Re: [quicwg/base-drafts] Document TCP RTO vs QUIC PTO (#3441)

Martin Thomson <notifications@github.com> Sun, 09 February 2020 22:37 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 0700A120052 for <quic-issues@ietfa.amsl.com>; Sun, 9 Feb 2020 14:37:32 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -7.999
X-Spam-Level:
X-Spam-Status: No, score=-7.999 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_IMAGE_ONLY_32=0.001, 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 ReCERDu3RPGQ for <quic-issues@ietfa.amsl.com>; Sun, 9 Feb 2020 14:37:30 -0800 (PST)
Received: from out-5.smtp.github.com (out-5.smtp.github.com [192.30.252.196]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 13D77120026 for <quic-issues@ietf.org>; Sun, 9 Feb 2020 14:37:30 -0800 (PST)
Received: from github-lowworker-39ac79b.ac4-iad.github.net (github-lowworker-39ac79b.ac4-iad.github.net [10.52.18.15]) by smtp.github.com (Postfix) with ESMTP id 0A9C19603CD for <quic-issues@ietf.org>; Sun, 9 Feb 2020 14:37:29 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1581287849; bh=OBo4ZyQZyDdfdzSoYaL96+KN7Ur8R7/C7M+rSZoMTQo=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=U7enaZ/u1VmF1iE8K7nV6Kn+URtS6m0vD3518MsvZl1ZvNxvvNCtjUDjKJiZchQAb wmiNapupOPDIVZXDyizK5kTH6zHR3ZjUoY0KHe2xWOssnz3CHSgW0lULyXsProPbGZ I3xDDwcC0fN0K9kbmku8q/8EaEqP7wvvUp4o5dZ8=
Date: Sun, 09 Feb 2020 14:37:29 -0800
From: Martin Thomson <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+AFTOJK35RAIEAWQGLXU5UMF4JW6CTEVBNHHCC7S66M@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/pull/3441/review/355639387@github.com>
In-Reply-To: <quicwg/base-drafts/pull/3441@github.com>
References: <quicwg/base-drafts/pull/3441@github.com>
Subject: Re: [quicwg/base-drafts] Document TCP RTO vs QUIC PTO (#3441)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5e4089a951d5_1c273fca0f8cd96c11384a"; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: martinthomson
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/FLyeyZU5V5HSobwLD383Zksy8Ys>
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: Sun, 09 Feb 2020 22:37:32 -0000

martinthomson commented on this pull request.



> @@ -228,6 +228,23 @@ QUIC endpoints measure the delay incurred between when a packet is received and
 when the corresponding acknowledgment is sent, allowing a peer to maintain a
 more accurate round-trip time estimate (see Section 13.2 of {{QUIC-TRANSPORT}}).
 
+### Probe Timeout Replaces RTO and TLP
+
+QUIC uses a probe timeout (see {{pto}}), with a timer based on TCP's
+RTO timeout.  QUIC PTO includes the peer's max_ack_delay in the calculation,
+instead of relying upon a fixed minimum RTO.  Unlike TCP's RTO, which collapses
+the congestion window upon expiry, QUIC does not change the congestion window
+and instead allows sending probe packets whenever the timer expires.  This is
+similar to TCP with F-RTO, but it does allow more packets to be sent when the
+congestion window was not fully utilized when the probe timeout expires. Though
+this is slightly more aggressive than TCP RTO, it's less aggressive than the
+congestion controller allowed.

Phrasing here suggests "than the congestion controller allows" or "than the congestion controller in TCP allowed" or something else.

-- 
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/pull/3441#pullrequestreview-355639387