Fwd: New Version Notification for draft-duke-httpbis-quic-version-alt-svc-00.txt

Hello HTTP WG,


We published draft-duke-httpbis-quic-version-alt-svc [0], please see the
forwarded email for more details.

To jog your memories, HTTP/3 [1] chose the "h3" ALPN name and linked it to
QUICv1. This value is used for Alt-Svc adverts and the real ALPN extension
in a QUIC handshake. HTTP/3 punted on defining how endpoints might agree on
the use of other QUIC versions.

Over in the QUIC WG we have continued to think about transport-level
version negotiation, and something that has come up a few times is the
effect on HTTP/3. While different solutions have been thrown around, the
common set of goals appears to be 1) avoid having to support QUIC v1
forever 2) avoid a version-negotiation-triggered-roundtrip.

To address these goals, draft-duke-httpbis-quic-version-alt-svc opts to
define a new "quicv" Alt-Svc parameter that contains a preference ordered
list of QUIC versions supported by the alternative. Clients that understand
the parameter stand a better chance of selecting a more desirable QUIC
version without triggering a negotiation.

Using an Alt-Svc parameter for QUIC version hinting isn't particularly
novel; older revisions of HTTP/3 [2] [3] tried different styles until the
matter was punted. However, given how QUIC version matters are evolving,
and that the HTTP WG has RFC 7838bis open currently, now seems like a good
time to consider formalizing a parameter and lock down the format.

Cheers,

Lucas

On behalf of the draft authors

[0] -
https://datatracker.ietf.org/doc/html/draft-duke-httpbis-quic-version-alt-svc

[1] - https://tools.ietf.org/html/draft-ietf-quic-http-34
[2] - https://datatracker.ietf.org/doc/html/draft-ietf-quic-http-00
#section-2

[3] -
https://datatracker.ietf.org/doc/html/draft-ietf-quic-http-02#section-2.1



---------- Forwarded message ---------
From: <internet-drafts@ietf.org>
Date: Fri, Mar 4, 2022 at 9:04 PM
Subject: New Version Notification for
draft-duke-httpbis-quic-version-alt-svc-00.txt
To: Lucas Pardue <lucaspardue.24.7@gmail.com>, Martin Duke <
martin.h.duke@gmail.com>



A new version of I-D, draft-duke-httpbis-quic-version-alt-svc-00.txt
has been successfully submitted by Martin Duke and posted to the
IETF repository.

Name:           draft-duke-httpbis-quic-version-alt-svc
Revision:       00
Title:          An Alt-Svc Parameter for QUIC Versions
Document date:  2022-03-04
Group:          Individual Submission
Pages:          6
URL:
https://www.ietf.org/archive/id/draft-duke-httpbis-quic-version-alt-svc-00.txt
Status:
https://datatracker.ietf.org/doc/draft-duke-httpbis-quic-version-alt-svc/
Html:
https://www.ietf.org/archive/id/draft-duke-httpbis-quic-version-alt-svc-00.html
Htmlized:
https://datatracker.ietf.org/doc/html/draft-duke-httpbis-quic-version-alt-svc


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.




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