5 ms·
It's actually about 60% the speed of light because there's no vacuum in buried fiber. But yes the rest of your point is accurate.
by scurvy 8y ago
It's actually about 60% the speed of light because there's no vacuum in buried fiber.
But yes the rest of your point is accurate.
- umvi 8y agoAlso, presumably light has to travel farther in fiber because it's constantly bouncing off of walls vs. straight line travel?
- e12e 8y agoI was going to dismiss it as insignificant, but if I read this right: https://en.m.wikipedia.org/wiki/Total_internal_reflection https://en.m.wikipedia.org/wiki/Total_internal_reflection an angle higer than ~42 degrees seems to indicate roughly a 50% longer path? That said, I wonder what the average "fractal dimension" of a city to city fiber link is - I suspect wavering path around buildings and along roads dominate the increase in path VS theoretical straight (curved along the earth) path?
- scurvy 8y agoDon't forget fiber splices for accidental cuts. Engineers have to try their best to match the existing refraction when splicing in the new patch. Tools help, but there's a lot of skill and craftsmanship there.
- e12e 8y agoBut a splice should either work, or not work? It is literally welding two glass strands into one?
- Hikikomori 8y agoA splice may or may not work, or something in between. The splice might cause enough attenuation that you go over your optical budget (signal strength and receiver sensitivity) so no link comes up. But it might come up just barely and then you may have some bad frames as a result.
- deleted 8y ago[deleted]
- Hikikomori 8y agoThis is true for multimode, anywhere outside short distances in datacenters you use singlemode where light does not bounce at an angle. A singlemode fiber acts as a waveguide, the signal travels in a single mode, this is mainly why it's good for longer distances, no modal dispersion.
- scurvy 8y agoThat is not true. Single mode fiber definitely comes in at an angle and bounces off the cladding. You still have a cone of acceptance at play. You're confusing multiple terms and concepts here.
- jimmaswell 8y agoThe point seemed more along the lines of "the ping is a function of the speed of light" to me, so not necessarily inaccurate. Although that does leave room for improvement like introducing a vacuum or making the lines more direct.