[quicwg/base-drafts] In Initial and Handshake packets, knowing undecryptable packets could accelerate handshakes with loss (#2894)

ianswett <notifications@github.com> Sat, 13 July 2019 11:00 UTC

Return-Path: <noreply@github.com>
X-Original-To: quic-issues@ietfa.amsl.com
Delivered-To: quic-issues@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id BAB7F120103 for <quic-issues@ietfa.amsl.com>; Sat, 13 Jul 2019 04:00:05 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -8
X-Spam-Level:
X-Spam-Status: No, score=-8 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=github.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id r54aM-pRrpV0 for <quic-issues@ietfa.amsl.com>; Sat, 13 Jul 2019 04:00:03 -0700 (PDT)
Received: from out-19.smtp.github.com (out-19.smtp.github.com [192.30.252.202]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 0A7B7120090 for <quic-issues@ietf.org>; Sat, 13 Jul 2019 04:00:02 -0700 (PDT)
Date: Sat, 13 Jul 2019 04:00:01 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1563015601; bh=ymAdbSxQJtKs+CmYofB//sC7vRJvpI8FlYaeZ2aEbnA=; h=Date:From:Reply-To:To:Cc:Subject:List-ID:List-Archive:List-Post: List-Unsubscribe:From; b=l5KtmxOc9lmfrokmfZdpgxQd5Y2QfhYLB/HRh1xwqefDsywKTyX6rSPbP9hshmtPA 6LQKVpwRt/zEr+XQpR7kA823+anuMOcSIVl3YBFljsJCTJ/jvudsiGoYl0JpyQ2PLA D0cEYPCZ/N+FimGmj3WR3y0F+7FluvifDQcEwAg0=
From: ianswett <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+AFTOJK5JGWXHJ27QNYVUHNF3G3WDDEVBNHHBXYFAF4@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/issues/2894@github.com>
Subject: [quicwg/base-drafts] In Initial and Handshake packets, knowing undecryptable packets could accelerate handshakes with loss (#2894)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5d29b9b16861a_2fe43ff6a96cd95c10706d4"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: ianswett
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
X-GitHub-Recipient-Address: quic-issues@ietf.org
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic-issues/EO_xHapdHEMXO9Xr6dh72ieOvSc>
X-BeenThere: quic-issues@ietf.org
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <quic-issues.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic-issues/>
List-Post: <mailto:quic-issues@ietf.org>
List-Help: <mailto:quic-issues-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sat, 13 Jul 2019 11:00:06 -0000

Currently Initial and Handshake packets include ACK frames, but the ack_delay is now unused when ACK frames are sent at those encryption levels.  We still have the ack_delay field, it just has no meaning and SHOULD be set to 0.
https://tools.ietf.org/html/draft-ietf-quic-transport-22#section-19.3

We could use the field to represent the number of undecryptable packets.  If we also changed the ack frame to allow 0 ack ranges(see below), then we could indicate a packet was received, but it was undecryptable early in the handshake.

This provides a richer signal than the previously proposed EMPTY_ACK frame, but should be optional to support in my opinion.  ie: The handshake will never rely on this field.

I expect this could be very useful for debugging as well.

Current Ack Frame format:

  0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Largest Acknowledged (i)                ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          ACK Delay (i)                      ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       ACK Range Count (i)                   ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       First ACK Range (i)                   ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          ACK Ranges (*)                     ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          [ECN Counts]                       ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


Proposed ACK frame format(so 0 ranges can be represented):
  0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     ACK Delay / Undecryptable Packets (i)            ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       ACK Range Count (i)                   ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          ACK Ranges (*)                     ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          [ECN Counts]                       ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

I thought removing Largest Acknowledged would be referenced elsewhere in the draft, but I can't find it anywhere else in transport, so that's not an issue.

If this seems like an idea people want to punt to v2, I'm fine with that, but I think it's worth considering.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/issues/2894