Fiber optic cables do not have cores in the same way that traditional copper cables do. The number of optical cores in an optical fiber is the total number of equipment interfaces multiplied by 2, plus 10% to 20% of the spare quantity, and if the communication mode of the equipment has serial communication and equipment multiplexing, you can reduce the number of cores. The core is where the light signals travel through, while the cladding helps to keep the. Single-mode fibre optic cables are comprised of one glass fibre strand with a fairly slim core diameter. Far less internal reflection is involved as light rays pass through it, therefore reducing attenuation and allowing for far higher speed data transfer over longer distances.