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

janaiyengar <> Thu, 29 November 2018 04:11 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id EBB6E12F1A5 for <>; Wed, 28 Nov 2018 20:11:38 -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 SQVqa3cqYPZQ for <>; Wed, 28 Nov 2018 20:11:37 -0800 (PST)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 5AEB312777C for <>; Wed, 28 Nov 2018 20:11:37 -0800 (PST)
Date: Wed, 28 Nov 2018 20:11:36 -0800
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1543464696; bh=X4RaIZ9GK+kVXK/iHUpqydDkBtyjS/AFUL7++eRjVWc=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=biXryWz9dxgOYk3Gm1PB5B/xb1t44oDrC97JkAhSlaxC4vZvBAFhluXGBrdMRSHh0 586cMLpC73PabjXQ9rJaiRRD5aVO2HC2Avdu5gN7tUJQpGAMnWqmcM8VJiBIqXRPsi DTvI/sSf+NofQzj0Bpn6H0fBC1vSr6lDDLLQr1BY=
From: janaiyengar <>
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_5bff66f88d355_7e7c3fc2938d45c426386e"; 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
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: Thu, 29 Nov 2018 04:11:39 -0000

In general, I think having an inflated RTT is better than a lower than actual RTT, since inflated RTT leads to a less aggressive sender and smaller than actual RTT leads to a more aggressive sender.

Admittedly, it's possible for there to be error when latest_rtt - (inflated) ack_delay > min_rtt.  That's the error that I had considered an accepted cost of using ack_delay.

It's fair to ask what should we do about a receiver that we consider might have a bad clock... I wouldn't be opposed to ignoring ack_delay entirely for the rest of the connection... I wonder if there are counter cases that I'm missing though where this ends up being too aggressive. In general, the receiver should be rounding *down* when reporting delay, not up.

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