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

Mirja Kuehlewind <mirja.kuehlewind@ikr.uni-stuttgart.de> Fri, 28 October 2011 13:52 UTC

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From: Mirja Kuehlewind <mirja.kuehlewind@ikr.uni-stuttgart.de>
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Subject: Re: [ledbat] Fwd: New Version Notification for draft-ietf-ledbat-congestion-08.txt
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Thanks, Arjuna.

I added two sentences here:
"LEDBAT takes the minimum delay it measures at any time as the base delay and 
compares the current delay measurement to this value to calculate the queuing 
delay. off_target compares the queuing delay to the dedicated TARGET chosen 
and is normalizes by the TARGET value itself."

Does this work?

Mirja


On Saturday 15 October 2011 10:56:49 Arjuna Sathiaseelan wrote:
> Another thing which I forgot to point out - in section 3.4.1 the term
> off_target suddenly pops up without an explanation. That needs to be
> resolved please.
>
> Regards
> Arjuna
>
> On 15 October 2011 09:37, Arjuna Sathiaseelan <arjuna@erg.abdn.ac.uk> wrote:
> > 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 <jana.iyengar@gmail.com> 
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: internet-drafts@ietf.org
> >> To: jiyengar@fandm.edu
> >> CC: jiyengar@fandm.edu, mirja.kuehlewind@ikr.uni-stuttgart.de,
> >>  greg@bittorrent.com, shalunov@bittorrent.com
> >>
> >> 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
> >> _______________________________________________
> >> ledbat mailing list
> >> ledbat@ietf.org
> >> https://www.ietf.org/mailman/listinfo/ledbat
> >
> > --
> > http://about.me/arjuna.sathiaseelan
>
> _______________________________________________
> ledbat mailing list
> ledbat@ietf.org
> https://www.ietf.org/mailman/listinfo/ledbat



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Dipl.-Ing. Mirja Kühlewind
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