[quicwg/base-drafts] Change max_packet_size to max_datagram_size (#3471)
Kazuho Oku <notifications@github.com> Thu, 20 February 2020 14:12 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 319E012003E for <quic-issues@ietfa.amsl.com>; Thu, 20 Feb 2020 06:12:25 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -7.999
X-Spam-Level:
X-Spam-Status: No, score=-7.999 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_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 TnXbeElmrtmY for <quic-issues@ietfa.amsl.com>; Thu, 20 Feb 2020 06:12:23 -0800 (PST)
Received: from out-3.smtp.github.com (out-3.smtp.github.com [192.30.252.194]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id B990A1200D5 for <quic-issues@ietf.org>; Thu, 20 Feb 2020 06:12:23 -0800 (PST)
Date: Thu, 20 Feb 2020 06:12:22 -0800
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1582207942; bh=zhr0ivQm9fcTQDtBsK9jWIVHAeKDz++1hOBZ2rq2Vjw=; h=Date:From:Reply-To:To:Cc:Subject:List-ID:List-Archive:List-Post: List-Unsubscribe:From; b=xhLGQRyRw84j1EnY0sQxYqe3cUpw8HfW1Iiqw1h1W42gCycxyb9CFpKvUgTbanJv3 J6jjMWe+8MYsYsZwGPX2Y8Qo7wRCwaa7RVOSoPvvcsS9T+a2IaZdTX/8Bd1Zs0ArQC OvBRGJK3WE9/rOHrin6UvNMTDdqgRrON4lu7egTA=
From: Kazuho Oku <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+AFTOJK3FAH4YUKCXPRO2PQ54LPDENEVBNHHCDYABKU@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/issues/3471@github.com>
Subject: [quicwg/base-drafts] Change max_packet_size to max_datagram_size (#3471)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5e4e93c65f75f_10f53ff74b4cd95c14406a"; 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
X-GitHub-Recipient-Address: quic-issues@ietf.org
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic-issues/G2d7t8LIKmBWSSnL21iTVEme5Fs>
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: Thu, 20 Feb 2020 14:12:25 -0000
At the moment, the max_packet_size Transport Parameter is a size limit of "a packet," and we seem to interpret that it means "a QUIC packet." I am not sure if that has been our intent. IIUC, the reason we have this TP is to tell the peer the maximum size of a "UDP datagram" that the endpoint can handle. Not the maximum size of a "QUIC packet." The problem with having this limit being defined at QUIC packet-level is that it allows the sender to send a coalesced packet that consists of multiple QUIC packets, each of them consuming max_packet_size bytes. For example, when responding to a client-sent Initial, a server is allowed to send a coalesced packet containing one Initial, one Handshake, one 1-RTT packet, each of them in full size, and expect the client to not drop the coalesced packet, assuming that the network can handle jumbo packets<sup>1</sup>. This means that a QUIC stack needs to be prepared of handling UDP datagrams at most `3 * max_packet_size` bytes. I do not think we would want to do that. Therefore, the proposal is to change the definition of the TP from max_packet_size to max_datagram_size. As an alternative, we can change it to max_ip_packet_size, but considering the BSD socket API, I think that max_datagram_size would be a more natural fit. [1] Note that there is a performance incentive to configure QUIC endpoints to send jumbo packets. -- 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/3471
- [quicwg/base-drafts] Change max_packet_size to ma… Kazuho Oku
- Re: [quicwg/base-drafts] Change max_packet_size t… ianswett
- Re: [quicwg/base-drafts] Change max_packet_size t… Nick Banks
- Re: [quicwg/base-drafts] Change max_packet_size t… David Schinazi
- Re: [quicwg/base-drafts] Change max_packet_size t… Junho Choi
- Re: [quicwg/base-drafts] Change max_packet_size t… martinduke
- Re: [quicwg/base-drafts] Change max_packet_size t… ianswett
- Re: [quicwg/base-drafts] Change max_packet_size t… Lucas Pardue
- Re: [quicwg/base-drafts] Change max_packet_size t… Martin Thomson
- Re: [quicwg/base-drafts] Change max_packet_size t… Kazuho Oku
- Re: [quicwg/base-drafts] Change max_packet_size t… martinduke
- Re: [quicwg/base-drafts] Change max_packet_size t… ianswett
- Re: [quicwg/base-drafts] Change max_packet_size t… David Schinazi
- Re: [quicwg/base-drafts] Change max_packet_size t… MikkelFJ
- Re: [quicwg/base-drafts] Change max_packet_size t… Martin Thomson
- Re: [quicwg/base-drafts] Change max_packet_size t… MikkelFJ
- Re: [quicwg/base-drafts] Change max_packet_size t… Jana Iyengar