Re: [multipathtcp] Options or Payload?

"Ford, Alan" <alan.ford@roke.co.uk> Tue, 10 November 2009 01:52 UTC

Return-Path: <alan.ford@roke.co.uk>
X-Original-To: multipathtcp@core3.amsl.com
Delivered-To: multipathtcp@core3.amsl.com
Received: from localhost (localhost [127.0.0.1]) by core3.amsl.com (Postfix) with ESMTP id 5AF293A684C for <multipathtcp@core3.amsl.com>; Mon, 9 Nov 2009 17:52:20 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -3.489
X-Spam-Level:
X-Spam-Status: No, score=-3.489 tagged_above=-999 required=5 tests=[AWL=0.110, BAYES_00=-2.599, RCVD_IN_DNSWL_LOW=-1]
Received: from mail.ietf.org ([64.170.98.32]) by localhost (core3.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7QPuDg-OocYr for <multipathtcp@core3.amsl.com>; Mon, 9 Nov 2009 17:52:19 -0800 (PST)
Received: from rsys001x.roke.co.uk (rsys001x.roke.co.uk [193.118.201.108]) by core3.amsl.com (Postfix) with ESMTP id 2E0BE3A67D3 for <multipathtcp@ietf.org>; Mon, 9 Nov 2009 17:52:19 -0800 (PST)
Received: from rsys005a.comm.ad.roke.co.uk ([193.118.193.85]) by rsys001x.roke.co.uk (8.13.1/8.13.1) with ESMTP id nAA1qcWE003357; Tue, 10 Nov 2009 01:52:39 GMT
X-MimeOLE: Produced By Microsoft Exchange V6.5
Content-class: urn:content-classes:message
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
Date: Tue, 10 Nov 2009 01:52:44 -0000
Message-ID: <2181C5F19DD0254692452BFF3EAF1D6808D7BB56@rsys005a.comm.ad.roke.co.uk>
In-Reply-To: <20091110.103522.15256464.nishida@sfc.wide.ad.jp>
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
Thread-Topic: [multipathtcp] Options or Payload?
Thread-Index: AcphpipTNgChHF0vTPCqCfg7zAMUzAAAVLQQ
References: <2181C5F19DD0254692452BFF3EAF1D6808D7BB51@rsys005a.comm.ad.roke.co.uk> <20091110.103522.15256464.nishida@sfc.wide.ad.jp>
From: "Ford, Alan" <alan.ford@roke.co.uk>
To: "Yoshifumi Nishida" <nishida@sfc.wide.ad.jp>
X-roke-co-uk-MailScanner: Found to be clean
X-roke-co-uk-MailScanner-SpamCheck:
X-roke-co-uk-MailScanner-From: alan.ford@roke.co.uk
Cc: multipathtcp@ietf.org
Subject: Re: [multipathtcp] Options or Payload?
X-BeenThere: multipathtcp@ietf.org
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: Multi-path extensions for TCP <multipathtcp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/listinfo/multipathtcp>, <mailto:multipathtcp-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/multipathtcp>
List-Post: <mailto:multipathtcp@ietf.org>
List-Help: <mailto:multipathtcp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/multipathtcp>, <mailto:multipathtcp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 10 Nov 2009 01:52:20 -0000

We had considered that, however the main reason against this was whether
certain middleboxes would split and coalesce TCP payloads thus breaking
the placement of the extended options - the TCP payload is essentially
no longer a continuous stream.

Wes Eddy proposed a "Long Options Option"
(http://tools.ietf.org/id/draft-eddy-tcp-loo-04.txt) which seemed to be
a possible way of doing a very similar thing, by negotiating to ensure
that long options would work along a path. Although, this draft is now
expired, and I'm not sure why it was dropped. Anyone know?

Regards,
Alan

> -----Original Message-----
> From: Yoshifumi Nishida [mailto:nishida@sfc.wide.ad.jp]
> Sent: 10 November 2009 01:35
> To: Ford, Alan
> Cc: multipathtcp@ietf.org
> Subject: Re: [multipathtcp] Options or Payload?
> 
> 
> Hello,
> How about having a simple option which indicates the offset for real
tcp
> payload?
> For example, if mptcp packets conveys 10 bytes control info in the
payload,
> set
> offset to 10 in the option.
> 
> Thanks,
> --
> Yoshifumi Nishida
> nishida@sfc.wide.ad.jp
> 
> From: "Ford, Alan" <alan.ford@roke.co.uk>
> Subject: [multipathtcp] Options or Payload?
> Date: Tue, 10 Nov 2009 00:58:48 -0000
> Message-ID:
> <2181C5F19DD0254692452BFF3EAF1D6808D7BB51@rsys005a.comm.ad.roke.co.uk>
> 
>  > Hi all,
>  >
>  > One of the big issues to be raised during yesterday's MPTCP session
was
>  > the question of whether TCP Options are really the right place to
be
>  > doing this. This is not the first time this has come up but
deserves
>  > further exploration.
>  >
>  > Specifically, instead of doing this with TCP Options, the same
>  > instructions could be included in the payload. Similar to TLS, the
data
>  > could be chunked and each chunk has a data sequence and length
header.
>  > These can be interspersed with control blocks to signal addresses,
>  > security of joining subflows to connections, and connection close.
A
>  > simple 2-octet TCP option would still be used in the initial SYN to
>  > signal MPTCP capability.
>  >
>  > This has the benefit that it would allow the signalling to have
>  > reliability, and we wouldn't be hit with option space limits, and
thus
>  > be potentially able to do better security algorithms. It would also
give
>  > us greater freedom in signals for future extensibility (for
example, if
>  > we wanted to signal ports for additional subflows, not just
addresses).
>  >
>  > On the downside, there may be cases where this could confuse
>  > middleboxes, e.g. expecting HTTP on port 80 and finding this kind
of
>  > data instead. However, since a TCP option would be used at the
start to
>  > identify capability, if this were dropped by a middlebox/proxy then
>  > MPTCP would not be used.
>  >
>  > What do people think is the best approach?
>  >
>  > Regards,
>  > Alan
>  >
>  > _______________________________________________
>  > multipathtcp mailing list
>  > multipathtcp@ietf.org
>  > https://www.ietf.org/mailman/listinfo/multipathtcp