Cell Relay Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] Re: Bandwidth or Latency?
In article <D6GCwu.A0y@madge1.demon.co.uk>, jobroin@madge1.demon.co.uk (Jason O'Broin) wrote: >Bill Halverson (William@Netpros.net) wrote: > >: Well ... the speed of light is the speed of light - photons in fiber or >: electrons on copper ,,, it's about the same. > >Ahem! I don't think so! > >The speed of light through fibre or copper is significantly less than the >speed of light in a vacuum - the refractive index is different. Optical fibre: refractive index = 1.47, the propagation speed is therefore roughly 200.000 km/s (2/3thd of vacuum) Copper twisted pair: depends on Capacitance and Inductance the propagation speed I normally see is above 150.000 km/s Copper coaxial cable: depends on Capacitance and Inductance the propagation speed I normally see is around 200.000 km/s Radio wave transmission: Free air!! the propagation speed is just below 300.000 km/s (the maximum) So indeed the speed is about the same, you normally do not notice the difference. Especially when your transmission is a mix of copper and radio-links! Hendrik Rood ---------- O O OO OO OOO Ooo [---------][---------] |===| \-/ |#######| |### ###| | # |__| |_ | |--| |--| \ O-----O O-----O O O-----O---\ |
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