httpbis K. Oku Internet-Draft Fastly Intended status: Standards Track L. Pardue Expires: 28 December 2026 Cloudflare J. Iyengar Netflix 26 June 2026 HTTP/3 over QMux draft-kazuho-httpbis-http3-over-qmux-00 Abstract This document specifies how to use HTTP/3 over QMux. Discussion Venues This note is to be removed before publishing as an RFC. Discussion of this document takes place on the HTTP Working Group mailing list (ietf-http-wg@w3.org), which is archived at https://lists.w3.org/Archives/Public/ietf-http-wg/. Source for this draft and an issue tracker can be found at https://github.com/kazuho/draft-kazuho-httpbis-http3-on-streams. 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 28 December 2026. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Oku, et al. Expires 28 December 2026 [Page 1] Internet-Draft HTTP/3 over QMux June 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. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 3. The Protocol . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. QPACK Considerations . . . . . . . . . . . . . . . . . . 3 4. Starting HTTP/3 over QMux . . . . . . . . . . . . . . . . . . 3 4.1. Draft Version Identification . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 5 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction As of 2026, HTTP/2 [HTTP/2] remains the most widely used version of HTTP across the Internet, although the adoption rate of HTTP/3 [HTTP/3] is increasing rapidly. HTTP/3 has several advantages over HTTP/2, primarily due to its use of QUIC [QUIC] as the transport layer protocol, which provides features like stream multiplexing without head-of-line blocking and low-latency connection establishment. However, given that QUIC's availability and accessibility are not as universal as TCP's, a complete migration of all HTTP/2 traffic to QUIC-based HTTP/3 seems unlikely. This situation necessitates HTTP deployments to support both transport protocols and their respective HTTP versions for the foreseeable future. Maintaining dual support is costly, as the two protocols differ in many aspects such as wire-encoding, flow control and stream multiplexing machinery, and HTTP header compression. Extensions operating at the HTTP wire encoding layer must be developed and Oku, et al. Expires 28 December 2026 [Page 2] Internet-Draft HTTP/3 over QMux June 2026 implemented for both HTTP/2 and HTTP/3, and both protocol stacks require ongoing maintenance to address bugs, performance issues, and vulnerabilities. To address this redundancy, this specification defines the method of running HTTP/3 over QMux version 1 [QMUX], which enables the operation of HTTP/3 over TCP and TLS without any modifications. Consequently, design, implementation, and maintenance efforts can concentrate on a single HTTP version: HTTP/3. 2. Conventions and Definitions 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. 3. The Protocol HTTP/3 functions over QUIC version 1, employing the set of operations (i.e., API) defined in Section 2.4 and Section 5.3 of [QUIC]. HTTP/3 over QMux version 1 utilizes the same set of operations that are available in QMux. 3.1. QPACK Considerations HTTP/3 uses QPACK [QPACK] for field compression as described in Section 4.2.1 of [HTTP/3]. QPACK is designed to operate over QUIC version 1, which does not provide guarantees of global ordering across streams. It provides flexibility for implementations to balance resilience against head-of-line blocking and optimal compression ratio (Section 2.1.2 of [QPACK]). QMux version 1 operates on top of a transport layer that guarantees in-order delivery and guarantees global ordering across streams. When HTTP/3 over QMux is used, QPACK decoders will never be blocked due to packet losses. To improve compression efficiency, QPACK encoders can reference a dynamic table entry as soon as the entry is emitted to the underlying transport, regardless of the SETTINGS_QPACK_BLOCKED_STREAMS value advertised by the peer. 4. Starting HTTP/3 over QMux HTTP/3 over QMux version 1 can be used for “https” URI schemes defined in Section 4.2 of [HTTP] with the same default port number as HTTP/1.1 [HTTP/1.1]. Oku, et al. Expires 28 December 2026 [Page 3] Internet-Draft HTTP/3 over QMux June 2026 When a client uses HTTP/3 over QMux for an "https" URI scheme, it uses TLS [TLS] with ALPN [ALPN] as described in Section 8 of [QMUX]. The ALPN ID for the final, published RFC is "h3qx". Until such an RFC exists, implementations MUST NOT identify themselves using this string. 4.1. Draft Version Identification [[RFC editor: please remove this section before publication.]] This draft describes HTTP/3 over draft version of QMux. In order to support interoperability over revisions, HTTP/3 over QMux drafts define an ALPN ID that captures both this document revision and the QMux revision in use. The ALPN ID defined by this draft revision is "h3qx-01", which represents HTTP/3 over draft-ietf-quic-qmux-01. 5. Security Considerations The security considerations from Section 10 of [HTTP/3] and Section 12 of [QMUX] apply. 6. IANA Considerations If this document is adopted and published as an RFC, it will have an action to create a new registration for the identification of HTTP/3 over QMux version 1 in the "TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry established in [ALPN]. 7. References 7.1. Normative References [ALPN] Friedl, S., Popov, A., Langley, A., and E. Stephan, "Transport Layer Security (TLS) Application-Layer Protocol Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, July 2014, . [HTTP] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP Semantics", STD 97, RFC 9110, DOI 10.17487/RFC9110, June 2022, . [HTTP/1.1] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112, June 2022, . Oku, et al. Expires 28 December 2026 [Page 4] Internet-Draft HTTP/3 over QMux June 2026 [HTTP/3] Bishop, M., Ed., "HTTP/3", RFC 9114, DOI 10.17487/RFC9114, June 2022, . [QMUX] Oku, K., Pardue, L., Iyengar, J., and E. Kinnear, "QMux", Work in Progress, Internet-Draft, draft-ietf-quic-qmux-01, 1 April 2026, . [QPACK] Krasic, C., Bishop, M., and A. Frindell, Ed., "QPACK: Field Compression for HTTP/3", RFC 9204, DOI 10.17487/RFC9204, June 2022, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [TLS] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . 7.2. Informative References [HTTP/2] Thomson, M., Ed. and C. Benfield, Ed., "HTTP/2", RFC 9113, DOI 10.17487/RFC9113, June 2022, . [QUIC] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . Acknowledgments TODO acknowledge. Authors' Addresses Kazuho Oku Fastly Email: kazuhooku@gmail.com Oku, et al. Expires 28 December 2026 [Page 5] Internet-Draft HTTP/3 over QMux June 2026 Lucas Pardue Cloudflare Email: lucas@lucaspardue.com Jana Iyengar Netflix Email: jri.ietf@gmail.com Oku, et al. 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