NETCONF Working Group Q. Wu Internet-Draft Q. Ma Intended status: Standards Track Huawei Expires: 18 February 2027 A. Huang-Feng Deutsche Telekom T. Graf Swisscom 17 August 2026 YANG Notification Transport Capabilities draft-ietf-netconf-yp-transport-capabilities-07 Abstract This document specifies a YANG module for discovering transport capabilities for YANG notifications. The module augments the YANG notifications capabilities model with capabilities for the notification transport protocol, transport encoding, and transport encryption. The capabilities enable a client to determine the notification transport options supported by a NETCONF or RESTCONF server at runtime or at implementation time using the YANG instance data file format. 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 18 February 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Wu, et al. Expires 18 February 2027 [Page 1] Internet-Draft YANG Notification Transport Capabilities August 2026 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 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Capabilities for Systems and Datastore Update Notifications . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 4 3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4.1. Updates to the IETF XML Registry . . . . . . . . . . . . 8 4.2. Updates to the YANG Module Names Registry . . . . . . . . 8 5. Implementation Status . . . . . . . . . . . . . . . . . . . . 8 5.1. Huawei VRP . . . . . . . . . . . . . . . . . . . . . . . 9 5.2. Cisco IOS XR . . . . . . . . . . . . . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . 10 9.2. Informative References . . . . . . . . . . . . . . . . . 12 Appendix A. Usage Example of interaction with UDP-Notif and HTTPS-Notif for Configured Subscription . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 1. Introduction The "ietf-system-capabilities" YANG module defined in [RFC9196] allows a NETCONF or RESTCONF client to discover capabilities supported by a NETCONF or RESTCONF server, including basic system capabilities and YANG-Push related capabilities. These capabilities can be provided at implementation time or reported at runtime, allowing a client to determine which YANG management features are supported by the server. Wu, et al. Expires 18 February 2027 [Page 2] Internet-Draft YANG Notification Transport Capabilities August 2026 YANG Notifications, as defined in [RFC8639] and [RFC8641], allow clients to establish subscriptions for receiving YANG notifications from a NETCONF or RESTCONF server. A server may support multiple notification delivery protocols, encoding formats, and security protocols. Knowledge of these capabilities can allow a client to select an appropriate notification delivery protocol and associated parameters when establishing a subscription. Currently, a client may determine whether a particular notification delivery protocol and its associated parameters are supported only by attempting to use them through configuration. For example, a NETCONF or RESTCONF server may reject a subscription request when the requested notification delivery parameters, such as the delivery protocol, encoding format, or security protocol, are not supported. As described in Section 3.2 of [RFC8641], a simple negotiation mechanism, such as inserting hints into an error response to a failed RPC request, can increase the likelihood of success for subsequent RPC requests involving subscription parameters. While such error responses can help establish a subscription, they are not widely supported and may result in unexpected failures or additional message exchanges between the client and server. This document defines a YANG module that extends the system capabilities model defined in [RFC9196] with capabilities specific to the delivery of YANG notifications. The module allows a NETCONF or RESTCONF client to discover, from a NETCONF or RESTCONF server, the notification delivery protocols, encoding formats, and security protocols supported for YANG notifications. The capabilities can be provided at implementation time using the YANG instance data file format or discovered at runtime through a YANG management protocol. 1.1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. The terms "subscription", "publisher", and "receiver" are used as defined in [RFC8639]. The terms "client", and "server" are used as defined in [RFC8342]. The term "transport protocol" is used as defined by the "transport" identity in [RFC8639] and refers to the notification delivery protocol used to deliver YANG notifications between a publisher and a receiver. Wu, et al. Expires 18 February 2027 [Page 3] Internet-Draft YANG Notification Transport Capabilities August 2026 2. Capabilities for Systems and Datastore Update Notifications Section 3.1 of [RFC8641] lists the NETCONF/RESTCONF server capabilities related to YANG-Push that are supported in the YANG module "ietf-notification-capabilities". These server capabilities are transport independent, session level capabilities. They can be provided either at the implementation time or reported at runtime. This document provides additional attributes associated with system capabilities that are related to the YANG notification delivery protocol: * Transport protocols supported for YANG notifications that a client can request when establishing a subscription. This includes HTTPS-based [I-D.ietf-netconf-https-notif] or UDP-based [I-D.ietf-netconf-udp-notif] transports for configured subscriptions. * YANG notifications encodings formats supported by the NETCONF/ RESTCONF server. This includes XML [RFC7950], JSON [RFC7951] or CBOR [RFC9254]. * Security protocols supported for protecting YANG notifications connections. This includes DTLS 1.2 [RFC6347], DTLS 1.3 [RFC9147], TLS 1.2 [RFC5246], and TLS 1.3 [RFC8446]. The model defined in this document augments the System Capabilities model defined in [RFC9196]. This model is intended to be used between an orchestrator and a network device that provides YANG notifications. A management network between the orchestrator and the network device is assumed to be available for exchanging YANG management information. The management connectivity and endpoint of the network device are expected to be provisioned as part of the management network configuration. The orchestrator can use the established management connection to discover the notification transport capabilities of the network device before establishing the notification subscription. 2.1. Tree Diagram The following tree diagram [RFC8340] provides an overview of the data model. Wu, et al. Expires 18 February 2027 [Page 4] Internet-Draft YANG Notification Transport Capabilities August 2026 module: ietf-yp-transport-capabilities augment /sysc:system-capabilities/notc:subscription-capabilities: +--ro transport-capabilities +--ro transport-capability* [transport-protocol] +--ro transport-protocol identityref +--ro security-protocol* union +--ro encoding-format* identityref 3. YANG Module file "ietf-yp-transport-capabilities@2026-08-13.yang" module ietf-yp-transport-capabilities { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-yp-transport-capabilities"; prefix yptc; 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-tls-common { prefix tlscmn; reference "RFC 9645: YANG Groupings for TLS Clients and TLS Servers"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: Authors: Qin Wu Wu, et al. Expires 18 February 2027 [Page 5] Internet-Draft YANG Notification Transport Capabilities August 2026 Qiufang Ma Alex Huang Feng Thomas Graf "; description "This module defines an extension to YANG-Push Notification Capabilities model that provides additional transport specific capabilities for YANG notifications. The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document are to be interpreted as described in BCP 14 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here. 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 (http://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 2026-08-13 { description "Initial revision."; reference "RFC XXXX: YANG Notifications Transport Capabilities"; } identity security-protocol { description "Identity for YANG notifications security protocols."; } identity dtls12 { base security-protocol; description "Indicates DTLS Protocol Version 1.2. DTLS 1.2 is obsolete, Wu, et al. Expires 18 February 2027 [Page 6] Internet-Draft YANG Notification Transport Capabilities August 2026 and thus it is NOT RECOMMENDED to enable this feature."; reference "RFC 6347: The Datagram Transport Layer Security (DTLS) Protocol Version 1.2."; } identity dtls13 { base security-protocol; description "Indicates DTLS Protocol Version 1.3."; reference "RFC 9147: The Datagram Transport Layer Security (DTLS) Protocol Version 1.3."; } augment "/sysc:system-capabilities" + "/notc:subscription-capabilities" { description "Adds subscription-related system level capabilities."; container transport-capabilities { description "Specifies capabilities related to YANG-Push transports."; list transport-capability { key "transport-protocol"; description "Indicates supported YANG notifications transport protocol for Subscribed Notifications [RFC8639] and YANG-Push [RFC8641]. Defines the supported transports, security protocols and supported notification encodings."; leaf transport-protocol { type identityref { base sn:transport; } description "Indicates the supported YANG notifications transport protocol for Subscribed Notifications [RFC8639] and YANG-Push [RFC8641]."; } leaf-list security-protocol { type union { type identityref { base security-protocol; } type identityref { base tlscmn:tls-version-base; } } description Wu, et al. Expires 18 February 2027 [Page 7] Internet-Draft YANG Notification Transport Capabilities August 2026 "Indicates the supported YANG notifications transport encryption protocols."; } leaf-list encoding-format { type identityref { base sn:encoding; } description "Indicates supported encoding formats for YANG notifications."; } } } } } 4. IANA Considerations 4.1. Updates to the IETF XML Registry This document registers a URI in the "IETF XML Registry" [RFC3688]. Following the format in [RFC3688], the following registration has been made: URI: urn:ietf:params:xml:ns:yang:ietf-yp-transport-capabilities Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. Reference: RFC XXXX (RFC Ed.: replace XXX with actual RFC number and remove this note.) 4.2. Updates to the YANG Module Names Registry This document registers one YANG module in the "YANG Module Names" registry [RFC6020]. Following the format in [RFC6020], the following registration has been made: name: ietf-yp-transport-capabilities namespace: urn:ietf:params:xml:ns:yang:ietf-yp-transport-capabilities prefix: yptc reference: RFC XXXX (RFC Ed.: replace XXX with actual RFC number and remove this note.) 5. Implementation Status Note to the RFC-Editor: Please remove this section before publishing. Wu, et al. Expires 18 February 2027 [Page 8] Internet-Draft YANG Notification Transport Capabilities August 2026 5.1. Huawei VRP Huawei implemented this document for a YANG Push publisher in their VRP platform. 5.2. Cisco IOS XR Cisco implemented this document for a YANG Push publisher in their IOS XR platform. 6. Security Considerations This section is modeled after the template described in Section 3.7 of [I-D.ietf-netmod-rfc8407bis] The "ietf-yp-transport-capabilities" 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 protocols have to use a secure transport layer (e.g., SSH [RFC4252], TLS [RFC8446], and QUIC [RFC9000]) and 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. All protocol-accessible data nodes are read-only and cannot be modified. The data in the module is not security sensitive. It inherits all the security considerations of [RFC9196]. 7. Contributors Wu, et al. Expires 18 February 2027 [Page 9] Internet-Draft YANG Notification Transport Capabilities August 2026 Ran Tao Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: taoran20@huawei.com Liang Geng China Mobile 32 Xuanwumen West St, Xicheng District Beijing 10053 China Email: gengliang@chinamobile.com Peng Liu China Mobile Beiqijia Town, Changping District Beijing 10053 China Email: liupengyjy@chinamobile.com Wei Wang China Telecom 32 Xuanwumen West St, Xicheng District Beijing 102209 China Email: wangw36@chinatelecom.cn 8. Acknowledgements The authors would like to thank Mohamed Boucadair, Kent Watson, Jan Lindblad, Reshad Rahman, Xiao Min, Per Andersson and Rob Wilton for their review and valuable comments. 9. References 9.1. 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, . [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, . Wu, et al. Expires 18 February 2027 [Page 10] Internet-Draft YANG Notification Transport Capabilities August 2026 [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, . [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, January 2012, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [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, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [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, . [RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, September 2019, . Wu, et al. Expires 18 February 2027 [Page 11] Internet-Draft YANG Notification Transport Capabilities August 2026 [RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022, . [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, . [RFC9254] Veillette, M., Ed., Petrov, I., Ed., Pelov, A., Bormann, C., and M. Richardson, "Encoding of Data Modeled with YANG in the Concise Binary Object Representation (CBOR)", RFC 9254, DOI 10.17487/RFC9254, July 2022, . 9.2. 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-16, 30 June 2026, . [I-D.ietf-netconf-udp-notif] Feng, A. H., Francois, P., Zhou, T., Graf, T., and P. Lucente, "UDP-based Transport for Configured Subscriptions", Work in Progress, Internet-Draft, draft- ietf-netconf-udp-notif-26, 29 July 2026, . [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, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252, January 2006, . Wu, et al. Expires 18 February 2027 [Page 12] Internet-Draft YANG Notification Transport Capabilities August 2026 [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . Appendix A. Usage Example of interaction with UDP-Notif and HTTPS-Notif for Configured Subscription The following instance-data example describes the notification transport capabilities of a hypothetical "acme-router". Wu, et al. Expires 18 February 2027 [Page 13] Internet-Draft YANG Notification Transport Capabilities August 2026 acme-router-notification-capabilities ietf-system-capabilities@2022-02-17 ietf-notification-capabilities@2022-02-17 ietf-yp-transport-capabilities@2026-08-13 Server Capability Discovery hnt:https sn:encode-xml sn:encode-json tlscmn:tls12 tlscmn:tls13 unt:udp-notif sn:encode-json unt:encode-cbor dtls12 dtls13 In addition, the client could also query notification transport capabilities from the NETCONF or RESTCONF server. For example, the client sends request message to the the server to query from the server. Wu, et al. Expires 18 February 2027 [Page 14] Internet-Draft YANG Notification Transport Capabilities August 2026 ================= NOTE: '\' line wrapping per RFC 8792 ================== The server returns server data export capability using as follows: Wu, et al. Expires 18 February 2027 [Page 15] Internet-Draft YANG Notification Transport Capabilities August 2026 hnt:https sn:encode-xml sn:encode-json tlscmn:tls12 tlscmn:tls13 unt:udp-notif sn:encode-json unt:encode-cbor dtls12 dtls13 Authors' Addresses Qin Wu Huawei 101 Software Avenue, Yuhua District Nanjing Jiangsu, 210012 China Email: bill.wu@huawei.com Wu, et al. Expires 18 February 2027 [Page 16] Internet-Draft YANG Notification Transport Capabilities August 2026 Qiufang Ma Huawei 101 Software Avenue, Yuhua District Nanjing Jiangsu, 210012 China Email: maqiufang1@huawei.com Alex Huang Feng Deutsche Telekom Barcelona Spain Email: alex.huang-feng@t-systems.com Thomas Graf Swisscom Binzring 17 CH-8045 Zurich Switzerland Email: thomas.graf@swisscom.com Wu, et al. Expires 18 February 2027 [Page 17]