Re: [ledbat] Fwd: New Version Notification for draft-ietf-ledbat-congestion-08.txt

[Arjuna Sathiaseelan <[e-mail]>]

Dear Jana and others,

 I went through the draft and am currently trying to figure out what
the performance implications are with the latest draft through
simulations (I have a few helpful UG students in India who have
volunteered to do this for me - this includes modifying the current
ns-2 code to reflect the latest draft). But unfortunately, I dont
think we will be able to tell anything useful before WGLC ends!

However I have one question ->
 " A CTO is used to detect heavy congestion indicated by loss of all
  outstanding data or acknowledgments, resulting in reduction of the
  cwnd to 1 MSS and an exponential backoff of the CTO interval"

So I am trying to see  whether heavy congestion actually means loss of
"ALL" outstanding segments - so how does LEDBAT behave according to
the current draft if atleast one packet went through? Just trying to
understand.

Regards
Arjuna

On 10 October 2011 00:51, Janardhan Iyengar <[e-mail]> wrote:
> Dear all,
>
> A new version of the congestion control draft is in the repository. There
> are two major mods in this revision:
>
> 1/ WGLC identified one major issue that needed to be addressed in the LEDBAT
> congestion control draft -- LEDBAT response to extreme congestion -- and
> we've tried to address that issue in this revision. We've added a new
> mechanism, the Congestion Timeout (CTO), for a sender to respond to extreme
> congestion. We do not specify how this should be implemented, but we do note
> that a CTO can be implemented with or without a timer. In terms of textual
> changes, we've added an update_CTO() function and a branch for what to do if
> no acks are received within a CTO amount of time in Section 3.4.2. We have
> changed the response to data loss to ensure that a protocol, such as TCP,
> that uses the same timer for both congestion control and for
> retransmissions, changes its cwnd correctly.
>
> 2/ We have set the values for INIT_CWND to 4 and MIN_CWND to 2, and have
> clarified the discussion of CURRENT_DELAYS and INIT_CWND/MIN_CWND in Section
> 3.5.
>
> Please comment!
> - jana
>
> --
> Janardhan Iyengar
> Assistant Professor, Computer Science
> Franklin & Marshall College
> http://www.fandm.edu/jiyengar
>
>
> -------- Original Message --------
> Subject: New Version Notification for draft-ietf-ledbat-congestion-08.txt
> Date: Sun, 09 Oct 2011 16:33:33 -0700
> From: [e-mail]
> To: [e-mail]
> CC: [e-mail], [e-mail],
>  [e-mail], [e-mail]
>
> A new version of I-D, draft-ietf-ledbat-congestion-08.txt has been
> successfully submitted by Janardhan Iyengar and posted to the IETF
> repository.
>
> Filename:        draft-ietf-ledbat-congestion
> Revision:        08
> Title:           Low Extra Delay Background Transport (LEDBAT)
> Creation date:   2011-10-09
> WG ID:           ledbat
> Number of pages: 19
>
> Abstract:
>   LEDBAT is an experimental delay-based congestion control algorithm
>   that attempts to utilize the available bandwidth on an end-to-end
>   path while limiting the consequent increase in queueing delay on the
>   path.  LEDBAT uses changes in one-way delay measurements to limit
>   congestion that the flow itself induces in the network.  LEDBAT is
>   designed for use by background bulk-transfer applications; it is
>   designed to be no more aggressive than TCP congestion control and to
>   yield in the presence of any competing flows when latency builds,
>   thus limiting interference with the network performance of the
>   competing flows.
>
>
>
>
> The IETF Secretariat
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>



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