[Iccrg] ICCRG review of draft-sridharan-tcpm-ctcp-02

[[e-mail] (Saverio Mascolo)]

did someone measure goodput and retransmissions? TCPs using a more
aggressive probing than VJ TCP usually seem to end up - in  good
cases- with similar goodput but at the expense of larger packet
retransmissions, which is not good!
-saverio

On Wed, Dec 17, 2008 at 10:45 PM, Eddy, Wesley M. (GRC-RCN0)[VZ]
<[e-mail]> wrote:
> Some time ago the IRTF Internet Congestion Control Research Group
> (ICCRG)
> was asked for its position on the safety of the Compound TCP behaviors
> described in draft-sridharan-tcpm-ctcp for Experimental deployment on
> the Internet.  This is part of the process described here:
> http://www.ietf.org/IESG/content/ions/drafts/ion-tsv-alt-cc.txt
>
> Below is the ICCRG review of the Compound TCP draft for input to TCPM.
> The ICCRG process itself resulted in a couple of iterations of the draft
> to clarify portions.  By my understanding, TCPM should now be using the
> review, the updated draft, and TCPM's own discussion and feedback loop
> to
> decide the fate of the CTCP document with the understanding that TCPM
> has a general charter item allowing TCPM WG Experimental specification
> of
> ICCRG-reviewed congestion control proposals (according to the ION
> above).
>
> ---------------------------
> Wes Eddy
> Network & Systems Architect
> Verizon FNS / NASA GRC
> Office: [phone]
> ---------------------------
>
>
> ICCRG Compound TCP Safety Review
> --------------------------------
>
> In July 2007, the ICCRG began reviewing the Compound TCP congestion
> control
> technique described in draft-sridharan-tcpm-ctcp-00 in terms of its
> safety for
> widespread experimental deployment on the public Internet.  This review
> was
> conducted as an input to the IETF TCPM working group, where the draft
> was being
> considered for possible Experimental publication.  The scope of this
> review
> does not include making or endorsing any claims about expected
> performance
> gains from using Compound TCP.
>
> Based on initial RG comments, an update (01) to the original (00)
> internet-draft
> was published.  Based on further RG comments, another update (02) was
> published
> and contains several further clarifications.
>
> After reviewing the draft and a number of other documents with results
> from
> testing and simulation, three public evaluations were submitted to the
> ICCRG by
> RG participants.  Several follow-on messages and comments were submitted
> by
> these and other RG participants.  Multiple independent implementations
> have
> been done of Compound TCP at this point in time.  Compound TCP has been
> experimented with in both simulators, testbeds, and campus/enterprise
> networks.
> On the matter of safety for experimental use, the implementers and
> experimenters
> seem to agree that the algorithm is safe, though in individual
> implementations,
> bugs have been found, unrelated to the algorithm itself. It is possible
> that
> clarifications to the specification will help to avoid this.  The RG
> seems to
> have consensus that the Compound TCP mechanism is safe for experimental
> deployment
> on the public Internet.
>
> References to RG participants' reviews and papers, presentations, and
> mailing
> list messages that contributed to the consensus-forming are provided at
> the
> end of this document.
>
> Its novelty from the current Standards Track congestion control
> techniques is
> that Compound TCP also contains a delay-based component.  Compound TCP's
> design only utilizes the delay-based component when loss is low and the
> congestion window has already grown large, and in other conditions
> reversts
> to the current Standards Track mechanisms.  This was noted by some
> reviewers
> as one inspiration of confidence.  The simulation results and analysis
> made
> available were also helpful, but were not found to be overwhelmingly
> convincing
> on their own. The implementation experiences, testbed work, and campus
> deployments weighed most heavily in the RG's mind as evidence of
> Compound TCP's
> safety.
>
> There was an open discussion item on the use of estimation algorithms
> for the
> queueing delay.  There was also a question lingering about how the
> algorithm
> behaves in wireless environments where latency variations may not be
> completely
> due to congestion, and a security-related question as to the possibility
> to
> disrupt the delay-based component by altering the material used to take
> delay
> samples.  These questions seem to apply to any congestion control
> algorithm
> that utilizes delay as a source of congestion information.
>
>
> Public reviews from:
> Wesley Eddy (Nov 1, 2007)
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2007-November/000358.html
> Mark Allman (Nov 29, 2007)
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2007-November/000378.html
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2007-November/000379.html
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2007-November/000380.html
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2007-November/000381.html
> Doug Leith (Jan 16, 2008)
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2008-January/000402.html
>
> Additionally, several thread comments from:
> Lachlan Andrew
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2008-February/000416.html
> Michael Welzl
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2008-February/000411.html
> Dino-Martin Lopez-Pacheco
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2008-February/000415.html
>
>
> Slides showing design and behavior:
>
> http://research.microsoft.com/users/dthaler/IETF%20-%20Compound%20TCP.pd
> f
> INFOCOM 2006 paper:
>  http://research.microsoft.com/users/dthaler/ctcp-infocom06.pdf
> Evaluation by Doug Leith, Lachlan Andrew, Tom Quetchenbach, Bob Shorten,
>  and Kfir Lavi, based on independent implementation:
>
> http://www.hep.man.ac.uk/PFLDnet2008/paper/Leith_DJ_Experimental%20Final
> .pdf
>  http://www.welzl.at/iccrg-mar08-slides/iccrg_compound_mar08.ppt.pdf
> Evaluation by SLAC (Yee-Ting Li):
>  http://www.slac.stanford.edu/pubs/slactns/tn04/slac-tn-06-005.pdf
> Behavior on under-buffered links:
>  http://www.hep.man.ac.uk/PFLDnet2008/paper/Kun_T%20Final.pdf
>  http://oakham.cs.ucl.ac.uk/pipermail/iccrg/2008-March/000441.html
>
>
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>



-- 
Prof. Saverio Mascolo
Dipartimento di Elettrotecnica ed Elettronica
Politecnico di Bari
Via Orabona 4
70125 Bari
Italy
Tel. [phone]
Fax. [phone]
email:[e-mail]

http://www-dee.poliba.it/dee-web/Personale/mascolo.html


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