4 ms·
This page is such a well executed interactive map. Really enjoyed it Is the math-planation of your random fact basically (thanks to https://news.ycombinator.c
by keepamovin 2y ago
This page is such a well executed interactive map. Really enjoyed it
Is the math-planation of your random fact basically
(thanks to https://news.ycombinator.com/user?id=Hikikomori https://news.ycombinator.com/user?id=Hikikomori for correcting the lightspeed in fibre medium from 3e5 to 2e5 !)
- lightspeed is 2e5 km/s ~ 2e2 km/ms, so/
- length (km) / 200 (km)/ms ~ K length (km) / 200 (km)/ms, so
- latency (ms) ~ K' length (km)
Where K is approximately 1.3 (K' is 1/155) and factors in things like:
- non straight line distance
- networking overhead / switching
- both ways / measurement error
Basically?
- Hikikomori 2y agoSpeed of light in a medium like fiber is about 200 000km/s.
- keepamovin 2y agoOh shit! Thanks. Good point. That actually makes it more plausible, as K is smaller.
- segfaultbuserr 2y ago1/2 c in circuit boards (FR-4), 1/3 c in cables, two useful numbers to remember.
- keepamovin 2y agoThanks, nice! But wait - so we have 1/2 c ~ 150 km/ms in circuit board. 1/3 c ~ 100 km/ms in cable. And... 2/3 c ~ 200 km/ms in fiber? I'm a bit confused about difference between cable and fiber heh :)
- segfaultbuserr 2y agoSorry, it was a typo. I meant 2/3 (including common cables and fiber optics), not 1/3.
- Hikikomori 2y agoDepends on what kind of cable? As twisted pair network cable is at 2/3.
- segfaultbuserr 2y agoWhat an embarrassing typo! I was thinking of 0.66, and somehow I thought 0.66 = 1/3 (must've been distracted by the "2" in 1/2). I should've written 0.66 or 2/3.
- adamcharnock 2y agoIt is possible I was measuring latency in a single direction, rather than round-trip-time. My memory is a little hazy now.
- keepamovin 2y agoNo I think you had it right. I was off on the speed. Anyway, it could have matched accounting K for other factors heh :)