Re: [multipathtcp] charter discussion

Olivier Bonaventure <> Fri, 07 April 2017 20:45 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 37104128BBB for <>; Fri, 7 Apr 2017 13:45:17 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -4.321
X-Spam-Status: No, score=-4.321 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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 Ta-0fcbrEWF0 for <>; Fri, 7 Apr 2017 13:45:15 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id B7B92126C26 for <>; Fri, 7 Apr 2017 13:45:14 -0700 (PDT)
Received: from [] (unknown []) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: by (Postfix) with ESMTPSA id 44B9E67D9B2; Fri, 7 Apr 2017 22:45:06 +0200 (CEST)
DKIM-Filter: OpenDKIM Filter v2.9.2 44B9E67D9B2
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple;; s=selucl; t=1491597906; bh=DOsVv/x16cIvklqZbS2ZpiKlRhlRpP43cs6iZWRLFvA=; h=Reply-To:Subject:References:To:Cc:From:Date:In-Reply-To; b=Qj9IocFC4SkI9xtuqLGMk4Q8Eu7kTUhLIwVgneH4giCuBUoVACl7XQU9F/qq2TqNZ 6hPGnzC9hcjQe9t5ZyBho3aHoaILCIKxZY4TLHOKbN3ER4298dtdF3w2vo6ZLwRaE3 t2cr5dvZsrisBs1ysvhyvIUg7qfuNCehY3/WJXho=
X-Virus-Status: Clean
X-Virus-Scanned: clamav-milter 0.99.2 at smtp-3
References: <> <> <>
Cc: "" <>
From: Olivier Bonaventure <>
Message-ID: <>
Date: Fri, 7 Apr 2017 22:45:05 +0200
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Thunderbird/45.8.0
MIME-Version: 1.0
In-Reply-To: <>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Sgsi-Spamcheck: SASL authenticated,
X-SGSI-MailScanner-ID: 44B9E67D9B2.A4C92
X-SGSI-MailScanner: Found to be clean
X-SGSI-Spam-Status: No
Archived-At: <>
Subject: Re: [multipathtcp] charter discussion
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Multi-path extensions for TCP <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Fri, 07 Apr 2017 20:45:17 -0000

>         Regarding the charter discussions that happened at the mptcp
>         session on
>         Thursday March 30, I asked a question but I could not understand the
>         answer, let me ask it again.
>         In chairs slides page 12, TCP SYN shown in Option 1 and Option 2
>         actually were different although the slides seems to show that
>         they are
>         the same.
>     Option 2 is SOCKS. Option 1 places control information in the SYN
>     and SYN+AC while SOCKS places this information in the bytestream.
>         In Option 1, if the proxy sends TCP SYN than is it OK in a
>         conversation
>         the destination does not know who the source is?
>     This is common with proxies. SOCKS and HTTP proxies for example
>     often use their own address to contact
>     remote servers and not the client address. draft-plain-mode proposes
>     a method to allow the proxy to learn the client address and thus use
>     it to reach the final detaintion
>         In Option 2, if TCP SYN sent was the original TCP SYN from the
>         source then
>         how come the TCP-ACK goes through the proxy?
>     Option 2 is SOCKS, thus the proxy uses its own address as a source
>     to contact the final server.
> So both Option 1 and Option 2 sends out TCP SYN with proxy own address
> as the source. I thought the two TCP SYN s were different?

In Option1, this depends whether the source address has been included in 
the SYN as explained in draft-plain-mode

>         A node sending a packet without its address as source address
>         means it
>         is router, right?
>     The node could have a pool of addresses like a CG-NAT
> The way I understand is TCP SYN from each user (possibly many per
> user) is effectively tunneled to the proxy using different mechanisms in
> Option 1 and Option 2, actually Option 2 makes it more implicit.
> It seems like not only TCP SYN but all three-way TCP handshake needs to
> be tunneled.

There are no tunnels.

> CPE has to deal with many parallel MPTCP connections to the same
> endpoint, the proxy. I think that HTTP proxy does not have this type of
> problem.

The HTTP proxy only carries HTTP traffic. The proxy described in 
draft-plain-mode works with anytype of TCP application.