Re: [multipathtcp] towards a potential work item on two-ended proxy

"Henderickx, Wim (Nokia - BE)" <> Tue, 26 July 2016 18:39 UTC

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From: "Henderickx, Wim (Nokia - BE)" <>
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Thread-Topic: [multipathtcp] towards a potential work item on two-ended proxy
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Subject: Re: [multipathtcp] towards a potential work item on two-ended proxy
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Phil, it is hard to answer this in an easy way. Here is a take

  *   one distinction is about how traffic gets route to the proxy: transparent assumes network policies outside the proxy handle this, whilst the plain mode route to an explicit address of the proxy. Depending on the deployment operators prefer one over the other
  *   Both of them need additional info for the proxy to operate
     *   Indication to distinguish E2E MPTCP flows vs proxied MPTCP flows
     *   Indication of addressing
     *   Indication of other protocols
     *   etc

From: multipathtcp <<>> on behalf of "<>" <<>>
Date: Tuesday 26 July 2016 at 17:07
To: "<>" <<>>, "<>" <<>>
Subject: Re: [multipathtcp] towards a potential work item on two-ended proxy

So far this discussion has made me a bit confused. Let me ask a specific question:-
Why do we need both transparent and plain mode? If these are addressing different usage scenarios, please explain them (in a paragraph?)  (this is important as a charter item would start by talking about the issue it was tackling – and then may mention some starting points or assumptions about the solution)
Plain mode involves a signalling protocol (extension to mptcp – I assume this would be in scope of a prospective charter); then subsequently a way of handling the actual traffic (UDP seems out of scope; TCP I’m not sure to what extent this would be in scope). Do I understand this right? Comments?

From: multipathtcp [] On Behalf Of<>
Sent: 21 July 2016 17:13
Subject: [multipathtcp] towards a potential work item on two-ended proxy

We started the discussion yesterday on a potential new work item on “two-ended proxy scenario” – where there’s an MPTCP proxy in both the CPE and an aggregation point (for instance). The current charter is that one end host is MPTCP.

If I can try and summarise the brief discussion yesterday (plus some side discussions) (please correct my inaccuracies):

-          there are now deployments & products with an MPTCP proxy at each end, plus planned Broadband Forum work (WT-348 is about to be made public, with subsequent work to follow). So IETF work is timely (eg help allow an operator to buy CPE from one vendor and aggregation gateway from another vendor).

-          However, some people object to going beyond the current charter’s “one-ended proxy scenario” (since the “two-ended proxy” discourages deployment of MPTCP to all the end hosts, which is the ultimate goal)

-          There are two proposals (transparent & plain mode: draft-boucadair-mptcp-plain-mode-08 & draft-peirens-mptcp-transparent-00). Are these addressing different use cases, or do we need to choose between them? would a (potential) charter item be to standardise existing draft(s), or to solve a problem /scenario?

-          I think there was mention (by Wim??) that there’s a third proposal – how does this fit in, or did I get it wrong?

-          One aspect of the plain mode draft is to allow transport of UDP traffic as well as TCP traffic. I think this is a proposal that should be discussed separately  - for instance it needs INT-area expertise.

I think it would be good to have more discussion before attempting to write some potential charter text (and then seeing if there’s consensus for it).

Philip Eardley
Research and Innovation
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