Subject: [multipathtcp] Charter text that is going out for external review

From: Magnus Westerlund <[email-masked]>
Date: Mon, 28 Sep 2009 11:40:20 +0200

Hi,

I have made some additional changes to the charter that will go out
today on external review. Thanks, Joe, Scott and Alan. There are still
time to word smith. But we should try to have an stable version this week.

Cheers

Magnus Westerlund

IETF Transport Area Director
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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 end-point pairs become unavailable 
during an ongoing session, especially pairs used to establish 
connections between additional end-point pairs. 

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 analyzed 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 application considerations document, presenting the impacts that 
MPTCP may have on applications, such as performance changes, and 
including 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. 

Where appropriate, this group is expected to coordinate with, and will 
use input from, the MIF working group to support 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 2010 - Submit to IESG basic coupled congestion control as an 
           experimental RFC
Mar 2010 - Submit to IESG protocol specification for MPTCP extensions 
           as an experimental RFC
Mar 2011 - Submit to IESG application considerations and API as an 
           informational RFC
Mar 2011 - Recharter or close WG

---

From: <[email-masked]>
Date: Mon, 28 Sep 2009 14:52:30 +0100

It looks good, couple of minor comments & typos (they don't stop it going out for external review)

>>The design 

Shouldn't the "especially" be about the original end-point pairs becoming unavailable?

>> An extended API will be defined to allow applications to 

maybe add "and so gain further benefit."

>>The WG will carefully analyzed
=> analyze

>>to enable congestion dependent multipath transport.
=> congestion-dependent

>>the MIF working group to support use of multiple 
interfaces.
=> the use

>>Goals and Milestones:
should they be listed in date order? (the Aug 2010 milestone is mis-ordered)

Best wishes,
phil

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Magnus Westerlund
Sent: 28 September 2009 10:40
To: [email-masked]
Subject: [multipathtcp] Charter text that is going out for external review

Hi,

Cheers

Magnus Westerlund

---

From: Magnus Westerlund <[email-masked]>
Date: Mon, 28 Sep 2009 16:00:57 +0200

> Shouldn't the "especially" be about the original end-point pairs becoming unavailable?

Yes, but I didn't want to assume that it can be called the original one.
 Especially as if you promote a pair to a special role it can become
unavailable and then re-assigned and then be lost again.

So is the formulation an issue?

I will fix the language errors below in my local copy.

Thanks

Magnus

-- 

Magnus Westerlund

---

From: Magnus Westerlund <[email-masked]>
Date: Mon, 28 Sep 2009 16:05:34 +0200

Hi,

New version. The milestones had become screwed up when I moved
everything to March 2011 instead of dec 2010.

Cheers

Magnus Westerlund

Chair(s):
 
    * To be decided

Transport Area Advisor:

Mailing List:

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

be followed to enable congestion-dependent multipath transport. It will 

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 application considerations and API as an 
           informational RFC
Mar 2011 - Recharter or close WG

---

From: Scott Brim <[email-masked]>
Date: Mon, 28 Sep 2009 10:09:07 -0400

> unavailable and then re-assigned and then be lost again.

There are two scenarios: Either the original pair continues to have
special status throughout the life of the session, or the problem of the
original pair becoming unavailable is just one special case of a pair
being "used to establish connections between additional end-point pairs"
becoming unavailable.  I would like us to head toward the second case
over time, but we have to support the first if only for compatibility.
The wording as it is now covers both of those.  I suggest keeping it.

Scott

---

From: <[email-masked]>
Date: Mon, 28 Sep 2009 15:23:04 +0100

Re-reading, I see that I mis-interpreted what was meant by the phrase

If: Pair-x is working, pair-y is set-up (by a msg over pair-1)
The phrase means "if pair-x disappears...

Maybe try this:

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. 

-----Original Message-----
From: Scott Brim [mailto:[email-masked]] 
Sent: 28 September 2009 15:09
To: Magnus Westerlund
Cc: Eardley,PL,Philip,DER3 R; [email-masked]
Subject: Re: [multipathtcp] Charter text that is going out for external
review

Scott

---

From: Scott Brim <[email-masked]>
Date: Mon, 28 Sep 2009 10:53:54 -0400

> between another end-point pair. 

wfm