Re: [multipathtcp] q about off-path proxy (explicit mode)

<philip.eardley@bt.com> Tue, 28 March 2017 23:09 UTC

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From: <philip.eardley@bt.com>
To: <nishida@sfc.wide.ad.jp>, <mohamed.boucadair@orange.com>
CC: <multipathtcp@ietf.org>
Thread-Topic: [multipathtcp] q about off-path proxy (explicit mode)
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Subject: Re: [multipathtcp] q about off-path proxy (explicit mode)
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Looking at the description
<< MPTCP is now seeing widespread deployment in networks to bond together two accesses, such as fixed and mobile broadband, by using an MPTCP-specific proxy or proxies. There are two scenarios. The first involves two proxies, one in the home gateway or Customer Premises Equipment and one in the network, both under the control of the operator. The other scenario involves an MPTCP-enabled smartphone, with LTE and WiFi, plus a proxy in the operator’s network>>

In the case with two proxies, the distinction is whether the proxy in the network is assumed to be on the default path or not (‘implicit’ vs ‘explicit’). In both cases it’s assumed that the home gateway is on the default path(!)

phil


From: multipathtcp [mailto:multipathtcp-bounces@ietf.org] On Behalf Of Yoshifumi Nishida
Sent: 28 March 2017 18:00
To: mohamed.boucadair@orange.com
Cc: multipathtcp <multipathtcp@ietf.org>
Subject: Re: [multipathtcp] q about off-path proxy (explicit mode)

Hi Med,

On Tue, Mar 28, 2017 at 5:20 AM, <mohamed.boucadair@orange.com<mailto:mohamed.boucadair@orange.com>> wrote:
Hi Yoshi,

Please see inline.

Cheers,
Med

De : Yoshifumi Nishida [mailto:nishida@sfc.wide.ad.jp<mailto:nishida@sfc.wide.ad.jp>]
Envoyé : lundi 27 mars 2017 16:18
À : BOUCADAIR Mohamed IMT/OLN
Cc : Yoshifumi Nishida; multipathtcp
Objet : Re: [multipathtcp] q about off-path proxy (explicit mode)

Hi Med,

On Mon, Mar 27, 2017 at 12:32 PM, <mohamed.boucadair@orange.com<mailto:mohamed.boucadair@orange.com>> wrote:
Re-,

Please see inline.

Cheers,
Med

De : Yoshifumi Nishida [mailto:nishida@sfc.wide.ad.jp<mailto:nishida@sfc.wide.ad.jp>]
Envoyé : lundi 27 mars 2017 13:21
À : BOUCADAIR Mohamed IMT/OLN
Cc : Yoshifumi Nishida; multipathtcp
Objet : Re: [multipathtcp] q about off-path proxy (explicit mode)

Hi Olivier, Med,

Thanks for the response. I have been thinking that it would be better if we can classify our use cases so that we can have clear vision for what to solve. Things I may want to classify is:
   a) solutions requires changes in only MPTCP or in TCP general
   b) solutions requires proxies to be on-path or solutions that work with off-path proxy.

We can think about the solutions for a) if we think it's necessary, but I am thinking that the proper venue for the discussion might not be this WG.

I think the approach Med mentioned requires the proxy to be on-path, so I would like to classify it as an on-path solution.
[Med] I’m not sure to follow you here. What I described is aligned with the target dual proxy case (https://tools.ietf.org/html/draft-nam-mptcp-deployment-considerations-01#section-4.2): the first proxy is embedded on a CPE. There is no technical problem there to intercept the traffic to be proxyied given that the CPE sees all the traffic.

Well, this classification might be a bit different from the way described in the draft.
What I meant for off-path (explicit) case is the cases where the proxy is not on the path between client and server. No more and no less.
[Med] I see. As you can read in the plain mode draft, implicit/explicit thing is drawn from the perspective of the MCP located at the network provider side.

I think I understand the perspective.
I am thinking that if we don't combine explicit mode and off-path, it will be less confusing (at least to me)
In my understanding, explicit mode can be used for off-path (probably for single proxy case) and on-path (probably for 2 proxy case)
Implicit mode probably will be used for on-path case only.

--
Yoshi