[multipathtcp] draft-boucadair-mptcp-plain-mode-07

[Behcet Sarikaya <[e-mail]>]

 Hi all,

Recent mails in this thread came to my attention because I work on the
hybrid access network issues and wish to convey my views on some of
the issues discussed.

First of all, the claims that there is strong operator interest on
this is over blown. Hybrid access is based on offloading some CPE
traffic to 3G/LTE network, I don't think mobile operators are fond of
such a thing.

Also I strongly concur with Yoshi's point of CPE to convert UDP or TCP
into MPTCP and requires
Concentrators to convert back MPTCP into UDP or TCP is a complex
process. The crux of this is the problems arising from the use of
MPTCP for tunneling, which is what this draft is advocating.

Here I recommend Joe Touch's Intarea draft
https://tools.ietf.org/id/draft-ietf-intarea-tunnels-02.txt
on IP Tunnels in the Internet Architecture. IETF developed many
tunneling protocols which are surveyed in this draft but none of them
are TCP/MPTCP based.
I also question suitability of this work to the charter. There is this
charter text:
Finally, the working group will explore whether an MPTCP-aware
  middlebox would be useful, where at least one end host is MPTCP-enabled.
  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 middlebox acts as an anchor
  between two MPTCP-enabled hosts. 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.

This draft has a middlebox called Concentrator but it is not trying to
enable MPTCP hosts to communicate with TCP hosts, it is just tunneling
the traffic. So there is no charter item that fits to this draft.
I strongly suggest staying away from making MPTCP a tunneling protocol.

Regards,

Behcet