Re: [conex] Fwd: New Version Notification for draft-wagner-conex-credit-00.txt

John Leslie <> Fri, 12 July 2013 10:44 UTC

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Date: Fri, 12 Jul 2013 06:44:17 -0400
From: John Leslie <>
To: David Wagner <>
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Subject: Re: [conex] Fwd: New Version Notification for draft-wagner-conex-credit-00.txt
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David Wagner <> wrote:
> we submitted a new draft describing potential definitions of credit
> and credit handling in the audit. 

   This strikes me as a good idea -- there has been confusion about that,
and having a separate draft will probably aid discussion here.

> Abstract:

   Let me comment on the Abstract before I read the whole draft...

>  Congestion Exposure (ConEx) is a mechanism by which senders inform
>  the network about the congestion encountered by previous packets on
>  the same flow.

   This indeed is the way we define ConEx.

>  In order to make ConEx information useful, reliable auditing is
>  necessary to provide a strong incentive to declare ConEx
>  information honestly.

   I personally disagree with this statement. (I'd be happy to go into
why I disagree; but I don't think this is the right email to do so.)

>  However, there is always a delay between congestion events and
>  the respective ConEx signal at the audit. To avoid state and
>  complex Round-Trip Time estimations at the audit, in
>  [draft-ietf-conex-abstract-mech] it is proposed to use credit signals
>  sent in advance to cover potential congestion in the next feedback
>  delay duration.  Unfortunately, introducing credit does not provide
>  incentives to honestly report congestion.  This document lists
>  potential issues regarding the proposed crediting and discusses
>  potential solutions approaches to interpret and handle credits at the
>  audit.

   That text belongs in an Introduction.

   IMHO, the Abstract should limit itself to something like:
" The ConEx Working Group is designing an audit mechanism to test
" whether congestion encountered is being honestly reported by the
" sender. This mechanism involves "credit" markings for possible
" congestion not yet encountered. This document discusses issues
" regarding such credit markings.

John Leslie <>