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Re: Long haul latency calculation?
"Christopher Wolff" <firstname.lastname@example.org> writes: > Dear Nanog: > I was wondering if there is a benchmark for long-haul circuit > latency... For example if I had a T1 circuit with 2900 miles > between the two end-points (and assuming the provider is best case > scenario) can I do something like (miles*latencyfactor) = 5 ms for > 2900 miles? it's gonna be a lot more than 5ms for 2900 miles. muxes and bit regens introduce a tiny amount of delay. there's delay for clocking the packet onto and off of the circuit (which becomes less significant as the speed of the circuit goes up, but is still a couple of milliseconds each way on a t1). remember that airline miles and road miles have nothing to do with circuit miles, and it is not uncommon to see a circuit go from dc to san francisco via new york, chicago, dallas, and los angeles. anyway, on a 2900 mile circuit the big delay factor is the speed of light. in glass, this is 200 million kilometers per second, plus or minus. that means you will never ever ever see less than 23 milliseconds each way. 46 for a ping. i would say that for a t1 circuit between two places 2900 miles apart anything under 70 ms is just dandy. ---rob