[e2e] TFRC vs UDP

[Phelan, Tom]

Hi Syed,

DCCP includes TFRC as one of its congestion control algorithms, and there has been quite a bit of discussion in the group of the impact of TFRC on streaming media applications.  The DCCP User Guide contains an extensive discussion of the issue.  Unfortunately, it's timed out of the drafts archive as we work out the future course of the guide, but it's available at http://www.phelan-4.com/dccp/draft-ietf-dccp-user-guide-02.txt.

Tom Phelan

> -----Original Message-----
> From: end2end-interest-bounces at postel.org
> [mailto:end2end-interest-bounces at postel.org]On Behalf Of Syed Faisal
> Hasan
> Sent: Thursday, March 31, 2005 8:37 AM
> To: gdc at iki.fi
> Cc: end2end-interest at postel.org
> Subject: Re: [e2e] TFRC vs UDP
> 
> 
> Hi Dado,
> 
> 
> >Syed Faisal Hasan wrote:
> >>
> >>To whom it may concern,
> >>
> >>TFRC was designed for use by the Continuous Media (CM) 
> applications. But 
> >>why will a CM application which is performing well using 
> UDP, use TFRC if 
> >>there is performance gap (more latency, less number of 
> packets transmitted 
> >>in the same time, high rate fluctuations in the beginning) 
> betwen UDP and 
> >>TFRC ? May be thats the reason we haven't seen any 
> applicatons using TFRC. 
> >>On the other hand there is no (I haven't found) research 
> which analyzes 
> >>the performance difference between UDP and TFRC. It is 
> clear that TFRC 
> >>will not perform exactly like UDP ( due to TFRC's 
> friendliness with TCP), 
> >>but how much can we expect from TFRC?
> >
> >
> >Hi Syed,
> >
> >the motivation is that although your application would work 
> fine and you (a 
> >single person in a society) would have a good welfare using 
> UDP, it is your 
> >fellow citizens that would potentially suffer from your actions. The 
> >network resource should be distributed fairly - whatever it 
> means. If we 
> >all started to disregard other users, the network might stop working 
> >properly - equivalent to anarchy in a society. Mechanisms 
> are needed to 
> >guarantee fair distribution of the resource. TFRC attempts 
> to provide 
> >mechanisms to distribute the bandwidth resource in the same 
> way TCP does.
> >
> >I think performance issues depend more on competing TCP 
> flows and the 
> >network than on the TFRC control algorithm.
> 
> I understand what you are talking about. But I want to know 
> the performance 
> difference of
> UDP and TFRC in the same scenario. Is there any published 
> research on this?
> 
> Faisal
> 
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