NETCONF R. Gagliano Internet-Draft C. Rennerskog Intended status: Standards Track Cisco Systems Expires: 21 March 2027 K. Larsson Deutsche Telekom AG J. Lindblad All For Eco 17 September 2026 RESTCONF Extension to Support Trace Context Headers draft-ietf-netconf-restconf-trace-ctx-headers-11 Abstract This document defines an extension to the RESTCONF protocol to support Trace Context propagation as defined by the W3C. About This Document This note is to be removed before publishing as an RFC. The latest revision of this draft can be found at https://github.com/ netconf-wg/restconf-trace-ctx-headers/blob/gh-pages/draft-ietf- netconf-restconf-trace-ctx-headers.txt. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-ietf- netconf-restconf-trace-ctx-headers/. Discussion of this document takes place on the NETCONF Working Group mailing list (mailto:netconf@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/netconf/. Subscribe at https://www.ietf.org/mailman/listinfo/netconf/. Source for this draft and an issue tracker can be found at https://github.com/https://github.com/netconf-wg/restconf-trace-ctx- headers. 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/. Gagliano, et al. Expires 21 March 2027 [Page 1] Internet-Draft RESTCONF Trace Context Headers September 2026 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 21 March 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 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. RESTCONF Extensions . . . . . . . . . . . . . . . . . . . . . 3 2.1. Error Handling . . . . . . . . . . . . . . . . . . . . . 4 2.2. Trace Context Header Versioning . . . . . . . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . 5 6.2. Informative References . . . . . . . . . . . . . . . . . 6 Appendix A. Example RESTCONF Calls . . . . . . . . . . . . . . . 6 A.1. Successful creation of New Data Resources (from Appendix B.2.1 of RFC8040) . . . . . . . . . . . . . . . 7 A.2. Unsuccessful creation of New Data Resources (from Appendix B.2.1 of RFC8040) . . . . . . . . . . . . . . . 7 Appendix B. Changes (to be deleted by RFC Editor) . . . . . . . 8 B.1. From version 10 to 11 . . . . . . . . . . . . . . . . . . 8 B.2. From version 09 to 10 . . . . . . . . . . . . . . . . . . 8 B.3. From version 08 to 09 . . . . . . . . . . . . . . . . . . 8 B.4. From version 07 to 08 . . . . . . . . . . . . . . . . . . 9 B.5. From version 06 to 07 . . . . . . . . . . . . . . . . . . 9 B.6. From version 05 to 06 . . . . . . . . . . . . . . . . . . 9 B.7. From version 04 to 05 . . . . . . . . . . . . . . . . . . 9 B.8. From version 03 to 04 . . . . . . . . . . . . . . . . . . 9 Gagliano, et al. Expires 21 March 2027 [Page 2] Internet-Draft RESTCONF Trace Context Headers September 2026 B.9. From version 02 to 03 . . . . . . . . . . . . . . . . . . 9 B.10. From version 01 to 02 . . . . . . . . . . . . . . . . . . 9 B.11. From version 00 to -01 . . . . . . . . . . . . . . . . . 10 B.12. From version 00 to draft-ietf-netconf-restconf-trace-ctx-headers-00 . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction Network automation and management systems commonly consist of multiple subsystems and, together with the network devices they manage, effectively form a distributed system. Distributed tracing is a methodology implemented by tracing tools to track, analyze, and debug operations such as configuration transactions across multiple distributed systems. The W3C has defined two HTTP headers, traceparent and tracestate, in [W3C-Trace-Context] for context propagation. These headers are useful for distributed systems such as those described in Section 4 of [RFC8309]. While the traceparent header is portable and mandatory, the tracestate header is optional and is used to carry vendor-specific data in a set of key/value pairs. According to the W3C specification, each operation is uniquely identified by a "trace-id" field and carries multiple metadata fields about the operation. Propagating this Trace Context between systems provides a coherent view of the entire operation as carried out by all involved systems. In [I-D.draft-ietf-netconf-trace-ctx-extension], the NETCONF protocol extension is defined, and we reuse several of the YANG and XML objects defined in that document for RESTCONF. Please refer to that document for additional context and example applications. 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. 2. RESTCONF Extensions A RESTCONF server that implements the Trace Context propagation mechanism defined in this document MUST support the Trace Context traceparent header as defined in [W3C-Trace-Context]. Gagliano, et al. Expires 21 March 2027 [Page 3] Internet-Draft RESTCONF Trace Context Headers September 2026 A RESTCONF server MAY support the Trace Context tracestate header as defined in [W3C-Trace-Context]. Note that while the W3C Trace Context specification mandates that tracing tools forwarding traces MUST propagate both traceparent and tracestate headers (Section 2.3 of [W3C-Trace-Context]), RESTCONF servers may act as trace endpoints rather than forwarding intermediaries. Since the tracestate header carries vendor-specific opaque data, its support is intentionally made optional to accommodate implementations that do not require vendor-specific trace context propagation. When interacting with these headers, the RESTCONF server follows the specifications of section 2.3 in [W3C-Trace-Context], therefore a RESTCONF server MAY also participate in a trace by modifying the traceparent header and the relevant vendor-specific parts of the tracestate header, for example when acting as an intermediary that contributes its own span to the distributed trace. 2.1. Error Handling It is NOT RECOMMENDED to reject an RPC because of Trace Context header values. If a server decides to reject an RPC because of Trace Context header values, the server MUST return a RESTCONF rpc-error with the following values: error-tag: operation-failed error-type: protocol error-severity: error Additionally, the error-info tag SHOULD contain relevant details about the error. Finally, the sx:structure defined in [I-D.draft-ietf-netconf-trace-ctx-extension] SHOULD be present in any error message from the server. 2.2. Trace Context Header Versioning The RESTCONF protocol extension described in this document refers to the [W3C-Trace-Context] Trace Context capability. The W3C traceparent and tracestate headers include the notion of versions. It would be desirable for a RESTCONF client to be able to discover the one or multiple versions of these headers supported by a server. Gagliano, et al. Expires 21 March 2027 [Page 4] Internet-Draft RESTCONF Trace Context Headers September 2026 [I-D.draft-ietf-netconf-trace-ctx-extension] defines a pair YANG modules that SHOULD be included in the YANG library per [RFC8525] of the RESTCONF server supporting the RESTCONF Trace Context extension that will refer to the headers' supported versions. 3. Security Considerations The traceparent and tracestate headers make it easier to track and correlate the flow of requests and their downstream effects on other systems. This information may be used by unauthorized entities to infer a map of a managed network. All advice mentioned in [W3C-Trace-Context] under Privacy Considerations and Security Considerations also applies to this document. The RESTCONF protocol has to (1) use a secure transport layer (for example, TLS [RFC8446] and QUIC [RFC9000]) and (2) use mutual authentication. 4. IANA Considerations This document has no IANA actions. 5. Acknowledgments The authors would like to acknowledge the valuable implementation feedback from Per Andersson. Many thanks to Raul Rivas Felix, Alexander Stoklasa, Luca Relandini, and Erwin Vrolijk for their help with the demo integrations. The help and support from Med Boucadair, Jean Quilbeuf, and Benoît Claise have also been invaluable to this work. 6. References 6.1. Normative References [I-D.draft-ietf-netconf-trace-ctx-extension] Gagliano, R., Rennerskog, C., Larsson, K., and J. Lindblad, "NETCONF Extension to support Trace Context propagation", Work in Progress, Internet-Draft, draft- ietf-netconf-trace-ctx-extension-08, 27 August 2026, . Gagliano, et al. Expires 21 March 2027 [Page 5] Internet-Draft RESTCONF Trace Context Headers September 2026 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [RFC8525] Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K., and R. Wilton, "YANG Library", RFC 8525, DOI 10.17487/RFC8525, March 2019, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . [W3C-Trace-Context] "W3C Recommendation on Trace Context", 23 November 2021, . 6.2. Informative References [RFC8309] Wu, Q., Liu, W., and A. Farrel, "Service Models Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018, . Appendix A. Example RESTCONF Calls All examples from Appendix B of [RFC8040] could be recreated in this section by adding the new header described in this document. We selected one example from that document as reference. Gagliano, et al. Expires 21 March 2027 [Page 6] Internet-Draft RESTCONF Trace Context Headers September 2026 A.1. Successful creation of New Data Resources (from Appendix B.2.1 of [RFC8040]) To create a new "artist" resource within the "library" resource, a client might send the following request: POST /restconf/data/example-jukebox:jukebox/library HTTP/1.1 Host: example.com Content-Type: application/yang-data+json traceparent: 00-405062f633be64ee006089dfca95a153-e021f9e263aad8e2-01 tracestate: vendorname1=opaqueValue1,vendorname2=opaqueValue2 { "example-jukebox:artist" : [ { "name" : "Foo Fighters" } ] } If the resource is created, the server might respond as follows: HTTP/1.1 201 Created Date: Thu, 26 Jan 2017 20:56:30 GMT Server: example-server Location: https://example.com/restconf/data/\ example-jukebox:jukebox/library/artist=Foo%20Fighters Last-Modified: Thu, 26 Jan 2017 20:56:30 GMT ETag: "b3830f23a4c" traceparent: 00-405062f633be64ee006089dfca95a153-e021f9e263aad8e2-01 tracestate: vendorname1=opaqueValue1,vendorname2=opaqueValue2 A.2. Unsuccessful creation of New Data Resources (from Appendix B.2.1 of [RFC8040]) [W3C-Trace-Context] specifies that a vendor MAY validate the tracestate header and that the processing rules SHOULD be followed. Example of a badly formatted tracestate header using the [RFC8040] example (Appendix B.2.1), in which a server receives a higher traceparent version 03: Gagliano, et al. Expires 21 March 2027 [Page 7] Internet-Draft RESTCONF Trace Context Headers September 2026 POST /restconf/data/example-jukebox:jukebox/library HTTP/1.1 Host: example.com Content-Type: application/yang-data+json traceparent: 03-405062f633be64ee006089dfca95a153-e021f9e263aad8e2-01 tracestate: SomeBadFormatHere { "example-jukebox:artist" : [ { "name" : "Foo Fighters" } ] } In this case, the server cannot parse the traceparent header and the response would be: HTTP/1.1 201 Created Date: Thu, 26 Jan 2017 20:56:30 GMT Server: example-server Location: https://example.com/restconf/data/\ example-jukebox:jukebox/library/artist=Foo%20Fighters Last-Modified: Thu, 26 Jan 2017 20:56:30 GMT ETag: "b3830f23a4c" traceparent: 00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-00 Note that the API call was successful, but the traceparent header is new with its trace-flags set to 0 and the tracestate header was removed. Appendix B. Changes (to be deleted by RFC Editor) B.1. From version 10 to 11 * Grammar cleanups B.2. From version 09 to 10 * Updated security considerations based on the Shepherd review. * Added Christian Rennerskog as a co-author. B.3. From version 08 to 09 * Explained MAY vs. W3C MUST for tracestate (OPSDir comment). * Mentioned "participating in a trace" (modifying headers) (OPSDir comment). Gagliano, et al. Expires 21 March 2027 [Page 8] Internet-Draft RESTCONF Trace Context Headers September 2026 * Fixed RFC 2119 boilerplate spacing to match the exact BCP 14 text. * Updated the document date. B.4. From version 07 to 08 * Improved the error-handling example to show the most common scenario based on the W3C standard. * Updated the dates. * Several edits based on OpsDir comments. * Added security considerations for QUIC and mutual authentication. B.5. From version 06 to 07 * More missing edits; updated dates. B.6. From version 05 to 06 * More missing edits. B.7. From version 04 to 05 * Removed unused references and terminology. B.8. From version 03 to 04 * Abbreviation change. * "ietf-trace-contex:trace-context-error-info" should have been a container in the example. B.9. From version 02 to 03 * Added abbreviations to the terminology. * Error messages are SHOULD to align with W3C handling. * Adapted the example to YANG module changes in the reference. B.10. From version 01 to 02 * Added WGLC comments. * Changed namespaces and module name. Gagliano, et al. Expires 21 March 2027 [Page 9] Internet-Draft RESTCONF Trace Context Headers September 2026 * Fixed an error in the error response. * Comments from Med Boucadair. * Removed markdown formatting of tracestate and traceparent, as the toolchain could not handle it properly. * Removed references to RFC 8341 (NACM), as the passage in the security considerations no longer needed it. * Rearranged the text in the introduction to include references in a more natural order. * Removed several references to "we" and replaced them with more neutral language. * Clarified that everything described as MUST requirements in this document applies only to RESTCONF implementations that support this document; other RESTCONF implementations do not need to care about it, as it is an optional extension. * Clarified that the YANG modules used by this document are defined by the sibling NETCONF document. * Lots of updated wording based on review feedback. B.11. From version 00 to -01 * Added Security Considerations. * Added Acknowledgments. * Added several normative references. * Added links to the latest document on GitHub. * Added a RESTCONF example for success and error. * Modified Error Handling to reflect better W3C alignment based on implementation feedback * Firmed up error handling and YANG-library to MUST-requirements B.12. From version 00 to draft-ietf-netconf-restconf-trace-ctx- headers-00 * Adopted by NETCONF WG Gagliano, et al. Expires 21 March 2027 [Page 10] Internet-Draft RESTCONF Trace Context Headers September 2026 * Moved repository to NETCONF WG * Changed build system to use martinthomson's excellent framework * Ran make fix-lint to remove white space at EOL etc. * Added this change note. No other content changes Authors' Addresses Roque Gagliano Cisco Systems Avenue des Uttins 5 CH-1180 Rolle Switzerland Email: rogaglia@cisco.com Christian Rennerskog Cisco Systems Email: crenners@cisco.com Kristian Larsson Deutsche Telekom AG Email: kll@dev.terastrm.net Jan Lindblad All For Eco Email: jan.lindblad+ietf@for.eco Gagliano, et al. Expires 21 March 2027 [Page 11]