IETF Logo Mail Archive

Re: [quicwg/base-drafts] Ignoring ACK delay can result in wrong RTT calculations (#3350)

Jana Iyengar <notifications@github.com> Wed, 15 January 2020 22:26 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 9F1CB12010C for <quic-issues@ietfa.amsl.com>; Wed, 15 Jan 2020 14:26:45 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.382
X-Spam-Level:
X-Spam-Status: No, score=-6.382 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_24=1.618, 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 Oe7D8a6MKt_z for <quic-issues@ietfa.amsl.com>; Wed, 15 Jan 2020 14:26:44 -0800 (PST)
Received: from out-15.smtp.github.com (out-15.smtp.github.com [192.30.254.198]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 571B1120992 for <quic-issues@ietf.org>; Wed, 15 Jan 2020 14:26:44 -0800 (PST)
Received: from github-lowworker-9bcb4a1.ac4-iad.github.net (github-lowworker-9bcb4a1.ac4-iad.github.net [10.52.25.84]) by smtp.github.com (Postfix) with ESMTP id 13D1326163D for <quic-issues@ietf.org>; Wed, 15 Jan 2020 14:26:44 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1579127204; bh=aR95QV0G0l1A13in4a9Ucobb6mphUqGl03hFoJXRD4k=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=2T2NeSvHXVhYVIoYCGWY5ahIraui3F7rib27lEoMzU0OIk+DYfrp4y5Bd9e9F/x39 /YWTIR+KK3veFA412Yzacd1WsXvQr/0lJQ091ndtKORXg6/71/sk54Yn0FOZ/05hX5 vM16+8iEHKR5cyKlVvcukGgA7O8X8ASur4Zkji68=
Date: Wed, 15 Jan 2020 14:26:43 -0800
From: Jana Iyengar <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+AFTOJK7K2D4E2TU25QEP3BN4FTCCHEVBNHHCBTTN5I@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/issues/3350/574886270@github.com>
In-Reply-To: <quicwg/base-drafts/issues/3350@github.com>
References: <quicwg/base-drafts/issues/3350@github.com>
Subject: Re: [quicwg/base-drafts] Ignoring ACK delay can result in wrong RTT calculations (#3350)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5e1f91a3b6a2f_28c33f9862acd96c2832be"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: janaiyengar
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/Vq6tKmJFdDrqAR4R_w76hkQo-EQ>
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: Wed, 15 Jan 2020 22:26:46 -0000

Our principle was that an endpoint should not use an RTT sample that is smaller than any RTT it has _directly_ measured.

What is in the draft, as Ian pointed out, is the conservative approach that protects the endpoint from poor reporting of ack delay. A poor min_rtt will lead you astray but that is because the endpoint does not have direct observation of a smaller RTT. Until it does, it is better to be conservative.

-- 
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/3350#issuecomment-574886270

v2.23.0 | Report a Bug | By Email