Network Working Group Z. Ali Internet-Draft Cisco Systems Intended status: Informational 6 July 2026 Expires: 7 January 2027 Problem Statement: YANG Modeling for Protocol Buffer Based Network APIs draft-ali-opsawg-yang-protobuf-problem-statement-00 Abstract Network devices increasingly expose management, telemetry, and dynamic service interfaces using gRPC and Protocol Buffers. Many of these interfaces carry ephemeral or runtime state that is not intended to be stored as persistent configuration. At the same time, the IETF has standardized YANG as the primary data modeling language for network management and operations. This document describes the problem space and identifies questions for the IETF community regarding the role of YANG in defining interoperable Protocol Buffer based APIs. 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 7 January 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components Ali Expires 7 January 2027 [Page 1] Internet-Draft YANG/Protobuf Problem Statement July 2026 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 . . . . . . . . . . . . . . . . . . . . . 2 2.1. YANG Data Modeling . . . . . . . . . . . . . . . . . . . 2 2.2. RFC 8342 and Ephemeral State . . . . . . . . . . . . . . 3 3. Industry Practice . . . . . . . . . . . . . . . . . . . . . . 3 4. Existing Tooling . . . . . . . . . . . . . . . . . . . . . . 3 5. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 6. Discussion Topics for the IETF . . . . . . . . . . . . . . . 3 7. Potential Direction . . . . . . . . . . . . . . . . . . . . . 4 8. Next Steps . . . . . . . . . . . . . . . . . . . . . . . . . 4 9. Security Considerations . . . . . . . . . . . . . . . . . . . 4 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 11. Normative References . . . . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4 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. Although the IETF has standardized YANG as the primary network management modeling language, there is currently no common IETF guidance describing how YANG models should be represented within Protocol Buffer schemas used by gRPC APIs. As a result, vendors often develop independent protobuf definitions despite representing similar information. 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. Ali Expires 7 January 2027 [Page 2] Internet-Draft YANG/Protobuf Problem Statement July 2026 2.2. RFC 8342 and Ephemeral State RFC 8342 defines the Network Management Datastore Architecture (NMDA). While Appendix B provides an example of an Ephemeral Dynamic Configuration Datastore, many currently deployed gRPC and Protocol Buffer APIs are not implementing the architecture described therein. Instead, vendors are exposing runtime information through implementation-specific protobuf schemas. 3. Industry Practice Many network vendors have adopted gRPC and Protocol Buffers. While the underlying information may correspond to concepts already modeled in YANG, the protobuf schema definitions are frequently vendor- specific, leading to challenges such as divergent semantics and the inability to reuse existing YANG standardization work. 4. Existing Tooling Tools already exist that can derive Protocol Buffer schemas from YANG models, demonstrating that technical conversion is feasible. 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: * 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? Ali Expires 7 January 2027 [Page 3] Internet-Draft YANG/Protobuf Problem Statement July 2026 * 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 [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, . Author's Address Zafar Ali Cisco Systems Email: zali@cisco.com Ali Expires 7 January 2027 [Page 4]