Network Working Group Z. Ali Internet-Draft Cisco Systems Intended status: Informational 2 November 2026 Expires: 6 May 2027 Problem Statement: YANG Modeling for Protocol Buffer Based Network APIs draft-ali-netmod-yang-protobuf-problem-statement-00 Abstract Network devices increasingly expose operational APIs using gRPC and Protocol Buffers. Many of these APIs provide ephemeral or runtime state whose lifetime is limited to a process, service, session, or device runtime. At the same time, the IETF has standardized YANG as a data modeling language for network management and has defined encodings for YANG data, including JSON and CBOR. This document describes the problem space and identifies questions for the IETF community regarding standards-based gRPC APIs for ephemeral operational state. The scope is limited to ephemeral operational state. Configuration data and configuration management operations are out of scope. 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 6 May 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Ali Expires 6 May 2027 [Page 1] Internet-Draft YANG/Protobuf Problem Statement November 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 2. Existing IETF Work . . . . . . . . . . . . . . . . . . . . . 3 2.1. YANG Data Modeling . . . . . . . . . . . . . . . . . . . 3 2.2. RFC 8342 and Ephemeral State . . . . . . . . . . . . . . 3 2.3. YANG Encodings . . . . . . . . . . . . . . . . . . . . . 3 3. Industry Practice . . . . . . . . . . . . . . . . . . . . . . 3 4. Existing Tooling . . . . . . . . . . . . . . . . . . . . . . 3 5. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 6. Discussion Topics for the IETF . . . . . . . . . . . . . . . 4 7. Potential Direction . . . . . . . . . . . . . . . . . . . . . 4 8. Next Steps . . . . . . . . . . . . . . . . . . . . . . . . . 4 9. Security Considerations . . . . . . . . . . . . . . . . . . . 4 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 11. Normative References . . . . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction The networking industry has broadly adopted gRPC and Protocol Buffers for communication between network devices, controllers, orchestration systems, and operational applications. Many deployed implementations expose information that is transient in nature and exists only for the lifetime of a process, service, session, or device runtime. This document focuses on that ephemeral operational state. Configuration data and configuration management operations are out of scope. Although the IETF has standardized YANG for network management, there is currently no common IETF guidance describing how YANG models should be represented within Protocol Buffer schemas used by gRPC APIs for this ephemeral state. As a result, implementations may develop independent protobuf definitions for similar information. This document describes the problem and seeks discussion of a standards-based path; it does not select a technical solution. Ali Expires 6 May 2027 [Page 2] Internet-Draft YANG/Protobuf Problem Statement November 2026 2. Existing IETF Work 2.1. YANG Data Modeling YANG provides a standardized framework for modeling configuration and operational state. These models provide a common vocabulary and semantics that can potentially be reused across management protocols and API technologies. 2.2. RFC 8342 and Ephemeral State [RFC8342] defines the Network Management Datastore Architecture (NMDA). While Appendix B of [RFC8342] provides an example of an Ephemeral Dynamic Configuration Datastore, many currently deployed gRPC and Protocol Buffer APIs are not implementing the architecture described therein. 2.3. YANG Encodings The IETF has also defined XML and JSON encodings for YANG data, along with a CBOR encoding [RFC7950] [RFC7951] [RFC9254]. These specifications are relevant to how YANG data can be represented. They do not define a protobuf mapping or gRPC service conventions for the state addressed by this document. 3. Industry Practice Many network vendors have adopted gRPC and Protocol Buffers. While some ephemeral operational information may correspond to concepts already modeled in YANG, protobuf schema definitions are frequently vendor- or platform-specific. Similar information can therefore have divergent semantics and representations. This fragmentation can require operators and vendors to implement multiple APIs, clients, adapters, and data normalization steps for similar operational capabilities. 4. Existing Tooling Tools already exist that can derive Protocol Buffer schemas from YANG models, demonstrating that technical conversion is feasible. For example, OpenConfig publishes a YANG-to-Protobuf transformation specification [OpenConfig-YANG-Protobuf]. However, different tools may generate different protobuf structures from the same YANG model, meaning tooling alone does not guarantee interoperability. 5. Problem Statement There is currently no IETF framework that answers the following questions: Ali Expires 6 May 2027 [Page 3] Internet-Draft YANG/Protobuf Problem Statement November 2026 * Should YANG serve as the authoritative information model for gRPC APIs? * How should ephemeral and dynamic state be modeled? * How should operational state be represented? 6. Discussion Topics for the IETF This document seeks discussion on the following topics: * Is there sufficient industry interest to standardize YANG-based protobuf modeling? * Does RFC 8342 adequately address current deployment requirements for ephemeral and dynamic state? * Should the IETF define a standardized mapping between YANG and Protocol Buffers? * Should generated protobuf schemas become a standardized artifact derived from YANG models? 7. Potential Direction One possible direction is for the IETF to define a framework in which YANG remains the authoritative information model, and Protocol Buffer schemas are generated using standardized rules to preserve consistent semantics across implementations. 8. Next Steps The authors believe that a focused discussion involving operators, vendors, protocol designers, and implementers would help determine whether there is sufficient interest to pursue future standardization work. 9. Security Considerations None. 10. IANA Considerations None. 11. Normative References Ali Expires 6 May 2027 [Page 4] Internet-Draft YANG/Protobuf Problem Statement November 2026 [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, . 11. Informative References [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, . [RFC9254] Veillette, M., Petrov, I., 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, . [OpenConfig-YANG-Protobuf] OpenConfig, "YANG to Protobuf: Transformation Specification", . Author's Address Zafar Ali Cisco Systems Email: zali@cisco.com Ali Expires 6 May 2027 [Page 5]