/netconf/>        WG List:  <mailto:netconf@ietf.org>        Authors:  Guangying ZhengZhou, et al.              Expires 9 August 2026                 [Page 9]Internet-Draft          Distributed Notifications          February 2026                  <mailto:zhengguangying@huawei.com>                  Tianran Zhou                  <mailto:zhoutianran@huawei.com>                  Thomas Graf                  <mailto:thomas.graf@swisscom.com>                  Pierre Francois                  <mailto:pierre.francois@insa-lyon.fr>                  Eric Voit                  <mailto:evoit@cisco.com>";     description       "Defines augmentation for ietf-subscribed-notifications to        enable the distributed publication with single subscription.        Copyright (c) 2026 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        (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 2026-02-05 {       description         "Initial version";       reference         "RFC XXXX: Subscription to Notifications in a Distributed          Architecture";     }     grouping message-publisher-id {       description         "Provides a reusable leaf of the message-publisher-id.";       leaf message-publisher-id {         type uint32;         config false;         description           "Identifies the software process which publishes notification            messages (e.g., processor 1 on line card 1). This field            is used to notify the receiver which publisher processZhou, et al.              Expires 9 August 2026                [Page 10]Internet-Draft          Distributed Notifications          February 2026            published which message. The identifier is locally unique to            the Network Node.";       }     }     grouping message-publisher-ids {       description         "Provides a reusable leaf-list of message-publisher-id-list.";       leaf-list message-publisher-id {         type uint32;         config false;         description           "Identifies the software process which publishes notification            messages (e.g., processor 1 on line card 1). This field            is used to notify the receiver which publisher processes            are going to publish. The identifiers are locally unique to            the Network Node.";       }     }     augment "/sn:subscriptions/sn:subscription" {       description         "This augmentation allows the Message          Publisher ID to be exposed for a subscription.";       uses message-publisher-ids;     }     augment "/sn:subscription-started" {       description         "This augmentation adds the Message Publisher ID to the          subscription-started subscription change notifications.";       uses message-publisher-ids;     }     augment "/sn:subscription-modified" {       description         "This augmentation adds the Message Publisher ID to the          subscription-modified subscription change notifications.";       uses message-publisher-ids;     }     augment "/sn:establish-subscription/sn:output" {       description         "This augmentation adds the Message Publisher ID to the          dynamic establish-subscription output.";       uses message-publisher-ids;     }Zhou, et al.              Expires 9 August 2026                [Page 11]Internet-Draft          Distributed Notifications          February 2026     augment "/yp:push-update" {       description         "This augmentation adds the Message Publisher ID in the          push-update notification.";       uses message-publisher-id;     }     augment "/yp:push-change-update" {       description         "This augmentation adds the Message Publisher ID in the          push-change-update notification.";       uses message-publisher-id;     }   }   <CODE ENDS>11.  IANA Considerations   This document registers the following namespace URI in the IETF XML   Registry [RFC3688]:      URI: urn:ietf:params:xml:ns:yang:ietf-distributed-notif      Maintained by IANA?  N      Registrant Contact: The IESG.      XML: N/A; the requested URI is an XML namespace.   This document registers the following YANG module in the YANG Module   Names registry [RFC3688]:      Name: ietf-distributed-notif      Maintained by IANA?  N      Namespace: urn:ietf:params:xml:ns:yang:ietf-distributed-notif      Prefix: dn      Reference: RFC XXXX12.  Implementation Status   Note to the RFC-Editor: Please remove this section before publishing.Zhou, et al.              Expires 9 August 2026                [Page 12]Internet-Draft          Distributed Notifications          February 202612.1.  Huawei VRP   Huawei implemented the Subscription Decomposition described in this   document for a YANG-Push publisher on UDP-based Transport for   Configured Subscriptions [I-D.ietf-netconf-udp-notif] in their VRP   platform.12.2.  6WIND VSR   6WIND implemented the Subscription Decomposition described in this   document for a YANG-Push publisher on UDP-based Transport for   Configured Subscriptions [I-D.ietf-netconf-udp-notif] in their VSR   platform.13.  Security Considerations   This section uses the template described in Section 3.7 of   [I-D.ietf-netmod-rfc8407bis].   The 'ietf-distributed-notif' YANG module defines a data model that is   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 no data nodes defined in this YANG module that are   writable/creatable/deletable (i.e., "config true", which is the   default).   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:   *  /sn:subscriptions/sn:subscription/dn:message-publisher-id   *  /sn:subscription-started/dn:message-publisher-id   *  /sn:subscription-modified/dn:message-publisher-idZhou, et al.              Expires 9 August 2026                [Page 13]Internet-Draft          Distributed Notifications          February 2026   *  /sn:establish-subscription/dn:message-publisher-id   The entries in the list above will show the identity of the   originating Publisher process.  Exposure of this information may   assist an attacker in mapping the distributed system 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.   Security Considerations defined in [RFC8639] do also apply for this   document.14.  Contributors      Alexander Clemm      Futurewai      2330 Central Expressway      Santa Clara      California      United States of America      Email: ludwig@clemm.org15.  Acknowledgements   We thank Kent Watsen, Mahesh Jethanandani, Martin Bjorklund, Tim   Carey, Qin Wu, Robert Wilton, Benoit Claise, Alex Huang Feng, Camilo   Cardona and Juergen Schoenwaelder for their constructive suggestions   for improving this document.16.  References16.1.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels", BCP 14, RFC 2119,              DOI 10.17487/RFC2119, March 1997,              <https://www.rfc-editor.org/info/rfc2119>.   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,              DOI 10.17487/RFC3688, January 2004,              <https://www.rfc-editor.org/info/rfc3688>.   [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>.Zhou, et al.              Expires 9 August 2026                [Page 14]Internet-Draft          Distributed Notifications          February 2026   [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>.   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,              and R. Wilton, "Network Management Datastore Architecture              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,              <https://www.rfc-editor.org/info/rfc8342>.   [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>.   [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>.16.2.  Informative References   [I-D.ietf-netconf-https-notif]              Jethanandani, M. and K. Watsen, "An HTTPS-based Transport              for YANG Notifications", Work in Progress, Internet-Draft,              draft-ietf-netconf-https-notif-15, 1 February 2024,              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-              https-notif-15>.   [I-D.ietf-netconf-notif-envelope]              Feng, A. H., Francois, P., Graf, T., and B. Claise,              "Extensible YANG Model for YANG-Push Notifications", Work              in Progress, Internet-Draft, draft-ietf-netconf-notif-              envelope-03, 20 October 2025,              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-              notif-envelope-03>.   [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-Zhou, et al.              Expires 9 August 2026                [Page 15]Internet-Draft          Distributed Notifications          February 2026              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>.   [RFC7923]  Voit, E., Clemm, A., and A. Gonzalez Prieto, "Requirements              for Subscription to YANG Datastores", RFC 7923,              DOI 10.17487/RFC7923, June 2016,              <https://www.rfc-editor.org/info/rfc7923>.   [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>.Appendix A.  Examples   This appendix is non-normative.A.1.  Dynamic Subscription   Figure 3 shows a typical dynamic subscription to the Network Node   with distributed data export capability.  The Subscriber is a   NETCONF/RESTCONF client and the Publisher Parent is the NETCONF/   RESTCONF server.Zhou, et al.              Expires 9 August 2026                [Page 16]Internet-Draft          Distributed Notifications          February 2026   +-------------+                 +-------------+ +-------------+   | Subscriber/ |                 |  Publisher  | |  Publisher  |   | Receiver    |                 |  (Parent)   | |  (Agent)    |   +-------------+                 +------+------+ +------+------+          |                               |               |          | establish-subscription        |               |          +------------------------------>+ component     |          |                               | subscription  |          |                               +-------------->+          |                               |               |          |                               |  Acknowledged |          | RPC Reply: OK, id #22         |<--------------|          | Message Publisher ID [#1,#2]  |               |          +<------------------------------+               |          |                               |               |          | notif-mesg, id #22            |               |          | Message Publisher ID #1       |               |          +<------------------------------+               |          |                               |               |          | notif-mesg, id#22             |               |          | Message Publisher ID #2       |               |          +<----------------------------------------------+          |                               |               |          | modify-subscription (id#22)   |               |          +------------------------------>+ component     |          |                               | subscription  |          | RPC Reply: OK, id #22         +-------------->+          |                               |               |          |                               |  Acknowledged |          |                               |<--------------|          +<------------------------------+               |          |                               |               |          | subscription-modified, id#22  |               |          | Message Publisher ID [#1]     |               |          +<------------------------------+               |          |                               |               |          | notif-mesg, id #22            |               |          | Message Publisher ID  #1      |               |          +<------------------------------+               |          |                               |               |          |                               |               |          +                               +               +                Figure 3: Call Flow for Dynamic Subscription   A "establish-subscription" RPC request as per [RFC8641] is sent to   the Parent with a successful response.  An example of using NETCONF:Zhou, et al.              Expires 9 August 2026                [Page 17]Internet-Draft          Distributed Notifications          February 2026   <netconf:rpc message-id="101"      xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">    <establish-subscription       xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"       xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">      <yp:datastore           xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">        ds:operational      </yp:datastore>      <yp:datastore-xpath-filter          xmlns:ex="https://example.com/sample-data/1.0">        /ex:foo      </yp:datastore-xpath-filter>      <yp:periodic>        <yp:period>500</yp:period>      </yp:periodic>     </establish-subscription>    </netconf:rpc>                 Figure 4: "establish-subscription" Request   As the Network Node is able to fully satisfy the request, the request   is given a subscription ID of 22.  The response as in Figure 5   indicates that the subscription is decomposed into two component   subscriptions which will be published by two message Message   Publisher ID: #1 and #2.   <rpc-reply message-id="101"     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">     <id      xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">        22     </id>     <message-publisher-id      xmlns="urn:ietf:params:xml:ns:yang:ietf-distributed-notif">        1     </message-publisher-id>     <message-publisher-id      xmlns="urn:ietf:params:xml:ns:yang:ietf-distributed-notif">        2     </message-publisher-id>   </rpc-reply>          Figure 5: "establish-subscription" Positive RPC Response   Then, both Publishers send notifications with the corresponding piece   of data to the Receiver.Zhou, et al.              Expires 9 August 2026                [Page 18]Internet-Draft          Distributed Notifications          February 2026   The subscriber may invoke the "modify-subscription" RPC for a   subscription it previously established.  The RPC has no difference to   the single publisher case as in [RFC8641].  Figure 6 provides an   example where a subscriber attempts to modify the period and   datastore XPath filter of a subscription using NETCONF.        <rpc message-id="102"          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">       <modify-subscription           xmlns=             "urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"           xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">         <id>22</id>         <yp:datastore             xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">           ds:operational         </yp:datastore>         <yp:datastore-xpath-filter             xmlns:if="urn:ietf:params:xml:ns:yang:ietf-interfaces">           /if:interfaces/if:interface         </yp:datastore-xpath-filter>         <yp:periodic>           <yp:period>250</yp:period>         </yp:periodic>        </modify-subscription>     </rpc>                  Figure 6: "modify-subscription" Request   If the modification is successfully accepted, the "subscription-   modified" subscription state notification is sent to the subscriber   by the Parent.  The notification, Figure 7 for example, indicates the   modified subscription is decomposed into one component subscription   which will be published by message Message Publisher ID #1.Zhou, et al.              Expires 9 August 2026                [Page 19]Internet-Draft          Distributed Notifications          February 2026 <notification       xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"> <eventTime>2007-09-01T10:00:00Z</eventTime> <subscription-modified       xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"       xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">     <id>22</id>     <yp:datastore         xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">       ds:operational     </yp:datastore>     <yp:datastore-xpath-filter         xmlns:ex="https://example.com/sample-data/1.0">       /ex:bar     </yp:datastore-xpath-filter>     <yp:periodic>         <yp:period>250</yp:period>     </yp:periodic>     <message-publisher-id     xmlns="urn:ietf:params:xml:ns:yang:ietf-distributed-notif">        1     </message-publisher-id>   </subscription-modified> </notification>   Figure 7: "subscription-modified" Subscription State NotificationA.2.  Configured Subscription   Figure 8 shows a typical configured subscription to the Network Node   with distributed data export capability.  Subscripton request has   been removed for brevity.Zhou, et al.              Expires 9 August 2026                [Page 20]Internet-Draft          Distributed Notifications          February 2026   +-------------+                 +-------------+ +-------------+   | Receiver    |                 |  Publisher  | |  Publisher  |   |             |                 |  (Parent)   | |  (Agent)    |   +------+------+                 +------+------+ +------+------+          |                               |               |          | subscription-started, id#39   |               |          | Message Publisher ID [#1,#2]  |               |          +<------------------------------+               |          |                               |               |          | notif-mesg, id#39             |               |          | Message Publisher ID #1       |               |          +<------------------------------+               |          |                               |               |          | notif-mesg, id#39             |               |          | Message Publisher ID #2       |               |          +<----------------------------------------------+          |                               |               |          |                               |               |          |                               |               |              Figure 8: Call Flow for Configured Subscription   Before starting to push data, the "subscription-started" subscription   state notification is sent to the Receiver.  The following example   assumes the NETCONF transport has already established.  The   notification indicates that the configured subscription is decomposed   into two component subscriptions which will be published by two   message Message Publisher IDs: #1 and #2.Zhou, et al.              Expires 9 August 2026                [Page 21]Internet-Draft          Distributed Notifications          February 2026 <notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">   <eventTime>2007-09-01T10:00:00Z</eventTime>   <subscription-started       xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"       xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">     <identifier>39</identifier>     <yp:datastore         xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">     ds:operational     </yp:datastore>     <yp:datastore-xpath-filter         xmlns:ex="https://example.com/sample-data/1.0">       /ex:foo     </yp:datastore-xpath-filter>     <yp:periodic>         <yp:period>250</yp:period>     </yp:periodic>     <message-publisher-id     xmlns="urn:ietf:params:xml:ns:yang:ietf-distributed-notif>        1     </message-publisher-id>     <message-publisher-id     xmlns="urn:ietf:params:xml:ns:yang:ietf-distributed-notif>        2     </message-publisher-id>   </subscription-started> </notification>    Figure 9: "subscription-started" Subscription State Notification   Then, both Publishers send notifications with the corresponding data   record to the Receiver.Authors' Addresses   Tianran Zhou   Huawei   156 Beiqing Rd., Haidian District   Beijing   China   Email: zhoutianran@huawei.comZhou, et al.              Expires 9 August 2026                [Page 22]Internet-Draft          Distributed Notifications          February 2026   Guangying Zheng   Huawei   101 Yu-Hua-Tai Software Road   Nanjing   Jiangsu,   China   Email: zhengguangying@huawei.com   Eric Voit   Cisco Systems   United States of America   Email: evoit@cisco.com   Thomas Graf   Swisscom   Binzring 17   CH- Zuerich 8045   Switzerland   Email: thomas.graf@swisscom.com   Pierre Francois   INSA-Lyon   Lyon   France   Email: pierre.francois@insa-lyon.frZhou, et al.              Expires 9 August 2026                [Page 23]