IETF Logo Mail Archive

Re: [quicwg/base-drafts] Add note about frequent RTT estimates (#2340)

ianswett <notifications@github.com> Thu, 17 January 2019 21:49 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 CDC6E12958B for <quic-issues@ietfa.amsl.com>; Thu, 17 Jan 2019 13:49:17 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -12.552
X-Spam-Level:
X-Spam-Status: No, score=-12.552 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-4.553, 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_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 Fu3gsQbHrSdY for <quic-issues@ietfa.amsl.com>; Thu, 17 Jan 2019 13:49:15 -0800 (PST)
Received: from out-4.smtp.github.com (out-4.smtp.github.com [192.30.252.195]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id B7D32130EE9 for <quic-issues@ietf.org>; Thu, 17 Jan 2019 13:49:15 -0800 (PST)
Date: Thu, 17 Jan 2019 13:49:14 -0800
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1547761754; bh=q+16D54i4xyNpmWu68dttvEQS57qxOr00vpPlKDEu2Q=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=uJ720LtbBmupi02Y+W9YQ+LS8i8f7mCm6eSI6M2pzA4Kkeny+bKji13/07KaTERRm nbNSRXtvLo2D/QNsmyXJGdXwCAIATyyl52dLF+Ne6g0nLZAFZX9JWc7Ij8gf4dXDM4 1ZGKgrC4DkprZof58dMKoKiA1fCNQwgd5QEXiTo0=
From: ianswett <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+0166e4ab28fb759aef1045456f29c7a05e51a2fe841bd50292cf000000011858ba5a92a169ce17d8cc13@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/pull/2340/review/193858610@github.com>
In-Reply-To: <quicwg/base-drafts/pull/2340@github.com>
References: <quicwg/base-drafts/pull/2340@github.com>
Subject: Re: [quicwg/base-drafts] Add note about frequent RTT estimates (#2340)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5c40f85a9e7db_31733f7f0c4d45c010844b"; 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/ac58BD-QV2Q44UgKfY9EDQa-H8E>
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: Thu, 17 Jan 2019 21:49:18 -0000

ianswett commented on this pull request.



> @@ -289,8 +289,14 @@ be subtracted from the RTT as long as the result is larger than the min_rtt.
 If the result is smaller than the min_rtt, the RTT should be used, but the
 ack delay field should be ignored.
 
-Like TCP, QUIC calculates both smoothed RTT and RTT variance similar to those
-specified in {{?RFC6298}}.
+A sender calculates both smoothed RTT and RTT variance similar to those
+specified in {{?RFC6298}}, see {{on-ack-received}}.
+
+A sender will commonly receive ACK frames that acknowledge larger packet numbers
+than before.  A sender might therefore take multiple samples per RTT (see

Suggestion: replace "A sender..." on with: "When multiple samples are generated within an RTT, the smoothed RTT may retain inadequate RTT history, as suggested in {{?RFC6298}}.  Utilizing multiple RTT samples per RTT in smoothed RTT and RTT variance in a different way is currently an open research question."

-- 
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/2340#pullrequestreview-193858610

v2.23.0 | Report a Bug | By Email