Difference between "physical reach" and "logical reach" of fibre optic Undergrad physics student here, working with fibre optic cables for my final year project, specifically to do with amplifying signals for fibre-to-the-home internet service. I understand the physical reach of fibre optics - the light attenuates as it passes along the fibre. But what is the "logical reach" of the fibre? I understand it is something to do with sending actual packets of information, but not much else. I have a practically no knowledge of data transmission, and a basic knowledge of photonics. Any help is appreciated.