Fiber Optic cabling is made with glass fibers. Provide very little variation in the signal they carry over long distances. The full potential speed fiber optic cabling can carry has not been reached even with Gigabit technology. These cables have greater bandwidth than electrical transmission through wires. Fiber Optic cabling is constructed of three concentric layers: The "core" is the central region of an optical fiber through which light is transmitted. Mode is a single electromagnetic field pattern that travels in fiber.