An Alt-Svc Parameter for QUIC Versions
draft-duke-httpbis-quic-version-alt-svc-00
This document is an Internet-Draft (I-D).
Anyone may submit an I-D to the IETF.
This I-D is not endorsed by the IETF and has no formal standing in the
IETF standards process.
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
|
|
|---|---|---|---|
| Authors | Martin Duke , Lucas Pardue | ||
| Last updated | 2022-03-04 | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-duke-httpbis-quic-version-alt-svc-00
HTTP M. Duke
Internet-Draft Google
Intended status: Standards Track L. Pardue
Expires: 5 September 2022 Cloudflare
4 March 2022
An Alt-Svc Parameter for QUIC Versions
draft-duke-httpbis-quic-version-alt-svc-00
Abstract
HTTP Alternative Services (Alt-Svc) describes how one origin's
resource can be accessed via a different protocol/host/port
combination. Alternatives are advertised by servers using the Alt-
Svc header field or the ALTSVC frame. This includes a protocol name,
which reuses Application Layer Protocol Negotiation (ALPN)
codepoints. The "h3" codepoint indicates the availability of HTTP/3.
A client that uses such an alternative first makes a QUIC connection.
However, without a priori knowledge of which QUIC version to use,
clients might incur a round-trip latency penalty to complete QUIC
version negotiation, or forfeit desirable properties of a QUIC
version. This document specifies a new Alt-Svc parameter that
specifies alternative supported QUIC versions, which substantially
reduces the chance of this penalty.
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://martinduke.github.io/quic-version-alt-svc-parameter/draft-
duke-httpbis-quic-version-alt-svc.html. Status information for this
document may be found at https://datatracker.ietf.org/doc/draft-duke-
httpbis-quic-version-alt-svc/.
Discussion of this document takes place on the HTTP Working Group
mailing list (mailto: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/martinduke/quic-version-alt-svc-parameter.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Duke & Pardue Expires 5 September 2022 [Page 1]
Internet-Draft An Alt-Svc Parameter for QUIC Versions March 2022
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 5 September 2022.
Copyright Notice
Copyright (c) 2022 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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. The quicv Parameter . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 5
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
HTTP Alternative Services (Alt-Svc) [ALTSVC] describes how one
origin's resource can be accessed via a different protocol/host/port
combination. Alternatives are advertised by servers using the Alt-
Svc header field or the ALTSVC frame. This includes a protocol name,
which reuses codepoints from the Application-Layer Protocol
Negotiation (ALPN) TLS extension [RFC7301]. Servers can advertise
multiple alternatives, in which case the order reflects the server's
Duke & Pardue Expires 5 September 2022 [Page 2]
Internet-Draft An Alt-Svc Parameter for QUIC Versions March 2022
preferences (the first value being the most preferred).
Clients can ignore alternative services, or pick one at their
discretion. A client might use any details from the advertisement,
in addition to out of band information, in determining if an
alternative is suitable or preferred.
While ALPN was originally intend to allow multiple applications to
utilize TLS or DTLS on the same IP address and TCP or UDP port, ALPN
can also usefully identify the transport in an Alt-Svc context. The
"h3" ALPN codepoint informs the client that it can use HTTP/3
[I-D.ietf-quic-http] for access, which in turn requires the QUIC
transport protocol [RFC8999].
QUIC is versioned. A client and server that both support a QUIC
version can, through a negotiation process, generally agree on that
version in no more than one round-trip. However, to avoid that
penalty clients might use the most commonly deployed QUIC version
(e.g. version 1 [RFC9000] at the time of writing), rather than the
version with the most desirable properties for the client's use case.
To avoid the round-trip, one solution would be to register unique
ALPN codepoints for each HTTP/3 and QUIC version combination.
However, this might complicate deployment of new versions and
deprecation of old ones: architecturally, an application should
provide its ALPN to its QUIC implementation. In this case, fully
deploying a new version in that implementation would require updating
all applications that use it.
Instead, this document specifies an Alt-Svc parameter that lists the
QUIC versions available to serve the resource. Clients that do not
understand this parameter will ignore it. They might default to the
most likely version, and/or incur a round-trip penalty in the event
of a mismatch. Clients that do process the parameter will connect
successfully using the most desirable version with high probability.
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.
This document uses the Augmented BNF defined in [RFC5234] and imports
parameter from Section 3 of [ALTSVC].
Duke & Pardue Expires 5 September 2022 [Page 3]
Internet-Draft An Alt-Svc Parameter for QUIC Versions March 2022
3. The quicv Parameter
This document specifies the "quicv" Alt-Svc parameter, which lists
the QUIC versions supported by an endpoint, using the hexadecimal
representation of the version field in a QUIC long header, as
indicated in [RFC8999]. Senders MAY omit leading zeroes from version
numbers.
quicv = version-list
version-list = DQUOTE version 1*( OWS, "," OWS version-number) DQUOTE
version = 1*8 HEXDIG; hex-encoded QUIC version
Examples:
Alt-Svc: h3=":443"; quicv="1"
Alt-Svc: h3=":443"; quicv="709a50c4,1"
Alt-Svc: h3=":443"; quicv="709a50c4,1", h3=":1001"; quicv="709a50c4"
The order of entries in version-list reflects the server's preference
(with the first value being the most preferred alternative).
Note that the quicv parameter applies to a single associated entry in
the Alt-Svc list. Servers MUST NOT provide a quicv parameter to an
entry containing ALPN codepoint that does not potentially utilize
QUIC.
If the Alt-Svc information resolves to a server pool that
inconsistently supports different QUIC versions, the parameter SHOULD
only advertise versions that are supported throughout the pool.
4. Security Considerations
This document inherits the security considerations of [ALTSVC],
especially the implications of "Changing Protocols" in Section 9.3.
There are few protocol properties guaranteed to hold across all QUIC
versions, so endpoints should be aware what capabilities are
intrinsic to the QUIC versions they are advertising.
This parameter reveals capabilities of the described server, but this
information is already available by inducing the server to generate a
QUIC version negotiation packet.
5. IANA Considerations
Please add this entry ot the HTTP Alt-Svc Parameter Registry:
Alt-Svc Parameter: quicv
Duke & Pardue Expires 5 September 2022 [Page 4]
Internet-Draft An Alt-Svc Parameter for QUIC Versions March 2022
Reference: This document
6. References
6.1. Normative References
[ALTSVC] Bishop, M. and M. Thomson, "HTTP Alternative Services",
Work in Progress, Internet-Draft, draft-ietf-httpbis-
rfc7838bis-00, 31 August 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
rfc7838bis-00>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/rfc/rfc5234>.
6.2. Informative References
[RFC7301] 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, <https://www.rfc-editor.org/rfc/rfc7301>.
[I-D.ietf-quic-http]
Bishop, M., "Hypertext Transfer Protocol Version 3
(HTTP/3)", Work in Progress, Internet-Draft, draft-ietf-
quic-http-34, 2 February 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-quic-
http-34>.
[RFC8999] Thomson, M., "Version-Independent Properties of QUIC",
RFC 8999, DOI 10.17487/RFC8999, May 2021,
<https://www.rfc-editor.org/rfc/rfc8999>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/rfc/rfc9000>.
Duke & Pardue Expires 5 September 2022 [Page 5]
Internet-Draft An Alt-Svc Parameter for QUIC Versions March 2022
Acknowledgments
TODO acknowledge.
Authors' Addresses
Martin Duke
Google
Email: martin.h.duke@gmail.com
Lucas Pardue
Cloudflare
Email: lucaspardue.24.7@gmail.com
Duke & Pardue Expires 5 September 2022 [Page 6]