Re: [quicwg/base-drafts] compensation of ack_delay is fragile against errors (#2060)

Kazuho Oku <> Fri, 30 November 2018 03:40 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 92024126C01 for <>; Thu, 29 Nov 2018 19:40:24 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -9.46
X-Spam-Status: No, score=-9.46 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.46, 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_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id 3stvsmdUzhqd for <>; Thu, 29 Nov 2018 19:40:23 -0800 (PST)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id EF603126BED for <>; Thu, 29 Nov 2018 19:40:22 -0800 (PST)
Date: Thu, 29 Nov 2018 19:40:21 -0800
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1543549221; bh=h4dUJSvfHZ1Spg23OXMWMyAJCEIXVoiNYjGP5G5oWUg=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=i/kyxMCdSKnGHjtB/u4tJZAnrQ6VtKQbVsIPgkNlvwOcGGPbmZyDgqShHtw3iERMk 11ol3M50/1q0xZG+iV0fBpCOhsL6pFPiXlluPwfelKdaUCzOkN+ra83UoZKMll4/QH BtWCby7ItAHyl2djvdDh8jgNOYuHjsUoRJABg/Lg=
From: Kazuho Oku <>
Reply-To: quicwg/base-drafts <>
To: quicwg/base-drafts <>
Cc: Subscribed <>
Message-ID: <quicwg/base-drafts/issues/2060/>
In-Reply-To: <quicwg/base-drafts/issues/>
References: <quicwg/base-drafts/issues/>
Subject: Re: [quicwg/base-drafts] compensation of ack_delay is fragile against errors (#2060)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5c00b125d2a78_4e63fd518ad45bc845586"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: kazuho
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
Archived-At: <>
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Fri, 30 Nov 2018 03:40:25 -0000

Thanks to @ianswett and @janaiyengar for all the conversation.

For connections that are advancing, I now think that what @ianswett says makes sense; capping the compensation to `max(ack_delay, max_ack_delay)` would not be an issue because ACK loss would not be happening too often in that case.

However, in case of a heavily congested network (or after disruption), capping the number means that we could have an unreasonably high SRTT. Seeing that is why I raised the issue.

Considering that, I think I might prefer @janaiyengar's suggestion to skip updating RTT information based on ACK frames with ack_delays that do not make sense.

You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub: