[R-C] Simplifying the TCP throughput algorithm

[Harald Alvestrand]

On 03/29/2012 01:07 PM, Ali C. Begen (abegen) wrote:
> I suppose these were random losses?
This is just putting numbers into the TCP throughput algorithm from the 
TCP-Friendly RFC using its parameter p, and trying to see what the 
implications of the result are.

I presume that p was assumed to be random in the derivation of the formula.
>> -----Original Message-----
>> From: rtp-congestion-bounces at alvestrand.no [mailto:rtp-congestion-bounces at alvestrand.no] On Behalf Of Harald
>> Alvestrand
>> Sent: Thursday, March 29, 2012 1:04 PM
>> To: rtp-congestion at alvestrand.no
>> Subject: [R-C] Simplifying the TCP throughput algorithm
>>
>> I did some extremely rough numerical experiments with the TCP throughput
>> algorithm.
>>
>> Results for TCP throughput in bits/sec at MSS=1440 bytes at various loss
>> rates:
>>
>> 0.001% loss: Throughput 4.5 Mbits/sec (HD can survive)
>> 0.01% loss: Throughput 1.4 Mbits/sec
>> 0.1% loss: Throughput 458 Kbits/sec (VGA can survive)
>> 1% loss: Throughput 144 Kbits/sec (good audio can survive)
>> 10% loss: Throughput 43 Kbits/sec (crappy audio can survive)
>>
>> These are stable in the first 2 digits over a large range of RTT (1 ms
>> to 100 ms).
>>
>> Interesting numerical result: In all cases, the second term of the TCP
>> throughput denominator is less than 1% of the first term, so a
>> reasonable approximation is:
>>
>> T = s / sqrt(p * 2/3)
>>
>> That's a simple formula.
>>
>>                    Harald
>>
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