Re: [quicwg/base-drafts] Remember UDP size limit for 0-RTT (#3498)

Kazuho Oku <> Wed, 04 March 2020 03:56 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id F0EBF3A0D4D for <>; Tue, 3 Mar 2020 19:56:38 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.696
X-Spam-Status: No, score=-1.696 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, DKIM_VALID_EF=-0.1, HTML_IMAGE_ONLY_28=1.404, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, SPF_HELO_NONE=0.001, 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 EF3ZvNmYAH47 for <>; Tue, 3 Mar 2020 19:56:37 -0800 (PST)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 556083A0D4C for <>; Tue, 3 Mar 2020 19:56:37 -0800 (PST)
Date: Tue, 03 Mar 2020 19:56:36 -0800
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1583294196; bh=bBd/jGwvnQ9uIa86/bHnxQGwJadTG4htEzymvVyfk8M=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=aQ+UpKpgxyY4fMXuOR4sNpj2rSXwJsFzGSuSyhTbPFaltDHLKFLmbokEYdNl92GFn 3FH4F+iJCcfceMdpzLwTcrQ//FFCJ2WlOm5lBUasOEeLUcbNcNdgD3ezRg7x4b6Cvw QhS+pOkMzzxyp0X9Q1qZHPyHmFigZmGuu9Aa+A9Y=
From: Kazuho Oku <>
Reply-To: quicwg/base-drafts <>
To: quicwg/base-drafts <>
Cc: Subscribed <>
Message-ID: <quicwg/base-drafts/pull/3498/review/>
In-Reply-To: <quicwg/base-drafts/pull/>
References: <quicwg/base-drafts/pull/>
Subject: Re: [quicwg/base-drafts] Remember UDP size limit for 0-RTT (#3498)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5e5f26f46b8d0_15b63fc730ccd968928d0"; 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: Wed, 04 Mar 2020 03:56:39 -0000

kazuho commented on this pull request.

 * initial_max_data
 * initial_max_stream_data_bidi_local
 * initial_max_stream_data_bidi_remote
 * initial_max_stream_data_uni
 * initial_max_streams_bidi
 * initial_max_streams_uni
+* max_udp_payload_size

While I agree that it is a good idea to encourage clients to remember the value, I'm not sure if we want to add max_udp_payload_size to this list. That is because doing so mandates the server to remember the max_udp_payload_size value that it advertised in the previous connection, and to not accept 0-RTT if the value has changed.

When a client reconnects from a different path, a path that the server thinks it is better to have smaller MTUs, it might be a good idea to let the server reduce the MTU. If 0-RTT packets succeed to come through (due to it being small or due to the maximum MTU being larger than what the server thinks is safe), there is no reason to drop them, just because max_udp_payload_size is going to be different.

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