Subject: [multipathtcp] Final? charter text?

From: Magnus Westerlund <[email-masked]>
Date: Mon, 12 Oct 2009 14:40:50 +0200

Hi,

I am now back working after a week in bed. Here is an updated version of
 the charter taking the last comments into account. The changes are the
following:

Taking Phil's proposed text about handling of end-pairs stop working:

"The design
must also consider what happens when an end-point pair becomes
unavailable during an ongoing session, especially a pair that has been
used to establish an additional path [for this connection] between
another end-point pair."

I also split item e. into two items and an additional milestone.

e. An extended API describing how applications can exploit additional
features of multipath transport. While MPTCP needs to be usable without
any application changes, this API should be an optional extension that
provides access to multipath information and enables control over the
usage of multipath.

f. An application considerations document, presenting the impacts that
MPTCP may have on applications, such as performance changes.

Mar 2011 - Submit to IESG an extended API for MPTCP as an or part of
           an experimental or informational RFC
Mar 2011 - Submit to IESG application considerations as an
           informational RFC

I hope IESG are fine with these changes. They have their chance to protest.

I also have to decided on chairs. But I do expect to be able to get the
official chartering out within a few days.

Cheers

Magnus Westerlund

IETF Transport Area Director
----------------------------------------------------------------------
Multimedia Technologies, Ericsson Research EAB/TVM
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Ericsson AB                | Phone  +46 10 7148287
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Multipath TCP Working Group Charter (Draft)
===========================================

Chair(s):
 
    * To be decided

Transport Area Director(s):

    * Magnus Westerlund <[email-masked]>
    * Lars Eggert <[email-masked]>

Transport Area Advisor:

    * Magnus Westerlund <[email-masked]>

Mailing List:
To subscribe: https://www.ietf.org/mailman/listinfo/multipathtcp
Archive:      http://www.ietf.org/mail-archive/web/multipathtcp/

Description of Working Group:

The Multipath TCP (MPTCP) working group develops mechanisms that add the 
capability of simultaneously using multiple paths to a regular TCP 
session. The primary output of the group will be the protocol extensions 
needed to deploy MPTCP, and adaptations to congestion control to safely 
support multipath resource sharing. Initially the WG will only produce 
documents that are experimental or informational. 

Key goals for MPTCP are: to be deployable and usable without significant 
changes to existing Internet infrastructure; to be usable by unmodified 
applications; and to be stable and congestion-safe over the wide range 
of existing Internet paths. That will include handling MTU discovery on 
a per path basis and NAT interactions. The design's success in meeting 
the goals should be determined through experiments. However, it is 
expected that some results from large scale experiments can only be 
achievable after the publication of the initial design. 

The working group will provide a modular architecture that is designed 
to be easily extensible and adaptable. In particular, the congestion 
control mechanism is separated from the mechanisms for identifying and 
using multiple paths. The working group will focus on a solution 
requiring modification of both peers. One or both peers are expected to 
have multiple addresses, which often results in different network paths 
that are at least partially divergent. However, multiple addresses, even 
on different network interfaces, are no guarantee that the paths are 
divergent at all. The design needs to address the issues associated with 
fully or partially joint paths and shared bottlenecks. The design should 
allow for future extensions to handle cases where path diversity is 
attempted through other means than using different addresses. The design 
must also consider what happens when an end-point pair becomes 
unavailable during an ongoing session, especially a pair that has been 
used to establish an additional path [for this connection] between 
another end-point pair. 

Whilst MPTCP will require modifications to the TCP stack at both the 
peers, all existing applications should be able to use the new MPTCP 
stack without modification and gain benefits from multipath usage. The 
impact on different classes of applications will be considered and 
documented. An extended API will be defined to allow applications to 
express particular preferences for how MPTCP operates, and to get 
additional information about MPTCP-specific run-time events. 

The WG will carefully analyze and address in the appropriate protocol 
documents all new security threats introduced by MPTCP.

The following items will be worked on:

a. An architectural framework for congestion-dependent multipath 
transport protocols. This is an overview document which tracks the 
technical documents, describing how the modular components fit together, 
and will describe the motivations and the general approach that should 
be followed to enable congestion-dependent multipath transport. It will 
also analyze how MPTCP interacts with existing infrastructure elements 
and other address agility mechanisms, such as Mobile IP, HIP and SHIM6. 
The results of any experiment performed during the development should 
also be included or referenced in this document. 

b. A security threat analysis for multipath TCP. The ability to change 
the addresses used during a TCP session opens up new types of 
vulnerabilities and attacks. These and their mitigations will be 
documented. 

c. A coupled multipath-aware congestion control algorithm. This 
algorithm is the multipath equivalent of SACK/NewReno congestion 
control. As experience is gathered from implementations of various 
congestion control algorithms, it is expected that the working group 
will be rechartered to pursue additional work in these areas. 

d. Extensions to current TCP to support multi-addressed multipath TCP. 
This covers all on-the-wire changes required to create a two-ended MPTCP 
solution using multiple addresses at one or both ends. It will be 
designed in a modular fashion to allow alternative address management 
schemes to be explored in future. This document will also include a 
basic security model.

e. An extended API describing how applications can exploit additional 
features of multipath transport. While MPTCP needs to be usable without 
any application changes, this API should be an optional extension that 
provides access to multipath information and enables control over the 
usage of multipath.

f. An application considerations document, presenting the impacts that 
MPTCP may have on applications, such as performance changes.  

Where appropriate, this group is expected to coordinate with, and will 
use input from, the MIF working group to support the use of multiple 
interfaces.

Goals and Milestones:

Mar 2010 - Established WG consensus on the Architecture
Aug 2010 - Submit to IESG architectural guidelines and security threat
           analysis as informational RFC(s)
Mar 2011 - Submit to IESG basic coupled congestion control as an 
           experimental RFC
Mar 2011 - Submit to IESG protocol specification for MPTCP extensions 
           as an experimental RFC
Mar 2011 - Submit to IESG an extended API for MPTCP as an or part of 
           an experimental or informational RFC
Mar 2011 - Submit to IESG application considerations as an 
           informational RFC
Mar 2011 - Recharter or close WG