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

Thanks Mirja - that helps :)..

Regards
Arjuna

On 28 October 2011 14:37, Mirja Kuehlewind
<mirja.kuehlewind@ikr.uni-stuttgart.de> wrote:
> Hi Arjuna,
>
> heavy congestion does mean that for CTO time no data have been received. If
> data was received LEDBAT will compare the respective delay measurement with
> the base delay and increase or decrease the cwnd (except it is already
> MIN_CWND). Then if less packets are in flight than the cwnd allows it will
> send out a packet. Normally, if in CTO time no packet was received, it is
> assumed that all packets are loss and fightsize might be reset to 0. But an
> algorithm how to detect packet loss is independent from LEDBAT and thus not
> described in this draft.
>
> I hope that helps...?
>
> Thanks for your feedback!
> Mirja
>
>
> On Saturday 15 October 2011 10:37:06 Arjuna Sathiaseelan 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
>
>
>
> --
> -------------------------------------------------------------------
> Dipl.-Ing. Mirja Kühlewind
> Institute of Communication Networks and Computer Engineering (IKR)
> University of Stuttgart, Germany
> Pfaffenwaldring 47, D-70569 Stuttgart
>
> tel: +49(0)711/685-67973
> email: mirja.kuehlewind@ikr.uni-stuttgart.de
> web: www.ikr.uni-stuttgart.de
> -------------------------------------------------------------------
>