Re: [multipathtcp] Towards a Multipath TCP Proxy work item

I agree we should document how proxies (single/dual ended) should behave in conjunction with MPTCP.
It is particularly important they don’t interfere with E2E MPTCP flows, etc.

So in essence I support adding this in the charter and document the scenario’s and the behaviour of the proxies

From: multipathtcp <multipathtcp-bounces@ietf.org> on behalf of "philip.eardley@bt.com" <philip.eardley@bt.com>
Date: Monday, 14 November 2016 at 15:32
To: Alan Ford <alan.ford@gmail.com>
Cc: "multipathtcp@ietf.org" <multipathtcp@ietf.org>
Subject: Re: [multipathtcp] Towards a Multipath TCP Proxy work item

i think we should move beyond "exploring whether it would be useful".

i'd like us to assess proposed solutions. i think we should say this is what we're doing - at the moment we've had quite a lot of discussion about one proposal. we should give the chance for other proposals, and make the discussion more structured (what are the assessment criteria).

i also think we should explicitly exclude non-tcp traffic  (i think non-tcp traffic is too big a topic for our WG)

phil

________________________________
From: Alan Ford <alan.ford@gmail.com>
Sent: 14 November 2016 06:11
To: Eardley,PL,Philip,TUB8 R
Cc: multipathtcp@ietf.org
Subject: Re: [multipathtcp] Towards a Multipath TCP Proxy work item

I think this work item is achievable by simply removing references to “at least one end” from the existing charter item on the proxy. So the item would now read:

Finally, the working group will explore whether an MPTCP-aware
middlebox would be useful. For example, potentially helping MPTCP’s
incremental deployment by allowing only one end host to be MPTCP-enabled
and the middlebox acts as an MPTCP proxy for the other end host, which runs
TCP; and potentially helping some mobility scenarios, where the middle box
acts as an anchor between two MPTCP-enabled hosts. Alternatively, neither
end host could be MPTCP-enabled but a pair of proxies could work together to
bring MPTCP benefits to such connections. The working group will detail what real
problems an MPTCP-enabled middlebox might solve, how it would impact the
Multipath TCP architecture (RFC6182), what proxy approach might be
justified as compared against alternative solutions to the problems, and
the likely feasibility of solving the technical and security issues.

In some ways, the two ended proxy work could even be seen as an extension of the previous operational experience work within this WG.

Regards,
Alan

On 10 Nov 2016, at 19:17, philip.eardley@bt.com<mailto:philip.eardley@bt.com> wrote:

Hi,
Perhaps this is speaking too soon, but it looks like the very active discussion is reaching some common understanding?

We’re trying to work out what a work item might look like, so would like to understand what assumptions we would make, eg about the scenario, & what common agreements we’d assume & restrictions on how the solution works. This seems important to frame work by WG. If possible we’d like discussion on these points to avoid getting into the fine details of one particular existing proposal.

What we’d appreciate is a summary of what the assumptions /understandings are about:
•         The scenario (for instance: the MPTCP-enabled host knows the address of the proxy (eg through configuration); and it knows the address of the ‘legacy’ host it wants to communicate with)
•         If any impact is already envisaged on the current MPTCP protocol’s fallback behaviour and coping with middleboxes
•         If we can agree that the solution is based on a new MPTCP option
•         If any impact is already envisaged on the current MPTCP protocol’s semantics (other than the new option) eg in terms of https://tools.ietf.org/html/rfc6824#section-4
•         If any impact is already envisaged on TCP’s semantics, or any mods are needed, or assumptions about its behaviour, etc
•         If any impact is already envisaged on other existing transport protocol’s semantics (presuming people still would like non-TCP in scope?)
•         Anything else that you think is needed in order to frame the work item

It may be clearer to do this for the two use cases (single-ended proxy, ie where only one host is MPTCP-enabled; and double-ended proxy, ie where neither host is MPTCP-enabled).

This may seem like a long list, but most of the answers can be “none” – we’ll end up with just a short paragraph or a few bullets in the charter.

We’d also have to work out interactions with non-MPTCP WGs, but Mirja and IESG will probably want the main input on this.

Thanks
Phil & Yoshi
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