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 number of. Fiber cores are the heart of fiber optic cables, transmitting light signals that carry data. Made from either high-quality glass or plastic, the core plays a critical role in determining the cable's performance. Essentially, the bandwidth potential and the ability to cope with higher data throughput over shorter distances is determined by the number of.