Practical guide to predicting latency effects?

Thu Apr 9 02:33:38 UTC 2020

On 4/7/20, Adam Thompson <athompson at merlin.mb.ca> wrote:
> I’m looking for a practical guide – i.e. specifically NOT an academic paper,
> thanks anyway – to predicting the effect of increased (or decreased) latency
> on my user’s applications.
>
> Specifically, I want to estimate how much improvement there will be in
> {bandwidth, application XYZ responsiveness, protocol ABC goodput, whatever}
> if I decrease the RTT between the user and the server by 10msec, or by
> 20msec, or by 40msec.
>
> My googling has come up with lots of research articles discussing
> theoretical frameworks for figuring this out, but nothing concrete in terms
> of a calculator or even a rule-of-thumb.

There used to be network simulators that claimed to figure that out for you - eg
https://opnetmodeler.wordpress.com/
  "Predict application performance using real traffic in a simulated mode"

I suspect all that died after encryption became the norm, since you
have to be able to see and understand what's going on before you can
predict what will happen after changing the network.  Take a look at
https://www.cse.wustl.edu/~jain/cse567-08/ftp/simtools/index.html
  the date is 2008 and all the references are http://xxx  (or maybe I
can't search worth beans & missed all the current references)

Or maybe simulation just got too expensive?  I vaguely recall sitting
through a few OPNET sales pitches in the early 2000s & people getting
excited about the product until they found out how much it cost :(

Regards,
Lee

>
> Ultimately, this goes into MY calculator – we have the usual north-american
> duopoly on last-mile consumer internet here; I’m connected directly to only
> one of the two.  There’s a cost $X to improve connectivity so I’m peered
> with both, how do I tell if it will be worthwhile?
>
> Anyone got anything at all that might help me?
>
> Thanks in advance,
> -Adam
>
> Adam Thompson
> Consultant, Infrastructure Services
> [[MERLIN LOGO]]<https://www.merlin.mb.ca/>
> 100 - 135 Innovation Drive
> Winnipeg, MB, R3T 6A8
> (204) 977-6824 or 1-800-430-6404 (MB only)
> athompson at merlin.mb.ca<mailto:athompson at merlin.mb.ca>
> www.merlin.mb.ca<http://www.merlin.mb.ca/>
>
>