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

Marten Seemann <notifications@github.com> Tue, 09 April 2019 01:08 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 1A33F1201A1 for <quic-issues@ietfa.amsl.com>; Mon, 8 Apr 2019 18:08:53 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -8.001
X-Spam-Level:
X-Spam-Status: No, score=-8.001 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_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 ORWWYGLvdx6x for <quic-issues@ietfa.amsl.com>; Mon, 8 Apr 2019 18:08:50 -0700 (PDT)
Received: from out-2.smtp.github.com (out-2.smtp.github.com [192.30.252.193]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 8E5E6120181 for <quic-issues@ietf.org>; Mon, 8 Apr 2019 18:08:50 -0700 (PDT)
Date: Mon, 08 Apr 2019 18:08:49 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1554772129; bh=f/6krUZYeFBR8aO01+wGc87QW4QuF8kVRhj6tN9x+EU=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=Bgdk/LV69aS52dPg2eZ8TkjjVbnKBxVibc6/iuHSjgQiv8ES2HNGeaOJS9flcDtpc Fz5q2BoA3eAatDSY7yOMs7gBtf55lxiIWj81rBHydmNn63Hmx9Pi+nv2gPLfOn1FLc fisnQlXvZwCQxEaLOzyb36kirdpKW4VoPP9hCWBA=
From: Marten Seemann <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+0166e4ab0acd1ef9d63f9d82d64e6c11ee854e2b760143e492cf0000000118c3b2a192a169ce19787a10@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/issues/2568/481062758@github.com>
In-Reply-To: <quicwg/base-drafts/issues/2568@github.com>
References: <quicwg/base-drafts/issues/2568@github.com>
Subject: Re: [quicwg/base-drafts] Reduce restrictions on valid RTT samples (#2568)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5cabf0a16ce0b_4ba83f90896d45bc59527f"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: marten-seemann
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/8C4DhTys-tQ-bVyTpjZ9G-EPVwM>
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: Tue, 09 Apr 2019 01:08:53 -0000

It might not be a lot of additional load, but a lot of additional complexity. For example, what happens if the peer never acks an ack-eliciting packet (either because it was actually lost, or as part of an attack)? You then have to somehow clear that packet from your history. If you use the normal loss detection mechanism for it, you have to be careful not to take any congestion controller action upon loss of that packet. You also don't want to set any timers based on non-ack-eliciting packets, etc.

I never suggested sending out-of-date information, that would indeed be a bad idea. There's just no need to send an ACK at all if largest_acked is not ack-eliciting, and I'm suggesting that we recommend (mandate?) that peers don't do it. They should just wait until they receive the next ack-eliciting packet.

-- 
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/2568#issuecomment-481062758