[secdir] [New-work] WG Review: Congestion Exposure (conex)

IESG Secretary <iesg-secretary@ietf.org> Tue, 13 April 2010 18:00 UTC

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Subject: [secdir] [New-work] WG Review: Congestion Exposure (conex)
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A new IETF working group has been proposed in the Transport Area.  The
IESG has not made any determination as yet. The following draft charter
was submitted, and is provided for informational purposes only. Please
send your comments to the IESG mailing list (iesg@ietf.org) by Tuesday,
April 20, 2010.                                       

Congestion Exposure (conex) 
Current Status: Proposed Working Group
Last Updated: 2010-04-08


Transport Area Director(s):
  Lars Eggert <lars.eggert@nokia.com>;
  David Harrington <ietfdbh@comcast.net>;

Transport Area Advisor:
  Lars Eggert <lars.eggert@nokia.com>; 

Mailing Lists:

Description of Working Group:

The purpose of the CONEX working group is to develop a mechanism
by which senders inform the network about the congestion encountered
by previous packets on the same flow. Today, the network may signal
congestion by ECN markings or by dropping packets, and the receiver
passes this information back to the sender in transport-layer
acknowledgements, The mechanism to be developed by the CONEX WG
will enable the sender to also relay the congestion information
back into the IP layer, such that the total level of congestion is
visible to all IP devices along the path.

The primary goal of the CONEX WG is to develop experimental
specifications to achieve the above in IPv6 networks. The WG will
also develop an abstract, higher-level description of the congestion
exposure mechanism.

Primary work items are:

* An Informational document containing an abstract description of
the congestion exposure mechanism that is independent of specific
transport protocols and congestion information encoding techniques
needed for different IP protocol versions.

* An Experimental specification of an IPv6 packet structure that
encapsulates CONEX information, defining a packet format and an

* An Experimental specification of a modification to TCP, for the
timely transport of congestion information from the destination to
the sender.

It is believed that the CONEX mechanism will be useful as a generative
technology that can be applied as a key element of congestion
management solutions in a wide variety of use cases. However, the
CONEX WG will initially focus on one use case, where the end
hosts and the network that contains the destination end host are
CONEX-enabled but other networks need not be. CONEX information can
assist the network operator's traffic management and, for example,
incentivize LEDBAT-like applications. Experiments on such use cases
are encouraged and the WG will solicit feedback from such deployments.
The WG may decide to document the experience from such use cases
in Informational documents, covering:

* Assumptions made

* Deployment considerations

* Advice on how to use the CONEX mechanism as an element of a
congestion management solution

* Security threats and advice on mitigation approaches (detailed
specifications of threat mitigation techniques are out of scope)

* Descriptions of results from experiments with the use case

The CONEX WG is only chartered to work a congestion exposure mechanism
for IPv6 networks. When the output of the WG has seen adoption and
has proven to be useful, the WG may propose to the IESG that it
should be rechartered to extend this effort.


Mar 2011 Submit abstract specification for the congestion
exposure mechanism to IESG as Informational

Mar 2011 Submit use case description to IESG as Informational

Sep 2011 Submit specification of IPv6 packet structure to IESG as

Sep 2011 Submit specification for modification to TCP to IESG as
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