Re: [quicwg/base-drafts] Reduce restrictions on valid RTT samples (#2568)

ianswett <> Tue, 02 April 2019 19:03 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 0D2C5120075 for <>; Tue, 2 Apr 2019 12:03:06 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -8
X-Spam-Status: No, score=-8 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_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 CqC4Zub7sOwv for <>; Tue, 2 Apr 2019 12:03:04 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 2B98B12013E for <>; Tue, 2 Apr 2019 12:03:04 -0700 (PDT)
Date: Tue, 02 Apr 2019 12:03:02 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1554231782; bh=w5sC4HJsZjqG4EezMhOMon7GRGry1RMHMhnc5Lt6GWM=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=gSW/pFrJiwcX7lgdCI4wx5c7RKp444UvN1h3jnSOngcVCUzmbgn4bCgJ+dtTU6jnw +cRuqvnj0NXVmBSvL7z/dlS5z7eq2ezPtakWEwd6ldVwm8MtUbL7v/jveuFm25w3uD 3ViLuAZSTWEBefXN7Kxs90GTdTZV96y9I/rZDlhQ=
From: ianswett <>
Reply-To: quicwg/base-drafts <>
To: quicwg/base-drafts <>
Cc: Subscribed <>
Message-ID: <quicwg/base-drafts/issues/2568/>
In-Reply-To: <quicwg/base-drafts/issues/>
References: <quicwg/base-drafts/issues/>
Subject: Re: [quicwg/base-drafts] Reduce restrictions on valid RTT samples (#2568)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5ca3b1e6bd694_5bc43f8f6b2d45bc1519e2"; 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
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: Tue, 02 Apr 2019 19:03:06 -0000

@nibanks In both cases, I believe the current algorithm of limiting ack_delay to max_ack_delay makes perfect sense.  In the case of CPU load, RTT should show up in SRTT, RTTVar, or both.

In the second case, the text also advises including any expected timer delay in your advertised max_ack_delay.

This issue is about what happens if the largest acked is an ACK-only packet(not ack-eliciting).  In this case, we do ignore the RTT sample, and I do think that could turn out to be problematic, particularly in very asymmetric flows.

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