[comm] Throughput on a lossy link

[David Halstead]

James,

Gene and I were mulling this over and remembered reading about the 
bandwidth wall you hit with higher latency links with even minor packet 
loss.

Baseline: To achieve a gigabit/sec throughput on a 1500MTU link with 
40ms RTT you need a packet loss of less than 0.00001%!!

A loss of 0.1% gives a max throughput of ~9Mbps for a single TCP stream, 
even for a 10Gig link of the same latency.

For more info see: http://sd.wareonearth.com/~phil/issues.html and

Not that this changes the plan to fix the local link to NMT, but that 
problem MAY also explain the 99.9% bandwidth loss to CV due to the 
1/(rtt*sqrt(loss)) term.

David


James Robnett wrote:
>     Just did the network tests with NMT.  Off hand it looks like
> there's a bad fiber somewhere between us since the tests ruled out
> the transceiver.
>
>     We're getting no where near the throughput we should be getting over
> that 1gbit link to NMT and UNM.
>
>     This *doesn't* explain the poor performance to CV,  in the AOC to
> NMT/UNM case we're missing many tens of percent bandwidth.  In the
> AOC to CV case we're missing 99.9% of the bandwidth.
>
> James
>
> Gene Runion wrote:
>   
>> https://staff.nrao.edu/wiki/bin/view/Ccs/MonthlyCommunicationMeetings
>>
>> There will be a communication meeting this Wednesday at 17:30UT/13:30ET/11:30MT.
>>
>> Locations: CV-conf (CV-209), GB-conf2 (GB-241), SO-conf (AOC-317)
>>
>> Gene Runion
>> 434-296-0327
>>
>>
>>
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