MASQUE L. Pardue Internet-Draft Cloudflare Intended status: Standards Track 13 July 2021 Expires: 14 January 2022 HTTP Datagram Prioritization draft-pardue-masque-dgram-priority-00 Abstract Application protocols using the QUIC transport protocol rely on streams, and optionally the DATAGRAM extension, to carry application data. Streams and datagrams can be multiplexed but QUIC provides no interoperable prioritization scheme or signaling mechanism itself. The HTTP Extensible Prioritization scheme describes how to prioritize streams in HTTP/2 and HTTP/3. This document adopts the scheme to support HTTP datagrams. Note tho Readers _RFC EDITOR: please remove this section before publication_ Source code and issues list for this draft can be found at https://github.com/LPardue/draft-pardue-masque-dgram-priority (https://github.com/LPardue/draft-pardue-masque-dgram-priority). 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 14 January 2022. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. Pardue Expires 14 January 2022 [Page 1] Internet-Draft HTTP Datagram Prioritization July 2021 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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3 2. Signalling Datagram Priority . . . . . . . . . . . . . . . . 3 2.1. Datagram Urgency . . . . . . . . . . . . . . . . . . . . 3 3. Scheduling guidance . . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 6.2. Informative References . . . . . . . . . . . . . . . . . 5 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction Application protocols using the QUIC transport protocol [QUIC] rely on streams, and optionally the DATAGRAM extension [DATAGRAM], to carry application data. Streams and datagrams can be multiplexed but QUIC provides no interoperable prioritization scheme or signaling mechanism itself. The HTTP Extensible Prioritization scheme [I-D.ietf-httpbis-priority] describes how to prioritize streams in HTTP/2 and HTTP/3. This document adopts the scheme to support HTTP datagrams [I-D.ietf-masque-h3-datagram]. The Extensible Priorities scheme for HTTP describes how clients can send priority signals related to requests in order to suggest how a server allocates resources to serving responses. When the protocol is HTTP/2, responses are carried on streams. When the protocol is HTTP/3, responses are carries on QUIC streams. Pardue Expires 14 January 2022 [Page 2] Internet-Draft HTTP Datagram Prioritization July 2021 While QUIC streams support multiplexing natively via use of a stream identifier, the QUIC DATAGRAM extension does not provide any such identifier. [I-D.ietf-masque-h3-datagram] defines a set of identifiers that can be controlled and accessed by HTTP. When the protocol is HTTP/2 or HTTP/3, one identifer relates to a request stream. A second, optional, identifer relates to an abstract context. [I-D.ietf-masque-h3-datagram] does not define any means for multiplexed datagram prioritization. This document describes how the Extensible Priorities scheme applies to HTTP datagrams. Signals sent by clients related to requests can also be considered input to server scheduling decisions regarding HTTP datagrams. 1.1. Notational Conventions 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. Signalling Datagram Priority The Extensible Prioritization scheme [I-D.ietf-httpbis-priority] provides a framework for communicating and acting upon priority parameters. It defines the urgency and incremental parameters and provides guidance to implementers about how to act on these parameters, in combination with other inputs, to make resource allocation and scheduling choices. Urgency communicates the client- view of request importance and incremental communicates how the client intends to process response data as it arrives. Parameters are communicated in HTTP headers or version-specific frames. Omitting a priority signal indicates to the server to apply default priorities. The core scheme is extensible, new parameters can be defined to augment the base ones. 2.1. Datagram Urgency The datagram-urgency parameter ("du") takes an integer between 0 and 7, in descending order of priority. This range matches the base urgency ("u") paramenter range. The value is encoded as an sf-integer. The default value is 3. Pardue Expires 14 January 2022 [Page 3] Internet-Draft HTTP Datagram Prioritization July 2021 This parameter indicates the sender's recommendation, based on the expectation that the server would transmit HTTP datagrams in the order of their urgency values if possible. The smaller the value, the higher the precedence. The following example shows a request for a CSS file with the urgency set to "0", any associated datagrams will be delivered with the lower urgency of "2": :method = GET :scheme = https :authority = example.net :path = /style.css priority = u=0, du=2 3. Scheduling guidance TBD - bikeshed 4. Security Considerations TBD 5. IANA Considerations TBD 6. References 6.1. Normative References [DATAGRAM] Pauly, T., Kinnear, E., and D. Schinazi, "An Unreliable Datagram Extension to QUIC", Work in Progress, Internet- Draft, draft-ietf-quic-datagram-02, 16 February 2021, . [I-D.ietf-httpbis-priority] Oku, K. and L. Pardue, "Extensible Prioritization Scheme for HTTP", Work in Progress, Internet-Draft, draft-ietf- httpbis-priority-03, 11 January 2021, . Pardue Expires 14 January 2022 [Page 4] Internet-Draft HTTP Datagram Prioritization July 2021 [I-D.ietf-masque-h3-datagram] Schinazi, D. and L. Pardue, "Using QUIC Datagrams with HTTP/3", Work in Progress, Internet-Draft, draft-ietf- masque-h3-datagram-02, 26 May 2021, . [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, . 6.2. Informative References [QUIC] 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. Acknowledgements This document is inspired by discussion by many people across HTTP, QUIC and MASQUE WGs. Author's Address Lucas Pardue Cloudflare Email: lucaspardue.24.7@gmail.com Pardue Expires 14 January 2022 [Page 5]