From nobody Mon Feb 15 12:07:24 2021 Return-Path: X-Original-To: quic@ietfa.amsl.com Delivered-To: quic@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 664853A10A7 for ; Mon, 15 Feb 2021 12:07:22 -0800 (PST) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -0.197 X-Spam-Level: X-Spam-Status: No, score=-0.197 tagged_above=-999 required=5 tests=[DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.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 WsQfN3Z8-raI for ; Mon, 15 Feb 2021 12:07:20 -0800 (PST) Received: from mail-io1-xd2d.google.com (mail-io1-xd2d.google.com [IPv6:2607:f8b0:4864:20::d2d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 9E0143A10A4 for ; Mon, 15 Feb 2021 12:07:20 -0800 (PST) Received: by mail-io1-xd2d.google.com with SMTP id u8so7914377ior.13 for ; Mon, 15 Feb 2021 12:07:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=LkLNsh09w1FN6BJ4ldtug886P2UPp6n1UqrGkgCnOH4=; b=NOWm+YvHQpSLAHLxzriJDsAuAqcIghPMKA5pnwaWW6PsqxzDy/mv0ymSsnZztny6Tz Zdh1OZeIBdu7JgjvUwE4puFnMIhBGBJADJ0wdfz5cI6SHp+5X42avxBnkwHFHwlytB8B zS+9PWoYjJuJ88zdPB55q9UkBKUyO2qwWUlrWmi8uJfTRsGHKKyuKr5B7SAmQ8MGN2QR 1XgrmRNny7r0d4Ii3Cf52XWAxSEh72D9KyorvW2r7x0LJinm6O2ChSRMYXLV8AA1uC2T vE+FQws8gTJSUCSTF1oVdVu3PNtGI5keKb84HkdjtazYFpJCrzUX9qdr6xbD9BhI56Qv 6wcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=LkLNsh09w1FN6BJ4ldtug886P2UPp6n1UqrGkgCnOH4=; b=PhN3hr0EnumKYwyXpUayV3BTIxq0ovRR8VBTOtt7SPuqdc7/Bs40Lch7VMxJ8ZTrvQ qrsProloY17pdOu5wgx3p5Olwqmgb91aCOy5gQnP18mhE+2duCiyZdlXabUksp5uCnYJ s3dwv+RkTLnvs3N/g0cUzxTU63rylye5fOn+yjl71DSaIgsxt8d+N3dTBUodgdmrODoZ vH/y7fR9ujEWspE1+8kqbRoyNzg+aKDTe5vZcXjA7apeBOqydkKBJphXTZ3y4jZPPqFX +uw/LaVQUYsXKDRw5/Q1vZsFRwhWE4PjtMKTqAgZdY6oHkSXOM8kUgU87KVk0cR9kTeT LPLg== X-Gm-Message-State: AOAM532Q9P8kGOuuVvnydH0EN965qUdw93qKdUh42qzsRDjtg3V2EWS4 Dt7zl2OkweQCJFryWS/VA1z1noK5DLeKAcS94HM= X-Google-Smtp-Source: ABdhPJyuof6J3u3hOWeZE7RuwgZRHvzlOPE3ZxG8nQ3GE6bljEzL8RpLKhP2p1fxvtq86gyZs6dx2L3EgqHXkbz+Ooo= X-Received: by 2002:a5d:818f:: with SMTP id u15mr13827734ion.95.1613419639760; Mon, 15 Feb 2021 12:07:19 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Martin Duke Date: Mon, 15 Feb 2021 12:07:08 -0800 Message-ID: Subject: Re: Options for QUIC Multipath To: sarikaya@ieee.org Cc: Christian Huitema , IETF QUIC WG Content-Type: multipart/alternative; boundary="000000000000806aee05bb658834" Archived-At: X-BeenThere: quic@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Main mailing list of the IETF QUIC working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 15 Feb 2021 20:07:22 -0000 --000000000000806aee05bb658834 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Thanks for all of this, Christian. FWIW, I am deeply concerned about the complexity of the second approach, and like that the first approach's changes are almost entirely sender-side. IIUC on the receiver side, the only requirement is enough state to keep more than 1 path validated and active at once. If the objective is to provide a way to get MP-QUIC experiments up and running, this is an important consideration. I am also quite fearful of undermining the assumption that sequence numbers increase monotonically; in particular, I'm afraid of messing up the key update logic. On Mon, Feb 15, 2021 at 7:48 AM Behcet Sarikaya wrote: > > > On Sun, Feb 14, 2021 at 4:23 PM Christian Huitema > wrote: > >> I authored two drafts proposing two different solutions for Multipath >> QUIC: QUIC Multipath Negotiation Option ( >> https://datatracker.ietf.org/doc/draft-huitema-quic-mpath-option/); and, >> in collaboration with colleagues at Ali Baba, Multipath Extension for QU= IC ( >> https://datatracker.ietf.org/doc/draft-liu-multipath-quic/). Apart from >> some details that could easily be aligned, the main difference is that t= he >> =E2=80=9Cnegotiation option=E2=80=9D maintains the property of QUIC Tran= sport >> to have a >> single packet number space for all application packets while the =E2=80= =9Cmultipath >> extension for QUIC=E2=80=9D specifies that there will be a specific pack= et number >> space for each path. I have now implemented both options in Picoquic. Th= is >> blog describes what I learned: >> https://huitema.wordpress.com/2021/02/14/how-many-packet-number-spaces-f= or-quic-multipath/ >> . >> >> To summarize, I believe now that both options work. The simple option >> requires some additional work for managing acknowledgement, but the >> multiple number space option adds a lot more complexity (41 new code >> branches compared to only 6), and will require a lot more testing becaus= e >> it also change the processing of the "single path" scenarios. The multip= le >> number space option also prevents the use of zero-length connection IDs, >> and thus causes additional overhead in some important deployment scenari= os. >> So, yes, both options work, but the simpler option provides simpler code >> and also less overhead. >> > > > Great! > I thought it was a given. > > Thanks for your hard work Christian. > > Behcet > >> In any case, I hope that this exercise will inform our efforts to >> standardize multipath support in QUIC. >> >> -- Christian Huitema >> >> >> --000000000000806aee05bb658834 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Thanks for all of this, Christian.

FWIW, I am deeply concerned about the complexity of the second appro= ach, and like that the first approach's changes are almost entirely sen= der-side. IIUC on the receiver side, the only requirement is enough state t= o keep more than 1 path validated and active at once. If the objective is t= o provide a way to get MP-QUIC experiments up and running, this is an impor= tant consideration.

I am also quite fearful of= undermining the assumption that sequence numbers increase monotonically; i= n particular, I'm afraid of messing up the key update logic.
<= /div>
O= n Mon, Feb 15, 2021 at 7:48 AM Behcet Sarikaya <sarikaya2012@gmail.com> wrote:
<= br>

On Sun, Feb 14, 2021 at 4:23 PM Christian Huitema <huitema@huitema.net> wrote:
=20 =20 =20

I authored two drafts proposing two different solutions for Multipath QUIC: QUIC Multipath Negotiation Option (https://datatracker.ietf.org/doc/draft-huitema-= quic-mpath-option/); and, in collaboration with colleagues at Ali Baba, Multipath Extension for QUIC (https://datatracker.ietf.org/doc/draft-liu-multipath-q= uic/). Apart from some details that could easily be aligned, the main difference is that the =E2=80=9Cnegotiation option=E2=80=9D maintains= the property of QUIC Transport to have a single packet number space for all application packets while the =E2=80=9Cmultipath extension for QUIC= =E2=80=9D specifies that there will be a specific packet number space for each path. I have now implemented both options in Picoquic. This blog describes what I learned: https://huitema.wordpress.com= /2021/02/14/how-many-packet-number-spaces-for-quic-multipath/.

To summarize, I believe now that both options work. The simple option requires some additional work for managing acknowledgement, but the multiple number space option adds a lot more complexity (41 new code branches compared to only 6), and will require a lot more testing because it also change the processing of the "singl= e path" scenarios. The multiple number space option also prevents the use of zero-length connection IDs, and thus causes additional overhead in some important deployment scenarios. So, yes, both options work, but the simpler option provides simpler code and also less overhead.



Great!=C2=A0
I thought it was a given.

Thanks for your hard work Christian.

Behcet= =C2=A0

In any case, I hope that this exercise will inform our efforts to standardize multipath support in QUIC.

-- Christian Huitema


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